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Fix ghosting problem (damping versus bolting printer to a desk)
I have a Monoprice Maker Select v2. It is the kind where the moving plate (heat bed) provides the Y-axis and the moving extruder provides the X-axis. It has a fairly rigid sheet metal frame. In addition, I added steel rods has Z-braces.
I see some pretty obvious ghosting. This happens for an inch or so right after every sharp turn. Clearly, vibration is to be blamed. I found two simple techniques that improves the situation:

soft floor mats under the feet (allowing the machine to move freely)
bolt the machine to the desk (preventing the machine from moving)

Surprisingly, these two opposites provided exact same level of improvement for ghosting. My question is: which approach is better? Moreover, to further improvement, should I use...

(extreme version of 1) hanging the printer from the ceiling using bungee cords (maximize the freedom to move); or...
(extreme version of 2) bolt the printer to garage floor (0 freedom to move) ?

Tried to print slower? Other jerk settings?

try tightening the belt first, made a big diff for my CR10...

please see my edit

You should add some pictures of the ghosting you are describing. Furthermore, I think there is an excellent answer already available, please look into https://3dprinting.stackexchange.com/questions/5389/what-causes-ghosting.

Ghosting is caused by differential movement between the bed and the head when the head undergoes acceleration. The forces add energy to a resonance in that differential vibration mode.
By changing how you mount the base, you will change the mode and probably change the frequency.
With the soft mounting, the bed can move more easily.  It will tend to follow the head acceleration better.  The whole system will still ring (you can't get rid of the momentum change), but you can cause the energy to go somewhere else and not excite that mode.
With the base bolted down tight, the base gets stiffer, increasing resonant frequencies.  You also may be making the base more resistant against racking or twisting motions.
It is completely credible that both interventions reduce the problem.  Of the two, I would prefer any intervention that increases the stiffness.
If you know your movement speed (perhaps from your configuration file) and can measure the linear frequency of the ringing, you can determine the resonant frequency that is being excited.  Depending on the frequency, you may be able to excite that frequency with an audio generator and transducer (maybe even just a speaker), such as with one of these: Dayton Audio Transducers.
With the system shaking at the right frequency, you can use your finger to find portions of the frame which are vibrating strongly, or maybe even your phone camera to make a high-speed video of the movement.

There are 3 options to reduce ghosting working on different methods.
Basics of motion physics
When the machine changes movement direction, it does so with a very short time difference delay between the head and the frame, inducing vibration. Let's assume the head makes just movements back and force around a point $x_0$ in the mid of the bed with an amplitude of 1. So the positional curve of the print head is $x_h=x_0+sin(\omega t)$. The second derivate of this is the acceleration $\frac {d^2} {dt^2}{x_h}=-\omega^2 sin(\omega t)$. The frame though lacks behind, it has a phase shift to this. It's movement is $x_f=x_0+sin(\omega t +\tau)$, so its acceleration is $\frac {d^2} {dt^2}{x_f}=-\omega^2 sin(\omega t +\tau)$. The factor $\tau$ is determined how the printhead is mounted (friction), the weight of the frame (it's inertia) and how stiff it is. It might change depending on the height due to the construction of the frame (changing stiffness).
We'll assume a 1-dimensional printer as it is easier to model, but in praxis, we'd have all three axis to look at to model the printer in its entirety.
Method one: less friction
One way to lessen the factor $\tau$ is to reduce the ability to transfer the motion energy between the print head and the frame. This means to reduce friction between the frame and the printhead. So better bearings are one way to do this.
Method two: lighter head/heavier frame
Another factor is the inertia differential. If the head has less kinetic energy and/or the frame higher inertia, this reduces the ghosting as with less energy available, the phase shift $\tau$ gets reduced. This is where bolting down the printer acts to some degree: the mass of the printer becomes the mas of the printer plus the part it is bolted to.
Here is where a super lightweight head on lightweight carbon fiber tube rails with Bowden setup (Hypercube design) shines: by having a super low mass, the energy transfer is hindered.
Method three: Stiffening the frame
The frame has a certain frequency it wants to swing at. To shift this, one can add stiffening rods or different mounting, which also increases the weight. This shifts $\tau$ down some.
Method four: Tuning $\tau$
Just adding mass to the printer and from the printhead or stiffening the machine has its limits. There is however a way to isolate the machine from other systems: put it on spring dampeners. As long as these dampeners are not in resonance to the frame's resonance, the machine itself can be tuned in itself. At this point comes in what you noticed when you put the machine on rubber mats: if the machine has a $sin(\tau)\to 0$, then the factor $\tau$ suddenly gets only little effect on the calculation. By the way, the symmetry makes it easy for us, creating boundries: $\tau \in \{0,2\pi\}$
Best Practice?
It is often hard to find the best way through calculations alone. Even Engineers use trial and error to look for where to add mass (using for exampele clay and weights) and look at complex measurements how much mass they need to reduce where to change the ring of the machine so the multiple factors in $\tau$ cancel each other out or get the resonance frequency where they want it to be.
For home use, it is often the best to fix it as easy as possible.

Ghosting is very well described in the topic What causes “ghosting”?.

Ghosting is an artefact in the print due to the vibrations in the
  printer that are induced by rapid changes of direction

To add to that answer and get on topic of your question and your possible solutions I'd like to say that neither of the solutions you provide is correct. What do we know? We know that ghosting depends on the mass of the printer head being accelerated and decelerated. This causes overshoots that are damped out by the construction causing the ripples or ringing effects that die out after a few mm of printing.
If the head is considered to have a mass M1 and the printer mass M2 (where M2 is larger than M1), the following simplified figure can be drawn:

Note that the head is without friction (which is not the actual case), when the head is subjected to a force, or suddenly a force acting on mass M1 disappears, the mass M1 wants to travel further; the spring and the damper then come into play causing a dynamic displacement of x1.
If you assume the printer to be bolted to the ground, M2 becomes the mass of the earth (M2 >>> M1) and solely the x1 displacement is taken into account. However, if you hang it freely (M2 > M1) or use rubber damping between the printer and you get a complex vibrating system where mass M1 influences the displacement of mass M2. E.g. M2 is now connected to the earth (or not if freely suspended) with its own damper and spring (or free). If x2 and x1 are in phase the effect may be even stronger than if x2 and x1 are out of phase. This all depends on the values of the spring and damper values and the involved mass weights. Although clamping down seems the best way to go forward, putting the printer on rubber matting or feet may be more comfortable as it reduces the vibrations.
This demonstrates that the displacement of M1 will always exist until you either fix the mass of the head (M1) or the force acting on mass M1 (lowering speed and jerk).

Personally, I would select the 2nd option.
The forces and vibrations inside printer will propagate over every single part connected. Having that in mind, making rigid external frame is just a part of the solution.
Please consider some extra points:

filament spool on the top bar adds vibration to the frame (get a rubber pad to separate hook from the frame - but I will remove it from the printer)
steper motors are mechanically noisy as well - get a stepper damper (as a piece of thin rubber between the motor and bracket)
moving speed and acceleration also adds a pressure to the construction, so high acceleration and braking need to be reduced (when you put hand on the frame you will fill all those movements (close your eyes))
stepper drivers also have an impact on the quality side (circled model skin)
you also could add an extra tensioners from top of the frame to the base.

Fixing it to the floor will be a benefit and considering points above will also improve printing quality.
an alternative lateral frame:

Stepper dampers (the rubber kind, not the electronic kind) should not be used as they do exactly the opposite of what you want. You need the connection to be stiff, not flexible with a stepper damper. I've used them.

@0scar - naming naming naming :) updated my answer to reflect what I had in the brain - thanks for increasing quality of the forum!

To fix ghosting it doesn't realy matter if the printer is bolted down or flying thru the air. The main point is to get rid of any movement in the printer construction itself.
What I mean: If you bolt down your printer, but all parts wiggle as hell, then you will have ghosting. And if you have a printer with no wiggeling parts, then the printer could theoretical even been moved while printing.
So reduce vibration sources or undock them with dumpers and made the frame stiff as possible.
sure a bold down would provide a reduce in flexibility in the printer, but if that would help also an internal reinforcement will do the job. (Like a extra frame)
For my personal 2 cents: I suggest to use a soft floormat to stop vibrations transfering to the table, because it would be annoying a.f. to stay in the same room if you have a vibrating device that uses the table top as a drum.

Ghosting is related to acceleration and weight of X and Y axis.

@FernandoBaltazar right. but mainly caused by wiggeling parts. to reduce even more you have to use stronger motors that can provide the accelerations.

Oh and I forgot: To reduce ghosting it is often usefull to reduce the maximum acceleration and especially the jerk.

loose parts makes unsharp edges, and vibrations makes wavy layers.

I got good results by mounting my printer on a concrete paving slab (obviously cleaned and sealed) and placing that on a foam mat. The combination of high mass and flexible mount has substantially reduced ghosting in my prints. Not my idea; I found it on a video on YouTube (linked below). Honestly not sure if this is the best solution from an engineering perspective (I like the idea suggested above of trying to find the resonant frequency) but it's easy, fast and cheap. And as a bonus, it has substantially reduced the noise level of my setup.

I'm missing something here. How about damping the movement of table and head by placing a tuned mass damper on table and head? Something like a mass that is mounted in the top of a skyscraper...


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Insulate hotend on Makerbot Smart Extruder
Simple question: how do you reinsulate the MakerBot Smart Extruders?
Backstory:
I work at the library. We've recently replaced the MakerBot (extruder connection issues followed by software incompatibility) with a Prusa.
As a new hire, I'm obsessed with the 3D printers. I'm trying to make it my mission to get the MakerBot working again, just so we can have two printers running.
It takes quite the request chain to get materials in and I had some plumbing tape on hand, so I tried to wrap it with that, per this thread. It's not going too well because of the housing around the Smart Extruder, which I cannot figure out to remove (easily and/or without voiding the warranty and taking it completely apart).
I imagine even with the cotton + Kapton tape, you'd need better access to the hotend than the housing allows.
Any help is appreciated!

I recently wrapped a LOT of hot PLA around my print head and, as a result, had to remove the kapton tape and the fibreglass insulation that came with it.
I was reluctant to use fibreglass because of the tissue embedding hazard and the lung hazard (especially on what is effectively an indoor appliance) and kapton tape is very hard to find in Australia.
After some research, I wrapped the print head in 100% wool felt that I bought from a fabric store (be very careful, as most craft felt nowadays is either acrylic, polyester or a poly/wool blend) and then bound it all up with teflon thread tape (plumber's thread tape).
Cotton has a scorch temperature of 150 to 200°C, while wool won't scorch until 500 to 600°C, and the teflon tape can handle temperatures between 200 to 300°C.
Did it work? Well I can now put my finger on the outside of the tape after the element has been at 200°C for 10 minutes, and only feel a little warmth. The print head heats up twice as fast, and I can run my massively oversized print cooling fan at 40% rather than the 10% I could use before. There is no odor of anything cooking off either. Success!

The flat pieces of felt? I might try that! I've been afraid to Crack open the extruder housing. Did you have to do that to re-wrap yours?

I just grabbed a 1/2 metre of felt from the fabric shop, cut a strip out using scissors and then snipped a hole for the extruder tube. Then wrapped the felt around the aluminium block, snipped another hole to let the nozzle through, then trimmed it to length.
Then I just grabbed the thread tape and kept wrapping until the extruder block was one plastic pink slab, with the nozzle and the tube poking through.

I didn't NEED to pull the extruder apart completely. I was able to unscrew the nozzle/block and tube arrangement from the stepper array. On the Geeetech, this is easy to do if you first unclip the stepper's cables, remove the fan from the stepper, then unscrew the whole array from the x-axis assembly. Remove the nuts from the extruder tube, and you're good to wrap.
However, I DID pull the nozzle and tube from the aluminium block as I needed to blowtorch a LOT of plastic off and out of them. I had to replace the teflon tube after, but it needed replacing any way.

WHOOPS.
On further experience, I can't recommend this just yet. I DO get a distinct hot wool smell on very long prints. Let me get back to people about how well this works over a longer time.

Strictly speaking, you do not require the insulation to be there. It is supposed to keep some of the heat contained in the core to allow more heat to be available for the filament to melt (basically higher print speeds and less chance of burning your fingers :) ).
If I go to the Makerbot website and look at the video Smart Extruder+ - 3D Printer Extruder - 3D Printer PLA Extruder
at 1:37, you'll see that the hot end is wrapped in cotton and Kapton tape. Like the stuff that is cheap and easy to buy:

and that the casing cover is removable, so you should be able to open it to insert new cotton. Why worry about voiding warranty? You can gain a working printer for a few bucks or bite the bullet and buy a new Makerbot Smart Extruder. I guess if you had warranty you could already have it replaced by now.

I do see the wrapped hot ends by themselves. All the information I've seen says opening the case voids the warranty and is something that can only be done by MakerBot? We got the Smart Extruder+ just before I started in March, but we don't have the service plan on them. I haven't had much luck finding information on the MakerBot! (And I'd thought the Prusa was a pain.)

If you're not satisfied, claim repair under warranty if it is a factory problem? Else, figure out to open the cartridge, maybe a local technician (e.g. one doing electronic/phone repairs) can be asked to help out.

source: Stack Exchange

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Adhesion problem (heat bed or extruder issue)
I am having an issue with the transition  from the first layer to the second. It seems that the first layer isn’t staying put on the hot bed and the extruder is dragging it around creating a ball of filament.

Is this a "height issue" or a "hotbed temperature issue"?

Also I ordered a new glass hotbed top.

Can I remove the tape that was on the hotbed when it came in the package?

Need more information: printer, slicing software, settings (temps and layer heights), speed

Have you found and fixed the problem? If so, has the answer below led you to the solution? Please vote to accept the answer so this question is not bumped up once in a while and can be removed from the unanswered question list. You may even add your own solution and accept that after 48 hours! If you have not been able to address the problem please update your question.

If the first layer is not sticking well to the bed it can be caused by several issues. Usually the height of the first layer plays a significant role as does the flatness of the bed. Temperature can definitely  also play a role; you want the temperature to be close or at the glass transition temperature of the plastic filament when it is in a sort of fluid state.
Personally I hated the original tape that came with the bed or blue tape I bought separately. Also the surface finish is nowhere close to printing directly onto the Aluminium bed or on a glass plate. For adhesion, a PVA based spray (e.g. hairspray, or more expensive special print spray like 3DLAC or even a glue stick), should be used as it becomes very sticky at elevated temperatures.
The tape can be removed, but should be replaced with something that grips onto the filament, see previous paragraph. I removed the tape after day one I got build my kit and started printing directly onto the Aluminium bed using the sticky spray.
To answer your questions, the following checklist determines the order in which you should solve your issue:

First check the nozzle position relative to the bed; this should ideally be the thickness of a single plain A4 paper.
Make sure the bed is level; what is meant that the bed is relatively level with respect to the nozzle, not water bubble level with respect to the Earth (you'd be amazed to find how many people do that).
Use the correct bed temperature; it is usually found on the tag of the spool of filament. Alternatively, look it up on the internet, or increase it at first with about 5 degrees Celsius at a time.
You could over-extrude a little for the first layer by increasing the extrusion multiplier for the first layer, or add some extra temperature to the extruder (increase with 5 degrees Celsius).
Printing brims or adding mouse ears or discs integrated in your design may also work to create more grip.

And yes you should remove the masking tape before you put the glass on as it would only act as an insulator.

Thank you very much, Oscar.  I will affect these changes and let you know.

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Steps per mm of extruder are incorrect after rebuilding
I have got a problem that after upgrading my printer to an aluminum frame my extruder went from around 400 steps per mm at 16 micro steps (which did match the manufacturer's recommendation perfectly) to a bit over 1000 steps per mm at 16 micro steps.
This is a problem for me, since the limited amount of steps per second lower my maximum retraction speed.
What I tried since the rebuild:

Replace and adjust the current of the stepper driver - no change, even with another type of driver on different micro steps, of course with other values, but also about 2.5 times too high;

Connecting another motor with another cable - the other motor with nothing attached to it drove the same angle as my extruder stepper.

Could it be that the ATmega2560 on my MKS gen 1.4 board got damaged? Or did I change something in the firmware, which does have this effect?
I am using Marlin 1.8.5 and a E3D Titan 1:3 geared extruder and I am using the same setup as before! E3D claims to have 437 steps per mm on a 200 steps/revolution Nema 17 stepper and 16 micro steps. This value was working perfectly fine before.
Update:
With an Arduino Nano I measured the amount of steps my board sends at 418.5 steps/mm (programmed in EEPROM and in firmware) on a specific amount of extrusion length
G92 E0 -> G1 F100 E30

and I got
5220 steps for 30mm extrusion (reproducible).

It should be
418.5 steps/mm*30mm = 12555 steps.

Where,
(12555/5220) * 418.5 steps/mm = 1007 steps/mm

to have the effect of 418.5 steps/mm
...which is, oddly, the exact number that I got by marking filament, extruding, measuring and calculating.

If you have changed the extruder drive, the one that press and feed the filament your steps per mm could change.

That's totally right, but i forgot to mention, i got a geared extruder and there are no spare parts that i could have mixed up

There you are, when you change the extruder, you should re-calibrate the extrusion length. Let me guess, the gear uses a 1:2.5 gear ratio :)

You should put that information (geared extruder) into your question, rather than in a comment.

I did edit my question. The ratio of the e3d titan extruder is 1:3 and it hat the ~400 steps per mm before

Ok, thanks everyone for at least taking time to read or thinking about this.
The Problem is an absolute mess and there are two possible reasons:
-> the octoprint eeprom editor is broken
-> the ATMega2560's eeprom is broken. as far as i know companies buy used atmegas to cheapen the price and the >100k writes on my chip has been reached
I will try to figure out the exact problem, if i find time in the next days.
My current setup is just deactivate eeprom and i'm good to go. Even wiping eeprom with a small arduino sketch will get the error to return.
Now i will be able to sleep again :D

Good that you post the possible culprits so that others may learn from it that even the electronics that you don't expect to fail may fail. This reminds me of the old days of a failing co-processor due to a print board crack failing to produce consistent log() function results (once in every thousand it failed to produce the correct value) try to trouble shoot that! It took days to find out.

After a rebuild, and certainly after changing to another extruder (e.g. replacing it by a geared extruder like you supposedly did as taken from the comments above before the edit, which now clearly is not the case) or setup e.g. other stepper drivers, you should always calibrate the extruder.
To calibrate you e.g. disconnect the hot end nozzle and command to extrude 100 mm. Be sure to make marks and measure the extruded distance. Divide the latter value by 100 to divide this result by the steps per mm value in the configuration file. So, if you measured 102 mm and commanded 100 for 400 steps, the new would be 400/(102/100) = 392. There is a lot to find on this matter on the internet. All can be done with G-codes that can be entered through a terminal connected over the USB port. E.g. applications as Pronterface, Repetier-Host, OctoPrint, etc. all have a terminal interface to the printer if connected over USB.
You could find more detailed instructions e.g. here, or this video.

I didn't change the extruder or stepper driver at all! That is what bugs me. And recalibrating works of course in regards of extrusion, but ~1000 steps per mm limits my maximum retraction velocity to 2500mm/min (theoretical: (max steps per second on mega2560 based borads) 45000steps/s / 1000steps per mm = 2700 mm/min). Over 2500mm/min the motor loses steps and submits bad sounds

@Bastian__ That is very strange indeed, I'll take a look at it later. Good you made it now clear in the question, as it was not clear! At first, it looked as if you changed to a new extruder in the conversion process.


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Issues with Proto-pasta filament extruding on prusa mk3
Has anyone run into problems printing with Proto-pasta's HTPLA on a Prusa MK3 (or any printer really)?
I picked up some samples from PP, specifically their glitter filament and a couple of the premium HTPLA filaments. I printed one small piece with the glitter filament the first night I got the package, but I haven't been able to get any of the filaments to print since.
Here's a video I shot outlining the issue's I'm running into.
The problem seems to be that the filaments won't extrude from the nozzle and this problem applies to all of the samples I got. If I unload the HTPLA and print with any of the other filaments I have been printing with (various inland filaments) they all print out fine.
I thought maybe I had a clogged nozzle so I did a couple of cold pulls with a different filament. The pulls came out clean each time. I tried loading the HTPLA back in and while the filament extrudes fine during the MK3's loading process it still doesn't extrude when trying to run an actual print.
I've read through Proto-pastas page on avoiding clogs with composite PLAs and adjusted my slicer settings accordingly but still can't seem to get a print out.
I'm printing with:

The Prusa i3 MK3
Slic3r Prusa Edition

Tried Extruder temp as low as 195c and as high as 220c
Speed of 50mm/s with first layer of 20 or 30mm/s
Tried at .15 and .2 mm layer heights

Stardust Glitter Flake HTPLA - 1.75mm
Cloverleaf Metallic Green HTPLA - 1.75mm
Winter Blue Glitter Flake HTPLA - 1.75mm

Any ideas??
UPDATE
Over the weekend I talked a bit with proto-pasta and did some tests on my own. Proto-pasta suggested disabling the filament sensor on my printer since the additives in some exotic filaments can falsely trigger the sensor.
I went to try this, but my sensor was already off.
I tried switching back to a known good filament and found that I couldn't get anything to extrude anymore. After researching a bit online I suspected that there may be an issue with a clogged nozzle, so I did a couple of cold pulls and then tried one of my known good filaments again. This time I was able to extrude and print out a full test without issue.
After that I switched to one of the HTPLAs and it started printing. I thought all was good, but during the course of the test print the nozzle clogged again and stoped extruding.
So I'm close, but not quite there. I'm wondering if cold pulling again to unclog the nozzle and then walking through some of the settings changes outlined in proto-pasta's page on avoiding clogs will help. If I spent the entire time walking through that page with an already clogged nozzle it would make sense that nothing worked. That page is more a list of preventative measures rather than reactive.
I'm going to dig in more tonight. I'll post back with an update.
Reply from Proto-pasta
I got a reply from Proto-pasta for some questions I asked regarding the nozzle dimensions I should use with their filament. The 0.4 nozzle borehole is not too small for the glitter, though the larger diameter will help it sparkle more.

Thank you for following up. Yes cold pulls that leave behind material can cause all sorts of trouble. It happens to me on the Lulzbot quite often, probably my biggest gripe about that machine.  Anyways, on to your questions:

Is this accurate? Should I print the glitter filament with a nozzle with a larger borehole diameter?
A larger bore is not needed, the glitter flake is quite small and flows through a 0.4 nozzle fine. However, using a 0.4 nozzle and printing layer heights of 0.1 or 0.05 with glitter can cause a shift in apparent color as it forces the glitter to lay down flat.

If so, what diameter should I use? 0.6?
While not needed, a 0.6 nozzle does allow for a better sparkle or shine from the glitter filament.

Are there other proto-pasta filaments that require a larger borehole?
Generally any metal or wood filled filament benefits from a large nozzle size. For example, wood filaments most people suggest a 0.5 for better flow but they do work at 0.4. For us, we like to use 0.6 on the metal fills as it allows for a good flow.

I have a spool of matte fiber htpla that I got with my last order. Can I print this with my nozzle?
The matte fiber was designed as a non-abasive alternative to the Carbon Fiber filament. It does not require a larger nozzle, a 0.4 will work just fine.

What is the first layer height? Some filaments require the first layer to be smaller some larger. Have you played with that?

I have not changed that. at the moment I have it set to .2 and the rest of the layers at .15. I'll try adjusting that height to see if it makes a difference. Also, I emailed proto-pasta after posting this & they emailed back pretty quick. They're going to take a more detailed look at my email (which was an adjusted version of this post), but suggested in the mean time to try turning the filament sensor off (which I had not tried). I searched a bit and found this post from prusa: https://help.prusa3d.com/l/en/article/UaW5ZNPYR8-filament-sensor#exotic_filaments, so this also may be promising.

Play with the first layer, increase or decrease it, put 5 degrees Celsius extra temperature in, over-extrude the first layer, make your bed more sticky (glue stick, hairspray or 3DLAC) etc. There are many parameters to play with.

Sorry, but your video is far too long & includes minutes-long sequences of no value. Please try to get to the point.  I saw a successful mid-air extrusion, so is your problem with the first layer(s)?  If so, what happens if you add a z-offset so the printer "thinks" zero is a couple mm up in the air?

@CarlWitthoft Sorry you thought the video was too long. I did not edit the video to make sure there's full context (I don't know what the problem is, so why would I cut sections out of my video on the problem that I only assume are invaluable? What if I cut something that I thought insignificant that someone else saw and triggered an "ah! that's it" moment for them?). My intention was to "get to the point" here in text and give the full context in the vid. I don't think it's a layer height issue. I'm updating my post with findings from the weekend.

These glitter filaments are horrible to print with a 0.4 MM nozzle , i am not even gonna attempt explaining why it doesn't work  . Go with a larger nozzle size try it with a  0.6 mm nozzle . Should work fine .

tl;dr
I had a dragging idler pulley that was causing extrusion issues. Opening the idler pulley door and working it a bit with my finger resolve the issue.
The detailed explanation
So after two weeks or so of troubleshooting, banging my head, taking a break, and coming back to it I'm finally getting good prints again.
I do believe the original problem started with the clogged nozzle due to the bore hole diameter being too small for the glitter filament as mentioned by Axel in the post comments (a bit rude about it, but still probably true), but there were other issues that I ran into.
Troubleshooting steps
General cleaning
After I switched back to inland filament (which had been working fine for months) I was still having extrusion issues. At this point it was due to the clog (I suspect).

I tried several steps to unclog the nozzle including the steps suggested by prusa support and cleaning techniques suggested by Tom amongst other places.
I also picked up a couple of pencil brushes on amazon including a small brass brush that's perfect for cleaning off the extruder pulley teeth.
Cold pulls
During these steps, I think I introduces the second problem without being aware of it. I perform a bunch of cold pulls (explained by Tom in his video and other videos and posts). During one of these cold pulls I forgot to loosen the MK3's idler pulley door before tugging. Once I noticed it I loosened the door, but I think that tug may have affected the idler pully getting it a bit gritty (I don't know how it would have done that, but it's my current guess).
At this point I was still getting extrusion issues and didn't think about the idler pulley being the issue, so thinking that the nozzle was still the issue I ordered a second E3D nozzle and some Ethyl Acetate which dissolves PLA.
Notes on Nozzles and Ethyl Acetate
E3D nozzles
A couple of helpful points I learned while researching these purchases.
There are a lot of cheap nozzles that say they work on the E3D, but be sure to read the comments from whatever nozzle you're looking at because apparently a lot of them either don't fit or don't print well.
I ended up purchasing a replacement nozzle sold directly from E3D to be safe.
Ethyl acetate
As far as the Ethyl Acetate, I was having a hard time finding it online when looking for it as a solvent without having to purchase the chemical in a giant jar. I didn't want to buy a jug, I only needed a bit.
After doing a bit more research I found out that it's the same chemical that entomologists use to kill insects for preservation and when you look for the chemical from that context you can find it sold in much smaller quantities. I was able to find a small jar of ethyl acetate on amazon for 7 dollars. Smaller, safer, and cheaper.
Finding the actual problem
Once the nozzle and ethyl acetate came in I pulled off the old nozzle, dropped it into the ethyl acetate to soak, put the new nozzle on (per the instructions from prusa's website), and reaccelerated the printer just to be safe. I tried printing a test block and it seemed better, so I then tried a larger print and while the printed model seemed better, it was still obviously having extrusion issues and crumpled in my hand.
With the nozzle ruled out, I started looking elsewhere on the printer. After watching a video from the 3D Printing Nerd on extrusion issues he was having on his MK3 I decided to check the extruder pulleys. When I tried to open my extruder idler pulley door I noticed I couldn't actually get it open; it seemed to be stuck on the bottom. I tried to free the bottom of the door, but couldn't without forcing it past my comfort level. Instead, I unscrewed the top of the pulley door to remove it.

From here I noticed two things, I didn't get the pulley teeth as clean as I though I had before and the idler pulley's mounting rod was extended just a bit (which is what was causing it to stick at the bottom). I adjusted the rod and put the door back on. It was printing better but still had extrusion issues.
I then watched the pulley during the filament loading and notices that while the extruder stepper motor was turning smooth, the idler pulley was stuttering a bit while turning. I imagine those little stops and starts were what was causing the extrusion issue.
I opened the idler door back up and worked the idler pulley a bit with my finger. It started to spin free (maybe there was gunk in it? maybe it was rubbing a bit against the mount? ¯\_(ツ)_/¯), so I closed the door and screwed it back in tight.
Ran a test print -> perfect.

I've run several prints increasing in complexity and it seems like I'm back to printing well.

How I introduced my own problem
As I noted above in the explanation, I think I introduced the problem during a cold pull where I forgot to loosen the idler pulley door. I know this explanation is super verbose, but when looking around, even after fixing the printer, I haven't really seen many people noting that on the MK3 you should make sure the door isn't screwed down when performing the cold pull. It's def a common sense move, but I don't see it mentioned as a potential for introducing a problem.
Also I didn't see a dragging idler pulley as a possible cause of extrusion issue so I thought I'd note it here as well.
Hopefully if anyone else has a similar problem on the MK3 this will be a source of help.


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Zortrax M200 skipping extruder
My Zortrax M200 has a skipping extruder motor, I’ve checked the seating of all connections and 3 different (electronic ribbon) cables and still can’t fix the issue. The gear is clean and have tried fresh filament.

Does anyone have any possible thoughts on why this happens?

The extruded motor will move in the desired direction and then skip back.
Loading the filament is fine. Tried new nozzles, blockages checked, etc.

What do you mean by cable? The electronics cable or the filament tube?

@0scar the electronic ribbon cable.

Is it skipping as in "no gear motion when it should be extruding" or as in "gear moves but filament doesn't move" ?  Radically different situations.

@CarlWitthoft it rotates and then skips backwards. Loading filament is fine. Tried new nozzles, blockages checked, etc.

Could you update the question as requested by @CarlWitthoft? This makes the question more clear on which issue to focus.

Every time I've had an extruder "skip", it was actually because some condition was causing excessive back-pressure.  Either the hot end isn't hot enough, the nozzle is too close to the bed, or something has clogged the nozzle.
If there is a "skipping" noise, then this is almost certainly the problem.  When a stepper can not advance, the magnetic field will continue to "step".  After the rotor is behind the steps by 180 degrees of field phase (which might be only a fraction of a degree os stepper motor shaft rotation), the rotor will snap back to re-align with the magnetic field.  The sudden movement of the rotor and the release of compression on the filament often makes a loud clicking or thumping noise.  If you can see the gear, it will jump backward and then rotate slowly forward before jumping backward again.
To see if it is the drivers, try extruding with no filament, or if you can, try moving filament through the extruder.  If it doesn't move at all, or doesn't move under light drag, it may be the driver, the wiring, or perhaps the motor.

This seems like a really good trouble shooting idea. I’ll give this a shot tomorrow. Thanks!

Check the pins on the motor. Are they bent? If yes - straighten them out with a screw driver.
This could be a stepper driver problem. If it is then bad luck. Zortrax hard solders their stepper drivers onto their control board (this sucks and is a pure monetization related move by them).

This results in you having to get a whole new set of connector cables and or new control boards every time something goes wrong.
Ask for a control board replacement with new connector cables, if your machine is still under warranty it should be free of charge.
Switch to different or cheaper machines like Wanhaos or Ultimakers if you want the same ease of use and cheap part replacement.


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Enclosure Ventilation
I am building an enclosure for my 3D printer (Anycubic i3 Mega) and I'm wondering about heat and ventilation for my machine. My enclosure is is build from five 50x50x50 cm Plexiglass frames glued together. Currently I'm using only PLA for printing.

Does my enclosure need ventilation so my 3D printer would not overheat?
If yes, what type of ventilation?

Is only drilling holes enough? or
Do I need to add some ventilator?

If I would print with ABS in the future would it change the answer?

When printing PLA you do not require an enclosure! PLA does not shrink as much as e.g. ABS. When printing PLA you should definitely ventilate your casing. I guess your steppers are also located in the enclosure, so you should be careful of not overheating the enclosure. Not only the steppers, but also think of the cold end cooling, too much heat in the enclosure means that the cold end cannot cool enough to prevent the filament to melt prematurely; this can lead to clogs. Also note that the printer electronics board may become too hot too (too hot stepper drivers will cause steppers to miss steps).

I once tried a towel over a Ultimaker 3 Extended to print a difficult filament to keep some heat in the enclosure; I encountered the above
  problems when I was young(er) and inexperienced :) We learn by trial and error some times!

However, ABS, requires control over the temperature during printing. Draft or uneven temperatures may lead to problems related to layer separation or heat bed separation. Many of the high-end box printers have doors available to enclose the front, this results in an enclosure with an open top (sometimes even for the top there are covers available). The heat of the bed then heats up the enclosure. A constant temperature of 45°C should not be too high to cause problems. When boxing it up completely, you could use a temperature sensor to monitor the enclosure temperature and schedule a fan to ventilate when it gets too hot.

Since the most 3D printing filaments causes particals it is not a bad idea to enclosure the printer. Also to reduce noise and smell of bad filaments.

I am building enclosement mostly to keep dust, cat fur and my cat (although he doesn't seem to be much interested in my new instrument of destruction :)) away from printer also noise reduction is a thing for me. Thank you 0scar for your answer based on this I will add to my project fan and a temperature sensor.


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Subtract of two STL files in Slic3r software
I have a question about Slic3r software.
I would like to subtract two parts. For example, I have an STL model, when I right click on the part, I can select Settings..., and in the Settings window, I can select modifier and I can select slab.with selecting proper thickness. Now we have two parts where one of them is inside of another. My problem is subtracting those two parts.
How can I subtract this part from another?

I'm not sure what are you asking about. Processing 3d model or positioning it on the build plate. A picture will help us to understand.

If you are asking how to create a new STL which is the union (or intersection) of two items, you probably need to use MeshLab or MeshMixer or other CAD tools.

you can actually do this with tinkercad, by turning one of the imports into a hole.

Slabs are not for subtracting - they allow you to apply different print settings to different parts of a model. If you would like to print only part of your model you need to cut the model in a CAD program. What are you trying to do?

Hi @Mahdi Shakeri. Your question sounds like how do I use cad question. Though you have some specific questions intermixed. I see others are struggling understanding as well. It would help us if you separate out the questions into bullet points, and to show us images of what you are struggling with. Every cad program is different, so the software you are using will help. Also make sure to check out https://stackoverflow.com/help/how-to-ask as you have some formatting issues as well.

When I open Slic3r, I can not find "modifier" in the Settings dialog. When you say I can select modifier, do you mean "I can click the Load Modifier... button" or "I can select a modifier"? Also, where are you selecting the "slab" from? I can't see that either. Please clarify these points. Editing your question and adding a few screenshots would help people to understand your question properly and may prove useful to other people having the same issue. Thanks.

Thank you for your time and detailed explanations.its long time that i know cad and use it every day.my problem with cad is importing and editing STL files.some times you find very good STL files or even OBJ files, but you going to edit it, cad cannot import stl file. i am trying to find another software to edit stl file.for example creating a candle mold from stl file.anyway thanks for your efforts

Given my limited familiarity with all the CAD tools that exist, I would fall back to something that I know does binary operations on volumes -- openScad.
One can create two objects, one from each of the two STL files, and subtract one from the other.  One can also compute intersections, unions, and other operations.
There are probably other programs that also do this, but openScad allows for doing in programmatically, so that once you have it right, you can update the objects without needing to redo the finicky part of the operations.
slic3r may do this, but I haven't seen such features in my multi-year use of slic3r for slicing.
When in doubt, IMO it is better to script something.  It is virtually never that I do something only once, especially in 3D printing where rapid prototype leads to rapid change and improvement.

+1 for OpenSCAD it is definitely the tool to do this; may want to put some example code showing how to load STLs and difference them.

Thank you for your time and detailed explanations.its long time that i know cad and use it every day.my problem with cad is importing and editing STL files.some times you find very good STL files or even OBJ files, but you going to edit it, cad cannot import stl file. i am trying to find another software to edit stl file.for example creating a candle mold from stl file.anyway thanks for your efforts.

With openScad, i do not exit stl files.   The stl file defines the object in operScan.  Then i add features to the object... drill holes... scale it... add a base... cut out parts i dont want.  Editing STL directly is difficult.   Adding to and changing a body is openscad is much easier.

This is definitely the way to go. OpenSCAD produces perfect cuts with no guesswork. Meshmixer struggles. High learning curve but perfect results once you figure it out. Simple example:
`// difference of two STLs in openSCAD
difference(){
translate ([-140,-100,0]) //move to position
import("/path/to/your/stl/file.stl");\
translate ([0,-0.5,52.85])  //move to position
rotate(a=90, v=[0,1,0]) // rotate around y for example
import("/path/to/your/cut/cut.stl");
}`

I am assuming your trying to perforate, hollow or cut your design in a specific shape that is the same as the inner 3D object or vice versa?
Do this with 3Ds max its just really easy there for such operations.
Please load into Autodesk 3Ds max and perform Boolean.
This is the link on how to use the Boolean tool, Boolean Compound Object
There are other software like magics where this can be done  but as you seem to be trying this for the first time. I will suggest only 3Ds max.

Thank you for your time and detailed explanations.its long time that i know cad and use it every day.my problem with cad is importing and editing STL files.some times you find very good STL files or even OBJ files, but you going to edit it, cad cannot import stl file. i am trying to find another software to edit stl file.for example creating a candle mold from stl file.anyway thanks for your efforts

@MahdiShakeri as much as i know editing STL files is a pain . Please do-not try it as a beginner ever . Its so much easier to just redesign . But if you really want to go down that lane please get a hang of Autodesk 3Ds max its the only software I would vouch for that can even attempt to edit .stl files .

Meshmixer will perform boolean operations between two STL objects faster than OpenSCAD.
Import the primary .stl, append the second .stl: the one you want to take away from the primary. In the Object Browser window select the primary and then hold the Ctrl key down and left click on the second, a window pops up giving you a boolean difference option.

Don't try to do it in the slicing program, instead create a new STL that is the difference.  The slicing program shouldn't be used to modify STLs.
Plus, this is a pretty quick and easy thing to do.  You can do a difference operation using OpenSCAD (as mentioned above) or atomiccompiler.com if you don't want to install new software just for one operation.

If the objects are manifold and has no issues, Blender can perform boolean operations. I would prefer blender over OpenSCAD as OpenSCAD crashes (at least for me) if there are issues with the mesh; over 3DMax because it is free, fast, and smaller to download and works in my choice of operating system.
Import STL files by File, Import, STL. If that option is not enabled: File, User Preferences, Add-ons, search for STL and enable that option.
Simply select the main object with right click, on the right panel find modifiers with wrench icon, click add modifier and select the operation (difference) and the other object. If the result is not satisfying, try Carve in the solver options. If there are problems in the result it is generally because of issues with the STL files. Use a tool fix those issues and try again.
Once you are happy with the result, you can export by selecting your object, going into File, export, STL and select Selected only option so that the negative object will not be merged with the carved result while exporting.

authors: Миша Совков spam


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3-D printing initial stage for a beginner
I am a new-bee to 3-D printing. I want to learn about it as much as I can. So, where to start? like a total beginner. Any suggestions are welcomed!

please see more here: https://3dprinting.stackexchange.com/help/how-to-ask

Hi and welcome to 3D printing SE! This is not an average forum site, but is specifically designed to solve specific questions. Before you ask a question, it is custom that you have familiarized yourself. Please try to Google "3D printing". E.g. https://3dprintingforbeginners.com/category/tips-techniques/, https://toms3d.org/ and https://www.youtube.com/channel/UCb8Rde3uRL1ohROUVg46h1A are a good place to start. If you have specific questions after that, please feel free to ask them. Do note the fore mentioned https://3dprinting.stackexchange.com/help/how-to-ask.

@0scar Thanks for the info! I guess, I'll better start learning then!

+1 for good luck. If you are wanting to build your own printer then the RepRapWiki is invaluable. A little hard to navigate maybe, but once you get a better idea about 3D printing as a whole, and start to design/build a printer, then you will definitely need some information from there at some point. Please come back here, to SE.3D Printing, when/if you have a specific issue that we can help you with. :-)

like anything else, youtube


text:
Not able to insert hobbed drive and filament in the extruder drive
I am building a AlfaMendel 3D printer (edited : The original question named it to be Prusa Mendel I2). I printed the extruder drive using PLA material from the STL available in the package but I'm not able to insert the hobbed drive as well as the filament in it. The dimensions of hobbed drive is correct.
Is the problem related to shrinking of print material while printing the extruder drive or something else.
I have included few pics of the extruder drive and hobbed drive.

This image shows the maximum possible insertion of hobbed drive in the extruder drive.

The MK7 and MK8 hobbed extruder gears have different diameters. One is 12 mm and the other is 9 mm respectively, so the question is what diameter is your hobbed gear?

Its MK8 with 9mm diameter

You need to add more information; e.g. what material you printed, a photo with the gear (tried to fit) in the printed part, measured dimensions, STL model dimensions.

I have used PLA to print the part, as much I remember the measured diameter of the hole in extruder drive was 7.9 - 8 mm (actually I don't have a Vernier Calliper at present) and I added one more pic in the edited version

Your parts are not in the Prusa Mendel i2 as found here or here.
Also note, quote:

Parts included in Github repository have the wrong dimensions for the
  nut traps! Download the correct version from [Thingiverse Greg's
  Hinged Accesible Extruder]

Are you sure you have the correct parts for the original Prusa Mendel i2? Maybe you have a different version? The original extruder mount uses an M8 hobbed bolt, not an MK8 hobbed extruder gear. The first is 8 mm in diameter, the latter is 9 mm in diameter.

Edit:
After you updated your post to hint to the correct printer, it appears that my answer still holds. You did use the incorrect extruder gear. The 9 mm gear doesn't fit in the extruder part as it requires an 8 mm diameter extruder gear.
It might be difficult to find a 8 mm hobbed gear with a 3 mm shaft diameter, they are usually 5 mm (as in the stepper shaft diameter) or 8 mm (as in the diameter of 8 mm bolts that are frequently used for extruder setups). You could redesign the part (load STL in a 3D CAD program and make the changes). By the way, PLA should not shrink so much. As can be seen in the photo's, it looks like your current printer does not print very accurately, that may also contribute.

Sorry for incorrect info. Actually the printer is not entirely Reprap Prusa Mendel but it is AlfaMendel AM1 which is similar to Prusa Mendel I2. The link for its manual is link. You may check page no. 126 of the manual for its extruder drive. Actually I didnot correctly read it, the printer requires a 8mm M3 hobbed drive, not the MK8 which I have. Buy the way, thank you for the answer :)

Can I print a hobbed drive using PLA, instead of purchasing a metallic one ?

@MSD No you cannot print that to use it functionally.

OK :)
Also, I am not able to insert the PLA filament into the extruder drive (via the hole in the very first pic), I think it has shrinked. What should I use to drill it to make it proper or some other way to make it correct ?


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How to calibrate Ender-4
I have just assembled the Creality3D Ender-4 kit a couple of days ago.
I completed some rewiring and everything seems to be wired correctly, I'm able to auto-home successfully, but this is the problem I'm having:
I tried printing a calibration cube.
The first problem I noticed is that the printing is starting on one corner instead of the center as specified on the Printer Settings in CURA (check settings below).
Second problem is that I'm getting significant distortion. The movement of the printer seems to be fine, no jerks of weird sounds. I tried all I know but I honestly don't know how to proceed with this. I have a couple of hours of experience in 3D Printing so I'm completely lost.
This is the result I got (Model printed with Raft for adhesion):

These are my CURA settings:
Printer

Extruder

Remove the tick mark of "Origin at center" your origin lies at front left.

The "Origin at center" does NOT say that your print will be start in the center, it says that the homing point is in center. Since this is very uncommon for 3 axis printers, you should try to remove this tick like @0scar said. Also other information like Material and settings would be interesting to help you.

possibly helpful:  https://makerware.thingiverse.com/groups/anet-a6-ender-2-dremel-3d/forums/general/topic:29342

@ Carl Witthoft : That helped a lot, its fixed now. I'll add the details as an answer below

If you could post an answer then that would be great, thanks. Slightly off-topic but what I find to be a bit strange is that the Ender-4 does not appear on the Creality3D website. Is it really new, and/or have they just not bothered updating their website recently? Or is it a clone/improvement made by someone else?

The first problem is solved by removing  the tick mark at Origin at center. Most printers have their origin at a corner (not Delta's, their origin is in the top center).
The second problem is a little more difficult to solve. Please note that a kit should be loaded with preset values that should be fair enough to print, your picture does not appear to print the calibration cube correctly, so you should try to eliminate each possibility one at a time. As said, your picture is not very clear, but it does not appear to be a cube, it looks more rectangular (also note that a raft is only interesting when printing difficult, read prone to warping, filaments like ABS).
What you could do is print simple squares (no raft, but use a brim or skirt), e.g. 50 x 50 mm (only 1 or 2 walls in width and a few layers high), and measure the printed size.

If these squares do not stick to the heated bed, calibrate the Z height to nozzle distance and re-level the bed or increase the heated bed temperature;
If the X and Y sizes  are different, you should calibrate the steps per mm for the direction that differs (M92 is the G-code to set the steps per mm; M500 to store the value to memory; these codes can be given over USB using specific programs that interface through a command line interface e.g. Pronterface, Repetier-Host or OctoPrintor alternatively in a .gcode file and loaded through the printer user interface);
If extrusion does look weird, measure the filament width at various sections of the filament with a vernier caliper and calibrate the extruder stepper and set the correct amount of steps per mm;
Finally, print the 20 x 20 x 20 mm cube and measure the height and adjust the steps per mm for the Z direction.

if you are using G-commands then it will be nice to tell OP how to issue them (proface, serial monitor etc)  to the printer - what do you think?

Fix was actually pretty simple.
I just removed the printer that I had setup on CURA following the manual provided by Creality (found on the provided SD Card) and started from scratch.
The one that worked was actually setting up the printer as a Creality CR-10 and then just changing the XYZ dimensions. This setup has the Origin at Center option unchecked as suggested in the comments.  That's all it took...

New results:

You must have messed it up a little as what you describe what you did you normally would not get this much improvement!

@Oscar : The provided SD card comes with a preset intended for the Ender4 the manual indicates to use that, however what worked for me was to start from a CR10 preset and change the dimensions afterwards. Not sure why the warping was happening but that fixed the issue.


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Geeetech GT2560: Electronic safety and power source
I'm about to build myself a 3D-printer.
After a long search for a brain for this one I came across the GT2560 from Geeetech, because it leaves a solid impression on me.
The manufacturer himself has a quite extensive wiki page for this board.
My idea now was to use an ATX power supply.
The PSU is a be quiet! BN257. On 12 V (combined) it can deliver 324 W. On 12V1 there is 20 A, on 12V2 16 A.
Would that be enough or would you rather use a 24 V power supply?
Since I have read some reports about the Anet A8 and its danger of overloading, I am a bit uncertain, even if the GT2560 looks a lot better than the A8.
Are the connections to which the heating bed and the extruder are connected sufficiently large to withstand 10 A and 15 A respectively, or should I solder the cables directly to the board from the very first?
According to the information I received from Dr. Search Engine, MOSFETs of type STB55NF06 are used. According to the data sheet, these can withstand loads up to 60 V/55 A. I don't necessarily need to replace them with external ones, do I?

these can withstand loads up to 60V/55A, yes, but only for a very specific meaning of "withstand". The 55A rating assumes/requires the MOSFET to be attached to a very, very large heatsink, dissipating a large amount of power. In practice, these MOSFETs aren't good for anything more than 10A or so. Take MOSFET power ratings with a very big grain of salt unless you know a thing or two about electronics.

@TomvanderZanden maybe a external Solid State Relay is a better choice?

It would be a better choice to make a separate question about MOSFETs ;-)

For sure. I will gather more informations on MOSFETs in general :-)

Whether 350 Watt is enough depends on the amount of Ampere can be generated over the 12 V lines. Computer power supplies add up the power of all the voltages! A nameless or cheap 350 Watt PSU may not deliver enough power (in the sense that they may never reach the given power), you should check that out. The high-end PSU's are usually well fabricated and can usually deliver more power (but should not be taken for granted!).

a typical (214x214 mm) heatbed is about 12 V/1.5 Ω = 8 Amperes (about 100 Watt),
a typical hotend is about 40 Watt,
steppers and board could draw another 5 Amperes (about 60 Watt)

This totals to about 200 Watt, which your PSU should be able to generate without a problem.
Those green connectors plug in and out of the board don't they, usually with those small pins, transporting up to 10 Amperes is not recommended, you should look up the ratings of those connectors.


text:
DQ542MA Driver proper settings for NEMA 17 Stepper Motor
Using a 24 V power supply I have two NEMA 17 stepper motors each driven by a DQ542MA stepper motor driver. I have the current settings on the driver set for a RMS of 1.69 and a pulse/rev of 400. When I run the motors they run extremely well but become extremely hot. I need help to figure out what would be the proper settings to use in order to stop the overheating.
Attached is a photo of the motor's setting tables:

It is completely normal for a stepper motor to get hot. Taking this datasheet for example, specifies a 80 °C temperature rise. That is, in an room that is 25 °C ambient temperature, the motors would get up to 105 °C.
To prevent the motors from getting as hot you could further reduce the operating current, but likely the temperature they're running at is normal.

and add a cooler as well :)

@profesor79 That should not be necessary. Steppers are designed to run without active cooling.

agree. I just don't like to get burnt when touching stuff


text:
Why turning off model cooling for first layer?
I had few printing troubles for first layer yesterday (will certainly ask there as soon as I can take photos) but one of the things I've noticed is that the model cooling fan (the fan that is supposed to blow air on the printed model, not the fan that regulates the noozle temperature) is turned off for printing the first layer.
It's a Dagoma DiscoEasy200, printing PLA on a non-heating bed (blue tape).
Wandering down stackexchange, I also read turn off the part fan for the first layer from https://3dprinting.stackexchange.com/a/5494/10836
So my question is:
what's the reason behind turning off the part/model-fan for the first layer?

Btw, I still lack reputation for that here but I guess a first-layer tag should be neat, knowing how important this is for 3D printing?!

I'm not sure that [tag:First-Layer] would actually be good for describing questions in a way that would help people with filtering.

Filament expands as it gets hot. Cooling the filament will make it shrink, so cooling the filament deposited on the bed can lead to adhesion problems and warping of your products. This is exactly the reason why you use a heated bed (the delta temperature is smaller). So keep the cooling off for the first layers and you'll be fine.

Additionally (having answered the question for not using cooling air for the first layer), I would like to add that sometimes you won't need any cooling at all (for other layers), or very little cooling.
Please do note that some filaments do not like to be cooled down too fast; this may lead to weaker layer bonding or other issues. E.g. POM filament will harden very quickly when cooled causing the nozzle to bump on the quickly hardened filament knocking the product over. Also I found that too much cooling air when using PETG leads to "string-cheese" products caused by insufficient layer bonding. ABS is reported to be even more sensitive for cooling (shrinkage during cooling is higher than of PLA or PETG filaments); a frequent advice is not to use filament cooling when using ABS filament.

Oh, now I get why heat bed is a plus, and I also get that cooling first layer is the total opposite of heating the bed... Thanks!

Thank you for this explanation, I believe it is the answer to my question here: https://3dprinting.stackexchange.com/questions/6878/why-does-my-part-cooling-fan-cause-stringing


text:
TMC2208 drivers - Microsteps configured incorrectly
I've just installed two TMC2208 drivers on my RAMPS board. I followed a very good step by step tutorial and after some issues, I got it nearly to work.
One problem I still have is that when I tell the printer to lift the Z axis by 5 mm, it lifts it by 10 cm.
I haven't changed anything regarding the steps/mm. Previously I had the Pololus, with 1/16 microstepping and now I also have 1/16 on configuration_adv.h file on Marlin 1.1.8
However what I noticed when doing a M122 is a line which reads:
msteps 256

which sounds like the microstepping was set at 1/256 instead.
Maybe somebody could tell me if I missed something?
UPDATE:
After some more digging into it, here is what I've done so far:

Solder the pins on the driver. Original from Watterrot
Solder the bridge pads for enabling UART communication
Solder the pin for the communication heading upwards
Change the configuration_adv.h on Marlin (1.1.8) and enable all that is to enable: USE_TMC2208, Enable debugging, selecting the Z axis, etc
Check the pins on pins_RAMPS.h and make sure they are available in my setting
Make a Y cable with the 1 kOhm resistor for the TX pin
Hook everything up

No matter what I did, the motor moves twice as much as requested. Although I set up 1/16 microstepping, the same I had with my Pololus, I performed the reverse calculation to find out that the actual microstepping on the driver is 1/8.
After more investigation, the issue seems to be that the driver is not recognized at all by the Marlin/Board. Thinking that it was a problem with the TX/RX communication, I dug into the available info out there and I found this, Bug: TMC2208 UART Communication uses wrong pins for SoftwareSerial #9396.
I proceeded to change the assigned pins for serial RX/TX, but everything is exactly the same.
I tried a different Arduino (original), another RAMPS board and even the 1.1.x and 2.0 bugfix branches from Marlin.
It seems that the driver is on "legacy" mode and software manipulation is not possible. Although I went through the steps to enable it.

tmc interpolate your steps to   256 in advanced configuration file:
#define INTERPOLATE       true  // Interpolate X/Y/Z_MICROSTEPS to 256

Mine even worse, I have all controllers TMC2208 and after some unrelated firmware update Z started to go twice match. Other axis are fine.

I had troubles with my TMC2208 V2.0 drivers on a SKR pro V1.1. This board has build in routes for serial connection, but the signal is expected on the NC pin not the PDN pin (UART is connected to the PDN only on the stepsticks board). I needed to solder/bridge the NC and PDN pins. Maybe your stepsticks boards don't have UART on PDN as well?

I don't have these controllers, but I read that with default settings the TMC2208 will interpolate the microsteps set by the I/O configuration pins to
256 microsteps. Please look into how you set up the dip switches / jumper caps on your board, it seems that only 2 are used (MS1 and MS2). Furthermore, can't you just decrease the count of the array  DEFAULT_AXIS_STEPS_PER_UNIT for the Z entry in your configuration file?

I can change the steps_per_unit, but that's a patch for the outcome, it's not solving the cause of it. I investigated further, please see the update on my original post...

Most likely your issue is related to the PDN_UART pin on TCM2208 Driver board, on some manufacturers boards the jumper is not set to UART mode by default, so most likely u need to solder jumper to right configuration. Look at datasheet of your driver board.
 for example
https://github.com/bigtreetech/BIGTREETECH-TMC2208-V3.0/blob/master/TMC2208-V3.0%20manual.pdf

He did that, it's mentioned in the UPDATE section


text:
Print only part (fraction) of a model
I've made a 9H-printing model tonight, and only a little part of it failed (because a support dropped off). I want to reprint only that little part.
How can I do that in Cura? How can I tell Cura to generate a gcode file so only that little part (inside the transparent cube below) will be printed?

I've placed the model upside-down on the Cura plate to "cut off" what was well printed. I've made a simple 3D cube model in Blender and placed it so it intersect with the part I want to print (I've set the "mesh type" of that cube to "don't support overlaps" for that). I've tried using "Mesh fixes: disable Union Overlapping Volumes" and the "Merge meshes" option, but the merge aligns the cube origin and the model origin (which I don't want).
What's the proper way to do such partial printing?

Btw, i'm not sure that I've used the "replacement-parts" properly, because it's a replacement part for the printed model, not for the printer (but keyword description is lacking)

The latest version of Ultimaker Cura can do that (version 3.6).
I have built models made of different material in the same model.
How to do this is:

Select your CUBE and select the icon "Per Model Setting" in left side menu.
choice "Normal model", select the following settings: Top/bottom thickness, wall thickness and infill percentage
Very Important: all above settings must be set to 0!
Select the model you desire to print and select the icon "Per Model Setting" in left side menu
choice "Modify settings for overlap with other model" and select the following settings: Top/bottom thickness, wall thickness and infill percentage
Select the desired infill percentage and the wall top/bottom thickness for the portion you want print
slice the model

Note: If you need to print supports, then in step 2 select "Modify settings for infill of other models" (instead of "Normal Model"), and in step 6 also select "Add Support" and any other support related parameters you may need. However, Cura needs at least one "Normal Model" to slice, so to fool it you need to also another Cube as "Normal Model" with the parameters of step 4 somewhere else in your build plate (it won't really print).

As far as I can work out, this also suppresses the supports, so fails for models which need them. Or this there something I've missed?

This works perfectly even in Cura 4.8
The only I had to do was to apply step 3 also to Top layers and Bottom layers settings. Just setting the thickness didn§t work and the cube still included top/bottom layers. Setting these to 0 as well fixed it.

In Cura 4.8, the toolbar on the left doesn't have names to the icons (anymore?) - could you modify the answer and describe where to click in terms of "2nd from bottom", etc.?

The most recent versions of Cura cannot do that for you. This is a removed feature (or better said: not ported from the old application to the new application), so installing an older version of Cura may work for you.
Alternatively there are many more pieces of (free) software that can do that for you. E.g. MeshMixer or the Slic3r application can do that for you. This video shows a demonstration how to do that.

On Tinkercad, you can import your stl and add "subtraction" cubes, and merge them with the parts you don't want printed.

I don't know if this helps but
download blender 3d, install
expoert your models as stl
import as stl file
enter into edit mode with tab key
and delete everything else
export as stl (maybe would have to set the scale to 100)

Hi, welcome to the 3D Printing SE! Please edit your answer and put proper punctuation or a bullet list (preferred) in your answer with the steps involved as the current answer is probably a valid answer but not very clear. While you're at it remove the typing errors :)

Indeed, that's how I proceed for splitting the model.

What you can also try is to separate the part from the rest of the model within your CAD software. In FreeCAD for example, you can use the mesh design workbench to cut the small part away from the rest, then you slice this small piece and print it.


text:
Uneven wall thickness with test cube
I noticed that one edge (which is also the starting point of the print) is always bigger than the other three. Additionally, the walls do not have the same thickness as well. The wall thickness (starting from the thick edge) starts very thin and gets thicker till reaching the thick edge again. Does anyone have a clue whats the issue?

Seems to be an error on your STL file, sometimes the polylines creates an inverted face or some line is broken.

are you printing from pc or from sd card?

I print from a SD-Card

This happens when you have poor retraction / oozing.
Signs of too high temp and poor retraction

Thick blob at start point, meaning moltin plastic is oozing out as you change Z position
As you see at the end of the line less material, you prematurely oozed out liquid plastic. As the melt zone is depeleated you get thinner lines.

Solutions

Increase retraction distance. This will remove the plastic from the melt zone and prevent some of the oozing.
Speed up Z axis lower and raising. Or decrease distances
Lower temps. Start with 3 cel increments. You want to go as low as you can without causing print defects.

You will likely need to do 1 and 3. 2 you really shouldn't need after you fix your temps.

As Fernando suggests, the problem is likely with your source file.  One easy way to verify this is to slice twice, rotating the STL by 90 degrees.  If both prints produce fat/thin sides in the same dimension on the print bed, then it's a printer problem.  If the fat side rotated with the STL orientation, then the STL is at fault.

@dgrat Also you can try to preview in Pronterface your gcode generated before printing, When I started to print I got this kind of errors,  so I previewed all my gcodes with that program. Now I  use 3D symplify this program give the preview with great detail at that moment on creating the slices; if the shape is correct then I create the valid gcode.


text:
Getting precise measurement of a complex rod
I'm trying to build a headrest for my Sayl office chair. For that, I'm designing a 3d-printed part that's going to fit on one of the existing rods of the chair.
Check out this picture:

How would you go about in getting the exact measurements of that white rod? I tried a caliper, and I'm able to get the width and depth, and I can just assume that the rod's profile is a perfect ellipse, which is probably a close estimate. But say that I want to get a more precise measurement. Is there any technique to do that?

You willing to disassemble the chair and use scanning techniques such as a 3-D laser scanner?   More to the point: what is the intended operation of your add-on part? Does it need to fit to a high precision or can it go with an oversize hole?

you can make a mold with modeling clay and then slice up the mold to take "samples" at a regular interval with a pair of calipers.

In an earlier comment you stated that you cannot take it apart. So without taking it apart, you could try to determine the profile the old-fashion way with a piece of cardboard and a short pencil, just cut the rough shape of the rod and place it onto the rod, then take the short pencil and draw the profile onto the cardboard with the pencil parallel to the rod. Measuring the distance from the pencil center to the pencil radius will give you the profile of the rod with that off-set. This technique, or the technique used to create notches in logs for log cabins may be used to find the profile at various sections which have to be entered in a 3D CAD model program and splined/lofted to get the surface of the rod.
Alternatively you could use a profile shape tool carpenters use:

You need to disasemble the part and measure it with special equipment, a caliper can help but only as reference since the part has an angled shape.
I recommend to use an optical comparator (base shadows) with this you can have X and Y data to calculate the angle and curves. If you want more precise measurements you can try an Optical Measurement Device (based camera), this also can give you Z but X and Y will help you a lot. Both equipments use a system called Quadra Chek many industries has at least one of this to assure his quality due meets all requirements for Ford GDT guides (geometric dimensional tolerances). no matter the manufacturer brand.
I´ve tried to measure with the phone or table application but is hardly to calibrate on each required dimension. I had to buy an optical comparator.

Depends on the accuracy required to meet the needs of the add-on part.

In an earlier statement the OP said Nah, can't pull it apart.

You could pull it apart and have it 3d scanned if you want to know the exact dimensions. There are companies that can do that for you at a certain price. Our company has used such services in scanning various parts before we obtained our own laser scanning device.
The question is whether you want exactly the same (dimension wise) part (maybe you do for ecstatic reasons) while a part that is a little more beefier would work also.
Edit:
Although tagged with 3D scanning, the OP did not mention whether he would be able to disassemble the part. 3D scanning is an option when taken apart. Another solution has been posted since.

Given that the question is already tagged "[3d] scanning", I don't think this really helps much. How do you get something 3D scanned? This is the equivalent of answering "How do I take a portrait photo" with "Using a camera.".

Nah, can't pull it apart. Thanks for the information though.

Well, if 3d scanning is out of the question if it is not taken apart, the whole answer can be deleted. Either way, the tag should be deleted as well.


text:
First layer height problem after changing nozzle
I have a problem with my first layer height. But lets start at the beginning:
I own a Tevo Tarantula Dual extruder printer with a endstop switch for Z axis.
No Auto bed level. 0.4mm nozzle.
Everything worked as it should. I home extruder with G28 command and level the bed using a piece of paper or a thickness gauge 0.1mm. In the slicer I set Initial layer height 0.2mm for layer height 0.1mm. The fisrt Layer looked perfect and sticked to the bed fine.
a few days ago it stopped in the middle of a print, nozzle clogged.
No problem i changed the nozzle to a spare one i had. It is not the first time i took it apart.
Here starts my problem:
After everything was build together again i home the extruder with G28, level the bed and start a print with the same settings i usualy used to print.
But either the first layer didn't stick to the bed at all or looks terrible.
i tried to level the bed again and also tried to get it to work with playing with the settings. But with no satisfactorily results.
Here is is the part my Question starts:
I noticed that the first layer is actually not at the same Z=0 if i use G28 to home and the Z0 it shows when i print a part.
For example:
Set G28 Level bed with 0.1mm thickness gauge.
Then start printing with layer height 0.1mm and initial layer height setting 0.2mm
The result should be 0.1+0.1+0.2 =0.4 real layer height (if i also count the 0.1 layer heigth(not sure if this is correct)) the printer shows here a Z of 0.2
But if i meassure it, it is around 0.7mm thats way to much.

I am confused why this is the case after i changed the nozzle. Considering i leveled the bed the exact same way i did before and used the same slicer.
The new nozzle is a little bit shorter but i made sure both nozzle of the dual extruder have the same height.
I do not understand why this happens. Is there a way to reset the Z?
I tried the M851 code but as far as i understand it, it i used for Auto-Bed leveling. It didn't work anyway, says unknown command.
I could work around the problem by adjust the endstop until it somehow works, but then if i want to level the bed and use the G28 code the nozzle would crash into the bed and that is not a satisfactory solution.
Would it suffice to set a z-offset in the firmware? I don't have much experience on that area.

;FLAVOR:Marlin
  ;TIME:737
  ;Filament used: 0.351177m
  ;Layer height: 0.1
  ;Generated with Cura_SteamEngine 3.2.0
  M190 S47
  M104 S197
  M109 S197
  M82 ;absolute extrusion mode
  G21 ;metric values
  G90 ;absolute positioning
  M82 ;set extruder to absolute mode
  M107 ;start with the fan off
  G28 X0 Y0 ;move X/Y to min endstops
  G28 Z0 ;move Z to min endstops
  G1 Z15.0 F9000 ;move the platform down 15mm
  G92 E0 ;zero the extruded length
  G1 F200 E3 ;extrude 3mm of feed stock
  G92 E0 ;zero the extruded length again
  G1 F9000
  ;Put printing message on LCD screen
  M117 Printing...
  ;LAYER_COUNT:9
  ;LAYER:0
  M107
  M204 S2200
  G0 F3000 X75.185 Y64.596 Z0.2
  M204 S1750
  ;TYPE:SKIRT
  G1 F1650 X76.267 Y63.316 E0.06132

What is unclear (i.e. to me) is whether you did change the z endstop height after the nozzle swap. If the nozzle is shorter, the endstop should change (be lowered) as the gap would be too large; so move it down. Setting a software offset will not work as it cannot get passed the zero level of the endstop (unless you enabled that in the firmware, but should not do if it evolves a mechanical switch). Please note that the initial layer is 0.3 not 0.4, the normal layer height should be omitted.

No i didn't change the endstop. Instead i moved the bed up to close the gap. If i use the G28 command it moves to Z=0. Bed is leveled in all corners and also in the middle and everywhere is the gap between new and old nozzle 0.1mm. If i start Print the gap now is drasticly bigger (0.7 mm). Adding all numbers Z shows 0.2 and the 0.1 when leveling should make 0.3 mm gap. But instead it is now 0.4mm higher. If i home it again with G28 and i measure the gap it is again the 0.1mm.

this is a common case in my TT....
Please check the y-carriage wheels - on the 2040 and 2020 profile.
Mostly you shall find a little wobble on one of the ends, that introduces instability in leveling, so you could level it, home it and another level is needed.
In my case, I decided to upgrade for dual-z drive - please see this
Another interesting Z upgrade:
option two
We can observe z-wobble by watching the x-axis on the left side (no lead screw), it will have a little delay in response when moving up/down comparing to the other side.

I checked all wheels. No wobble. If i home the level is ok repeatadly.

in that case could you post first 30 lines from g-code generated file?

Had time to do some more testing. I think you were right, the leveling is not the same if i move the Z-Axis up a little bit and then home again. Thats where the gap was coming from. Although there is no noticable wobble in any of the carriages.
Thanks for the help.


text:
Efficient packing of models with chains
I have a model where several solids are linked with chains. The original design contains a lot of empty space.
I am looking for software, which can automatically move the solids and fold the chains such that the total build volume gets smaller (total build volume is a major cost driver on shapeways.com). Obviously, the topology of the design must not change, i.e., it should be possible to return the model to the original state without breaking chains.
I tried Blender - Rigid Body Physics, but that has stability issues.

This is relatively easy to do in any CAD/mesh software.  For example, if you load import the model into Meshmixer, you can select a given solid and N links of chain connected to it (using "expand selection to groups" or similar to be safe). Then use the "Separate" command to allow you to move/rotate that subset on its own. All you have to do is make sure the two chain links at the point of rotation remain disjunct.
Once you've moved everything around, just SelectAll and export.

I was looking for an automated solution, as the model is very complex. (My original question was unclear)


text:
OpenSCAD library for empty space/holes
I am working on a design in OpenSCAD, and need (would want) two things that seem tedious to hand-code:

A pattern of holes in a wall, for less weight/material. Could be round holes or some geometric pattern.
Empty enclosed space, with some grid-structure for stability. Again, for saving weight/material (and time during the printing).

Are there any libraries for these things?

I'm not aware of libraries that do that for you (but you can create your own, see end of the answer), but creating a relieve hole pattern is not that difficult or tedious using iterator functions (e.g. the for loop). Note that it may not be a good idea to make enclosed holes inside your object, see the bottom section "Internal cavities in models" at the bottom of the answer.
Small OpenSCAD test script:
 tol=0.2;

 difference(){
   cube([100,100,10]);
   for (x=[10:20:90]){
     for (y=[10:20:90]){
       translate([x,y,-tol/2]){
         cylinder(r=9,h=10+tol,$fn=180);
       }
     }
   }
 }

This can be used for both parts of your question, but in case the pattern needs to be inside an object you need to lower the value of h in the subtracting cylinder and raise/translate it (you could use the center=true in the cylinder function as a parameter and raise the center to the middle of your object translate([x,y,objectThickness/2])). You could make a module of the recurring pattern yourself to create your library.
note: Replace cylinder with cube or any other geometrical solid or (2D) pattern (use linear_extrude) to subtract from your part.

Internal cavities in models
Note that it is not always wise to create your own spacing/grid structure enclosed in the model. Please read the accepted answer of this question. This answer explains that slicer applications work best with true solids!


text:
Delta printer nozzle not moving square with a perfectly level bed (as if the bed is bent... but it isn't)
I've been having this problem with my delta 3D printer where my nozzle isn't moving flat with my print bed (as if the bed is bent) but I have used the edge of my steel ruler and it seems to be perfectly flat. I have properly leveled my bed with a piece of paper and have checked the whole printer to make sure it's square but the problem continues.
What else could be the problem?
Addition info (from comments)
The gap grows and shrinks in a parabolic manner and it makes it impossible to get a good first layer. the printer is a FLsun Delta Kossel. The links don't appear to be loose. Is there a way I could share a video?
Upon further inspection I found a bit of play in one of the links, I tightened the bolt and the play is gone but it didn't fix the problem.
I have been playing around a bit and I found that the nozzle is closer to the bed in the center than it is near the edge.
I did some research and it's a calibration issue but I have no idea how to fix it. Does anyone know a quick and easy way to calibrate a Kossel Delta 3D printer?

welcome on 3d Printing. Could you kindly add a photo of the printout and point us to the stl file, that will give us more details to help you.

When you say the bed is physically planar, does the nozzle gap grow linearly from one edge to the other, or does the gap grow and shrink in a  parabolic manner?    I haven't used a Delta printer, but it is quite possible that the V-linkages are slightly out of alignment.

You should post the model name & number of your printer, along with any alignment processes recommended by the manufacturer.

It sounds like your bed (or rather the Z0 plane - see tjb1's comment below) is convex. The video that I refer to in my answer is dealing with a convex bed, so it should give you a pretty good idea of what steps you need to take. If your bed was concave, i.e. the nozzle is further away from the bed at the center than at the edges, then you would need to do pretty much the inverse, i.e. you will need to raise where the video lowers, and lower where the video raises.

@Greenonline it may cause some confusion saying the bed is convex/concave as people may think it's the actual print surface that is incorrect where it's actually the Z0 plane that is incorrect.  The beds will have some imperfections but an incorrect delta radius can cause several mm of movement up or down as the head travels across the bed.

@tjb1 - Thanks for the feedback, as I wasn't aware of that fact - I only know what I have seen in the video. I've modified my comment. You should post that info in your answer as it is significant enough to merit more than just a comment..

Unfortunately, we can't inline YouTube videos at the moment, but that may change. However, you could post a link to a video.

Have you found & fixed the problem? If any of the answers helped you to get an answer to your question or come to your own conclusions then please do vote & accept an answer (using the tick button next to it). This helps us reduce the unanswered questions list & stops the question from being bumped once in a while. If you found another answer (than those already posted), please add that answer (& accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

Delta radius controls how the print head moves from the outside to the center.  From the comment you posted, it sounds like your radius is too large which is causing it to hit in the center and you need to make it smaller to bring the center up.  This is not always a number you can directly change as it is sometimes calculated using other offsets so you will need to find that in your firmware.  Also after doing this you're likely going to need to adjust endstops for each tower again or the Z travel to fix your 0 point.
I would recommend following the steps listed here for your calibration.

I have absolutely no idea how to edit the firmware and it seems super over whelming for a beginner like me. my printer has been calibrated in the past but not by me, A friend was upgrading to a better printer and basically gave his old one to me. so i have none of the old firmware settings. so am i going to have to redo all of the firmware tweaks? or is there a better way. thanks for the help

Unless you have a newer controller like Re-Arm, Smoothieboard, or Duet then the firmware is likely flashed and not recoverable in a readable format as far as I know.

are there any really good and simple start to finish guides for beginners?

That really depends on what kind of controller you have.  Boards like RAMPS can support many different firmwares so it's really up to you on what firmware you want to use but certain boards are limited and may required more tweaking or a copy of the firmware from the manufacturer.

i use repetier host, could it be a slicer problem? because when i first got the printer, it printed fine. i got a new laptop and i think that's when the problem started.

If it's truly changing nozzle position as it moves across the bed then it's unlikely to be the slicer.

then why would it go from being perfectly fine to having this problem?

oh, i just thought of something. when i got my new laptop repeteir host seemed to think that z0 was below the bed, so to fix it i moved the end stops upward. would that have caused the issue?

@DanCrankshaw It would screw up the 0 plane and may cause it to be tilted from the actual print bed but it shouldn't create a high center condition.

Calibration, the part everyone fears. It is actually not that hard.

Calibration on any printer is difficult, but especially so on deltas, as there construction is more complex than a cartesian printer.
Print beds are rarely flat (maybe in 1% of cases they are flat), and are usually either convex or concave.
Have you manually calibrated the printer (at both the center and the edges), such that you can just about get a sheet of paper between the print bed and the hotend nozzle, at z = 0? This last check ensures that the first printed layer of extruded filament is actually touching and "presses on" to the print bed.
I seriously recommend that you watch this video #18:Calibration for a great explanation on the use of the paper. This video is for a Delta printer, a Kossel XL (although the Kossel Mini is also covered) and it clearly demonstrates the height that the zeroed print head should be at, and how to check using a sheet paper.
It is an hour long tutorial video, by Tom of BuildA3DPrinter.eu, and it shows you step-by-step how to calibrate the printer, and also how to deal with deformed beds (concave/convex). It uses:

Arduino IDE, and;
Pronterface
and performs the calibration by adjusting, in the firmware:
MANUAL_HOME_Z_POS, and;
DELTA_SMOOTH_ROD_OFFSET

Here is a run down of the video's contents:

0:00 Intro: The perfect first layer can be obtained, either with/without a probe (the printer is, arguably, better without probe) This tutorial is without the probe.
0:55 Arduino software loaded with Marlin firmware source, looking at the file configuration.h and in particular, the line #define MANUAL_HOME_Z_POS
2:30 - Ensure that the Pronterface USB port is disconnected as otherwise this will inhibit the Arduino IDE from connecting to the printer.
3:20 - Initial test - Gap at the center of the bed

Connect with Pronterface and use the following G-code commands
G28 Home the printer head
G1 Z10 Bring the head down...
G1 Z5 a bit more...
G1 Z4 a bit more...
G1 Z3 a bit more...
G1 Z2 a bit more...
G1 Z1 and if the head hits bed then this is too close
G1 Z2 raise the head again
Paper thickness is 100 microns, place under the head
G1 Z1.5 lower the head again, but no by so much as before
Slide the paper between head and bed. The paper should move freely, but with some friction felt (you should be able to hear the head lightly rubbing against the paper)

7:11 - Deduction of actual distance from print bed is 1.5 mm
7:30 Return to firmware, and finely tune MANUAL_HOME_Z_POS in the Arduino IDE, disconnecting Pronterface again and upload.
8:10 - Return to printer

Connect with Pronterface, again, and use the following G-code commands
G28 Home
G1 Z5 F5000 Move head down rapidly
G1 Z2
G1 Z1
G1 Z0 and the head comes to a rest at the correct distance from the bed
Retest with the paper

9:30 Final test

G28 Home
G1 Z0 Go from home straight down to the bottom

10:02 - Further calibration

G1 Z0.2 Raise head ever so slightly to give us some room
In Pronterface - Move the head horizontally
G1 X50 - Moves head 50 mm to the right
In this case, if there is a larger gap between the head and the bed. This means that the bed is curved, and convex. If the gap was smaller, or the head hits the bed, then the bed is concave

11:40 - Diagram of convex and concave print beds
12:10 - Endstops

G1 X-40 Moves the head to the left (of center) and the head is now further away from the bed than in the middle.

13:20 - This means that the endstops are not correctly positioned. So, before tackling the concave/convex issue, it is first necessary to adjust the endstops, for each tower.
13:37 - Tackling the tower positions individually

G1 Z10 For safety reasons, leave a margin of 1 cm.

14:08 - Calibrating the X tower (left tower). Note: The commands will depend on whether you have the Kossel or the Mini.

Printer moves in three axes:

X: parallel (to the front);
Y: perpendicular (to the front);
Z: height (not of interest at this point).

X tower is not in either of these axes exactly
G1 X-100 Moves the head to the side but 6 cm away from the X tower
G1 X-100 Y-60 Positions the head next to the tower correctly
G1 Z5 - Lower the head bit by bit
G1 Z2
G1 Z1
G1 Z0 and the head is still 1 mm too high

16:50 Endstop needs to be adjusted by 1 mm lower. There are two ways of doing this:

Lower the endstop itself - good for large changes
Adjust the screw - good for smaller adjustments. Turn it anti-clockwise, and raise the screw by 1 mm.
-G28 Home
G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X-100 Y-60
Mini G1 X-60 Y-35

G1 Z2
G1 Z1
G1 Z0 Head hits the bed
G1 Z0.2
So the end stop needs to be raised by 0.2 mm, by re-adjusting the screw (turning it clockwise).
Now home it the head, G28
And bring it down G1 X-100 Y-60 Z0 and it should not hit the glass and the paper should slide underneath

21:00 Minor re-adjustment and fine tuning so that the paper slides without the need a too much force.
21:50 Repeat for each tower
22:15 Y Tower (right tower)
-G28 Home

G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X100 Y-60
Mini G1 X60 Y-35

Repeat the above process - remember to test with G28 and G1 X100 Y-60 Z1 for safety, and then adjust the Z command
This is an iterative process

28:04 - Z Tower (rear tower)
-G28 Home

G1 Z10 Bring head down 1 cm above bed
Move to the tower:

XL: G1 X0 Y120
Mini G1 X0 Y70

Repeat above process

30:14 Re-check! each position (center, X, Y and Z towers)

G28 Home
G1 X0 Y120 Z0 Check Z tower & drop head (head should not touch the bed)
G1 Z10 Raise head (see below)
G1 X-100 Y-60 Move to X tower
G1 Z0 Drop head (head should not touch the bed)
G1 Z10 Raise head (see below)
G1 X100 Y-60  Move to Y tower
G1 Z0 Drop head (head should not touch the bed)
Calibration of the endstops is now complete

31:30 Why the Z10?

G1 Z10
G1 X0 Y0
The first calibration was the center point, but now the endstops have changed and as the bed is either convex or concave, we therefore raised the head by 1 cm, using the Z10, to avoid hitting the bed in the center. Now test it
G1 Z2 Lower head slightly
G1 Z1
G1 Z0 If the bed is concave then the head is still too high! Conversely, if the bed is convex the the head will hit the bed.

32:40 Adjusting the DELTA_SMOOTH_ROD_OFFSET in configuration.h - alter the physical parameter of the printer:

Convex: Increasing DELTA_SMOOTH_ROD_OFFSET lowers the hotend in the center
Concave: Decreasing DELTA_SMOOTH_ROD_OFFSET raises the hotend in the center
Adjust the setting in the Arduino IDE and recompile and upload (ensure that Pronterface is disconnected)

35:07 Testing the new DELTA_SMOOTH_ROD_OFFSET setting - again in Pronterface:

G28 - As the firmware has changed, we must re-home.
G1 X0 Y0 Z0
You will notice the the center point has not changed! It is the same. However if you go to the tower positions you will see that the (previously) perfect gap has changed. This is because by changing the DELTA_SMOOTH_ROD_OFFSET the center stays in the same place but the edges change instead. So, for the convex bed, we have virtually bent the surface, without moving the center point down, and moved the rim up (or, for a concave bed, down - depending upon the direction of the adjustment), thereby flattening the bed.

37:10 Demonstration of adjustment
37:51 Adjusting the height

Return to the firmware and change, again, the #define MANUAL_HOME_Z_POS line that we changed at the beginning, adjusting it by the amount that the head is from the center point.
Disconnect Pronterface and upload the new adjusted firmware.
Then reconnect Pronterface, and Home (G28) and drop to zero (G1 Z0).
The head may still a little too high.
Then move to the tower, and the head may be too close to the bed, without any gap. This means that the bed is still convex and further adjustment is required of the DELTA_SMOOTH_ROD_OFFSET and then, obviously, the MANUAL_HOME_Z_POS.
Again, this is a bit of an iterative process. Don't forget to home after any firmware updates.
Finally once the bed is flat (i.e. it has been virtually flattened in the software) and the gap between the head and the bed is the same at the center and the towers, then adjust MANUAL_HOME_Z_POS (an adjustment of 0.05 or less may be required) to get the paper test just perfect.

44:35 Check each tower (screw adjustment, of the endstops, may be required). As the bed has been flattened, mechanical sub 0.1 mm adjustments may be required. Note that the firmware does not need to be re-uploaded, when making mechanical changes - although the head will always need to be re-homed (G28) after each change.
The head should now be at the correct height.
47:14 - Extruder Calibration