This is something I’d been curious about since the Falcons came out, but from my (admittedly short) search on CD, not much has come up about it.
Did any teams try 3d printing the Falcon 500 spline pattern? What printer(s) did you use? How did it hold up? Are there any tricks you found to getting it to print better, slide on better, be stronger, etc?
My team tried to print a spline profile to attach printed 36t HTD pulleys to the Falcon’s on our shooter. We printed them on a prusa with ABS and they weren’t quite good enough to slide onto the spline shaft easily. After a good bit of struggling to get them onto the shaft straight we got Markforged ones made. Those slid on the shaft fine, but they eventually started to wear around the spline and the fit started to loosen up. After breaking our second onyx pulley we ended up taking a steel pinion from VEX and printing around the gear profile, that held up much better for us, even out of ABS. I bet the printed spline shaft would have done better in a less intense application but we never really tried anything special to get them working. We moved quickly between design ideas and didn’t want to wait on printing any more than we had too, once we found the pinion idea we never went back and tried to improve the spline profile print.
I don’t expect any 3d printed plastic to survive in such a high torque application. I would attempt the method that 4481 used for their 3d printed pulley in this post, assuming you have some pinions for the Falcon already:
We have not actually done it, but it seems like under sizing the hole and melting in a pinion could be the easiest and strongest option.
I wonder if you could apply a thin layer of acetone to the shaft first to dissolve some of the ABS and make it adhere better to the shaft.
Our Falcon drive pulleys and Falcon shooter pulleys.
Onyx on the comp, PLA on the practice. Only reported problem was from one that was poorly printed and that failure wasn’t the spline interface rather the hub collapsing from the belt tension.
We printed on our Prusa for our shooter. First in PLA for the practice bot, one broke and was replaced by ABS, one is still going. Comp bot were printed out of ABS.
These were direct driving our shooter wheels through a VP. We used the Vex file for the print.
If we ever get back I would like to experiment with nylon and Prusament PC.
Once we saw the spline shaft for the Falcon, we almost immediately wanted to test how a 3d printed mate would hold up.
In our experience, the Falcon shaft itself failed before our 3d printed adapter (onyx filament).
As Clayton stated…We printed splined hex shafts on our Markforged and they seemed to work great.
We usually tend to be on the aggressive side of printing things. We did do the falcon splines on prototype pulleys that held up fine. For peace of mind on the competition robot we printed the 9T 20DP profile into the pulleys that were mounting direct to the Falcon and then used the 9T falcon spline pinions.
The spline prints would have probably done fine for the season too but it was a reasonably easy accommodation to not have to worry about it going forward.
We printed 36T GT3 shooter pulleys with Falcon splines powering 4" wheels and ran them through all testing and events with no issues, including a full teardown to inspect them after our week 1 event.
Ours were printed slightly undersized so it was a decent hand press to get them on the Falcons, which may have helped.
We jumped to printing pulley’s that we pressed 12T pinion into. These show keyed pinions because we were waiting on our Beta order to show. But in the mean time we started cacluating how we mite use the motors for a flywheel application.
We didn’t have any failures in the shop or week zero.
We 3d printed a falcon spline to 1/2" hex adapter it was used for a 1:1 belt drive for our shooter, we would pop 40 amp breakers on spin up and never had a problem with it. The adapter was printed out of onyx (nylon with chopped carbon fiber) on a markforge mark two.
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