I have some Polycarbonate filament that I’ve been meaning to try on my printer at home, though my team has used Polycarbonate on their printer on a few occasions, but ran into a number of issues with it.
Like ABS, Polycarbonate is prone to warping as it cools, and the higher temperatures required to extrude it make it more difficult to cool it slowly; this means that larger parts will be more difficult to keep attached to your build platform, and you may even have issues with layer adhesion as the previous layer may cool too quickly for the next layer to properly adhere to it. Personally I would also recommend avoiding the use of rafts with polycarbonate as they are very difficult to remove cleanly, though unfortunately this also makes it more difficult to keep parts attached.
There is certainly nothing wrong with using Polycarbonate filament if you can get it to work (in theory, the resulting parts are stronger than other materials), but to be honest, I have yet to find a part that I needed to 3D print for an FRC application that couldn’t be made with just regular PLA (though perhaps at a higher infill setting) and do the same job, but easier and cheaper.
I did some experiments with Gizmodorks PC a couple weeks ago. For large pieces (6" diameter) I had issues with the middle section staying on the bed. Unsure what was causing that. For smaller prints I had some issues with my bed staying at temp (didn’t have time to dig into that issue) I did get a test cube printed and found the layer adhesion to be garbage. I THINK if I were to print in an enclosure I would have better results. I also have to check the fan speeds to see if that inadvertently got turned on which would likely cause poor layer adhesion.
To print gears and other parts - I know of folks who have had good experience with Taulman’s Nylon 910. All the steering pulleys on 323’s off season bot were printed with that and they seem to be holding up.
Disclaimer - for competition parts I don’t think printing pulleys and gears on a consumer printer is a great idea. Most gears and pulleys are widely available in materials far better suited for the loads involved and with far more consistency. I HAVE printed pulleys and sprockets in the past but mostly for FTC scale bots.
In the case of something like a drive system, I’ll agree that printing gears and pulleys for timing belts is not a good idea, but there are certainly plenty of low-load applications that they would be more than adequate for. For example, this year my teams robot used 3D printed PLA pulleys for our polycord ball feeding system that worked great.
I’m not afraid to print timing belt pulleys on an Afinia H800 printer, if I need them faster than McMaster or need some custom attachment methods. Built-in pulleys can be so useful in the right application. (Not for FRC, but for some tough work.) ABS material. Royal pain to get the support material off the teeth, though.
Yes! PC is absolutely viable for FRC teams. In fact, I think that moving away from ABS and PLA is one of the biggest steps towards 3D printing structural components for FRC. However, it isn’t as simple as just changing out the filament cartridge and riding off into the sunset. PC requires some effort to get printing, but it’s absolutely worth it.
First off, make sure that your printer has an all-metal hotend. Older and/or cheaper nozzles have teflon (PTFE or PEEK) near the melt zone, so they can’t handle temperatures above ~240C. Having an all-metal hotend means you can run temps about as hot as the heating element can attain, which is good cause you’ll be at around 300C for printing PC.
You may need to add some type of enclosure to your printer. I’m a big fan of using polycarb sheet to hold in the heat. You don’t want it airtight, but you do want to limit airflow, especially if you have a draft in your printing area. There are quite a few guides on how to add enclosures to your printer. This is a pretty good general guide to using PC. Also, once you master PC, you can look into using Nylon. It’s got some very great uses.
We’ve tried using PC, and we’ve found that you need to print fairly hot (~300°C) on top of lightly oiled PEI. In general, we prefer using Nylon 910; it suites us well for even high power applications like DT gears at near 100% infill.
I’ve had a very positive experience with Alloy 910 for a variety of FRC and non-FRC applications. Acceptable shrinkage, decent balance of ductility/strength. I pretty much only print with Alloy 910 and “premium” PLA these days.
I have a heated PEI bed and apply a glue stick before printing. I’ve definitely forgotten to apply it before and have had the filament adhere anyway. I use Taulman’s published print settings and that’s about it!
What I’m trying to say is that the learning curve for 910 was way easier for me than say ABS. I feel like I am spending more time iterating functional designs instead of designing around the limitations of the material.
All of the pulleys on 323s off season bot are 3dprinted out of nylon (don’t remember what type) that is including the drive sprockets for 5mm gt3 belt with 2 775pros runing through it. Only had one failure and that was because an axle bolt fell out. Keep in mind though this is on a 70lb robot geared at 19 feet a second.
I’ve made some 910 parts that have been exposed to water, but don’t have much experience with that specific application. I’ve made parts for bikes and boats that don’t seem to have been affected by rain exposure. I have no experience with submerged parts. My experience leads me to think that moisture absorption swelling would be of minimal concern in a typical FRC application.
The big concern with moisture absorption is that it boils off during printing causing garbage surface finish and weak layer absorption. For FRC applications I wouldn’t worry about moisture from the air?
I was actually speaking more generally, not just for FRC uses. I’ve had a few personal 3D printing projects that have involved water exposure and I was curious if 910 could be a more durable alternative material for similar applications or if it would be damaged or break down when exposed to water like Polycarbonate can.