3d printers and robots

[Andrew Schreiber]

Originally Posted by EricH

I've got some experience with PLA. Haven't done anything with ABS. PLA is to some extend biodegradable, but haven't tested that at all. I've found that the color of PLA tends to have a pretty hefty effect on how it prints and how it'll hold up. Set for one color, print a nice part, change colors and print the same part with the same settings and it might not be the same--depends on how close the colors are. (White tends to crack easily and without warning, for example; most other colors will at least warn you.)

I've never had this problem with ABS. Could it be a function of dye in the PLA changing the melting point? ABS seems to melt pretty much the same no matter the color. (Disclaimer: only used Makerbot supplied stuff on my own printer, work used 3d something or rather as their source, no major problems there either)

[EricH]

Originally Posted by Andrew Schreiber

I've never had this problem with ABS. Could it be a function of dye in the PLA changing the melting point?

I think that's what we were thinking at one point, or something like it. We tend to run on the cool side of PLA's range, at something like 185 C or 190 C (after 220 C proved to be a little too warpy after the parts cooled), so that might also have something to do with it.

We have ABS, but haven't used it yet to my knowledge--IIRC, we were concerned about the smells/fumes we've heard it has.

[Andrew Schreiber]

Originally Posted by EricH

I think that's what we were thinking at one point, or something like it. We tend to run on the cool side of PLA's range, at something like 185 C or 190 C (after 220 C proved to be a little too warpy after the parts cooled), so that might also have something to do with it.

We have ABS, but haven't used it yet to my knowledge--IIRC, we were concerned about the smells/fumes we've heard it has.

It has a slight burnt plasticky smell and I wouldn't use it in an enclosed small room. However, nothing I've read says anything too bad about it. I will say that it warps even more and you have to print on the high end of things (I run my nozzles at 220C and the heated bed at 115C). Enclosing the build area is important, without the top enclosure I had some pretty major warping.

[eli2410]

Originally Posted by Thunder910

Does the uPrint support importing Inventor models?
Is that a feature that is standard among a lot of 3D printers? Or is it only specific ones?


Thanks for your help, everyone! This could turn out really well for us.

Exporting as an .stl file, which is the standard for 3d printers.

[Andrew Schreiber]

Originally Posted by eli2410

Exporting as an .stl file, which is the standard for 3d printers.

Just check your units to make sure you're exporting it properly.

[coalhot]

Originally Posted by stinglikeabee

I have been trying to find some photos of a full-on OpenBeam Mendel (http://www.hive76.org/modified-mende...ing-wednesday), with only the injection molded OpenBeam components used for framing. This would allow you to build up from components without the need for a 3D printer to make the framing components.

Sorry for digging up a old post. Having been to Hive76 when that Mendel unit was there, it's a nice setup. There also were some specialty heads for it (to print sugar), but that's more of a novelty thing. Unfortunately, the person who had it got a job out of state and moved, so that's not at Hive76 anymore (here's a piece about his work). I'll poke around and see if I can come up with a few pics.

I will say that the MakerBot Replicator 2 is really nice, I've had the opportunity to see one in person and in action. A prof here at temple has one, and uses it to make mounting brackets for a few sensors (among other things). It's just about as good as the Statasys printer that the engineering dept has (minus the Stratasys having a full oven). EDIT: didn't realize the Makerbot printed PLA. It's a nice setup, but other than that probably not really useful as much in a robotics application.

Just my $00.2

[protoserge]

Originally Posted by coalhot

Sorry for digging up a old post. Having been to Hive76 when that Mendel unit was there, it's a nice setup. There also were some specialty heads for it (to print sugar), but that's more of a novelty thing. Unfortunately, the person who had it got a job out of state and moved, so that's not at Hive76 anymore (here's a piece about his work). I'll poke around and see if I can come up with a few pics.

Just my $00.2

Thanks!

BTW, this thread is far from "old", so I don't think you have any need to apologize, even if my post was two pages back

[Andrew Schreiber]

Out of curiosity, has anyone played with any of the delta style printers like the Rostock?

[yash101]

We do not use ours too much (as per what I know). We do, once in a while, print a CAD Model of our entire robot. However, I think that 3D Printing is quite a great idea for FRC Robotics. ABS is very strong, strong enough for many heavily-used things. It also makes a great substitute to going to the shop to find the exact part. However, the technology has tremendous areas of improvement required. The resolution is not good enough for many applications where absolute accuracy is required. Also, the process is slow. The ABS is also dangerous. If it goes through too much stress and catches on fire, three toxic vapors are released, CO2, CO and HCN. A 3D Printer is just a very expensive injection moulding system that doesn't require a mould. I came up with the idea of a 3D printed stirling engine, running backwards, to test my design. After some research, this idea has been erased because of danger.

In Short: Do not use 3D printing in high friction or heat. Do not set alight on fire, and only use it where you know it will work. A milled aluminum piece will work way better.

[yash101]

BTW, according to the previous post, I was referring to ABS thermoplastic (just to ease any possible confusion)

[yash101]

Originally Posted by stinglikeabee

Yes, but if you want to design and sell something, you can't use either of them in academic license form.



Great bit of information there. What colors tend to print "better"? When you say the other colors warn of cracking, I assume you're referring to the discoloration gradient when the plastic is nearing its yield stress?

I do not know what "color" is most discolor resistant because I have never used colored ABS, but however, white seems the best because even under deformation, there will be no effects. However, I thing a liitle bit of color could be helpful because it acts as an indicator for stress/strain/deformation.

[protoserge]

Originally Posted by team1165wins

We do not use ours too much (as per what I know). We do, once in a while, print a CAD Model of our entire robot. However, I think that 3D Printing is quite a great idea for FRC Robotics. ABS is very strong, strong enough for many heavily-used things. It also makes a great substitute to going to the shop to find the exact part. However, the technology has tremendous areas of improvement required. The resolution is not good enough for many applications where absolute accuracy is required. Also, the process is slow. The ABS is also dangerous. If it goes through too much stress and catches on fire, three toxic vapors are released, CO2, CO and HCN. A 3D Printer is just a very expensive injection moulding system that doesn't require a mould. I came up with the idea of a 3D printed stirling engine, running backwards, to test my design. After some research, this idea has been erased because of danger.

In Short: Do not use 3D printing in high friction or heat. Do not set alight on fire, and only use it where you know it will work. A milled aluminum piece will work way better.

The plastic 3D printing (additive manufacturing) is not a "very expensive form of injection molding". These are two entirely different manufacturing processes. A 3D printed part will not have the same strength characteristics of injection molding. The most beneficial aspect of additive manufacturing is the production of complex geometries. There are some things you cannot make with injection molding since it is a process that relies on subtractive machining.

On a per-part prototype production run in low quantities, 3D printing is far more cost-effective, and for the hobbyist, the cost of most printers and a fair bit of material (dozens or hundreds of spools of filament) is cheaper than one mold.

Aesthetically, there could be improvement on the output of many of the 3D printers. Most are able to print at 0.1mm layer resolution. The accuracy really depends on the user calibrating the machine and fine tuning the machine for consistency. From a part design perspective, this may or may not be required. Like all manufacturing technologies, you have to understand the requirements for the part you are producing and its use to determine the best production technique.

I would sure hope no one intends to burn their plastic part.

Originally Posted by team1165wins

I do not know what "color" is most discolor resistant because I have never used colored ABS, but however, white seems the best because even under deformation, there will be no effects. However, I thing a liitle bit of color could be helpful because it acts as an indicator for stress/strain/deformation.

The comment on color is focused on the effects on plastic strength due to the dyes added. ABS is naturally a white color, so if the dyes reduced strength, the natural ABS would be the best choice for part strength in most cases. There is obviously more to the filament strength than the dyes: manufacturer, batch, moisture absorption, time on shelf, etc. all have an effect.

[yash101]

What I am thinking about to boost accuracy and resolution is to make it more "smart." If it is printing a cylinder, the printer should move the head in a circle to improve upon the resolution. Also, instead of printing a thin layer at a time, print thinker layers where the shape isn't changing and print small layers where accuracy is required. Our school's ten grand 3D printer doesn't have those features!

[EricH]

Originally Posted by team1165wins

What I am thinking about to boost accuracy and resolution is to make it more "smart." If it is printing a cylinder, the printer should move the head in a circle to improve upon the resolution.

Gcode doesn't exactly do well moving in anything other than a straight line. Most machines, including 3D printers, use Gcode. What this means is that for most machines, the circles are simply very small straight line movements.

Also note: You're talking about simple X-Y movement here. You move a distance X, you move a distance Y, you can do both at once by going point-to-point... but moving in a circle is pretty tough. Not impossible, just tough. You're dealing with two quadratic variables instead of just one or none...

Also, instead of printing a thin layer at a time, print thinker layers where the shape isn't changing and print small layers where accuracy is required. Our school's ten grand 3D printer doesn't have those features!

There's a really good reason for this, that maybe you don't quite realize. One of THE key definers of resolution is the tip size--how thick the material can come out. That does NOT change. It can be changed between builds, true, but then you have to reset the calibration of the machine--there's been previous discussion on the impact of having the tip too high for the tip size or vice versa. Changing during a build means a dual-head model, with both heads having a different tip, which means changing the calibration on the fly, if I'm not mistaken. That could get ugly pretty quickly--imagine rebooting the gyro while it's processing data, because you need to change the zero point.

I bet the reason that $10K printer doesn't have those features is quite simply that the cost/benefit analysis showed that the cost of the company's time and any parts needed for extra resolution/speed would far outweigh any benefits to the consumers, and drive the price up to $15K or higher, which means fewer customers pick that company.

[DampRobot]

Originally Posted by EricH

Gcode doesn't exactly do well moving in anything other than a straight line. Most machines, including 3D printers, use Gcode. What this means is that for most machines, the circles are simply very small straight line movements.

Also note: You're talking about simple X-Y movement here. You move a distance X, you move a distance Y, you can do both at once by going point-to-point... but moving in a circle is pretty tough. Not impossible, just tough. You're dealing with two quadratic variables instead of just one or none...

Isn't circular interpolation via the G03 command actually quite good on most CNC machines, ie better than just linking a bunch of small line segments? Maybe I'm incorrect, but it seems like it would be more effective, accurate, and efficient for a 3D printer to read a G03 command rather than a huge block of G01 X Ys. Perhaps most 3D print controllers aren't advanced enough to do this kind of interpolation though, and need to run through a bunch of segments instead...