Slicer Settings for 3D Printed Pulleys

We have been 3d printing pulleys for 2 seasons and we are happy with the durability of them. However, we are not sure about the efficiency and couldn’t find a accurate testing method. I have a few questions about this topic and would like to get the other teams opinions.

First of all, what are the suitable materials? We have been 3d printing with PLA since it is easier to print but I want to try other common ones such as ABS and Nylon.

I always tried to maximize the layer height in order to increase the resistance of the parts. However, I believe that it will increase the friction. So what could be the optimal point for a 0.4mm nozzle.

Also, what percentage and pattern of infill is most suitable for pulleys? We mostly use triangle for parts that only get radial load such as pulleys and cubic for the rest of the parts.

Finally, some teams use huge flanges that are probably impossible to print without supports. I think using support material can cause bad layer quality. What can be a good solution to this problem? A few ideas that come to mind is printing the flanges seperately and gluing them and the other is using supports only on the outside of the pitch of the pulley.

I’m also aware that many teams use markedforged printers and don’t bother with the slicer settings too much. However, we only get can print common materials with simple printers :smiley: .

By the way I am using Cura for slicing the parts.

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What are you printing on? Nylon may be outside of what your printer can do.

Have you tried Ninjatek Armadillo? It’s rigid TPU, so prints at a lower temperature and is pretty tough. (But does not work well if you need much in the way of supports.)

For the past season, we used aluminum pulleys but we are now transitioning towards printed pulleys. After a good amount of testing, we’ve found that printing Prusament Polycarbonate Carbon Fiber is the best material without a markforged. It does require very high temps so not all teams are able to print it.

We’ve also tried printing it with the flanges separately but found that any amount of load on the flanges would make it pop off (this could be because the glue we used was too weak).

We now print with supports, 75% infill (we found anything above has diminishing returns), 3-4 perimeters, and a gyroid infill pattern.

We do not have enough data about the layer height to make an informed decision but it seems that the strength of PCCF is more than enough for our needs.

I am using highly modified custom printers, that are capable of printing Nylon. I have a direct drive setup with dragon hotend that can withstand the heat. For the TPU part I don’t think that using soft materials is a good idea for a pully since it can change its size depending on the speed eventhough its durameter is higher than the standart ones.

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All our pulleys this year were printed in Duramic PLA+, solid, with .3 layer height on the Prusa Mini+ printers. The only issue we had was accidentally melting some of them into our intake due to a spacing issue. We had I think somewhere around 20 pulleys on the robot, primarily on the ball path.

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Armadillo is a rigid TPU – not flexible at all. We used it for the spool on our climber this year and several pulleys in places where we were worried about the strength of PLA.

We also used the Duramic PLA+ on an Ender 5 printer - 4 layers at 0.2mm and 30% infill. This was not scientific, it just worked well for ball path pulleys. ThriftyBot star inserts were added on load bearing (non-idler) pulleys.

We did melt a few pulleys against the sides of a flexible polycarb intake. Please make sure your spacers are wide enough to keep the pulley away from stationary parts at all times.

David

We used Prusament CF PC for almost everything this season. It prints like an absolute dream, arguably better than Duramic PLA+ that we and other teams use.

We usually did .24-.3 layer height, with 20-30% gyroid infill. The only time a pulley broke was due to incorrect spacing and it welded itself to the polycarb plate it was next to.

Slap an all-metal hotend on an ender 3 and you’re off to the races!

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We use a mix of Onyx, PETG, tough Pla/pla+, and SLS nylon 12. All of them work well for us but they all require different strategies.

For FDM pulleys, we generally use a 0.4 nozzle, 2-4 walls, and 20-50% density. For MarkForged parts, we almost always run .125 layer height. We occasionally run 0.2 when we need parts the same day. On the prusa printers, it’s generally 0.15 to 0.3 range. We run all SLS stuff solid by nature so we will pocket them out or slim the cross section down to 1/8” range.

For flanges, we run larger flanges on systems in motion to help keep the belt on the pulleys. Something like our intakes this year ran huge flanges to stop the belt front walking off during impacts. Internal systems that are static will get a flange that is flush or close to flush on the belt to help with mounting/clearance.

For support on these flanges, you have 3 choices. You can print with a soluble support if you have a dual extruder printer (we do this on Ultimaker S5’s), you can print same material support, or you can design in supports to the middle and cut them off after printing. I prefer to use same material support. You can modify Z support offset in cura to help with adhesion/not wanting adhesion. Make sure when you change this, you go to the preview window and look to make sure you have Blank layers between the support and the part. Your probably using a single layer now but try it with 2 and 3 layers offset. You will tune this for your material but it makes a world of difference. Also check your horizontal expansion on the part and support to make sure you don’t have “bleed” from one part to the support which makes it much harder to remove support. You will see a slight decrease on the support surface finish but it is purely internal and does not matter. A quick razor blade or just run the belt in after.

Try these above and feel free to PM me any questions.

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I’ve had good results with steeper angles on the flanges than you see on the Aluminum press on flanges; this makes the printing work a LOT better. You also need to thicken the flanges.

I’m using 0.4mm nozzle, 0.1mm layer, glass filled nylon, and solid for smaller pulleys.

I doubt you will find much difference in friction between find and coarse layers, but it would be interesting to test! Coarser layers RADICALLY speed up printing, but will make the top flange harder to do.

On a fancy slicer you could use coarse for the ribbed area and fine layers on the flanges!

I got in trouble when I printed multiple pulleys; very organized boogers that I had to dremel out. Flange supports were actually pretty easy to remove and to clean up after (most of the crud was on the crests of the teeth).

1706 uses eSun pla+ and micro center pla+ (blue ofc :slight_smile: ). Toward the beginning of the season we printed with 2 perimeters, and 2 top/bottom layers. At the end we switched to 4 of those and 100% cubic infill. Tuning the printer for accurate dimensions is important, but we use 0.2 later height or 0.36 for a 0.6 nozzle

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From what I remember we have pla+ filament, just whatever we can find, 100% infill and supports for final robot and extra robot parts, prototyping is normally 15% infill

One of the best ways we’ve found to handle this is to print in two pieces. One is basically a top hat, containing the middle and one flange, while the other is the other flange, with a small cutout on one side so the center fits in it. Get good precision, and they basically snap together. Add in appropriate constraints on the shaft so they can’t pull apart (there should be minimal side-load, so it doesn’t take much!), and you’re golden.

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print with a large flange on one side and set it up so each end has the flange on opposite sides

You can, but that puts a seem right in the middle. That provides a potential spot for the belt to squeeze into, pushing the two halves apart slightly to do so. May not be a problem with some setups (anything using a wide belting or strap, most likely), but it may be with others! We’ve used printing for high-stress spools in the past (like for a catapult), where that type of weakness would cause a failure at some point. Thus nesting that seam inside of one of the flanges, you get rid of that weakness altogether!

I am a huge fan of the Prusament CF PC and the Ninjatek Armadillo but for most cases the Duramic PLA+ is sufficient and considerably cheaper.

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With only a few exceptions for custom alum-machined pulleys, we use the same settings for pretty much every pulley on our bots.

We print in either Prusament PETG or Hatchbox PLA (the choice is based on the use of the pulley, go PETG for more rigor and PLA if it’s low load). We’ve also experimented with Atomic Filament’s PETG as well and have had no problems.

For settings, our parts are sliced in either PrusaSlicer or Cura because we just outsource our printing to students and mentors. Either works, but there are a few big factors that you need to keep an eye on. Most importantly, 4+ walls always. Depending on the quality of your printer, you can even push 6 or 7, but we rarely go beyond that as it’s largely unnecessary. Perimeter count is much more effective in beefing up your parts than infill percentage, although I would still recommend 20-30% infill, and we usually use gyroid or grid, once again depending on who’s printing the pulley. We haven’t had problems with layer height, and I think there’s actually a great CNC Kitchen video based on the strength of different layer heights. Because speed is king during build season, we are usually rocking 0.25-0.32 layer height for our pulleys, and haven’t noticed excess wear in our belts. I would also note that you may want to print a little hotter than normal with a bit higher flow multiplier, as you will strengthen your parts dramatically, although they may not be as pretty.

In terms of flanges, we just use a parametric model in SolidWorks for almost all of our pulleys, which has a relatively standard flange - these print great with decent part cooling and no supports, which also reduces printing time. Unless you’re loading your pulleys awkwardly or they are experiencing a lot of vibration, I wouldn’t worry about just using a normal flange. The one area we had to opt for something a little more intense was our intake, which undergoes by far the most vibration out of any subsystem on our bot this year. These we machined out of aluminum with specialty large flange pulleys.

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Not as big of an issue if you screw the halves together…

I routinely do ABS pulleys for work. A few notes:
-I don’t usually care much about support–it’s not that bad to get out in most cases even with both flanges. Takes time, though, and whatever you do don’t use a hex pattern on your support.
-Allow some print allowance if you do that anyways. Had some interesting times trying to find the slip…
-We just use the same settings as on every other ABS print we do. Maybe more shell, maybe a bit more infill. Stock, came-with-printer slicer.

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We use PETG with the following settings:

  • 0.3mm layer height
  • 4 vertical shells
  • 80% cubic infill
  • supports with 4mm pattern spacing and 100% XY separation (to make them easier to remove)

These settings have worked fine for us, but we haven’t done any formal testing and optimization. (These are Prusa Slicer settings but should be similar in Cura.)

Seconded here - you can see the difference in the slicer too with 2 walls vs. 4 walls. 4 walls with a .4mm nozzle will completely fill in the pulley tooth where 2 walls does not -

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PLA+ works fine until it doesn’t - if your belt starts to skip, they will very quickly melt due to friction. Onyx will too if you abuse them enough. That’s the one downside of printed pulleys, but usually something mechanically has gone wrong if this is happening or your belt tension is not correct.

I also never use supports. It just creates more cleanup and the teeth never come out as clean as they do just printing without supports. Add a few extra mm to the pulley width and clean up any overhang grossness, but usually they come out fairly clean when you chamfer the pulley flanges.

We ran a lot of printed pulleys this season and it seems like the future. It’s just too easy and gives you a ton of flexibility to go print an odd tooth count pulley if maybe you didn’t hit the center to center distance the first time around.

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