My guess would be that it takes less time (maybe not less machining time but the lead time to have them at hand) to mill out the hex on the CNC mill than broaching 2+ robots worth of brass gears. Also, milling the hex gives 1690 more control over its tolerance and could possibly help eliminate backlash (although for this purpose I don’t think it’s a major concern).
That’s what I thought at first, but based on how small the relief is I’d imagine you get some decent amount of tool deflection. Plus, a broach is generally ground to tolerance so it should have some tight tolerances. Unless of course, the time savings as you said.
We don’t have a 1/2" hex broach on hand, plus the mentor responsible for it said he preferred it to be milled out
That’s interesting; How well does the hex fit?
Do you have any photos from the setup on these? Home Making Bevel gears is a really cool application.
We have access to 5-axis mills through our sponsor Elbit, a defense contractor. We try to make as much of the robot as possible in house on our CNC router to speed up manufacturing time (and make replacing parts easier when we inevitably find things need to be changed), but every year we end up sending some of the more complicated, higher-tolerance, weird material, or high volume parts to outsourcing. We’ve never purposefully used their 5-axis capabilities, but we know in the back of our minds that it’s available if we need it.
Notice I said “never purposefully used”. That’s because in 2019 one of the parts we sent them to make was designed by one of our newer students and the model was sent out without being thoroughly checked. When we get the parts back from our sponsor, they mentioned that it was funny to see we finally used their 5-axis mill. Turns out the part was a normal 3-axis billet part, but to make it look nice the student rounded the sides of the billet. So these relatively simple parts that should have taken 10-15 minutes to machine accidentally became parts that took an hour or more each. Notice how the sides of the part are slightly rounded. That’s the 5-axis at work!
That’s awesome. I love that they were happy to have fun with the part. What was it used for?
A nice, tight fit, just like we wanted
Unfortunately no, the facility in which they were made does not allow any photography
They’re amazing supporters of ours, and they love it when they get to help us design and build the robot. We’re very glad to have them as sponsors.
That part connected the profile that held our climber wheels to the lead screws that drove them into the ground. Our climber that year never really worked right, and we only climbed to HAB 3 once in an official match. The profile ended up getting absolutely destroyed in a playoff match before it got replaced between competitions (for another system that also didn’t really work)
Multi axis machining is not a super competitive advantage in FIRST. You can make cool stuff, but cool does not win matches. The time and cost investment does not make sense for the FIRST Competition. With that said, FIRST is a side project in my career as an educator. My primary focus is to produce career and college ready students…so we machine lots of parts with “cool factor”. Also, it is worth mentioning that students CAD/CAM and CNC all their own parts. We do not sublet parts or have mentors come and save the day. It takes about two years of training to get a student to run five axis mill without direct supervision. A big investment in time, but these kids get careers and that is what FIRST is all about.
The first pic is a vector wheel. Props to team 125 for posting the cad.
Just out of curiosity - did you actually use these wheels on the robot? Why did you make them out of Aluminum rather than some kind of plastic? Also, could they have been made in one piece with two setups for the roller pin holes?
We did use the wheels on our intake. Plastic works fine and we made some 3d printed wheels for testing. The aluminum wheels was a task that a senior did in week five after the robot was functional, so no important time was lost. I am waiting to see how the plastic wheels do outside frame perimeter in heavy defense. Plastic vector wheels are still new to FRC.
The metal VIW would be a great core for a casting mold. You would have much nicer surface finishes than using a 3D printed part as your blank
Also, my personal reason for asking was to see the community doing cool stuff with expensive toys rather than to look for justification for buying a machine
I’m not from 971, but I think the parts for their 2018 shoulder and 2017 center pillar (don’t remember if if was the first or second revision) were made on a 4 or 5 axis machine at one of their sponsors’ facilities.
Regarding 971 parts (thanks for thinking of us), the parts you are probably thinking of were fabricated on 3-axis mills, but they demonstrate how creative you can get with a 3-axis mill.
2017 center column which fed balls from an indexer which wrapped around this column, up into a shooter which sat on top of this column.
2017 - photo of the column being assembled with some other parts (provides a sense of scale):
2018 aluminum joints:
2018 - The joints after they were epoxied on to carbon fiber tubes, forming a very lightweight but rigid double-jointed arm:
I thought the 2017 pillar was 4-axis. If it’s 3 axis I’d be interested in how the setups worked out on that!
It was Live tooling lathe with no Y-axis, so technically 3, Steve just read my email reply wrong
How did you guys design the center shooter column? I couldn’t even imagine designing something like that in onshape.