text:
How to identify nozzle wear?
E3D-Online and Make Magazine have written about the potential damage printing carbon fiber and glow-in-the-dark filaments can do to your printer's nozzle.
What I can't seem to find is what clues or warning signs to be on the lookout for if your nozzle has taken a significant amount of wear. I've printed a few hundred grams of glow filament personally and have not noticed any change in print quality.
E3D says you may have "unpredictable, erratic printing" with a worn nozzle. Can anyone explain or provide examples of this and when a replacement is necessary?

Obviously, when you notice your print quality deteriorate... Don't fix it if it ain't broke.

Somewhat off topic, but if you plan on printing more of such kind of filaments, consider getting a hardened steel nozzle

Where did it say that glow in the dark causes the same effects?

It's fairly common knowledge. Depends on the particle size though, some GITDs are more abrasive than others.

If you want to check directly (say, before doing a big or important print), I'd get a set of tiny drill bits (one of many sources: http://www.amazon.com/SE-Drill-Mini-Sizes-82615MD/dp/B0052Z9TJG). If the next size larger than should, fits through the nozzle, then it may be time to replace the nozzle. The bits are also useful in general...

I believe the little experiment made by E3D - the same link you provide - answers your question very well. Several points about wear can be found in this article. After printing only 250 grams of ColorFabb XT-CF20 (carbon fiber filament):

The nozzle diameter had increased markedly
The inner walls of the orifice (opening) showed deep sharp ridges and grooves
The tip of the nozzle had become critically rounded, and shortened

All of these symptoms were found repeatedly for standard brass nozzles.
In particular, I believe the last of these symptoms may be the one most easily identifiable without accurate measuring equipment (and without observing print quality).
With regards to reduction in print quality, these symptoms could be simulated by:

Setting the nozzle diameter too big in your slicer
Leveling your bed too high (the rounded tip will also reduce the length of the tip)
Printing with a partial clog that interruptus normal filament flow (due to the grooves and ridges)

Exactly what this will look like on your printed part is hard to predict, but I would assume you could see blobs, under-extrusion, poor layer adhesion, as well as an irregular surface finish of your top layers.

One of the things I look for is if you pull the print head a good ways off the bed and have it extrude. It should just squirt plastic straight down.  If it bends sharply in one direction, or even curls back on itself, then that is a sign of damage.

TL;DR You could compare the nozzle to a similar new nozzle to look for wear.

The creators of the Olsson Ruby Nozzle have published some pictures of wear on brass, steel and hardened steel nozzles. From their website the following image is taken:

Depending on the amount of filament that is being printed, not only the internal dimensions, but also the outer dimension change considerably. This is clearly visible in the images. Comparing your nozzle to a similar new nozzle might give you an idea of the wear of your nozzle. It is expected that long before the nozzle reaches this state, you need to readjust the bed to nozzle distance and the flow modifier, you will see this in the quality of your prints and the first layer sticking to the bed. So, the more (frequent) you need to tinker to get the print to stick or to print successfully and dimensionally correct, the bigger the change your nozzle has worn.

According to

 the inner diameter doesn't change much, but, as said by @0scar, the nozzle shortens and at the end you get to the inner cavity.
Check the length and you are done.

You can check for shortened nozzle length using a set of feeler gauges to measure the gap from bed to nozzle. https://en.wikipedia.org/wiki/Feeler_gauge

A worn nozzle is not necessarily shortened. Also, this seems like a pretty unreliable method unless you (1) used feeler gauges when you first installed the nozzle, and remembered the exact gap between nozzle and bed (2) while using the nozzle, never changed anything to the set up like leveling the bed (3) the bed and nozzle were/are perfectly clean when measuring.


text:
Maintaining fine details while applying smoothing methods
I've been reading and experimenting with Acetone vapour smoothing on some printed ABS parts. My problem is that I need to selectively smoothen the printed parts which vapor smoothing doesn't allow. In particular, the cogs, whose sides I was trying to make smooth ended, up with smooth rounded tips, which was a disappointment.
An example of what I was trying to smoothen is would be something like this:
So how can I maintain fine details (like the cog tips in the image above) while applying smoothing methods to printed parts?

A technique I've used in the past is to make a acetone slurry of the same filament used to print your object, and carefully paint the details you need to smooth.  You must be careful and only do a very thin coat or you may damage your print. You can add extra coat if needed to make sure the acetone has evaporatored from the previous coat of ABS filaments slurry.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
Drilling 3D-printed plastic
I need to do some post processing of my 3D-printed models that includes adding some holes. For each of PLA, ABS, PETG and other 3D-printing materials:
In what ways is drilling a hole in a model made from that material like or unlike drilling wood? Is it worth getting special "plastic drilling bits" that cost tons of money or can I use regular high speed drill bits? Do these plastics have grain that they will split on when drilled into, and if so, what are ways to avoid such splitting? Are higher speeds better, or lower speeds, or should I only use a finger-twirled bit holder?
Are some 3D-printing materials easier to drill than others?
What other methods also work for creating a hole in the different types of plastics?

In its current form, this question might be too broad. (At the moment of this writing, It has some close votes on it). However, I believe the question is useful. Maybe we should split it into questions for drilling in separate materials. I do think a canonical question about drilling 3D-printed plastic would be useful.

Have to get this out of the way... Can you just print the hole into the part instead of drilling? That's usually best, when possible.
If you need to drill, you'll definitely want to print an undersized hole and then ream it out with the drill. This both provides alignment for the drill and adds extra plastic around the region you'll be weakening. If you don't know where the hole needs to go in advance, fill the model with a hex pattern of tiny holes in the general region of the future drilling. This is an easy way to strengthen the area with more plastic without making the entire part solid. (Using a slicer that allows localized print settings will also work.)
The hole should be aligned more or less vertical or "across the grain" (+/-45 degrees aligned with the Z axis) to ensure there are nice, strong hoops of plastic around the hole to keep it from splitting. Drilling into a printed part (particularly PLA) from the side / parallel to the XY plane is highly likely to split it. It may even be ok at first but crack later under load or due to creep.
Regular wood drill bits work ok, but you need to go slow and take nibbles, leaving the plastic time to cool so it doesn't melt and stick to the bit. (Coolant is an option.) Use a pilot hole, piloted bit, or step drill to remove less plastic per pass. A really sharp bit will perform dramatically better than a dull bit.
Put something hard and drillable like wood behind the plastic part to help avoid breakage and bit-jamming when you break through the opposite side.

I wouldn't recommend drilling a hole in a 3D printed part in a traditional sense like with wood. Instead, I would merely ream a 3D printed part.
I've done this quite a bit where I'll print my holes at a slightly smaller than nominal size and use a standard carbide drill to ream the hole.
Things to consider:

Printing the holes smaller than nominal will ensure your hole is not printed larger than nominal
Printing with a higher shell will ensure you can remove the material without exposing the infill

Note that drilling directly into (or thru) an infill area of the part could lead to cracking of the part later, depending on the hole's functionality. In general, a printed hole (even if reamed) will be significantly stronger than one drilled through an infill area.

This is exactly what I've done in countless parts and I've never had problems.
I usually shrink the diameter by a mm or so and make sure I'm doing lots of perimeters. I wouldn't want to drill into infill... that could get messy.

In addition to the good answers already given, I'd like to add: Use a sharp drill bit, and don't go too fast. Dull drill bits and fast rotation are more likely to heat up the plastic (especially PLA) to a point where it gets soft again, and then you're usually in trouble because instead of a clean round cut, the material will start to bend and tear. And if you allow it to cool around the drill bit - well, I destroyed a thread tap this way...

Really good point about the sharpness! Anyone familiar with cutting plastic with traditional manufacturing is familiar with this issue, but a lot of hobbyists are not. +1

The weird part is, I have had much more succes drilling at high temperatures than low ones. The high temperatures soften the material, allowing to drill away parts of the plastic lines without breaking the structure apart. It also seams to strengthen the area around the hole.

Drilling is indeed possible, but as stated in previous answers you should preferably do this along the vertical from the print bed for maximum strength,  and if possible use an undersized hole as a starting point/guide. Drilling horizontally may cause the layers to separate but if you clamp down in the z-direction you're much more likely to succeed. It's likely to start cracking if even a relatively small torque is applied (one layer with bad adhesion is enough to make it surprisingly weak). If you still need to apply torque from the horizontal consider reinforcing the structure in the z-direction or splitting your print and gluing/fusing the pieces together to get some strength in both directions.
Two holes of decent strength (one along the vertical and one along the horizontal) can also be achieved by adding vertical holes and bolt the layers together.
When drilling take care not to apply too much force and make sure the excess doesn't get stuck in the drill bit. Any drill bit should work but I find that wood ones have a slight higher tendency to make the bit jam.

The primary difference between drilling FDM printed plastic and wood is that the plastic part is not solid the entire way through, and that plastic will melt or burn at much lower temperatures than wood.
If you know before printing that you're going to want to drill the part or potentially need to, then you'll want to modify the design of the part such that there will be sufficient internal reinforcement and material in the location of the drill site. The way I've done this in the past is put a through hole through the the entire part and slightly undersize the hole. Then I also increase the number of shells on the part so that the threads will have some extra material to bite into.
If you know you're going to need a hole in the part but not sure where then I'd suggest using the highest level of infill possible on the print so that your part will be as close as possible to being solid plastic. Or if there are a few areas you think might need to be drilled you can build your own internal structure but that can take a lot of time.
If you didn't know your part was going to need to be drilled AND you printed with minimal infill then be very careful about drilling and only use minimal pressure to cut through the top layer to avoid crushing the part. Then once the part is drilled all the way through consider filling the part with an epoxy to reinforce the hole location (if necessary).
Best case scenario though is knowing where and how big you need the hole to be before print. Of course though specs change on the daily.
As for the heat generated from the drilling process I haven't had much trouble with dissipating it. My 'method' for drilling a printed part (technically reaming) is that after I align my hole with my drill press, I then tap the drill-bit cutting only a millimeter at a time, then retract, wait a few seconds then repeat until all the way through. A little time consuming but my reasoning is to minimize burning and overheating of the hole due to the cutting friction.
In all honesty I think my drilling approach is overkill. But, every time I've needed to do it has been due to an error in modelling. I didn't have the time to reprint and was under a time crunch. My post processing step therefore did not have the option to fail so I was extra careful. Whether it was overkill or not it definitely worked, and it's always better to be a little more cautious than late.

I realize this is an old post .. but playing around with drilling PLA myself ..
100 % infill .. and use dish soap for a lubricant .. it seemed to work really well ..
I am a hobby machinist .. had a lathe and mill years back and used all the proper oils etc .. but in this case didnt want to expose the pla to oils and I did that once on a part I was trying to wet sand .. and it appeared as though the pla absorbed some of the oil ..
Well that just gave me all kinds of thoughts and ideas as far as oil absorption goes .. lol
Maybe need to experiment with how much a piece of PLA will absorb if its even measureable ..
Anyways .. agree with all above .. and could give the dish soup a try in hopes that it will help lessen the amount of heat generated ..

Soap as a lube is a good choice, I use water for wet sanding myself.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Filament extrudes at an angle
On one of the nozzles on my printer, the filament comes out at a 45 degree angle.  It seems that this causes problems with adhesion to the bed and overall quality.

What caused this problem?
How do I fix it?
How do I prevent it from
happening in the future?

When you say extruder, do you mean the nozzle?

I corrected it.

@TextGeek, I believe Eric was referring to the spelling, not the question. ;)

@EricJohnson Has this question been resolved for you, or are you still looking for an answer?

Yes, I used a thin wire to clean the nozzle.  I also did a series of pulls to remove the debris higher in the extruder.

I've personally had this happen when I had a minor clog in my nozzle.
My first steps to fix this would be:

Make sure the exterior of your nozzle is clean. I've had bits of plastic pull at the extruding filament and change it's direction.
Attempt a "cold pull" or "atomic pull". On my Replicator 2 I do this by removing the extruder motor, heating up the hot end, manually pushing a length of filament through the nozzle, letting it cool slightly and tugging the filament (and hopefully the clog) out of the nozzle.

Also make sure that you change filaments the cleanest way possible. As suggested a cold pull can be used:
http://3dprinting.stackexchange.com/questions/233/how-should-i-clean-my-extruder-when-changing-materials

If you're extruding into the air, it's actually quite normal for the filament to come out in seemingly random directions. This shouldn't cause problems because the filament should always be getting squished onto the bed/layer underneath (or during bridging, getting stretched). The way the filament comes out in free air doesn't reflect how it behaves during printing.
If you are experiencing troubles then perhaps the nozzle is clogged with a small piece of debris (or, unlikely) the nozzle is actually damaged. There's little you can do to prevent that apart from using high quality filament and being careful not to damage the nozzle.

You beat me to it! :)

You very likely have partial clog in your hotend (the side which is clogged is the angle the extruding filament bends to) or have some plastic somehow stuck on the nozzle surface which the extruding plastic almost sticks to, like two droplets of water merging into one.
If its the latter, clean the hotend. It's easier to remove the plastic on it while its hot and soft, but don't burn yourself.
If it's a clog, that's more complicated.
First, you can make sure if it is indeed a clog or not by extruding into the air and measuring the wire with a caliper.
If it's thinner than it should be and your slicer settings are fine, then its a clog.
Ways to get rid of clog:
1) Replace the nozzle with a new one.
2) Break the clog with a sharp wire.
3) Take the hotend off and clean the nozzle with acetone ("acetone bath").
4) Blow torch on a removed nozzle. Dangerous thing to do for some but it works. If you're not confident or experienced to do this and the previous two solutions don't help, then go with option 1.


text:
Making your own filament
I"m considering making my own filament, with a device like the one at http://www.thingiverse.com/thing:380987. Partly because it's another machine to build, which is cool, but also to save money on filament.
Has anyone here tried to make their own filament? My main questions are:

Is the quality comparable to typical off-the-shelf filaments? Put another way, with reasonable tuning can one produce filament that's good enough to use without a lot of frustration?
Does it require a lot of attention to tuning, monitoring, or other details (which make it less worthwhile / more time-consuming)? Warning of pitfalls to avoid is also welcome.
Are there useful things one can do this way, that are hard to achieve with off-the-shelf filaments? For example, unusual materials; better control of diameter, density, etc; or mixing one's own colors?

Quality depends on 3 things:

Quality of pellets (purity, fillers, color)
Where/how they are stored before and during the extrusion (humidity, contaminants)
Have a filter in your extruder to get rid of random junk and air bubbles ending up in your filament (250 micron wire mesh filter)

There's no secret formula the filament producing companies have, they just have very efficient and very fast filament producing machines (of course very expensive, too). But when it comes to vanilla ABS or PLA, it's almost the same content.

Personal experience: no. If you get the same pellets, store it in the same place and run your extruder in the same place, it should behave the same.
I don't think there is some filament mixture you won't be able to find anywhere, but you might be able to make it yourself cheaper. Example: mixing strontium aluminate powder for glow in the dark filament (come in many colors, not just green).

I'd recommend this design: http://www.instructables.com/id/Build-your-own-3d-printing-filament-factory-Filame/
It produces filament pretty fast (one full 1kg spoon in 3-4 hours). Just make sure you have enough experience to not electrocute yourself while assembling this as the heaters use mains power.
I personally think the commercial "hobby" extruders are not worth the money. I also own the Filastruder and it's just no different and slower than the above, unless you care about a pretty plywood case for your extruder I see no advantage and since it uses off-the-shelf parts itself why bother buying a kit like that than sourcing the parts yourself?

You can basically use any machine that pulverizes your pellets into small pieces.
One guy on 3dhubs, explained it in details.
My conclusion is that you can recycle everything using this data gathered from research up in link there.
Also, you can use any plastic material and pulverize it into pellets (even from the bottles) and you can try to do this process. Only thing that matters is quality of product.
I was thinking about pellets from vinyl records. I bought one big collection before one year, and there was around 500-600 records that are completley useless. So, you can pulverize them and repeat the process, because process of making vinyl records and process of making bottles is completley different, and uses different kind of plastics.
So to draw a conslusion: everything depends on quality of pellets.
And to answer on your three questions:

Is the quality comparable to typical off-the-shelf filaments? Put
  another way, with reasonable tuning can one produce filament that's
  good enough to use without a lot of frustration?

No, it isn't Your filament would be lower quality if you don't get a great pellets.

Does it require a lot of attention to tuning, monitoring, or other
  details (which make it less worthwhile / more time-consuming)? Warning
  of pitfalls to avoid is also welcome.

Yes it does. Check the link up there.

Are there useful things one can do this way, that are hard to achieve
  with off-the-shelf filaments? For example, unusual materials; better
  control of diameter, density, etc; or mixing one's own colors?

Again, it all depends on type of filament you like to use. I wrote about plastic filaments.

Vinyl records might be a good source for PVC, but the question is: is it a good filament?

Producing own filament is a challenging task. I see main pitfall in producing filament so it has same quality as you get in shop. You have to:

constant round-shape diameter
diameter tolerance ±0.05 mm
avoid bubbles and other defects
avoid object in filament (depends on pellets quality)
store pellets properly (high humidity is a problem)

Additionally you have to deal with spooling, because it affects the diameter too (if you roll filament too fast then you reduce its diameter).
It takes a lot of time and frustration to develop such a machine. If you would like to produce own filament, consider buying a filament machine:

Strooder (£960) + Strooder spooler (£192)
FilaFab (£745 - £1495)
ExtrusionBot (\$720) (Spooler included)
ProtoCycler ($1700)
FilaBot (\$1600) + Spooler (\$600)

If you would like to use different material then ABS/PLA then take a look on Strooder documentation - they confirm usage of PP, PET, HDPE, HIPS, PE, even wood filament.
Is it not better option to print directly from pellets? Take a look on Universal Pellet Extruder for RepRap (model).

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Taking a new hotend into operation (cleaning, forming, etc)
When installing and using a new hotend for the first time, which steps of action should be taken before. This will probably be more applicable to chinese clones than to authentic products (is the statement true?): Should a certain cleaning procedure be carried out (removing swarf/shavings for example)? Should mechanical precision be controlled and if necessary improved (de-edging and nozzle size are two things I could think of)?
I know the topic How should I clean my extruder when changing materials?, which is a nice addon read, but I am concerned about brand-new extruders.

I noticed that your question has a few answers available and has been open for a while, just curious if any of the available answers was able to help. If not, then what questions do you still have?

So far, these are my experiences to make a new hotend work properly.

Read the instructions. The ones of the 'original' if it is a clone.
Check the parts. Is everything included you need?
and check the design, if it is a clone. It might not be the same as the one they're trying to copy. Figure out the differences (as far as I encountered mainly the heatbreak/inliner design)
There is no immediate need to mechanically check the nozzle if it passes an optical check. You will be calibrating the extrusion anyway and unless you're unhappy with the results, there are most likely more severe impacts than the accuracy of the nozzle diameter.
Cleaning should be done to some extent. You wouldn't want any visible leftover products from the hotend's production in the extrusion path. Anything that you can't see will most likely be removed easily by the filament and should only be a problem when there are other more significant flaws.
You maybe want to install a heatbreak into the heatsink with lots of thermal paste to transfer the heat as effectively as possible. A defined and short meltzone is key for reliable operation.
You also maybe want to add some thermal paste for the thermistor/thermocouple to ensure quick heat transfer here.
You maybe want to insulate your hotend thermally to not lose heat by dissipation. I asked a question about that process here: Efficient and easy way to thermally insulate the heat block of the hotend?
Test whether the filament is easily guided into the heatbreak, so that it doesn't stop being extruded by catching an edge or deforming over one.
Check the two valuable answers of TextGeek and Dimitri Modderman, there's good information in them!

This answer is most likely not complete and totally up for discussion. I appreciate any addtional answers and comments to improve on the topic!

I haven't done anything special to set up mine. But it's probably worth doing a general cleaning. I'd swab it off with alcohol, including running a q-tip or similar inside the fiber feed path. Then blow out the nozzle with compressed air to make sure it's clear.
You could measure the nozzle diameter by fitting fine drill bits in to see which is the largest one the passes through freely. Be sure to measure how much fiber your extruder really takes in when you ask it to extrude a certain length -- but that's about the extruder, not the hotend per se.
Finally, I'd check the insulation, if any. I got a couple hot ends that had big gaps in/around the insulation. I've found that "high-temperature gasket maker" is great for improving insulation (depends, of course, on the shape and design of the specific hot end.

+1 for the basic cleaning and measuring.
The knowledge of the actual nozzle size would be important to take it into the software, correct?
How about improving interior gliding abilities with an additional PTFE liner if it could help?

Yes, there should be a setting for nozzle size in the software, and nozzle size also affects layer height (I generally set layer height to about 80% of nozzle size). I don't know about the PTFE; it could be interesting to try it.

I heard some people are using silver polish on a pipe-rag (not sure what the English word is, it's a long metal wire with threads on it to clean a pipe (for smoking). Then put the pipe-cleaner in a cordless drill and spin it around to polish the inside the hotend to have it silky smooth inside.
Also i heard some people put a hotend in canola oil and cook it, supposedly the canola gets on the hotend (like baking in a new chinese wok pan, you put oil and heat it to create a nice oily film).
I always bought original J-heads and switched to E3D only for my Delta printer. Never had to clean anything, but heard the chinese clones sometimes lack the finish the "real" products have.


text:
In the standard PC Cable Wire that goes from the wall outlet to the switching power supply, are they standard and what are the wire specifications?
What are the specifications of the three wires inside a PC cable that is used to connect the switching power supply to a US AC outlet.
The positive, negative and ground appear to be the same gauge stranded cable, and I've heard that it can handle 10A, but beyond that I don't really know what the rest of the specifications for the wire are.

What's the question exactly? What specification are you looking for? Wires can have plenty of specifications like minimum bending radius, but they aren't really of interest for you if you just want to connect the power supply to the outlet.

Well how many AMPs it's good for and what the metric and AWG Wiresize is; the strand number... here's a chart that has a list:  http://www.zierick.com/pdf/wire.pdf but I don't know which one it is...

Why do you need to know the wire size if you already know that it's good for 10A? You probably used this cable before to connect your PC (or other device) with the outlet without asking these questions. What's the specific concern that you have now? It looks like this belongs on [electronics.se]

Well I just want to learn what I'm doing...and I'm using the wire to attach a switch and plug to the printer.  I'm going to crimp terminals using a crimping tool; and I want to make sure the switch, it's fuse as well as the electrical connection terminals are correct for the wire, so they don't melt.   I bough a stripper/crimper, not that cheesy thin black one that everybody uses but one that's between that and the $78 ones...it's a Commercial Electric Double Jaw Stripper Crimpper.  Ultimately, I'd like to avoid a fire, or damage to the house wiring.

It's not the wire or its specifications that melt anything, it's the power that goes through them, which is determined by the load: the power supply that supplies your printer. The standard wire can handle what the outlet can supply. If your printer draws more power than that, you have other problems. If you buy a bigger TV you don't start thinking about metric wire sizes either, do you?

No, but I'm but I don't build my own TVs or fix them...

The PC power cable itself is universal and is held to some ISO or EIA standard, but the power supply is mostly what you have to worry about as it is the most fragile and needs to convert a certain amount of incoming energy from AC to DC or regulate the energy. The PC cable is simply just copper wire/terminals. Tom van der Zanden I think answers your question directly, but the third dimension provides the "Teach you how to fish" type of answer.

Very basically speaking, electricity works like this:

There's some source that delivers a certain voltage.
You have a device that operates at a certain voltage. The device voltage and supply voltage should always match. No, don't put that 120V US device in a 230V outlet in Europe.
The device does something. By doing something it draws current. Most devices also draw some current when not doing anything.
How much power your device draws is the product of these two values:voltage x current = power

So far, so good. In your case:

US AC outlet.

the voltage is 120V.
On this other question of yours you linked to this power
supply on amazon. Besides being available gift-wrapped, it
states the following feature:

You can choose the input voltage (110V/240V) by switch.

110V ≈ 120V, which means the device voltage matches your supply
voltage.
The supply can deliver 30A at 12V on the DC side which means 360W.
If it could transform the electricity ideally, without any
inefficiency, that would be 3A at 120V on the AC side. But your
supply is unlikely ideal. Wikipedia suggests 60-95% efficiency.
Let's be super pessimistic and assume 50%. That means half the power
that goes into the switch power supply is turned into heat. In order
to still get the 360W out, you have to insert 720W. That means
your device draws 6A on the AC side.

What does this all mean for your wire?
What wire size do you need for this supply?
Coincidentally, the above link to the amazon website showing your power supply also suggests the following PC ATX power supplies to me:

Sentey Power Supply 725 Watt
Sentey Power Supply 1000 Watt

Let's get this straight: You can buy a power supply for a PC and plug it into your outlet without even thinking about what a wire size is. You'd just plug and play. That PC power supply will potentially draw more current than the power supply of your 3D printer. A standard wire would be able to supply either one of the PC ATX power supplies linked above and would not have a problem delivering a lower current to the power supply of your 3D printer.
The switching supply doesn't have a plug like a PC ATX supply, but that on its own doesn't make it any less secure (if wired up properly). It's just less common for household appliances.

Ultimately, I'd like to avoid a fire, or damage to the house wiring.

That's a good and valid concern.
PC Power supplies deliver 12V and supply more than enough current (like the examples above). They are probably in use in your house already and did neither set it on fire nor damage the house wiring.
A switching mode power supply is just as secure and if bought from a known brand unlikely to do you any harm either if used properly and within its specifications.
Ultimately, this is not a question of secure electricity but a trade-off between secure electricity and the price to pay for it. The standard wire and it's specifications have little to do with this.

Personally, I also use a cheap switching power supply made in china for my printer. It's very noisy and I pull the plug when I leave it unattended.

"Besides being available gift-wrapped"... ROTFL!

It's somewhat unclear what you mean by "standard PC cable", but virtually all desktop computers use IEC C14 sockets/IEC C13 plugs. Such connectors/sockets are rated for 10A 250V and thus you can safely assume that the cord itself will also be able to handle this voltage and current. 10A is what is specified by the IEC, certain North American standards agencies rate C13 cords for up to 15A.
The IEC standard also specifies that the conductors inside of a C13 lead have a cross sectional area of at least 0.75mm^2 and at least 1mm^2 if the cord is longer than 2m.

authors: زعيم القراصنة


text:
When building a RAMPS 1.4 based printer, can I safely plugin just some of the components to test if they are working?
If I need to test out some of the components of a RAMPS 1.4 based 3D Printer, can I only plug some of them into the board (not all of them) and test them out?
I'd like to test out the NEMA 17 motors without testing the heated bed or extruder.  Is this safe and why?

If by components you mean motors, fans, or heated bed, then yes. This is even suggested in the Final Setup instructions on the RAMPS wiki.

If you think you may have mistakes (in your setup) you can install only one stepper driver during initial testing and risk only one stepper driver.

There are also printers using RAMPS with no heated bed and other machines that have no extruder at all. Furthermore, from an electronics perspective: if nothing is connected across a terminal no current will flow and therefore there is no damage that can be done. Obviously if you short out the unused connections there will be problems.

Nice reference! :)

Yes, you can. By leaving components unplugged you would simply have some pins powered that are not in use. But even with all your components plugged in, you would still have some unused, powered pins on your board, so I wouldn't think too hard about that. In some cases it might be needed to mount e.i. fans to cool your electronics while running, but for testing a few stepper motors, you will be just fine.
Exactly how you would address each individual motor depends on your setup, however. My best bet would be to simply rely on your "default" firmware (such as Marlin), and then run commands for testing through Pronterface/PrintRun or similar.
Alternatively, you could upload your own sketch/firmware to the Arduino, and manipulate each stepper driver individually. This is a somewhat more advanced option, though.

As others have also said, this is generally fine. The main things I'd avoid are:

Don't plug or unplug "heavy" items (mainly motors and heaters) with power on; turn everything off first. This is especially true for motors, whose coils produce a hefty back-voltage when disconnected.
Be extra careful about stepper drivers. For example, some printers use 2 motors for Z, so if you test each axis against one driver, the current requirement may be quite different for each axis.
Plugging in a limit switch backwards on RAMPS is likely to short +5V straight to ground, which is worth avoiding.


text:
Stepper Motor Linear Acceleration Python (raspberry pi)
I am working on a Python code (below) that accelerates a stepper motor until it reaches a specific amount of steps.
for s in range (steps):
if s < accelerationsteps:
    lateststep = self.onestep(direction, stepstyle)
    time.sleep(s_per_s)
    s_per_s = s_per_s - ((astart - aend) / accelerationsteps)

s_per_s = time in between each step
astart = starting speed in second/step (for example 0.5)
aend = speed at which the acceleration should stop (for example 0.05)
accelerationsteps = amount of steps over which the acceleration should happen
The problem is that the velocity increases in step per second per step instead of step per second per second, and is therefore increased exponentially instead of linear. I have found this article that explains in mathematical terms how one can achieve a linear increase with a stepper motor but I have not managed to translate that into my python code.
I would highly appreciate it if someone could help me with this and I think it would be very useful for people using steppers on the Raspberry Pi in general (I have only found a solution for the Arduino here
Thank you very much in advance.

I'm voting to close this question as off-topic because "using steppers on the Raspberry Pi in general" is not within the scope of this site.

Try [raspberrypi.SE] or [electronics.SE].

See also http://stackoverflow.com/questions/34319469/stepper-motor-lineair-acceleration-python/34322201#34322201

Thank you for the comments, sorry I should have posted a link to the original question. Someone advised me to ask this question here. I'll have a look at the Raspberry Pi or Electrical Engineering sites. Cheers!

There are no good 3d printer controllers running directly on the Pi, but for Python implementation of stepper acceleration control, you may want to look at the Redeem code for Replicape.

FWIW, question asked on SO: Stepper motor linear acceleration


text:
Can general purpose polystryene (not HIPS) be used for 3D printing?
High Impact PolyStyrene (HIPS) is a frequently used filament in 3D printing.  It has been touted to have simular properties when printed to ABS and is especially useful for support structures (if the user has a multi-nozzle 3d Printer) as it is soluble in Limonene.
General Purpose PolyStyrene (GPPS) is frequently used in disposible cups, cutlery, etc.  I don't believe I have seen it as a 3D printing filament.  This is not styrofoam for the purpose of this question despite the identical chemical properties as the incorperated air makes it difficult to recycle.
Would filament produced from GPPS, be usable on most FFF 3D printers that are capable of using ABS, PLA, and HIPS? Are that any particular issues observed with such filaments that would not be observed with HIPS (besides the implied decrease in impact resistance)?
Note: For the purpose of this question, I am assuming that the filament can be produced and am concerned about whether the filament would be usable for support structures and infill.

In principle, it should work fine as a filament, since it's used extensively in the plastic extrusion industry, but I don't think you'd get great material properties out of it. ABS and HIPS incorporate polybutadiene into a graft polymer structure for a very good reason: the butadiene sections in the long molecular chains kind of "stick together" as a distinct solid phase to produce what amounts to micro-bubbles of rubber inside a matrix of hard styrene or acrylonitrile-styrene plastic. This compound microstructure is what gives HIPS and ABS favorable impact toughness and some minor flexibility.
The flexibility is important -- the stiffer a filament is, the more it will tend to warp while printing. Based on chemistry alone, I would expect styrene to be somewhat more prone to warping than ABS. And it would certainly be more brittle. So there doesn't seem to be much reason to use it as filament.
Interesting sidenote: PLA/PHA has very favorable mechanical properties because the PHA forms a very similar flexible microstructure inside the hard PLA matrix. PLA/PHA is good stuff because it mimics ABS and HIPS!

On the other hand, polystyrene is much harder than HIPS, so there is a reason.


text:
How to use a multimeter to test how many amps RAMPS is pulling?
This is in with my other question about components and the other question about electricity; how can I check to see how many amps are being pulled?  Can I check a component at a time to make sure I'm not going over the limit, and then just add them all in together once I've summed the amps to make sure it's safe to hook everything up.  The amps shouldn't change right?
What settings should my multimeter be set to?  And to check how much it's pulling, do I just put the multimeter's leads on the green terminals on RAMPS 1.4?

@TomvanderZanden - whilst it is technically only about how to read current draw with a multimeter, it is specifically about the current draw of a 3D printer control board, and so the many answers which have been provided may be rather useful to other 3D printer users. You make a very good point about shorting the power supply, though.

@TomvanderZanden I agree with Greenonline, this may be useful to others looking to troubleshoot their 3D Printer explicitly. Therefore the context should reside in the 3D Printing network.

To measure amps (current), the meter has to be wired in series with the item to be measured (for this reason, ammeters are designed to have very low resistance).
This has the down-side that you have to disconnect the component to put the meter in line with it. That makes it hard to do the "check a component at a time" method you mentioned.
An ammeter measures actual current flow, so you really can't test a component for it in isolation. Components can have wildly different "current draw" depending on the situation. For example, motor current varies with torque and speed; current through a resistor varies with the voltage across it; and so on.
There are special "clamp-on" current meters that just clamp around a conductor and report the current by using induction. Very nice if you have one.
If you just want the total current the entire RAMPS board is pulling, put the ammeter between the power supply and the RAMPS power input connection(s). Be very sure not to have the meter set to read volts or ohms when you do this (it might or might not survive).

Also be sure the meter you use is rated for current measuring well beyond the current you think you'll see, or you'll either blow the internal fuse or destroy your meter.

A multimeter set to volts or ohms will have very large input impedance and is unlikely to be damaged in any way. You have neglected an important point of current measurement using a multimeter: you usually need to swap the probe lead over to the socket for current measuring. Most multimeters can only measure up to 10A which is less than the heated bed may draw.

The easiest method is to use a Clamp On amp meter on either the hot or neutral of your power supply.
In most cases clamp on meters only work with AC xor DC power so you would only be able to get the reading on one side of the power supply.
Multiply this number by the voltage and you get the wattage.

The power to both pairs of the (green) terminals on the RAMPS board is only D.C., so he would require (as you say) a DC Current Clap meter.

If you don't want to stick a multimeter on the wire, I recommend getting a kill-a-watt meter. Pretty much, you plug it into the wall, and plug the printer into the meter, and it has a little screen that shows the result.

I like this idea.  It sounds safer.

@leeand00 - The downside of this method, is that you would also be measuring the additional power used by the power supply (and any losses therein). Also, the current reading would not be the same as the current drawn by the RAMPS board, as the step-down transformer in the power supply will reduce the voltage to 12/24V, but, possibly, increase the current. This method works if you want to measure the total power used (including any power lost in the power supply), but will not give you accurate current reading for the RAMPS board, per se.


text:
How do I wire the z-axis motors in parallel on the Prusa i3?
There is a little circuit board, or breadboard or something in the diagram of the wiring for the i3.
And it's mentioned that the z-axis motors need to be wired in parallel but beyond that they don't give you much detail about parts or how the wires go in.
Can someone provide me with some more detail on this?

In the diagram, they do show the wires connecting together, which is right. You can accomplish that just about any way you like, so long as you pair up the wires correctly from one motor to the other.
I'm assuming both "Z" motors are the same type and have the same color-coding for their wires. If not, you'll need to figure out the correspondences first (you may want to post another question if you need a hand with that, since it's pretty specific and generally useful).
Many control boards have "headers" sticking up, with 4 bare pins for each motor. Connectors that plug right onto those are readily available, such as at https://www.sparkfun.com/products/10364.
Some ways you can wire the motors in parallel:

Some control boards, like my RAMPS 1.4, provide 2 sets of header pins next to the Z stepper driver board. In that case, just put a connector on each motor (if they're not there already), and plug them in next to each other.
If there's just one set of header pins (or one Z-motor socket of some other kind) on your controller, make a "Y-cord" by soldering the wires from one connector (that plugs to the controller) to 2 4 pin connectors, one to mate with each motor.
Or you can skip the 2 extra connectors entirely, and just solder the motor wires to the wires from the connector: 2 reds to red, 2 blacks to black, or whatever.
If your controller just has empty holes, either solder in header pins and do as above (preferred, IMHO), or wire directly into the holes, splicing the 2 sets of motor wires if there's only one set of holes.

Motor and connector wires are wildly inconsistent, so make sure you get them sorted out right if they aren't already. The first thing is to check continuity: find 2 pairs of wires, which are the ends of two separate coils. If your motors have more than 4 wires it's trickier.
With RAMPS (see handy diagram RAMPS 1.4 RepRap Arduino Mega Pololu shield),

the 4 pins are commonly labelled (starting from the one nearest the power-supply end of the RAMPS board):
2B 2A 1A 1B

It means coil 1 and coil 2, each of which has ends A and B. I find this unclear because it could just as well have been numbers for the coils, and letters for the ends (if you wire it that way it won't work). So be sure you have continuity (maybe 15 ohms or so) between the wires you connect to 2B and 2A, and between the wires you connect to 1A and 1B.
The really good thing about this pin order is that if a motor is running backwards all you have to do is power off and then turn the plug around. That's one reason I think it's important to keep connectors in there, rather than soldering directly.

For some unknown reason, everywhere everybody is saying that Z stepper motors need to be connected in parallel... And this was always the only obvious way, until recently some people started to connect these motors in series.
And I personally started to believe the right way is to connect them in series.
All stepstick drivers are some kind of current limiting devices (you could read more about chopper mode). It is all about current.
Connecting in series will guarantee that both motors receive the same current in all situations. And as result you could expect the same behaviour from both of them.
The bad thing when they are in parallel, is that the motor with the bigger load will get more current and as a result the other one will get less current and could skip steps. Of course, in an ideal situation, this should never happen but don't forget about Murphy's law ("whatever can go wrong, will go wrong").
One more thing - why did I change my wiring and connected my Z motors in series: At some moment I found that one Z motor was disconnected but the other one was working and this resulted in a broken printer geometry. When Z motors are in series and if one of them fails or disconnects, the other one will not work either. You will get always synchronous operation from both of them!
I made this Z splitter that works fantastic:

There are two coils in each stepper motor driven by different pair of wires.  This is a really helpful contribution how to connect 2 z-axis motors to a mainboard with only 1 z-axis socket.

The wiring in this splitter pairs are red-blue and green-black, so the Splitter puts the "lower" pins on one circuit, and the "upper" on the other. As a result, step commands from either circuit affect the motors synchronously. To minimize errors, it would be a good idea to make both branches connecting to the splitter as even in length and as short as possible.


text:
What are the pros and cons of collecting parts yourself, versus getting a DIY kit and then modifying it?
I'm thinking about buliding my own 3D printer from scratch.
Is it better to buy a starter DIY kit and try to build your printer around it, or to order separate parts for printer, and then to combine a printer?

Hi. It seems like your question really is "What are the pros and cons of collecting parts yourself, versus getting a kit and then modifying it?". Currently, I think your question title poorly reflect that intention (it is too generic), and also, your second paragraph does not seem to add anything to the question, which means you would be better off removing it. Also, in your last paragraph, try to ask the question so that it does not request an opinion based answer, as such questions are generally frowned upon in the SE community.

From a general point of view, there are a few things to consider.
If you buy a kit:
Pros:

You get some insurance that you have all the parts that you need to get a functional printer - all the electronics, structure, bolts, nuts, screws, washers, wires and so on.
Most likely, all the parts you get are made to fit together.
You will (usually) get a manual, often a community that can help you out, and sometimes even technical support.
Sometimes, it can be cheaper than buying each part separately (but it can also be more expensive)

Cons:

You have limited/no options to customize your printer to your own preferences without purchasing additional parts.
Some kits can be difficult to upgrade later or may be locked to some configuration or software.

My opinion:
The way I look at it, the better option for you depends on how you want to spend your time. That is:

If you get a kit, you can spend more time building.
If you collect all the parts yourself, you will have to spend time planning, ordering parts (possibly multiple times) in addition to actually building the printer. A possible lack of manuals could also increase the building difficulty.

If you don't already own a 3D printer, I would recommend getting a kit, simply because struggling with trivial things like parts not fitting together can take away the fun for many people.

Nice answer. Would you consider also pointing out that kits can also be more expensive? Something like: "It can be cheaper than buying each part separately (but it also can be more expensive)."

@hroncok, thanks for your comment! You are right. Kits are certainly not always cheaper.

I'd recommend buying a kit for your first printer and building your second, if for no other reason than you will probably want/need to print at least one part when you build your own, and if you don't have a working printer...

I built my first printer from scratch, though it's fairly similar to an oversize MendelMax 2. It was a good learning experience, but very frustrating at times. Overall, I think I'm glad I did it that way, but a kit would have gotten me printing much faster and a bit cheaper.
Here are my main impressions from the experience...

You should already be familiar with most of the basic skills involved: soldering, wood- and/or metal-working, electronics, etc. And don't forget software -- I wrote a lot of Arduino code for various things along the way.
You'll need to be diligent about searching for answers online, because there's no manual to go to. This group should make it a lot easier now than it was last year.
Some problems will have great answers online; some won't, or the answers will be hard to piece together. I found that stepper motors have a "lore" all their own, with several subtleties I didn't expect.
You'll have to decide how "from scratch" you want to go -- I bought completed Arduino Mega and RAMPs boards, but you could buy a kit or components for those instead, or even design your own electronics altogether.
You'll make mistakes and spend money to recover. For example, my Y-axis motor couldn't move the build platform nearly fast enough (too much inertia), so I had to re-work that axis entirely, using a much more expensive lead screw, plus bearings, blocks, couplers,....
If you think you might want to sell the printer later, I imagine it would be easier if it's a known design.

That said, it's a blast except when you get stuck; and the satisfaction when your first successful print comes out is pretty great.
Oh, one other hint: especially for hardware, buy in bulk. You can probably get 100 of a certain bolt online for the price of 10 at your local hardware store. Give or sell the leftovers to help others get started.

A few months ago I bought a cheap (220 USD) Prusa i3 kit from China and put it together. Putting it together was fun and still a bit of a challenge. It was also nice to have pre-configured firmware already loaded onto the Melzi board that came with it.
So for the downside: The board (Melzi) that came in the kit only supports one extruder so if I want to add more extruders later I have to replace it. This means that in that case I would have paid for two boards.
Maybe you should ask yourself what your #1 goal is. If you are mostly interested in having a printer for use in other projects, then a kit might be what you want. If your main interest is having something to tinker with, then maybe you should go all in and make everything from scratch.

Three great answers have already been posted, and it has been extremely interesting to read them. I shall try not to repeated what has already been said.
I have sourced the parts separately for three different printers:

P3Steel (the frame was a kit, mind: Orientation of long thin rod on P3Steel v4)
Wilson II
Kossel XL and Mini

I have been coding Arduinos and Pis and building robots and quadcopters for a few years now. Then, in November 2016, because I needed a prop guard for a ZMR250 quadcopter that I found hard to obtain, but easy to print, I started reading about 3D printers (mostly RepRap wiki, and then individual blogs of straight forward builds, as well as design modifications, of Prusa, P3Steel, Wilson and Delta/Kossel printers), watching countless construction videos and asking questions here on SE 3D Printers, and reading other's questions and answers, as well as going through eBay for hours at a time, looking up parts and making numerous Bill Of Materials (BOMs) and blogging the information that I gleaned. So this gave me a good grounding and starting point for when I did get around to ordering. In fact, the process is still on going...
After ordering the parts, in December, piecemeal, I then had to wait for a month for the parts to arrive from China, during which time I read some more, and revised what I had already learned.
I then, finally, got to work on the P3Steel, in January, but two and a half weeks later, before I had finished it, I had to move to BKK for an extended period.
I suffered delays with the P3Steel build due to postal latency, obviously, but also, some partial kits where missing critical parts (see Is the 8mm x 20mm bearing axle for the X-axis idler (of a P3Steel) a custom part?), so I had to get them machined in Thailand (because it only costs around $3 to get something machined here). Hopefully, when I get back to the UK, I should have everything to hand and be able to finish the build in a few weeks maximum
Once in Bangkok, I started sourcing parts for a Wilson II, and then, subsequently, a Kossel, mostly because the aluminium and steel rods are a quarter, to a half, the price that they are in Europe. Also, I had to go through the ordering process again, getting parts from China for these two printers - however, the parts from China only take two weeks to arrive to Thailand, not a month or so, for the UK. The Wilson II parts I plan to take back to the UK, in order to complete the build there, hopefully printing the plastic parts on the P3Steel, when/if the P3Steel is completed.
Note, that seven, or eight months, down the line from when I first took an interest in 3D printing, I still haven't completed a single printer, yet. However, I sure as hell have learnt a lot. Note: most of the delay is due to the six month relocation away from my printer build in the UK.
Also, due to my reading of the modification blogs for the Wilson and Kossel, I have recently been re-purchasing upgrades, before I have even fitted a bolt together, for the Kossel and Wilson, let alone completed either of the base builds. For example, I have just purchased Chinese aluminium vertices, rather than the plastic PLA prints that I got from Sintron. So I have ended up with a fair collection of spare (redundant?) parts, but again, it has helped me gain a great insight as to what works well, and what does not.
To reiterate that which TestGeek has said, one major tip I would have is (and I read this on a forum when I was first getting into 3D printer building), if you are sourcing the parts separately, is to buy bulk (get packs of 10 pcs, 50 pcs, 100 pcs), and buy more than you require: nuts, bolts, bearings, GT2 belt, GT2 pulleys. The price comes down phenomenally, and you can resell the spares, locally, for about as much as you paid for the whole lot, online, thereby covering, or almost covering, the cost of the printer. Plus, spares come in handy for further builds down the road. Don't buy anything from the US (unless you are already in the US, I guess) - the import/postage fees are outrageous.

TL;DR
In the same way as you learn more from building a kit as opposed to buying a pre-built printer, you will learn more sourcing the parts separately, but it might cost more, in redundant parts. Also:

Research extensively first
Buy bulk
Be prepared for delays, be patient
Be prepared for an iterative design


text:
How to choose a right 3D printer filament type?
There are a big variety of them that can be found at the market. Some of them have similar characteristics, the other varies from each other.
What are props and cons of cheaper filament vs expensive filament?
How to choose which filament to use?

I've edited the question.

The edited question (which is a very different question) is a duplicate of: http://3dprinting.stackexchange.com/questions/5/how-is-pla-different-from-abs-material?rq=1

Determine what properties you need the filament to have.
There are a very wide variety of filaments because they all have somewhat different properties.  You need to determine what properties you need your final print to possess.  For instance, ABS can be smoothed used acetone and PLA is biodegradable. More exotic filaments could be conductive or be extremely flexible. Do not neglect to consider safety of the plastic in your application. A full list of properties is too broad for an appropriate answer from this site.

Determine what you printer is designed to handle.
Most printers can handle PLA and ABS with little issue but higher temperatures are required to use some materials such as nylon and polycarbonate.  Determine beforehand what your printer is designed to handle.  This includes determining whether you have and appropriate heated bed or other accessories.

Determine what you can afford.
Printing not only requires the cost of the weight of filament in the final print but all of the support structures and misprints you produce. Not only should you look for inexpensive filaments, but you should look for ones that are good enough quality you don't waste time and money fighting problems with the raw material.

All in all, this will vary case by case.  I would recommend that you start with PLA or ABS as they are common and relatively easy to work with but that you do your own research into what each individual filament type has to offer..


text:
Methods for smoothing 3D objects
How do I smooth 3D printed objects? What is the best / common method to do this?

Can you define what is dangerous for you?

Something more simpler than sanding and corrosive materials.

This question has changed so much that the answers are no longer accurate?!?

Abrasive blasting is the only other method I can think of which you haven't said you don't want to try.
It is certainly the easiest method provided you have access to one.
Different forms of abrasive blasting include:

shot blasting (metal shot) - I suspect it would be far to abrasive but I've never tried it.
sandblasting - you have to be careful but this is basically sandpaper attached to a wand. I've used it with great success.
bead blasting - using plastic beads. It might actually be the best option but I've never tried it.
media blasting - usually uses ground up shells. Might work but I've never tried it.

Get a rock/jewelry tumbler and some tumbling media such as stainless steel shot, and try tumbling your print.
For 3D printed plastic, your print will (a) need to be sturdy, and (b) not have any fine details or small parts that you don't want to be worn away. With metal you will tumble it for hours in order to smooth and semi-polish the surface. With plastic, I would recommend a much shorter time period.
One person tried this using screws as his tumbling media, and has some interesting results to show for it. Part 1, Part 2, Part 3, Part 4. Basically, you can get a metallic coating on your plastic print that is made up of tiny bits of the tumbling medium. You'll need to add a protective coating to keep it from rubbing off, but it's cheaper than buying metallic filament.
(Thanks to Mark Walter's comment for the linked articles)

Walter Hsiao has a nice writeup of doing this. He started by tumbling metal filled plastic, but then noticed that a fair amount of the tumbling media ended up on the surface so he used it to coat the plastic. The effect looks nice though I suspect may not be super durable. link


text:
What parameters affect cylinder regularity?
I'm printing cylindrical pins for a spool holder, but all my pins have irregularities on the external surface of the cylinders (see photo for partially printed pin with irregularities).
It's hard to tell for sure, but it appears that the hot end will occasionally move a piece of soft plastic it previously laid down.
I've tried decreasing print speed, travel speed, and layer height but I still get the irregularities.
What parameters are most likely to effect cylinder regularity?

Could be moisture in the filament, overextrusion, partially clogged hotend, too high extruder and/or bed temp or a combination of these.

Thanks Leo. I'm a 3d printing n00b. I hadn't even considered any of those things.

You should make that an answer instead of a comment so I can vote it up and accept it.

Looks like wicked over-extrusion to me.

I'm not sure though. Could be other things as well. Like it could be a thermistor malfunction which causes reading fluctuations which causes overextrusion only in some parts, or could be a partial clog cuasing it, or something else.

BTW I'm sure your question is about very uneven/bumpy printed object surface, not about printing circular objects. The main issue with circular objects is backlash, we should make a topic about that one day. But you should edit the title of this one.

Hi. What infill percentage are you using here?

@TormodHaugene I've tried .2 and .3

@LeoErvin You might be right, but in my limited experience, I have a lot more difficulty getting a smooth surface on small cylinders than on large flat surfaces.

Then it's probably (still not 100% certain) overextrusion. It's simple, on large objects you still use the same perimeter and shell widths. So the size of the print increases, but the overextrusion amount doesn't. It's like how your eyes don't get bigger since childhood... or something...

This is probably a result of bad quality filament. If you haven't changed much in your setups, haven't changed slicers, but may have changed spools, then this might be the result. I would try using another spool and perhaps switch suppliers. I know it's expensive and there seems to be a stigma around it, but MakerBot Industries provides quality PLA (some ABS also).
Other than that, you've done some of what I would suggest in this case which are the following:

Speeds
Layer height

My only other suggestions would be:

Check how level your build plate is
Check material requirements. ie ABS is ideal between 230-240C according to MSDS with about 110C build plate temp, PLA between 210-230C. Sometimes too hot of a hotend can result in overextrusion or ooze.
If the cylinder is smaller, try changing your slicing settings to have a time minimum for each layer. In my experience, a material like ABS will begin to flare out with variations in the print environment. When the material flares out, as the nozzle comes across the area again, the flared areas will be pushed aside. If you adjust your slicing settings to about 15 seconds (refer to this calculator), then the material will have time to cool slightly from its plastic state. You can cheat this slightly by adding another object somewhere further on the plate with the same height, since the time it takes to rapid to the area and print the layer might be enough time for cooling.

I would also recommend doing some in depth maintenance to eliminate in obvious problems (such as cleaning your nozzle, rods, belts, etc.)

Quality of filament != how much moisture it has absorbed. Any quality filament can abosrb moisture...

You're right, (quality of filament) != (amount of moisture absorbed) directly. However, (amount of moisture absorbed) is a contributing variable to the (quality of filament). If you're a machine shop and buy your steel from a boat yard, that means you're probably using bad quality material and thusly need to find a better supplier. You, as the manufacturer can inhibit bad quality in your materials as well by storing/handling them improperly. I'll update my answer later to include more things to look out for or some proper storing/handling techniques.

Indirectly as well. I'll be perfectly honest with you: that's an unrealistic analogy, and I believe so is this. So if my food is rotten what's the probability that it's me storing it improperly rather than the company which produces it? I don't think it's a 50/50...

My response was unrealistic to simplify my point. Also, I am not inferring any probability, there are no statistics in my responses. I'm merely stating possible problems and any potential solutions I have for those problems stated. I'm editing my answer to remove my reference towards your comment to avoid any further confusion that I'm directly relating moisture to the OP's issue.

Well an unrealistic analogy doesn't help prove anything. I really don't see where you're going with this. If you've removed the part of the moisture being the problem your answer is based on a premise that the OP has changed spools which he hasn't mentioned he has. Also, what do you mean when you say "Speeds" and "layer height" as possible issues.

Also, just changing spools is trying to solve a problem without figuring out what the issue is. Unless you know what you're fixing the issue might come back and haunt you some other way in the future. It's just putting band-aid on it  (These comments I made are just to make these points known to the OP, nothing personal involved).

While I appreciate your constructive criticism, the comments of an answer are not the proper place to log helpful information. If you feel that you can provide substantially different information, please post your own answer. I will continue to update my answer, however, as I learn more about the OP's situation.

I disagree, because my info doesn't answer the question itself


text:
What makes Pronterface wait for user?
I'm using Cura with the Pronterface UI to slice/print and sometimes printing just stops - always in the first layer - when it happens the printing screen shows "Waiting for user", when I press the button on the printer printing resumes.
I don't know when this happens, it just happens about once every 5-10 prints, when this happens if I close the printing window and immediately click "print to usb" to reopen it the problem doesn't repeat.
This only happens with the Pronterface UI, it doesn't happen with Cura basic UI or when printing using an SD card.
Not using Pronterface isn't a good option because when I'm fine-tuning a model it much more convenient to send a test print from the computer and not copy the gcode to an SD card and print from the printer.
My printer is Robo3D R1+

Hi! Do you know if this happens when Pronterface is the "program in front"? I have had issues like this where Pronterface gets starved for resources because it is laying in the background while I do other stuff on my computer.

@TormodHaugene no, its not related, it also happens when Pronterface is the active window and the computer isn't doing anything else

That's the temperature problem that you've encountered.
The temperature of bed and hotend is reported every few seconds. Per default, first that sets is the bed temperature, then you need to wait for the bed to reach it, then warm up the hotend, and then start printing.

I don't think the problems are related, first because the stopping started long before I started messing with the warmup sequence and second because the stopping also happen after 10 minutes pre-warming

hm... can you give some more data here? My buddy had similar problem, and it was the temperature problem, so I've posted that as an answer.

I don't have more data to give, I haven't found any consistency in when this happens (except that it's always in the first layer), it just happens randomly, I really have no idea what is causing this - I will look at the temperature reading next time this happens


text:
How to improve face that are printed on support?
Is there anything I can do to improve the bottom side of surfaces that are printed on support?
I always try to rotate the model so that surfaces that need to look nice are on the sides or top, and, if possible I divide the model into smaller parts to minimize the amount of support.
But sometimes there is an object that has an irregular shape that need support no matter how I rotate it and can't be broken down into smaller objects with no support.
And then, after removing the support I get a very ugly ridged face that takes forever to sand.
To clarify, I'm not asking about making supports easier to remove, I don't have a problem with this, I'm talking about making the surface that touched the support better looking after removing the support.
Is there anything I can do to improve the look of the face that is printed on supports?
I'm using Cura to do the slicing and printing, I'm using the "lines" support type, my printer is the Robo3D R1+

I think in theory if the orientation of the support "lines" would be perpendicular to the outher shell lines they would be easier to separate.

@LeoErvin - I don't have a problem separating the support, only that the face that is built on top of support looks horrible. I've edited the question to clarify.

Could you include a picture of what it looks like so it would be easier to diagnose?

@Nir I know what you meant. The point I was making is if it is easier to separate, it means they weren't merged too much to begin with, so there wouldn't be any merged (common) plastic parts (bulges) left after you remove the support that you then need to sand down. If the lines of the support were layed down perpendicular to the lines of the print, I believe that would help the above. Does that make sense?

@EricJohnson - I spent hours sanding the part and didn't take pictures before sanding, I will take a picture the next time

@LeoErvin the problem wasn't bulges left by the support structure, it was big thick bulges much larger than the thin support columns

At this point we can't guess much. Could be anything really. Maybe the distance between the support columns was too much and the overhang between them still didn't have enough strength to support itself. Without image or more details we can only make guesses.

@Nir were you still having troubles? Do you need other suggestions to resolve your question?

@tbm0115 currently I believe there is no solution - its just the realities of bridging - and any model that require support below a face that should look good is just not a good model for 3d printing (at least with a one-hotend fdm printer)

The basic answer to your question is to create better bridging or overhangs on your machine. Bridging is when you are printing between two solid pieces (like a bridge). Overhangs occur when printing off of a single solid piece and coming back. Most slicing engines allow extra settings for speed, fan power, etc for these parameters, just refer to this terminology.
A very common and simple solution in getting features to 3D print properly is to just slow down! If you're not a in a rush to get the part done, you bring down all of the feedrates in your slicing engine. MakerWare has mine at 90/150 mm/s for print and rapid. Typically I'll bring that down to about 50/90. My reasoning is the more time you give the plastic to cool, both while and after printing the layer, the more rigid that layer will be for the next one. When briding or overhanging, there will typically be a sagged area in the print. You can minimize this by providing the plastic more time to cool. Also keep in mind that printing on supports is still technically bridging (printing between two solid pieces).
Another thing to keep in mind is adhesion from one layer to the next matter just as much between the current layer and the previous as the current strand to the one next to it. So, in some cases, increasing your shell could possibly make it easier for the infill/roof/floor strands.

On the other hand, move the hotend too slow and the hotend will have more time to heat/melt the plastic that it is close to. Even if you use fans around the hotend.

@LeoErvin that depends on the material. A material such as ABS would probably benefit from having the hotend nearby as ABS needs more of a gradual cooling. While you wouldn't want to get to the point of melting previous layers, having a higher ambient temperature in your build area can help ensure the structural integrity of your part once it finally cools.


text:
Is there a G-code for waiting?
My printer has an auto-leveling feature that works by touching the build plate with the tip of the nozzle.
I started using a BuildTak surface and BuildTak is damaged when you push a hot nozzle into it.
So I edited the start G-code to run the auto-leveling before heating up the hotend
But ABS doesn't stick to the build surface unless I pre-heat the hotend and wait about a minute.
So now I'm looking for a G-code command to put at the end of the start G-code that will make the printer wait a minute before printing
The sequence I'm looking for is:

Heat up the bed
Auto level
Raise the hotend a little bit so it doesn't touch the build plate
Heat up the hotend
Wait a minute (that's the only part that is missing, everything else works)
Start printing

Any way to insert a delay into the G-code?
I'm using Cura to slice/print, my printer is Robo3D R1+

G4 P60000   as explained here:http://reprap.org/wiki/Gcode#G4:_Dwell

Hi, @Nir! So, you want to set hotend temperature, and wait until it is warm before printing (at the end of start.gcode)? I generally doubt you really need to explicitly set a delay - it is basically a hack to overcome (not fix) the problem!

@LarsPötter That should be an answer, not a comment!

@TormodHaugene - I wrote the entire back story as to why I'm looking for this, if you have a better solution I'm open to trying it

@Nir, I believe I answered that previous question. It's getting late now, but I can have a look at it tomorrow, if you like! :-)

@Nir, could you post the code in start.gcode  that you are currently using? I believe ´M109 S{print_temperature}´ is the command you are looking for, as was posted in the previous question. Did that work?
http://3dprinting.stackexchange.com/questions/454/how-to-configure-cura-to-run-the-z-probe-before-heating/469#469

@TormodHaugene - yes, M 109 works, everything works perfectly for PLA but ABS doesn't stick to the bed, if I pre-heat the hotend (and remove the M 109) the ABS does stick to the bed - so my working assumption (that I have to test) is that it takes a little bit of extra time for the heat to make it from the thermistor to the tip of the nozzle

@Nir, Oh, I see. In that case, you are probably right that adding a delay or "Dwell" (with G4) is the way to go. :-)

The G-code to delay is G4.
G4 P60000 will wait for one minute. The P is in milliseconds. Some firmware also accept a S Parameter that has the seconds. So, if supported, G4 S60 would do the same thing.
The details for this and all other G-codes are documented
here.

In my end-G-code, I shut off the hot end, and wait several minutes before shutting off the fan. I was getting communications timeout errors and the fan would never actually shut off from the code (using Monoprice Select Mini with Octoprint). If this occurs for you before the print, it will not print at all. I resolved it by simply breaking it up unto a series of shorter delays.

For cncjs, the command is G4 P0.5 for half a second, for example. i.e. it's a float, not an int.

so the P actually behaving like the S parameter (seconds instead of milliseconds).  Can you also put that information into here: https://reprap.org/wiki/G-code#G4:_Dwell

3D printer firmware tends to use P whereas CNC firmware (eg. LinuxCNC, GRBL, etc) uses P floating point. You have to test it on your specific firmware to make sure.

An alternative solution to using a hard delay with the G4 dwell command, is to increase the time that the temperature set with M109 has to be held before it continues with the next command.
In Marlin, this setting is named TEMP_RESIDENCY_TIME, and can be found around line 150 in Configuration.h. By default, this is set to 5 seconds, which looks like:
// Actual temperature must be close to target for this long before M109 returns success
#define TEMP_RESIDENCY_TIME 5  // (seconds)

If increasing this setting solves your exact problem, I cannot say, but it could be worth looking into.

Thank you Fernando Baltazar for the G-code you used to solve the hot end cooling issue after bed levelling probing. I did change M190 to S60 but kept everything else. This worked.
G29 ; Autonivel
M190 S35 ; set bed temperature
G1 Z4 F240 ; lift nozzle
M109 S195 ; wait for temperature to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
M104 S210 ; set temperature
G92 E0
G1 E-1.5000 F1800
G1 Z0.225 F240

I´m using this code for my prints.
    G29 ; Autonivel
    M190 S35 ; set bed temperature
    G1 Z4 F240 ; lift nozzle
    M109 S195 ; wait for temperature to be reached
    G21 ; set units to millimeters
    G90 ; use absolute coordinates
    M82 ; use absolute distances for extrusion
    M104 S210 ; set temperature
    G92 E0
G1 E-1.5000 F1800
G1 Z0.225 F240

On M190 S35, the nozzle is still on the low position (1.2mm), then goes to 4mm then waits for the extruder temperature Ex. 195°C; when the extruder reach the 195°C for 10 seconds then the printers starts to print going the nozzle to 0.22mm while the nozzle reach the second temperature of 210°C. On This time its allow me to clean the nozzle and normalize the temperatures for a good prints.
Note:
To avoid the nozzle stays many time on low position (1.2mm) normally I preheat the bed at 35°C. some times to heat the bed takes a longer time than heating the nozzle. This is the main reason that I prefer to preheat the printer.


text:
Mushy small top layers?
I just added a fan to my printer because very small layers seem to come out very badly. For example, the 5mm PLA cube that's the top level of the test shape shown below. Watching closely, I can see that the newly-extruded fiber is pushing the previous layer(s?) around pretty freely. And when the object is finished, the little top cube is bulging, rounded, and still soft to the touch.
The 2nd-to-top level of the object is also quite small and quick, but often comes out nicely (if anything, it was better before I added the fan).
The fan is a squirrel-cage with about a 2.5cm square outlet, pointing at the nozzle from about 5cm away, running full speed. The extruder is a Mk9 from http://www.makergeeks.com/duexretopr.html.
I also tried telling pronterface to wait if a level was too brief, but that setting seems not to do anything.
What else can I try? It seems like this is a not-enough-cooling problem, but perhaps something else too?

looks like pillowing : http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#pillowing

Is this the first of our questions that made it into the "Hot Network Questions"? Even if not, nice to see some question from 3D printing show up there. +1

Hello @TextGeek, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept your own solution. Thank you.

Layer Times
See my answer to this question and pay particular attention to my suggestion about a minimum layer print time. I'm not sure if all slicing engines provide this option, but I know MakerWare/MakerBot Desktop and (possibly) Slic3r allow this setting.
Basically, when you're extruding smaller features like this, the previous layer(s) are still very hot and possibly very pliable. So, as your nozzle moves around above the previous layer, the nozzle may (and probably will) push some of this molten plastic around. Chances are you can see it to a certain degree while it's printing. You can definitely see this in a most drastic state if you print a tall and small diameter cylinder. You'll notice that the part will become almost exponentially unstable the higher it goes.
By increasing the time your printer takes to print a single layer, you are allowing the previous layer(s) to cool closer to the ambient temperature of the build space, and hopefully not as molten.
Please refer to this calculator or a similar one for material cooling times. For a standard shell setting of about 2-3 (0.4mm nozzle) will yield about 130sec to cool down to room temperature. I would recommend (for ABS/PLA at least) about a 15second minimum for each layer, possibly longer depending on the size and spread out of the features.
Also note that this can be cheated by simply printing multiple items in the same build plate with the same heights (ie. multiples of the same part). Naturally, it will take longer for the machine to print the rest of the parts and therefore allow each layer to cool slightly before being printed over.
Active Cooling
Again, some slicing engines have an Active Cooling setting. I don't personally have this option setup on my machine, but I believe it regulates the flow of air directed at your nozzle (usually by use of a mounted fan). This can help cool the layers a bit faster. With ABS, this might result in some pretty bad warping mid-print.
Feedrates
Try bringing down your feedrates to provide the printed portions of the current layer more time to cool if the above options aren't available. Note that you might also bring down your hotend temp to shorten the time it takes to cool the plastic.
All else fails
My only other suggestion is stated above, try printing duplicates on the same plate. My diagnosis is that the previous layers aren't cooling down enough before the next layer begins.

I was going mad printing something with lots of bits that had little 'posts' as connectors - most of them printed perfectly but one of them the post always seemed to go all melty and squidgy - it was taller than the rest and was the last thing that was printed and this is exactly the problem! Thank you!

Nice post! I can confirm that Slic3r provides good support for controlling printing speed and fans with regard to minimum layering time. For the reference, I will add a separate answer on that soon. :)

I found that the REASON my top 5mm cube was mushy was mostly because I had set a minimum layer time of 15 seconds.  Slic3r handles this by slowing down if the layer will otherwise be printed too quickly.  This causes the very hot print nozzle to be held in the very-tiny print area for too long and it keeps the plastic warm and mushy.  When I increased the time to 30s it got worse.  I turned it off completely and now it's much better.  Still need a fan on PLA, though.

@phord how large of an object were you trying to print? If the feature was small on top, then when the printer is idly waiting to continue the next layer, it is most likely waiting directly above the small feature and slowing the cooling process. For smaller parts/features it might be best to "cheat" the process by adding a small object in the corner of the print bed that the printer can idle over.

@tbm0115 Slic3r doesn't idle to create the wait time. It slows down. I've seen the failure on the same test part in the OPs photo with ABS. The part comes out clean when "slow to cool" is disabled.

Also try printing two of the same object, if it is small. This will also allow more time for the plastic to cool down between each layer.

I believe you might be having an issue with insufficient cooling. Remember the suggestion to have wait times per layer to let the previous layer cool? Well, I think with your setup and print not only do individual layers overheat, but individual parts of each layer. You either need to try more direct or dual fan cooling or maybe use a nozzle with thinner outer diameter which will have less surface to heat the layed down plastic surrounding it.