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How to unclog a clogged extruder?
I have a Wanhao Duplicator i3 v2 (A.K.A. Maker Select, Cocoon Create).
My extruder got clogged: I noticed that it wasn't extruding, so I stopped my print, removed the fan, heatsink and the extruder motor and I saw that the clog is at the heater block level.
This is a what I have:

As you can see, there is some PLA clogged at the very beginning of the 1.75mm hole in the extruder block.
I can see there is something white inside (a stone? something that is not PLA?). I tried to heat up the extruder to 250°C and pushing with an hex tool but the block did not move.
I solved a lot of clogged nozzle issues with the cold pull method, it always worked like a charm, this time I tried too but as a result the PLA filament broke and the "stone" is still there.
Does anyone know if there is a way to unclog the extruder in this situation?
Do I have to change it?

I'm sure this is not the best solution, and if you have some ethyl acetate you should try that before going "the hard way".
Ethyl acetate is a solvent for PLA, so if you soak the extruder into it PLA should melt and free the extruder.
That said, this is the "hard" solution that worked for me.

You'll need:

A drill
A 1mm drill bit
A 1.5mm drill bit

Insert the 1mm drill bit into the drill. If your drill has a setting to reduce the drilling speed, take this to the minimum speed. If your drill doesn't have such options, you'll need to push the drill button very gently.
Put the drill bit on the pla block (be sure to not touch the cooling block, you might ruin it). Start drilling at the minimum speed and push very gently, until you get a side-to-side hole on the PLA (you know it because you feel no resistance at all while pushing the drill).
Take the 1.5mm drill bit and repeat the same operation. At this point my PLA block literally exploded (now I have some broken PLA inside my room, don't know where) and the extruder was finally free.
I hope this helps someone. Please notice that you need to be very gentle in order to avoid breaking parts of your extruder, but if I managed to do it, you can do it too ;)
As previously said, if you have ethyl acetate try soaking the extruder into it to make PLA dissolve before trying this. Try this solution only if all other options didn't help.

I've used similar techniques but with a pin-mount handle.  That way you can rotate the drill bit very slowly and with minimum pressure.  Retract regularly to clear the bit of loose material to avoid jamming.

Steps:

Take the tip off, assuming it has a tip.
Heat up the extruder.
Take a length of plastic and push it though the extruder.
If the tip is clogged, then take a micro hand drill to clear the blockage.

This may not help, but I have a printrbot and when it clogs I heat up the extroder to 210C(for pla) or whatever the normal temperature is. Then manually push your filament through the hole till it's as far as it can go, then drop the hotend temp to 100 degrees C. When it is at 100C pull the whole filament out and hopefully your clog will come out too. After that just cut off the end of the filiment that has the clog on it. And you're good to go.

Thanks for the answer, but as I wrote in the question I already tried the cold pull method (= the one you described), and it didn't work.


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Why would one choose 12 V from 24 V, from a safety standpoint?
I have seen many people saying on this site and many other 3D printing websites that 24 V systems are safer, compared to 12 V systems. By safer, I am talking in terms of fires or other electrical and component failures.
Why would a 24 V system cause less danger? I would think that 12 V would be safer because it is very common (automotive) and many parts have been around for a while that use it. Although there are an increasingly amount of boards that support 24 V, many don't or need fuses or other parts that do support 24 V.
Also, many parts that I have used are rated for 12 - 24 V. A 12 V power supply can go a bit over fairly comfortably. A 24 V power supply can't without partially going over the rating.
If I had to build a printer designed with safety as a main priority, what voltage would be best?

safer than what?   further, are you confusing component safety and personal safety?

Safer than 12 V. I am talking about risks of fire or other electrical failures. Edited to include details.

A component rated for 24 V nominal will have enough margin to allow for supply variation. The more sensitive components are protected by regulators (which are likely to be specified to work up to 32 or 36 volts). Automotive 24 systems run at 28 V when on-charge, just as an example.

The most important "safety" advantage when using 24V (compared to 12V) is that to get the same power, you only need half the current. A 192W heated bed would need 16A at 12V, but only 8A at 24V.
Since one of the most common safety issues is underrated screw terminals being used for the heated bed (just search for "3d printer fire"; you'll find quite a few pictures of charred plastic around screw terminals). For example, the screw terminals on RAMPs board are only rated for up to 12A. That would be okay at 24V, but well over the limit at 12V.
Since the wire gauge is dependent on current, you can also use somewhat thinner wires with a 24V system (or equivalently: wires that would melt in a 12V setup won't in a 24V setup). The power dissipated in a wire scales quadratically with current, so the same wire being used in a 24V setup would only waste a quarter of the heat of that wire in a 12V setup. There is also less strain on switching devices (such as MOSFETs or relays). The same applies here: power loss is quadratic with current.

As a caveat, note to select correct hardware! E.g. a heated bed for 12 V with a fixed resistance will consume twice the current at 24 V, requiring thicker wires; hence just switching to 24 V is not necessarily more safe!

From a pure safety standpoint there is nothing about a 24v system that is distrinctly more safe than a 12v system. I see you added comments about something involving wire sizes. This is not really a factor.. I would say not knowing what wire size to use is a whole other issue. There is nothing stopping you from putting on larger wires.
The following websites verify the fact that a 24v needs smaller wires. Though again the system it self is not safer because the wires required are smaller.

JamesTown
SDC minimum wire gauge to distance chart

I will also note the size difference is negligible anyways. It is not a major difference.
Now one exception to this. If you had a 24v and a 12v compatible board. I would pick a 24v. The reason is not that the wire sizes needed are different. But for the reduced danger of the CONNECTOR that the wires attach to. I see quite often in the flashforge owner group boards that have caught fire due to a cheap connector that can not handle the load for the printer.

I have seen comments on this site with people who have seemed pretty convinced that 24 V is much safer. They have talked about how smaller wire sizes are needed, and how if you undersize wires it isn't as much as a problem with 24 V. I wrote this question to see if there were any other reasons that 24 V was preferred from a safety standpoint.

You want to use a higher load with smaller wires.. I think these guys are trying to get you to burn your house down.. Don't believe every yahoo on the internet...

Their main argument is that with a higher voltage, a smaller current is needed, and therefore smaller wires. Undersizing wires will lead to heating, and not fires. Is that not true?

Wire size is a bit out of the scope of 12 v 24.. Someone with an EE background will come along and answer better than me. I have found some google results. However the size changes are marginal.

For sure, updated with the info in question. Not a myth, more of an exaggeration. Again your printer will heat up way faster on 24v.

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Bed design for magnetic easy release when printing PLA
I print on a glass bed covered with BuildTak. Prints stick well, release is difficult. They sell a mod, self adhesive magnetic sheet that holds a steel plate which in turn you put the BuildTak on making it easier to get your prints off by twisting the flexible steel as opposed to chiseling your print off a glass plate while attempting to not peel chunks of the expensive Buildtak off.
Magnetic sheets have different strengths proportional to thickness in milimeters. I can get 0.03 mm locally which provides 85 lbs pull per sqft. and was wondering if this might work. It's hard to find the stronger pulls, 0.045 mm and 0.06 mm which can pull 115 and 145 lbs respectively.
I'd prefer cut my own new bed sandwich rather than pay 90 bucks for one.

Has anyone made a bed using adhesive magnetic sheet>
What thickness magnetic sheet has worked for you?
What thickness steel are you using?

Assume it has to flex easily to twist the part of and also flexible enough for the magnet to pull it flat.

With respect to the comment by tbm0115:

I don't think you need that much magnetic pull for this application. Adhering basic coin magnets to a material in a large array should secure the material appropriately for a desktop printer.

I see where you are going with coin magnets. Have you tried this? In the original Makerbot Cupcake this is how it was done though with larger build surfaces you get warp on metal plates. Most metal sheet comes from the plant on a roll. Though your metal looks nice and flat, temperature changes will cause it to warp and as you know with SLA printers, a changing bed can cause a failure. This happened on the original Makerbot replicator 1st release followed by using a machined plate as a replacement.

Whats the question?

I don't think you need that much magnetic pull for this application. Adhering basic coin magnets to a material in a large array should secure the material appropriately for a desktop printer.

Hi, Davepix, and welcome to 3D Printing SE! As pointed out by several here already, exactly what you are asking about is a bit unclear at the moment. I have therefore put your question on hold, so that you may clearify this by editing your question. When you are done, press the reopen link below your question.

I see where you are going with coin magnets. Have you tried this? In the original Makerbot Cupcake this is how it was done though with larger build surfaces you get warp on metal plates. Most metal sheet comes from the plant on a roll. Though your metal looks nice and flat, temperature changes will cause it to warp and as you know with SLA printers, a changing bed can cause a failure. This happened on the original Makerbot replicator 1st release followed by using a machined plate as a replacement.

Follow up:
I used the 6mil magnet, cut a sheet of thin steel, (about .5mm) to fit, added a layer of Buildtak and now it's much easier to remove prints, build surface is very flat. I assume you could deform the metal beyond the magnet's ability to flatten it but it works quite well. The metal was cut with sheet metal snips, risky as they can bend the sheet. Probably better done with a saw though.

Try using buildtak flex. https://www.buildtak.com/product/flexplate/
or cheaper alternatives:
http://www.printinz.com/printinz-plate-3d-printer-bed-upgrade/

This does not answer the question, which asks about DIY solutions, and doesn't ask for suggestions of commercial alternatives.

@Tom van der Zanden I disagree, The OP was hinting at a DIY approach because of known cost to OP for said materials was too high, however he/she did not explicitively declare that they were looking for DIY solution. Therefore offering a cheaper alternative might be useful to to the OP since the price was the initial cause for hinting at a DIY approach.

@Eagl3 Welcome to the group! Though I have to agree with Tom. See "I'd prefer cut my own new bed sandwich rather than pay 90 bucks for one." "Has anyone made a bed using adhesive magnetic sheet", "What thickness magnetic sheet has worked for you?"
"What thickness steel are you using?"  Just keep in mind we have to be fairly strict on answering the question precisely given our format. So don't take offense.

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Stepper Motor for Prusa i3
We have stepper motors with these specs:

1200 mA
4 V
3.2 kg • cm

Are these enough for building a Prusa i3 3D printer?
(I live in Turkey and these are the specs of the NEMA 17 they sell in here)

Pet peeve: Torque is measured in kg·cm, not kg/cm.

Hi TuanSSM. This question is too vague. I can link you 3d printers that work off Lego kits. Or ones made from DC motors from HP printers. If there was an electronics you were looking to use or so on.. we could help.

Are they really 32 kg•cm, and not 3.2 kg•cm (or 32 N•m)? That seems either awfully high, or I am reading it wrong..?

Awful answer, I know, but it depends... on where you are going to employ them:

are they are all, or just some, of the axes, or;
just for the extruder?

If they are for use in translating movement of the axes, then the weights of:

the y-axis plate;
the x-axis carriage, and;
the print head,

will all come into play - amongst many other things.
With a torque of just 32 N • cm1, they seem, at first glance, to be a little underpowered - a torque of 44 N • cm (4.5 kg·cm) is the recommended minimum. Also, the current, of 1.2 A, seems to be a tad on the low side, 1.5 - 1.8 A is recommended.
There are some great resources on the RepRapWiki. See:

NEMA 17 stepper motor, and;
Stepper motor

The minimum (recommended) specifications, for a Nema 17 stepper motor, are:

1.5 A to 1.8 A current per phase
1 to 4 V
3 to 8 mH inductance per phase
44 N·cm (62 oz·in, 4.5 kg·cm) or more holding torque
1.8° or 0.9° per step (200/400 steps/rev respectively)

You may be able to get yours to work, but is it worth the hassle, just to save a few quid? Best to get the recommended, and most popular steppers, which are:

Kysan 1124090/42BYGH4803;
Rattm 17HS8401, and;
Wantai 42BYGHW609

Obviously, you don't have to use one of these three motors - other stepper motors can be used. On the Nema 17 Stepper motor link, above, there is a table of a number of stepper motors, of various makes and models, that have been proven to work.

Further Reading
Motors, a thread on the RepRap forums - specifically for the Prusa Mendel v2, so not entirely related to the i3, as the steppers for the z-axis are less than those for the x and y axes, but it is a good informative read nevertheless.

1 I assume that you actually mean either 32 N • cm, or 3.2 kg • cm.

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How to make a steel mold from a 3D print in high detailed resin?
I'm looking for information on how to make a steel mold from 3D print model using high detailed Resin.
My model is a custom made figurine/mininature of 6 inch.
Can anyone share companies that can make high detailed steel molds either in US or China.
Thanks,
-Uday.

Hi, welcome to the site! I voted to close your question as primarily opinion-based. We focus on technical questions here, that have more-or-less objective answers. As such, asking for (a list of) companies that do X doesn't fit very well with StackExchange's framework. Please see http://3dprinting.stackexchange.com/help/dont-ask. You could improve your question by focussing more on (a specific) technical aspect about mould making, but asking for a general overview of the process might be too broad.

Hi, Bhaskar, and welcome to 3D Printing SE! As described by Tom, questions asking for "the best" provider, filament, printer etc. are usually discouraged for being primarily opinion based. I therefore have to put your question on hold for now. A better suited question would be to ask about the details of molding techniques, and similar (as long as they relate to 3D Printing!). :-)

Sorry about that! Please delete the question. Thanks!

Unless you have proven demand, you should start with aluminum tooling. It's much cheaper than steel, and (I'm assuming you want this for injection molding) you can produce quite a decent amount of parts from aluminum tooling if you handle it carefully.
Why do you want your tooling to be based on a 3D print model? Typically, for greatest accuracy, the tool and die company works from your original CAD work that you printed the 3D model from.
In terms of companies, Protolabs does plastic injection molding: https://www.protolabs.com/injection-molding/plastic-injection-molding/

Thanks a lot for inputs, this 3D model is made of ZBrush (STL file). Can this file help in making CAD work? Here is the sculpture in the original. https://globindian.files.wordpress.com/2015/07/bajirao-peshwa-hindu-king-ranveer-singh-india-love-story-3.jpg

@Bhaskar What formats are accepted will depend somewhat on the tool and die company. Protolabs claims to accept STL files. https://www.protolabs.com/resources/faqs From a technical standpoint, STL is reasonably well suited to tool and die applications, and can be expected to work great for art. SolidWorks is probably slightly better for technical parts.


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How come firmware isn't uploaded?
I am calibrating my Kossel XL with a new Marlin firmware changing the MANUAL_Z_HOME_POS since I have modified my print bed.
I change the value in the Marlin code and upload it through Arduino (the editor on Windows 10). It has worked many times before with the exact same version of Arduino.
When I then use Pronterface and issue G28 (home all) followed by G1 Z30 (just to be on the safe side) it shows that Marlin wasn't uploaded at all. It is a the same height as before. It's a 22.2 mm difference so it is easy to see.

I have tried restarting the Arduino board before and after upload.
I have tried unplugging the USB cable before and after upload.
I also tried two different USB ports.
The computer has been rebooted.
I have examined the Arduino editor's settings, so it uploads to the correct destination (COM3 in my case). It is as it should be. It, of course, reports "upload complete".

What can be the cause of this?

Is it perhaps reading the value from EEPROM instead of from the firmware?

No, I have changed MANUAL_Z_HOME_POS before the same way.

Are you sure that the firmware is not being uploaded?
You can debug this changing the STRING_VERSION on Configurations.h.
If the version is not being changed, I would suggest trying to use another computer to upload the firmware or even another board.

It may be some trouble with the board, thanks for the tip, will try.

I changed the machine name CUSTOM_MENDEL_NAME and that is shown on the display after I uploaded so I guess there is some other problem.


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Is PLA filament conductive?
I am planing on printing something that will make contact with PCB boards. The print will be most likely to be in PLA. I don't want to fry the PCB board so I want to know if 3D printed PLA objects are conductive.
I googled and found out about special non-conductive PLA and conductive PLA. But what about the conductivity of normal PLA?

If it was conductive people would already be using it for 3D printed PCBs.

Technically everything is conductive to some degree. Unless you've got some super sensitive components in general you'll be good. PLA can be used as an insulator so long as the voltages are low enough i.e. the 3-9 volt range you're probably good to go

Normal PLA is non-conductive. You can take an $\Omega$-meter to a test part if you're really concerned somehow you have some PLA that is conductive.
There is a caveat that your color may include metal flake or graphite of some kind. Depending on the density it may be conductive. But I've tested my silver on hand and it gave me infinite resistance.

Okay, good to know. Thanks! I would test it with a meter but I don't have one.

@Alic cheap meters are pretty cheap. Example, which I can't vouch for: https://www.amazon.com/Ranging-Digital-Multimeter-Voltage-Current/dp/B00HC5GXZM . If you're doing anything with circuits, you'll be much happier to have at least something like that on hand though. (Better ones are better, but more expensive)

One note, EVERYTHING is conductive to some degree. The OP should keep in mind that for their case non-conductive PLA will 'probably' be fine for their application. 3D printers are fairly low voltage in general. But, don't treat it as gospel in all cases. I.e. Don't make a high voltage shield out of PLA...or any 3d printed plastic, better yet just don't mess with high voltage period.

PLA itself falls in the category of non-conductors, with a resistivity ($\rho=R\frac A l=\frac 1 \sigma$) in the order of $10^{16}\ \Omega \text m$ (see here), similar to other plastics. Following image gives an idea of the values of resistivity for usual conductors and isolators, insulating materials have resistivity greater than $10^9\ \Omega\text m$, conductors have it smaller than $100\ \Omega \text m$ (copper is about $10^{-8} \ \Omega \text m$):

However, PLA can be mixed with some amounts of a conductor as graphite, making the filament a conductive material (not as good as, by example, copper). This filament can be used to create some kinds of electric circuits.
Other additions (coloring, ...) could also change slightly its properties.
Obviously, if PLA reaches glass transition temperature or melting point, holes can appear in the surface, breaking insulation.

PLA is non-conductive at room temperature, but when you heat it up over 70 C it is no longer as great an electrical insulator as the part will begin to fail. These temperatures could occur in electrical shorting situations or even increased electrical resistance in a circuit over time. I would hesitate to use PLA in electrical scenarios with a lot of load. As the resistance drops in the PLA (The resistance is still very high) and load begins to run through the PLA you have a recipe for a fire.
http://onlinelibrary.wiley.com/doi/10.1002/eej.21272/full/
The other problem with a printed PLA part is that many times they are permeable to liquids. This means that if you say you get salt on them say from your hands and condensation say from your humid living environment... current cant pass through your plug.

Is this really a practical concern? The paper shows the conductivity rising from 10^-17 S/m at 25C to 10^-12 S/m at 150C. That still (even at a temperature at which the part has pretty much melted) isn't very conductive at all.

Is "a lot of load" at welder scale, mains scale, electronicals scale, or bioenergy scale?

Under nominal use cases you will not run into a problem, but that isn't really the concern. The concern is when things go wrong or things get wet. https://pevly.com/wp-content/uploads/2017/06/ABS-ANET-A3-heatbed.jpg Your heated bed for instance can have runaway resistance resulting in the plastic heating up well beyond 150C which is lower than the temperature you roast a chicken.

It's non-conductive, but I would check to make sure with any colored filament. Black may have iron oxide or carbon black which may give it minor conductance.


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FDM: Clear=transparent part
I intend and would like to print a transparent hemisphere. I have a Taulman T-Glase clear 1.75 mm filament and I have XTC-3D.
You can read this interesting page, Hacking t-glase to look more like glass!
First question, what kind of printing settings should I use? Should I go for a low infill percentage or a high one? Should I go for line or hexagon? I would say 5% line but perhaps there is a better setting.
Then, how should I use XTC-3D as mentioned on the above link? I'm a little bit confused how it can make the part more transparent.

Infill needs to be 0% or 100%, as I understand it. For a clear effect (rather than just allowing light to pass through diffuse) it is important to avoid any air-filament boundaries which don't follow the bulk geometry.

How big a nozzle do you have?

My nozzle is 1.75mm

Your filament is 1.75mm, your nozzle is probably 0.40mm.
Or you're printing with a firehose.

I have a Flashforge. This is correct. 0.4mm.

First I would hedge your expectations.. I am very familiar with t-glase. It is very translucent but it is not clear and no amount of post treatment will make it 100% clear. Their example is the only exception where you have a simple print where it has only a single layer. By applying the clear coating they have normalized the wall and made the surface even. Thus no more light diffusion.
You could likely get the same effect with good sanding but good luck sanding a 1 wall thick print. Also note they do not show any solid parts. If they cannot get a solid part to look good and clear, then really you shouldn't expect to be able to.
Any infill will cause it to be non clear. Any extra shells will also create air pockets, lines, etc and make it non clear. If you really want clear, FDM is not the way to go. The only way I could imagine to print an item clear with FDM is to create a cast, then cast it with resin or glass..
If you consider how the plastic is applied, you can see there is no real way make it 100% air pocket free.. See below,

Image taken from here.
The best I can recommend for settings. Make your temp spot on. If you boil the material you will have less translucency. Play with over extruding (too much material) in a Limited amount. Might reduce gaps. I would also try to print in BIG THICK lines. Less lines, less diffusions.

You can get clear objects, even with FDM and multiple walls. ColorFabb has demonstrated it to work.

Refraction of light is caused by changes in medium or angle of inflection. Any changes in medium will cause refraction, as such to be the most clear you would not want pockets of air. This means that if you are printing single layer 0% would work. The best appearance would most likely come from 100% infill as there would be no changes in the medium. The epoxy you linked to appears to smooth the surface, The smoother the surface, the clearer it will look. It is the same reason why you don't see clear textured mirrors or windows.

Welcome to the group @Faleroi! I feel like we have very similar points however I still wrote my answer as I felt that there was a need for a bit more expansion and supporting materials.

You are never going to get perfectly transparent prints, even if you were using real glass. Because of the way FDM prints, you would have fissures where the layers bond to each other. You can get good results if you use 0 or 100% infill and sand, then smooth the outside shell. If you are expecting optical quality, look somewhere else. However, I have successfully printed very nice diffusers for LED's with clear filament.

You will not get perfectly clear prints with FDM because of the mechanics of FDM printing there will always be tiny gaps. But, you can get pretty close as demonstrated by a ColorFabb tutorial.
A clear filament and printing an object at an elevated temperature (more than normal) and enough material to close the gaps (e.g. 110%) should be able to produce transparent prints, for example:


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Is it possible to 3D print a front bumper grille for a Honda Accord CL7?
I probably have to find out all the answers myself, but I could really use somebody else's experience.

what material should I use, so the grill does not bend when exposed
to the heat coming from the radiator
I have to print the part in slices; what glue can I use to join them lately, again so it resists the heat from the radiator and doesn't catch fire
is there maybe a CAD file describing this part, so I don't have to manually create it from scratch?

I would recommend against doing this as it'll probably void your insurance if you use a non-approved material and process (which includes bonding parts together).  The last thing you want is something which has a lower flash point than the OEM grille, for example.  Much more sensible to find one at a salvage yard or eBay

@CarlWitthoft: yes, that's what I was thinking as well. Unfortunately, as one of second hand parts dealer told me, cars tend to crash frontally which means it is extremely hard to find these parts in good condition :-|

If you really want to make it your self I would suggest printing a mould for the bumper would be easier, then you could try making the part with fiber glass or some other material, and you could embed an aluminium or steel frame to provide strength and attachment points.

@user802599: please create an answer, I'll mark it as such. Thank you very ,very much for your suggestion, I think it's a bright idea.

Regarding the heat from the radiator. Place your hand where the grill will be. If it's not too hot for your hand, it won't be too hot for your 3D printed part. Also consider that the cooling fan is pulling air through the radiator, away from the grille, keeping the heat from reaching it, generally speaking.

Your best bet for the material would be one of the high temperature filaments like the ColorFabb HT ones, they can take quite a punch when it comes to heat.
As for the model, you could try to source one of the grills that is at least as good in shape as possible and get it scanned, there are people offering this as a service for example over at 3dhubs.com
Glue is really depending on the part, I would suggest creating a click-together type of system so the "glue" is only stabilizing it and not beeing a structural component. You can also get hold of a 3D Pen and weld the parts together with the same material used to print.


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3D printer extruding too thick
Last night there was an error in printing that caused the printer to stop printing, but kept the hotend on. This morning I discovered that it had fused to what it was printing after remaining on all night - it took some time to remove.
Prints afterwards showed signs of under extrusion. Now when I tell it to extrude a millimeter, it no longer extrudes a thin strand, but instead exactly a millimeter of filament comes out the same diameter as it went in. Cleaning the hotend has done nothing, cleaning the extruder has done nothing.
I'm left with two conclusions, either:

this is what is supposed to happen, it was broken the whole time, I had calibrated it for the broken setting and just need to recalibrate everything, or;
something, most likely the nozzle, is broken.

Rather obviously if the output is 1.75 or 3 mm diameter, the nozzle isn't even there any more.

Thats what confuses me. The nozzle is still there, at least it still appears to be there. If it somehow broke i havent found any fragments.

When you have a disaster print like this you almost always get carbon in the hot end. I have micro hand drills (0.2 mm) that I carefully use on the tip of the nozzle. There are also atomic pulls where you add plastic, heat it up till it extrudes then let it cool. Once cooled to 70°C pull hard. Repeat until pulls show no black. Or, if your nozzles are cheap just replace them.
Note next time this happens, turn the hot end on so you can remove it quickly. Sounds like you chipped away.

Thanks for the advice, the hot end was on the entire time, even when i went to remove it. There was a load crack when I was finally able to separate it. Cleaning the hotend thoroughly removed a somewhat large amount off black stuff, and it still extrudes to thick. I have decided that the nozzle chipped and ordered a new one.

Honestly replacing it is usually the best way. 10 bucks to save hours of your time. I've also manage to damage hotend tips with wire cutters before trying to clean them. Or I break micro drills in them.

It also can simply be the PLA.  I have had PLA that runs thick no matter what setting I use.  I know it's the PLA because when I replace it then it goes back to normal.  I have tried temp ranges from 200-220 °C; all with the same results.  I even dried the PLA for 9 hours and still did it.
Sometimes the PLA just sucks aka a bad batch.

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Will my Duplicator i3 be able to print this hole in the vertical wall without infill?
Will my Duplicator i3 be able to print this hole in the vertical wall without infill?
The wall is 7mm the diameter of the hole is 24mm, the shell thickness is 0.8mm.

Hi @AndyAndy Welcome to the group. Unfortuantly this site is not the best at questions like this asking for an opinion. We prefer to see more solid questions such as at what kinds of prints are we able to print without infill. Or what are ways we can reduce the material needed for pints such as this one. Also the answer is yes, if you use a lot of outer shells.. Specifically on the top layers..

What do you mean by a lot of outer shells?

Is your question what is a shell, or what I mean by many? https://3dprintingforbeginners.com/glossary/shell-2/
Shell
Also know as outline or outer perimeter, the shell represents the outer wall of a 3D print.
Used in plural (“shells“) in conjunction with a number to describe the maximum thickness given to the outer wall. Printing with 4 shells means that your objects’ outer wall will be 4 times your 3D printer nozzle’s diameter (i.e 4 X 0,4mm = 1,6mm outer wall).

Do you really mean infil, or are you asking about support structure to handle bridging at the top of the hole?  And why not lay the part flat & print that way?

@StarWind I think this is a reasonable question, and it isn't opinion-based at all. Whether an object is printable can be established simply by trying to print it, or a more experienced 3D printer operator might be able to tell off-hand. It would be a good idea to add the settings used (the dimensions of the hole have since been added).

The answer is yes. However I notice that some knowledge is missing due your comments.
The walls of the part is formed by 1 or several lines, this lines are called shell.
The Infill is the part that fills all within the walls or shell; you can set the infill by 5% to 100% depending in how strong you need the printed part or set 0 to get an empty shell.
The printer can be able to print any part, but some areas will need supports, this suports is a kind of outerfill to support areas that could overhang basically walls with 45 degrees or less, this support can be easily removed from the final part


text:
How to Make Use of 3 mm Filaments?
I'm not really sure if I'm asking the right question here, but I just made a noob mistake of buying 3 mm filaments instead of 1.75 mm. I have a Makerbot Replicator 2 which I've been using and so far it is pulling in 1.75 mm quite well.
Is there any way I can still make use the 3 mm filaments, or do I need to use the filaments on different models? If it is the latter, which particular model is able to pull in 3 mm filament well?

Alvin, you will need to research. I know of no comparison site which lists printers based on filament diameter.

Thanks, Davo. So far, what I have learnt is that I need to mod the extruder and nozzle to be able to use the 3mm filaments.

Research also if modifying the extruder will void your warranty.

The extruder shouldn't need to be changed, I would have thought that just the hotend (and maybe the nozzle) would need to be changed.

The title you have chosen for your question is not very good. Asking for a list of printer models (or even just a recommendation for a single printer) does not make a good stack exchange question, because an answer would need to be unreasonably long, or would be opinion-based because we'd need to recommend one particular printer over all the others. Perhaps you can edit the title (and the body of the question) to focus on whether/how you can use 3mm filament in your printer and how you can tell whether a printer accepts 3mm filament.

Return the filament (or sell it) and buy the proper diameter. Save yourself a lot of trouble.

This is not a definitive answer (and has turned into a ramble), as I have not yet had to change my filament size.
However, initially, I would have thought that only the hotend and the hotend's nozzle would need to be changed, from one that can handle the 1.75 mm filament to 3 mm. If the extruder is spring loaded, then it should adjust itself to the thicker filament, without a problem. If not, then you may have to do a slight manual adjustment.
However, after doing some further reading, there may be other factors that need to be considered, such as:

Extruder gearing;
Melt time (which would imply a different feed rate)

It could be worth having a close look at the aperture of your hotend. If, in the unlikely situation, it looks as if the hotend would accept 3 mm (or if you could remove the lining so that it can), you may not need to actually change any hardware, but instead just try tweeking the feedrate in the software, because as your nozzle is less than the width of the filament anyway, then it will be fine for both 1.75 mm and 3 mm. A 3 mm filament would require more heating, and therefore a slower feedrate than a 1.75 mm feedrate. Once the filament has melted, so long as the pressure from the extruder is sufficient, then the molten filament should come out of the nozzle. However, this may be a less than satisafctory method and result in some dubious prints.
There is an interesting thread on the RepRap wiki, 1.75mm Filament vs 3mm Filament, that discusses most of the points above.
It should be noted that the advantages of 3 mm filament has over 1.75 mm are that it is:

cheaper
stiffer (less flexible) and thus "easier" to push through the hotend.

As an aside, one interesting point raised in the thread, is that maybe a smaller extruder can be used, for the narrower 1.75 mm filament, thus resulting in a lighter print head. I am not sure how true that is.
This article, Converting a 3D printer from 3mm to 1.75mm, does the reverse of what you want, and comes with a video. It states that, as you have already found, that the hotend needs to be changed:

The printer [Thomas] is changing out to accept 1.75mm is the Lulzbot
  Mini, one of the most popular printers that would ever need this
  modification. The only required materials is a new hot end suitable
  for 1.75mm filament, a 4mm drill, and a few wrenches and allen keys.
  It would be a smart idea to get a hot end that uses the same
  thermistor as the old one, but that’s not a deal-breaker as the
  problem can be fixed in the firmware.

Alternatively, you could leave your printer as it is and use a 3mm to 1.75mm filament converter, which may be a bit of overkill for just one reel of filament1.
The bottomline
To be honest, is it worth the hassle, time and expense of having to modify and re-calibrate your printer (or worst case, change the model of the printer), just for the price of a reel of filament (assuming that you did not bulk purchase a bunch of reels)? It may be better to stick to one filament size (i.e. your original size) for all of your projects, and so resell the reel of 3 mm and stick with the 1.75 mm printer and buy the correct filament2.

1 See also Conversion of 3mm ABS filament to 1.75mm
2 See also Tom's answer to Conversion of 3mm ABS filament to 1.75mm
See also Can 1.75mm filament be used in a printer that takes 3mm filament?

Thank you for taking your time to actually write it like a literature review, even. I'll still need to experiment on it. I've actually upvote your answer nonetheless, but my reputation is too low to show an effect. I am looking into changing the hot end first. Wish me luck.

@AlvinHerawan - Not a problem, it was interesting for me too. Yes, you need 15 rep points to upvote. I've just given you 5. Remember to revisit this post when you have enough rep... Good luck! :-)

The extruder hobbel bolt (or whatever is used) is usually shaped round to better grip the filament. The radius of the teeth won't grip 3 mm filament at all, therefore it will likely skip or skid very easily, especially given the increased grip required for 3 mm filament. 1.75 <> 3 mm is a complete overhaul of anything related to the extrusion path. I did it.

@FarO - You should post that as an answer... it's useful info and should have more prominence than just a comment... I'll upvote it.

@Greenonline I think that was I found here on 3dp.SE back when I thought about the same!

Well... Usually when one buys a 30 dollar roll of plastic they don't replace a 1k machine..
That said you can change out the extruder. The extruder is what matters. So if you have a Prusa i3, you can go and buy say a e3d hot end that is made for 3mm.
Usually we see 3mm on Bowden printers like the Ultimaker. Everyone else has moved to 1.8.
I would just toss this on craigslist and get the correct plastic.

Yeah, agree with you ... I was just curious with this 3mm size. Of course I'd rather toss the whole spool ... perhaps find a use for it somehow, someday.

Late to the party here but I am doing this exact thing. I stupidly bought like a dozen rolls of 3mm filament for about $6 a Kg. I think trying the switch should be fun...but I have 7 printers so its no big deal to tinker on one of them.
What you need to do is modify the extruder. I have done this successfully using the crappy plastic extruders which come with most budget printers. You have to drill out the filament path to fit the 3 mm filament. It does get a little tricky to get the filament to run through nicely.
You actually do not need to modify your hot end other than your Bowden tube and your nozzle. Regular Bowden tube is 2 mm ID and 4 mm OD, so you just order 3 mm ID and 4 mm OD tube. Please note that this plan will not work for an all metal 1.75 mm hotend.
For the nozzle you can often find 3 mm compatible nozzles. Unfortunately they don't seem to be made for the MK10 hotend. So I simply ordered big ole 1 mm nozzles made for 1.75 mm and I am going to drill out the back for the 2.85 mm (3 mm) filament.
I am excited to see how this all works. You can get some really good deals on 3 mm filament and I suspect that it will actually work much better for things like TPU since it is significantly more rigid due to the increased diameter!

Any modern and decent drive gear (single or dual) is shaped round (concave) to better grip the filament.

Some are flat, but only the cheapest and least performing ones.

(from Reprap wiki)
The concave part designed for 1.75 mm filament will be too small to accept 3 mm filament, it will grip it so weakly that it will skip or skid very easily, especially given the increased grip required for 3 mm filament.
1.75 <-> 3 mm is a complete overhaul of anything related to the extrusion path. I did it so I know...


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3D printing a boat hull
I am wondering if it would it be feasible (at an affordable price) to 3D print a boat hull (small dimensions, maybe something like 60x40x20 cm).
I am mostly concerned about:

durability (against salty water, UV rays, extreme temperatures
(under the sun or in a cold ocean)
strength (the material should be able to resist some chocs and maybe a little bit of pressure if a wave was to smash on it).
waterproofness

Those characteristics should last during extended periods of time in water (at least several months, maybe more, about a year or two).
Is there any easily accessible 3D printing material that would match those characteristics?

Quick point to clarify, 60x40x20 isn't small. That's actually quite large for the printing world.

You will really need to specify your constraints better because the short answer is yes, what you describe is entirely possible, but without knowing whether you are limited to a particular budget, process, or aesthetic, it's not a particularly useful answer.
Some machines (ex. Stratasys Connex 1000) will print models up to 1m in length, so sure, you could print an entire hull with the dimensions you specify.
Pros:

Monohull construction
Excellent surface finish
Many resin options are UV and salt water resistant with decent enough durability

Cons:

Ridiculously expensive machine with decently expensive resins
It will waste plenty of support material in printing (which means added cost too)
Not really easily accessible, but some design studios will have them and will print things for you, for a cost

Other machines (ex. Ultimaker 2 Extended) will print models up to 30cm along the vertical axis. It would require some assembly in the end, but you could segment your build and get a boat hull in the end.
Pros:

Easily accessible
Fairly low cost (Maybe under \$1000 for the machine vs nearly \$1M and many filaments cost 1/10th that of polyjet resins or sintering powders)
The materials themselves can be UV resistant and salt water resistant

Cons:

Joinery and seams create passageways for water ingress, so you'd need secondary sealant
The FDM process itself isn't always watertight, so you'd need sealant anyway
Low interlayer adhesion limits the tensile strength along one axis and the shear strength in one plane, so you'd either need composite hull panels with varying print orientations (in which case, just do a composite layup instead) or a fairly careful analysis of principle hydrodynamic stresses

There's significantly more to the discussion as well, but without really understanding your design constraints, it's difficult to give any concrete advice.

Thank you for this detailed answer ! Well, honestly about the cost I was mostly interested in actually getting an idea of how much it could be and compare that to other methods (the goal is to make it as much inexpensive as possible but to ensure that it will bear ocean conditions) , i'd be curious to know the price design studios would make you pay just to print with a 3D printer like Stratasys Connex 1000.

@TrevörAnneDenise The studio I am most familiar with is Fathom in Oakland, CA. I know of some online services as well (like Shapeways and i.Materialise), but you're likely looking at the low-thousands (USD) as a starting point. Realistically, you would be far better off with a composite hull. Use an FDM assembly and layer matrix reinforced fibers on the inside and outside. Strong, light, and relatively inexpensive.

Something similar has been done in ABS already, although I don't expect it gets left in the water for years. See the video, showing a kayak being printed in many ABS sections of about one cubic foot, then bolted together and sealed.

It is totally fine, it is what I did a lot at my previous job. I 3D printed cases for underwater stationary equipment, mini-submarines and simple buoys, and almost all of them work fine. In fact, most of the failures I had were the breach of sealant. Or someone forgot to close the lid.
For example this thing I've made.
To make watertight objects, follow the rules:

You may use PLA. Over the course of a few years in water it degrades only in color, unless exposed to direct sun heat for prolonged times.
Obviously, use several outer shells.
If you are making floating thingy, and there is a free space in your hull, do NOT leave it empty! Instead, make it solid in the model, and set slicer to use sparce hexacomb infill with a solid layer every 20-30 layers. This way, your model will be made of hundreds of isolated pockets of air, so a breach of a hull in some place will not sink it. You can also drop lead pellets into those pockets as they are made to weight the ship properly.
Set nozzle diameter to layer height ratio to more than 3. It will produce nice thick layers welded shut. For example, use 0.7 nozzle for 0.2 layer or 0.4 nozzle for 0.1 layer. The last one can be a bad choice if your extruder can't provide that little flow and tears layers. In general, obtain those bigger nozzles for technical parts. 0.4 nozzle is for toys, really.
Remember that wires conduct water just as well as electricity - water runs between the isolation and the copper core. No wires should go through the containment.

Thank you for this detailed answer and all of those advices, that's really interesting especially the part about not leaving the free spaces empty !

Probably feasible, Affordable or simple probably not. To start from an affordability perspective, kayaks normally weigh around 20 kg, they kayak in the video mentioned in the other answer weighs in at 30kgs. Assuming you print all your parts perfectly, your using \$15 a kg filament, and you use 25 kg of abs you are looking at a minimum of \$375 in material just to print the kayak. After this the cost would only go up because now you need the parts to fasten it all together, the seat ect... In other words, it will probably be no cheaper and a whole lot more time intensive then buying one.

Thankak  you for your answer ! I am not planning to build something as big as a kayak, so the cost wouldn't be as high !

I would give it a try, but dont expect it to be watertight. Print the hull and paint it with some epoxy and you will be fine. (outdoor paint job, epoxy is bad for you)


text:
Can K-type thermocouple disconnects be used with thermocouple based 3D printers?
I currently have a Replicator 2 and a couple of clones. I'm a fairly experienced 3DP user and builder but one issue that I have over and over again is the very brittle screw type thermowell assemblies that get damaged whenever you try to replace a nozzle or repair your hot end.
I'm wondering why I don't see more of the quick connect type thermocouple assemblies, like this K-type male.
It would be a great help on 3D Printers allowing easy disconnect of screw type thermowells without damaging them. Is there a reason that these are not being used?
I was hoping someone with experience with these could tell me if they are worth trying out on some of my builds without risking some kind of dangerous situation.

I spent a while messing with thermocouples on my printer, but haven't tried these connectors. It looks promising, though it might be tricky to mount in a really small space. If you don't get a more specific answer, since they're cheap your best bet might be to just try one and see. If you do, please post back to let us know how it goes. Good luck! -s

This connector looks as an overkill. Haven't you considered simple dupont-type 2.54mm connector?

Not sure if this is the reason, or just A reason, but thermocouples create a pretty small voltage for a given temperature, whereas thermistors have a larger (easier to read) change in resistance. I would expect that a thermocouple would require slightly more sensitive instrumentation to read it than a thermocouple. And seeing as space requirements aren't that significant on a 3D printer using the easier to read thermistor, despite its size, seems like the better option.
I prefer thermocouples myself, since they don't need calibration and effectively lifetime guaranteed (aside from mechanical failure). However almost every project I've ever worked on, the Sparkies always seem to push for thermistors rather than thermocouples.


text:
Advantages of GT2 over a rack
Many 3D printers employ a GT2 band for the y-axis plate and the printhead in the x-axis carriage.
However, there seems to be the obvious disadvantages of:

stretching (and need for adjustment) and;
possibly slight inaccuracy, or "wobble" (for want of a better word (as wobble is often used in describing z-axis deviations)), due to the elasticity of the band.

Is there any particular reason why GT2 is used over a straight forward rack and pinion system?

In particular, for the y-axis plate, as a rack would appear to me, be:

easy to install;
more accurate, and;
require a lot less adjustment1.

If the rack is made from aluminium, surely weight can not be a major factor...  or can it?
Is cost a factor? A pinion seems to cost around \$10-\$15 (650 B\$, here in BKK, Thailand), which is obviously more than a reel of GT2 and a couple of GT2 pulleys.
Would the rigidity of the rack be less forgiving of an imperfectly aligned axis, something which the GT2 band and pulleys combination would not be so affected by?

TL;DR
Which of these factors cause designers to use GT2 en lieu of a rack?

Accuracy
Weight
Cost
Maintenance
Tolerence of non-square axes, manufacturing errors.

1 Maybe constant adjustment is not required on an everyday basis, but the tension would still need to be checked now and again, whereas a pinion would not have this requirement.

With a belt system, the belt engages roughly half the pulley. This, and the tension in the belt, ensures the belt always engages the pulley tightly. A belt and pulley system is thus relatively forgiving.
With a rack and pinion system, only a few teeth engage at any given time. To avoid backlash and get the same kind of "tight" engagement, both the gear and the rack need to be made with very high precision. The carriage also needs to be very well constrained, because any wobble of the rack relative to the gear introduces backlash (or binding). Moreover, you also need to keep the rack and pinion well lubricated lest they wear out prematurely.
Given that belt and pulley work well enough, I don't see why you'd need to move to rack and pinion. The main advantage of rack and pinion is that the rack isn't elastic. The maximum length of a belt system is limited by its elasticity, but given we aren't building meter-long 3D printers anyway, that advantage of rack and pinion does not apply.

Nice explanation, thanks. So it is similar situation to my query about the z-axis threaded rods being constrained at the top - the more rigid the driving mechanism the more backlash comes into play. Which leads me to wonder whether the use of a GT2 band, instead of a threaded rod, would reduce wobble and banding in the z-axis...

I know this is old, but it is also factually wrong. There is NOTHING that prohibits a pinion based system to use multiple gears to connect. And there are PLENTY of examples (as in: commercial products) that demonstrate this system with high precision, including commercial 3d printers. Also, it all depends on "buy quality components, maybe have the whole setup machines well", which is not "not possible". And finally, it has the advantage of a fixed carriage weight and fixed known compression, while this is a variable for a classical belt system where longer printers mean a WAY longer belt.

@TomTom I never said it was "not possible", which is something you put in quotation marks as if I said it. The answer doesn't even imply that; it is simply stating some reasons why the vast majority of printers use belts (and not racks). It would be interesting if you provided some examples of commercial 3D printers using rack and pinions so we can see how they do it.

Thre is no need for this as I would assume anyone interested is smart enough to use google. And check CNC machines - QUITE common. MORE concerning is that you miss the obvious alternative - multi belt systems, either as double belt or as belt drive. Those combine pretty much both advantages, including WAY lower stretch on the belt (as the receriving belt on the machine CAN be a rack, OR can be GLUED to the machine over the whole length. The moving belt part then is ABSURDLY small and CONSTANT (i.e. 15cm, regardless of length of movement).

" but given we aren't building meter-long 3D printers anyway, that advantage of rack and pinion does not apply"
Says WHO that we're not.  Maybe when you said this that was the case, but someone already made out a 600 x 600 x 600 mm printer already when you MADE this remark four years ago.

@TomvanderZanden: I can give you at least ONE commercial example of a rack and pinion based system:  https://www.roboze.com/en/  Sorry, the whole notion that keeps coming up and coming up that belts are everything amazes me.  It's just that it's simple- but as you migrate to more and more industrial use of the FDM and other processes, you would expect people to move to lead/ballscrews along with rack and pinion systems.  The claims for belts being superior are...dubious at best.

@Svartalf The question is why "many 3D printers employ a GT2 band [...]". Very large 3D printers were and still are very uncommon, and so are 3D printers that use rack-and-pinion in place of belts. Moreover, the answer doesn't claim that belts are "superior", but that it is more difficult to make them (and thus more expensive) for relatively little advantage. This explains why we see belts on many 3D printers (considering that most 3D printers are $300 consumer-grade ones). Your example of a (presumably) very expensive industrial machine only confirms this.

Ah, but the presumption is incorrect.  If many jumped off the edge of the Grand Canyon, it doesn't lead that YOU should too...  ;)
Simply put, the statement is...heh...in error without a qualification and the dismissal of the other out of hand because everybody uses belts is ALSO so.
As for difficult to make them...I think that there's SEVERAL that've been easily made, with the recent https://www.thingiverse.com/thing:4031698 and https://www.thingiverse.com/thing:4795199.  It's not simpler.  It's CHEAPER and one should b e HONEST about that instead...

Best you read my comment.  Your claims of MOST printers is...heh...accurate after a fashion- but not WHOLLY the reality there.  There've been designs that use lead screws other than the linked and they had volumes of 600x600x600.  Good luck on getting belts to work there- and yes, it was a DIY and no, it's not the norm...   But then, here we are, with you claiming that the opposite IS the norm- that belts are the SOLE answer because the other isn't practical, which is vastly removed from the truth there as you framed it.

The answer so others can understand is that it's cheap and simple to run with a belt.  Much of the 3D printers these days either stem from the sintering systems that were developed years ago and things that rose out of the RepRap community where a Lead Screw that had the precision needed to do proper 3D printing at decent speeds was out of reach for most of the community.
It's a bit of, "we've always used belts," and then people come up with all sorts of stories to validate the dubious take to begin with.
At one point in time (to be specific...around a couple of years BEFORE the question was asked here...) the costs of a lead/belt-screw system for anything other than a Z axis solution for a Cartesian or a Core-XY was prohibitive for a hobbyist or a system bought off shelf or build by them.
It was too hard and expensive to get straight enough parts with precision to actually make anything other than small toy systems with those.  We wouldn't get into racks as they were even MORE expensive.  With the precisions we were previously working on and with in the community at the time this question was originally posed, it was something that only made sense for select solutions.
As you scale larger (Hey, we're now professionally making HUGE parts with this stuff) it makes much, much more sense.  For certain classes of manufacturing...it actually makes sense with certain filaments to make short run parts for almost ANYTHING, including things in the automotive space.  At that juncture, prototyping, fixing "impossible" to repair situations on older cars, etc. makes some sense to get more precision or vastly larger size.  Desireable becomes the ability to make printers with volumes up to 2 meters in size.  Professional space?  Maybe.  But telling people that a pinion isn't making any sense?  Heh...hardly.  Same goes for lead/ball-screws.  Several have made incredible printers fairly cheaply that can print seemingly impossible print runs (Hung at a 45 degree angle in mid air and print...) with some of this stuff.  Is it cheaper?  No.  Does it make sense?  Possibly.  Especially if one wants to DIY a massive print volume printer (waves hand).  I want a meter and a half cubed on a side print volume that I can enclose to crank out ASA prints of Smart body panels, for example...  You're not getting that with belts- too stretchy, even with PU steel core belts.
Frame it in from a relative cost perspective (It's only going to be about 25% more costly on a DIY or commercial product with a speed upside and precision that might make it WORTH that...but understand that an Ender 3 designed that way will run 350 dollars instead of the 200 or thereabouts it currently runs) and you're going to be more realistic and honest on the question's answer.  Saying it isn't practical...even from when the post originated isn't being exactly forthright in this day and age- and disregards that a person MIGHT just be willing to spend the more money for the precision, etc.

authors: Матвей Меньшиков


text:
3D prints keep suffering from warping
I have a Prusa i3 made by Geeetech. My 3D prints keep suffering from warping when printing with PLA.
Whenever I print something with a base at about 10 cm x 10 cm, at least one corner of the print would warp up. I've read numerous articles about warping and tried all sorts of methods. My printer's bed is level, and heated to 60°C. My bed is made from clean glass. I've tried all sorts of adhesives. I tried blue tape, and used hair spray.
The only way for me to combat this is gluing the base to blue tape with 502 Glue. I used brim and the whole brim just warps up. I sometimes leave the model printing over night. For the first few hours it's perfectly flat. When I go back to it the next morning I'd find one corner warped up. This is very dysfunctional to my prints.
Is there a reliable way to stop this warping from happening?

For ABS it will warp unless you build a heat chamber.
That said the tricks to reduce warping come down to:

Material, i.e. PLA is less likely to warp;
Use a fan, it helps so much;
Make sure you have temps calibrated well - Too hot is more warp;
Use a raft. The Makerbot uses a raft and no heated bed;
Make sure the room is not drafty. Having it by the window will result in warping;
Adding a large brim also helps;
I find good ol' glue sticks work the best at keeping the print to the bed;
SMASH the first layer. This one is controversial. I personally do first layer at 130% and print speed of 30%. You get elephants foot sure, but it's on the bed real good.

Tom is right. It is very very hard to print that big of a piece without warping. That said I have done very large pieces on my Ultimaker, using a fan, glue stick, MatterHackers PRO PLA and no raft. But again that's on an Ultimaker.
Note you can build a heat chamber pretty easily. Specifically a passive heat chamber.

Whether a fan helps depends on the material (with ABS, typically not so much). I'm not sure I'd recommend a raft. I think they're a bit antiquated.

I am assuming it is PLA as they are doing 60c. Far as a raft, my Makerbot can do some impressive prints without a heated bed. But the makerbot guys have some serious knowhow behind them. (Too bad they didn't choose to do a high quality printer)

I have found a 5mm brim really helps prevent corner lift.

@Davo I agree that, w/ PLA, a brim is a great help.  but see my answer as well.

Updated to include brims :-)

I did not mean for a brim to replace other suggestions, but rather to supplement them.

I did not replace

For PLA, I use a brim.  The other thing that makes a big difference is obsessive care in levelling the bed and setting the Z-origin.  Ideally, the first layer extruded (including the brim), should be almost "squished" onto the bed rather than being laid down at a height that allows a near-circular cross-section.
If the extruder head is too low, almost no filament will come out.  If it's too high, there'll be very little adhesion.  FWIW, I think a heated bed helps here, as it slows the cooling of this first layer and improves the adhesion as the fluid-phase 'grabs' the surface.

It might be useful you confirm again the bed levelling. I had warp on big pieces despite I thought my bed was properly leveled but in fact, for some reasons, the bed was too far from the head on one corner. If you face the same issue, you should see the bottom part of your print is showing the filaments not well melted to each others on the 1st layer. I really make sure the nozzle is gripping my paper sheet (almost scratching it when I move the paper).

Source (at least in part):

SolidWorks 2015 Tutorial with Video Instruction, page 11-6, and;
12 ways to fight warping and curling, June 23, 2011 by MakerBlock

Curling
As printed plastic parts cool the different areas of the object can
  cool at different rates. 1  Depending upon the parts being printed,
  this effect can lead to warping and curling.  Although PLA has a much
  lower shrinkage factor than ABS, both can warp and curl, potentially
  ruining a print.  There are some very common ways to deal with this
  potential problem, the most notable being a heated build platform.
  However, sometimes that might not be enough.

Use a heated build platform.  A heated build platform helps keep the lowest levels of a print warm as the higher layers are printed.
  This allows the overall print to cool more evenly.  A heated build
  platform, sometimes abbreviated as HBP, helps tremendously with just
  about any ABS print and large PLA prints.
Print with a raft.  Rafts are a printing option in ReplicatorG and Skeinforge.  They’re basically a large flat lattice work of printed
  material underneath the lower-most layer of your printed object.
  They’ll also help reduce warping and curling by allowing your printed
  object to adhere better to your flat build surface.  Other variations
  on this are to print with a larger raft and/or a thicker raft
  comprised of more layers.
Calibrate your starting Z height.  A good first layer makes all the difference.  If your starting Z axis height is too high, the extruded
  filament won’t be able to make a good bond with the platform.  If you
  think your Z axis starting height is too high, try lowering it by
  0.05mm increments until you find a good first layer.
Get the right build surface.  Some people have experimented with different surfaces such as steel, titanium, glass, different kinds of
  plastic, different kinds of tape, and foam board.  However, I find
  both ABS and PLA seem to stick really well to hot or warm Kapton tape.
Clean your build surface.  ABS and PLA stick better to a clean build surface.  Keep it clean of dust, pieces of old prints, and any
  other debris.
Print slower.  Printing slower allows finer detail, better adhesion to the build surface and lower layers, and gives the printed part more
  time to cool evenly.
Print cooler.  Printing at a lower temperature isn’t always an option.  Ideally, you should be printing at the lowest temperature
  required for extrusion and that allows good interlayer adhesion.
  However, trying lower temperatures isn’t for the faint of heart.
  Printing at a too low a temperature could cause harm to your extruder
  motor or extruder.
Eliminate drafts or enclose your robot.  Forrest Higgs found that having his 3D printer too close to an open window caused very uneven
  heating across his build surface.  This in turn caused the side of his
  prints closest to the window to curl.  Since keeping the window closed
  wasn’t an option for him, he compensated for the window drafts by
  adding a heat lamp.  Cupcake and Thing-O-Matic owners might have an
  easier time of eliminating drafts by simply enclosing two or three of
  the sides of their robots.  It will also have a fortunate side effect
  of helping to control fumes.
Design with mouse ears.  Zach Smith’s solution was to add little discs to corners of an object to help those corners stick to the
  platform.  These essentially serve as “mini-rafts” to give those
  corners more surface area and better adhesion without having to print
  an entire raft.
Design with aprons to hold down corners.  Forrest Higgs suggested adding “aprons” around an object to be printed, while that object was
  being printed on a raft.  These low thick pieces of plastic help keep
  the raft flat and help prevent any curling or warping from affecting
  the desired printed object itself.
Design with surrounding thermal walls.  While Forrest Higgs’ apron approach provides a mechanical advantage of essentially holding down
  corners with a chunk of plastic, Nophead has added thin surrounding
  walls to his designs to act as baffles to keep warm air around the
  printed object as it moves around.  He’s postulated that a very thin
  surrounding wall could have the same beneficial effect as printing
  inside an enclosed build chamber.  Interestingly, it seems that
  Nophead suggests that designing objects with more rounded corners
  might also help avoid curling and warping at those corners.
Reduce infill.  When printing a model you can chose to print it hollow, completely solid, or some percentage between zero and 100.
  However, as Nophead points out even the plastic inside a model exerts
  a force on the entire printed object as it cools.  It stands to reason
  that the more plastic you have, the more those pieces of plastic will
  pull against themselves and the build surface as they cool.  By
  reducing infill there will a reduced amount of internal tension as the
  object cools.  Reducing these internal forces by printing with a lower
  infill ratio can help reduce curling and warping as well.

At least part of this answer (the first line in fact) has be taken verbatim from an article on pintrest. You need to provide a reference, and URL is you are copying content from other parts of the web.

@MentorsHouse please consider providing attribution for articles when you copy and paste them as your answer... I believe this is the article you copied, so please include this link and attribution to the article in your answer.

Also posting a giant article is quite the eye sore...

@TomvanderZanden I understand that this was a direct copy from another site. However, seeing as how the provided link is now dead on Pintrest.com, it's 1) difficult to trace the infringement and 2) excuses the copying of content. This discussion can continue to debate the legal status of this copyright infringement that the user will never receive monetary compensation for over a private chat. I obviously have little problem with this particular post given the circumstances, but I do heavily  encourage you to message another moderator on this post to get a second opinion.

@tbm0115 - I've managed to track down the source, please see edit

@TomvanderZanden - I've managed to track down the source, please see edit


text:
Can I design or remix a model in SketchUp Make and legally share it via Thingiverse, MyMiniFactory or similar?
SketchUp Make is licensed for non-commercial work only.  This includes the output from the software.

Trimble Navigation Limited and/or its affiliates ("Trimble") gives you
a personal, worldwide, royalty-free, non-assignable and non-exclusive
license to use the executable version of the Software for
non-commercial use only. Non-commercial use means: you may not sell,
rent, lease or lend the output of the Software or the Services.

The above retrieved 2016-02-07. The full SketchUp Make license can be found on the SketchUp website.
In what ways does this restrict my use of SketchUp Make generated material with sites that allow the sharing of models (and deisgn files)?  This would include sites such as Thingiverse, MyMiniFactory and 3D Warehouse.

For example, must I always set a non-commercial license for my designs?
Thingiverse allows several different license choices to be selected.
Can I permit the design to be printed by someone for money?
Thingiverse has links to 3D HUBS and Print a Thing which can be disabled per model.
Obviously the SketchUp Pro license makes many of the restrictions on what can be done with the output go away, which would be much simpler.  However I do not expect to generate anywhere near the costs of purchasing a license ($695 US at the time of writing) by tweaking a few designs now and then.

I want to comply with the licenses but I need to understand the limits of what I am permitted to do with SketchUp Make in order to do that.  It may be much more prudent for me to invest my time in learning other tools that have no restrictions on what can be done with the output.
As this is a legal question it might matter what jurisdiction I am in and what jurisdiction the sites I may share to are in.  I am based in the UK.  Thingiverse is based in the State of New York.  MyMiniFactory uses the Laws of England as a base.  3D Warehouse selects the State of California.

I have asked the same question on the SketchUp Community Forum https://forums.sketchup.com/t/can-i-design-or-remix-a-model-in-sketchup-make-and-legally-share-it-via-thingiverse-myminifactory-or-similar/38627?u=tafthorne If any definitive answers turn up on either site I will try to cross post them.

Maybe I should be asking this question on Law rather than 3D printing?  Some aspects of this are context specific though.

Ask on Law, and refer them here for a perspective from printers. Law should provide a more accurate reading of any formal aspects of the language.

As @SeanHoulihane suggested I have now raised the same question on Law http://law.stackexchange.com/q/17013/10851

Please do not cross-post questions. I would suggest deleting your question on SE.Legal as it hasn't got an answers.

@SeanHoulihane - I know that this is a bit old, but when advising users to post on another site, please remind them to delete the original post in order to avoid cross posting. In this case, it seems a bit late to delete this post as it has two answers, whereas the cross posted Q on SE.Legal has none. I've flagged the Q on SE.Legal for deletion.

Again, I'm not a specialist in intellectual property law (or any other sort of lawyer), but I have a different interpretation.
There is a potential difference between the use of the product, and the use of the derivatives of the product. For example, GCC has a restrictive (open) license, but its OK (in some contexts) to use the compiled code in a commercial product.
Generally, you (as creator of a work) will own all of the rights to a work. The supplier of the tools you use does not usually gain any rights to the resulting work.
So long as you don't gain from your use of the tool, it is probably OK for other people to profit from the use. Sharing with non-commercial should be your safest option if you're worried - but be aware that this doesn't prevent people from taking your design to a print service indirectly.
Their license says:

Non-commercial use means that you may not sell, rent, or lease the
  output of the Software

This implies that they are not making any claims to restrict how other non-connected persons might use your works. Its specifically talking about use as part of employment, or you making a gain.
I would also note that to me the language in the license does not look to have been drafted with a clear understanding of intent on this issue.

This doesn't have anything to do with transfer of rights of the works. If they say "you can't distribute what you make with our app" then distributing what you make with their app is a violation of the license and you would be liable for damages - even though they do not have any rights to your work.

@TomvanderZanden Agreed, but I don't see a no-giveaway clause in the license.

@SeanHoulihane I am never that sure if 'sell' does not include the idea of 'sell for £0.00'.  It is still a permanent transfer of a good, rather that a temporary one which would be covered by rent or lease.

So unlike Carl Witthoft's answer below @SeanHoulihane believes that I do not have to apply a non-commercial license to my output.  All I must do is refrain from selling the output or possibly agreeing to print one of my works as a service for which I receive an income or gain.  I am glad it is not just me that sees multiple readings here.

IANAL, naturally, so take this with that in mind.
From what I've read and been instructed, any software which is licenced as non-commercial cannot be redistributed or incorporated into any commercial software product.  The other thing about "noncommercial" software licenses is that they can't be used for corporate design work -- as opposed to home user hacking.
Now, all you need to do is ensure that the license restrictions remain with the mixup files you post.  There is no doubt that, so long as you do that, you are free from any legal problems that a downstream vendor may incur upon trying to sell the hardware produced.

So your interpretation would be that I am OK to share the works as long as they carry a 'non-commercial share alike' style of license or more ideally refer back to the SketchUp Make license.


text:
CT Segmentation Model Intersection
I am using (micro)CT data and generating 3-D models using CTAn - a SkyScan piece of software: Bruker - Control and reconstruction programs.
Basically I am using simple thresholding to create 3-D model STL files.
What I would like to do is get the number of voxels where the surface area of the two models touch.
Imagine having a model that is a sphere with another model within it that is exposed on a portion of the sphere.  I want to know the surface area of that exposed portion.
Does anybody have any advice?  I have been banging my head against tools like 3D-Slicer, Seg3D, ITK-Snap and so on and have not been able to find this capability.

This solution assumes the following
a-The scaling factor for the object is correct i.e real world dimensions .
b- There is a .STL file available .
c- This will take some 3ds max skill and time .
Steps to be followed -
1- Take the .stl file into Autodesk 3ds max .
2- Now we are going to trace the exposed surface using a process called reptology . Here is link to get you started - https://www.youtube.com/watch?v=azkbuZloTqo .
3- Once you are satisfied with recreating the mesh and sure it is as accurate as humanly possible , run the measure utility on the recreated part .
This is the link . https://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/3DSMax/files/GUID-12CDEA7A-042E-4CB3-9BF6-8191D3290CD8-htm.html .
If there is a upper side and a lower side to the model then you should divide the surface area in half ( in this case it would be ).
3Ds max is very accurate if your part is designed properly .
4- This can be done directly on the .STL file if you can efficiently isolate your target area , lemme warn you this is not an easy task .STL files are notoriously difficult to edit. ( its much easier to redesign on top  )
Try it should work out fine .
Please do not waste time processing .STL files on 3D-Slicer, Seg3D, ITK-Snap
they are mostly for file preparation i.e (.STL file generation ),viewing and study purposes only .


text:
Changing raster angle, raster width and build orientation in Ultimaker Cura
I want to try out different combinations of

raster angle,
raster width and
build orientation

in Ultimaker Cura.
I don't see any settings where I could change these. I am using Cura 2.3
Any suggestions how I could change that?

First: Update Ultimaker Cura. The latest is currently 3.5.1.
You can specify the angles and widths with the settings Infill Line Directions and Infill Line Width.
If you want them differently for different objects on the build plate you can specify those settings in the per-object settings menu on the left.


text:
Question about polypropylene with glass fiber reinforcement
My 3D printing experience is primarily with ultrasonic additive manufacturing (embedding FBG sensors into aluminum/process-based research), and recently I was approached by someone interested in the potential value of using polypropylene (PP) for FDM.  My understanding is that it is fairly difficult to obtain meaningful results with it, but again this is out of my expertise.  I saw a few references to glass fiber reinforcement, something that is more up my alley, and have essentially the following questions:

Is there a decent market/interest in cheaper polypropylene filament/coming up with improved parameters for PP printing?
Is there an interest in cheap glass fiber reinforced-polypropylene (GFR-PP) filament?

If you have anything relevant to add on that I haven't considered, please feel free to chime in as well.

I would personally be SUPER interested in any new material that has increased mechanical properties. My primary concern with it would be though if the glass fibers would be all that useful in an FDM process since none of the fibers would bridge the layers. My guess would be that the layer strength would be improved but the layer bonding would be unaffected/


text:
Print circle arcs without supports
I'm still putting aside money for buying my first 3D printer and I'm designing all the things I have to print.
As I have a lot of things to print I would like to print as much of them as possible in a single print.
I have some arcs of circle (between 90° and 320° and 10/30 cm of diameter) and I'm going to slice them so I'll be able to print many of them, vertically, in a single print. I read in the internet that I cannot print over 45°... but starting from where?
The image below shows how I would like to print my (orange) things

I suppose I can print my things without supports because from Y-start to Y-end they are <= 45° (as the green line shows) is that right?
The red line, instead, shows a case where the angle, starting from a (Y: 50%) point, is higher than 45°.
So the question is: Can I print my things in such way?

The overhang is from 1 layer to the next. 45 degrees relates approximately to a 50% overlap from one extrusion to the one above.

Why don't you want to print them horizontally?  It would seem a lot easier. BTW, your axis system there is left-handed.  You should fix that.

@CarlWitthoft I want to print them vertically because if I print orizontally I can print 5-6 at same time, if I print vertically I can print 60-70 (a small part) of them with one print. Moreover the shape constraints me to use supports https://i.stack.imgur.com/9kuwT.png

There are a lot of variables here...
If you did at ..

higher resolution.
Calibrate your machine extremely well. Trial and error. Minimum temps and speed.
If you use a fan.

IE bad calibration.

Good calibration at a slower speed and lower temp.

What is going to happen is you will get a lot of junk, lines, loops, stringers that you can later remove with clippers. See the first photo for an extreme case. It still printed.
Also if you use the right material as well. Some material, will do bridging better, IE ABS has a longer molecular chain than PLA so it tends to do overhangs / bridges better.
Images from ultimaker

This depends on your material, your nozzle diameter, and your layer height. In general, shorter layer thicknesses with wider path widths will give better overhangs. And note that the last bit of each of the larger arcs are nearly horizontal, and I do not expect them to work well without support material.
See the excellent answers at How can I improve the overhang angles my printer can successfully print?

Awesome and I think it might even work!


text:
I'm searching for a tool to generate 2D PDF of one side of my model
I've created a model in  OpenSCAD, mainly some cubes (not really cubes, but lengthy braces using cube()) and cylinders with cylindrical holes in them, to hold several PCBs.
The barrels will accept a 3 mm PCB standoff, which will then hold the PCB.
I would like to print the top view in the exact measurements on paper, to check for alignment before printing the bracing on my 3D printer.
The tool I'm searching for should be able to generate a drawing of all edges seen from one side, like a technical drawing.
I've used FreeCAD and OpenSCAD for now, but any tool running on Ubuntu should be fine.

OpenSCAD has a great feature called projection which allows you to select a vertical location and effectively "cast a shadow" of the part. The projection becomes a 2D object scaled to the original model.
One can rotate, translate or otherwise transform the model prior to performing the projection function, in order to get the appropriate 2D drawing.
The resulting "model" is rendered using F6 and can be output as .DXF or .SVG as well as a number of other formats that might not be as useful to you.
EDIT: I've been recently using Onshape to create drawings from 3D models. It's also a free program, browser based which allows you to import your STL model (or other acceptable formats). Once imported, a drawing can be created with three-view and isometric, or you can edit to create only a single view. This can then be exported/downloaded as a PDF.
The screen capture image below is from a project I've recently created. The original STL file was imported and the result is quite clean.


text:
What is a w/t ratio?
I have seen a few guides mentioning w/t ratio but I can't find anything which defines it.
I am using Simplify3D with a Wanhao i3.

Can you put the question into a context? What is the ratio referring to? A printer? Filament? Software? Presumably, you are referring to guides about Simplify 3D? Can you edit your question and provide links to, and quotes from, these guides, showing where w/t is used?

It appears to refer to calibration factor called Width over Thickness.
From Calibrate your 3D printer to print parts to fit

Here is the list of necessary variables for this calibration to work,

Carve/Extra Decimal Places (float) : change to 5
Carve/Edge Width over Height (ratio) : nozzle diameter/layer height
Inset/Infill Width over Thickness (ratio) : nozzle diameter/layer height (initially)
Dimension/Filament Packing Density (ratio) : needs calibration (equivalent to the reciprocal of the extrusion multiplier in Slic3r)
Scale/XY Plane Scale (ratio) : needs calibration

authors: สุดารัตน์ อดทน


text:
Prusa's P.I.N.D.A. XYZ axes calibration fails with generic message "Consult the manual"
I have just built a Prusa i3 MK2 printer. One of its features is automatic XYZ axes calibration done using inductive probe which is located next to the nozzle.
In my case, this calibration procedure failed with the message:

XYZ calibration failed. Please consult the manual.

The manual on this problem reads:

XYZ calibration failed. Bed calibration point was not found.
  Calibration routine did not find a bed sensor point. The printer stops close to the bed
  point, which it failed to detect. Please verify, that the printer is assembled correctly,
  that all axes move freely, the pulleys do not slip and the print nozzle is clean. If
  everything looks good, re-run the X/Y calibration and verify with a sheet of paper
  between the nozzle and the print bed that the print nozzle does not touch the print
  bed during the calibration routine. If you feel a friction of the nozzle against the sheet
  of paper and the nozzle is clean, you need to screw the PINDA probe slightly lower
  and re-run the X/Y calibration.
XYZ calibration failed. Please consult the manual.
  The calibration points were found in positions far from what should be expected for a
  properly assembled printer. Please follow the instructions of case 1).

My nozzle is new, therefore clean and I have already checked that all axes move without any problems. The manual does not seem to offer any additional advice.
I tried to put the PINDA probe lower. It had helped the calibration, but at the same time the probe was lower than the nozzle, which means I couldn't print with it being on the extruder.
What else can I check? How to find the issue? This is my first printer, so I'm totally clueless.

One thing, and the one that eventually solved my problem, is to update the firmware. Firmware update instructions: Upgrading firmware - Prusa3D
The only thing you might get stuck on is selecting the right COM port.

Go to the device manager (run devmgmt.msc)

In COM and LPT section, you should see port for your printer by name. Select that port number in the firmware update tool.

In my case, I had to run the calibration twice before it worked. I had no problems since then.

I suggest that you ask on shop.prusa3d.com and click the Forum tab button. The folks there are very friendly and knowledgable. I'm sure you can get some help. You can also email support.
There is also a question form at the bottom of www.prusa3d.com where you can ask questions.
I'm sure you can get it going. I have a MK2 also and it has done very well by me!

Hello, I actually posted there too. I got no reply (or their email notifications don't work).

@BillWaggoner While there can be some great resources elsewhere on the internet, please try to be more specific when linking to other sites. Ideally, a Stack Exchange answer, based on a link, will have a summary of the content of the link(s) as well as the link and attribution. This allows users to make an educated decision on whether its worth going to the other link.


text:
3D printing problem: waved walls
The problem
When I print with my mElephant 3D printer from Makeblock, the prints come out with waved walls like in the picture below. I am using PLA filament from https://makeblock.lt

What I tried
I tried changing temperatures 190-220, tried to change the flow rate. Also checked if the bolts are not lose. Everything seems good.
My printer

Are the smooth rods held with a screw in the end on both sides?

Possible duplicate of Unidentified problem in printing

This issue is a mechanical related issue called "Z wobble".

I had the same problem with ABS, but printing different test objects I found out that the distance between the wavy structures depends on the cross sectional area of the object. Printing the testcube in 70.1% (1/sqrt(2) times of the original size) takes half the time per layer and the distance between two grooves doubles. I was printing ABS with 0.1 mm layer height and the simple bang-bang heat bed controller. The temperature is clearly wandering for 4° with a period of aproximately 2.5 minutes, which corresponds to the groove distances. After changing to a PID controller for the heated bed the temperature stayed within 0.1°C and the problem was gone. Several hundredths of a millimeter thermal expansion of the heated bed can have substantial impact at 0.1 mm layer height!
You can enable the PID controller for the heated bed in Marlin or Skynet firmware by enabling (removing the //) here:

//#define PIDTEMPBED

and disabling (putting // at the beginning of the line) here:

#define BED_LIMIT_SWITCHING

in Configuration.h. Calibration of the PID controller can then be done with the GCODE Command:

M303 E-1 S90 C8

for 90°C. I had to preheat the heated bed before, otherwise the calibration would run into a timeout. The command will return parameters for the PID algorithm. The values can then be applied by the

M304 P579.01 I100.87 D586.0

GCODE command (here for example values). Everything can then be saved to the EEPROM with

M500

Bang-Bang controller:

PID controller:

Welcome to 3dprinting.stackexchange.com, @uiop!  This is an awesome, informative and well written answer, happy to have you onboard! :)

Repeating patterns like that usually stem from issues in the Z axis.  This is likely caused by bent screws which in turn cause the X axis to move around.    Are the top of the threaded rods constrained?  If they are, an easy fix may just be to let the top of the threaded rods float around by removing the constraint.  Most Prusa i3's use 5mm threaded rod for the screws and 8mm smooth rod, does your printer use the same setup?
If your printer has 8mm (or 5/16") threaded rod you could try to get some that are straight or the better solution would be to get the 5mm threaded rods and just print adapters to hold the 5mm nut inside the trap.  This would require new couplers (aluminum or rubber/plastic hose), 5mm threaded rods, nuts, adapters (printed) and a small change to the firmware.  This works because the 5mm rod is more flexible than the 8mm smooth rod and less likely to force the carriage around.
If you already have the 5mm threaded rod/8mm smooth rod then I would look to make sure your X axis is tight and does not move around on the Z axis smooth rods.
This would be easier to point out if you include a picture of your printer.
Edit:
If your printer is the mElephant from Makeblock then I would try removing the bearings at the top that constrain the threaded rods and try the print again.

Thank you for your detailed answer! I updated the question with images of my 3D printer.

It seems I edited my answer the same time you added the picture.  I would try removing the bearings at the top that the threaded rods are held in if you can easily do that then try that print again.

removed top bearings, problem persists

Do you see noticeable movement in the threaded rods?

@gpson The bearings are part of the problem, not the complete solution of problem (but should be left out). Your steppers have integrated lead screws, any mis-positioning of these lead screws leads to x and y movement of the screw when advancing up or down. You need to separate this movement. One solution is using separate lead screws and springy couplers (but these introduce also problems). A better solution is to remove your lead screw nuts and print a sort of a lift platform that contains this nut, then you separated x and y movement from the lead screw completely.

I have the same problem with a home made mini extruder. This happens only if the bearing stops rotating together with the extruder gear.
I notice that:

The gear collects burrs of PLA while feeding, so reducing the traction to feed the PLA
The bearing stops rotating when the pressure is too high or too low.
The heat of chamber is too high and starts to smooth the PLA before arrives to the nozzle and needs to regulate the speed of the fan. This creates less force on feeding.
The PLA has a mixture of ABS
PLA has part hardened due overcooking, extremely dry, etc.
The PLA have irregular diameters, for example is nominally 1.75mm but some sections vary 1.8mm or 1.9mm
The nozzle starts to get cold due direct fan air flow. (maybe your main problem)

:) I've been a Quality Engineer for 20 years for plastic and metal processes, so I've had to analyze why I've had lots of problems, especially in cold weather.
I was thinking on buying a new extruder like you have, but if you have the same problem I do, the Extruder is not the problem. You need to check the points I described above.
This is the extruder I have, http://aprendiendo.laconeccion.com/mini-extrusor-3dp.

Looks like something is catching on the z axis. A bent peice would likely cause much smaller deformations unless it was very obviously bent. Something could be loose, allowing the vertical play, perhaps the motor mounts.
More likely I think is a level-difference between the z-axis worm gears, possibly caused by an obstruction, lack of lubrication, or possibly even the wrong lubrication. That's where I would look. Further, since it's a very consistent pattern, my guess would be your issue can be isolated to the tops and bottoms of the z axis worm gears. Even if it's not the issues I think, the issue most likely located at the top or bottom.

I had a very similar problem once and the culprit was the relative position of the filament spool and the printer. The spool was standing on a coaster next to the printer and it turned out to be enough to create a pulling force on the filament. I have moved the spool to a shelf above the printer and the problem was gone.
However, your printer seems to have a way more rigid Z axis than mine, so it is unlikely the issue here.

Is your printer new?
It could be that the factory settings for the step number per millimeter or inch on the "Z" axis stepper motors. I personally have not had this problem however you might want to check out https://www.simplify3d.com/support/print-quality-troubleshooting/.
Hope this helps  :)


text:
How do you 3d print from an existing part when you have no CAD drawings?
We have a toy with some broken parts, an Executivity Gear Master. I don't think it's made anymore. Some tiny parts were easy to break and we'd like to 3d print some replacement parts. We don't have CAD or any other 3D drawings file, just a few of the unbroken parts. What's the best way to get some of these printed? Do I have to turn this into a 3D file first? (Is there a quick way to do that from the part itself?) Or is there a way to do it where I just need the part, rather like getting a spare key cut from a pre-existing key being used as the template?
Here's a photo of the part I need to print. Placed next to a quarter for size comparison:

I've seen the same parts used in a marble run toy I had as a kid - you might be able to find them with a bit of searching.

You can't print without a 3D model first. There are various ways you can go about this (or pay someone to do the same for you, ignoring any IP issues).
It is possible to generate a 3D model from a sequence of 2D photographs (there is even software which will allow you to do this freehand on a phone). Equipment exists which is specifically designed for this process, and you have likely heard of the services which allow you to get a 3D print of your own body.
You can take a 2D photo and import this into a 3D drawing package. Copy the features into a mesh, and extrude it. This might be a good approach for a complex shape, particularly if appearance is more important than precision.
For the shape you show here, the simplest approach for anyone with modeling experience is maybe to just draw it from scratch (with a few key dimensions). Your shape is only made up of a handful of primitive shapes.
Experiment in TinkerCad which is an online 3D editor to see if you can handle this yourself. It's not clear if you have your own printer, but this sort of part should cost less than $1 to print.
Strength might be a problem if they are already breaking...

As a side note: you say that several of the parts have been easy to break. While you are creating a new model from scratch, you also have a possibility to add reinforcement or otherwise improve on the design!

Whats the software to make a 3d image from 2d snaps on a phone?

@davidgo http://www.123dapp.com/catch

Unfortunately, There's no easy way to go about this. The easiest solution is to model the part from scratch. A pair of (digital) calipers is an invaluable tool for doing that.
Given that the part is rather small and (presumably) needs to fit with something, you need very precise measurements. 3D scanning or photogrammetry (reconstructing the models from 2D photographs) are not suitable for this, as they generally result in a model that needs clean up and can't be printed directly (which would be more work than modelling from scratch) and moreover the dimensions won't be accurate enough.


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Snapping to Ground - 123D Design
It's my first encounter with 123D Design, and first time playing around STL/3D printing in general. I can't find much information about the grid. But I noticed, while trying to move it, you can actually raise it from the grid. Does this affect how it will be printed? Does the print have to be snapped to the ground for it to print properly? Or is the grid relative, used for approximation?

The position matters a lot if you use the default STL file without doing anything in the slicer.  I've used 123D extensively and when I've inadvertently left a gap between the part and bed (and not snapped it to the bed in the slicer), the printer tries to print in mid air.  Use "d" to "drop" the object to the grid.  Different slicers have similar commands that will attach a face to the bed.  I use Simplify3D.