02-05-2014 22:37

Joe G.

Re: pic: 4speed1

Cool setup. Is that carbon fiber on the plates? What was the core material?

Was any kind of auto-shifting used? What kinds of speeds did this achieve?

And, why the huge teeth on the final stage gears?

02-05-2014 23:07

Redo91

Re: pic: 4speed1

I would take a guess that they manufactured the final stage of gears themselves. Whatever method they used, that was the size of tooth they may have been able to make.

02-05-2014 23:26

Joey Milia

Re: pic: 4speed1

This is a very cool use of carbon fiber. It looks like it's foam core. What thickness is the carbon fiber plate? How did it handle having the bearings in it? Did you have to use inserts for the bolt to prevent crushing the carbon fiber?

It looks cool and you have me interested.

03-05-2014 01:51

DampRobot

Re: pic: 4speed1

Saw this team at either SVR or SAC and can confirm this. They mill their gears, using an 1/8" endmill IIRC, and say that they like how they can get gears a lot quicker than through SDP-SI.

03-05-2014 06:07

Bryce Paputa

Re: pic: 4speed1

How did you make the carbon fiber plates? Would it be possible to make a piece with a 90 flange?

03-05-2014 14:33

Mark Sheridan

Re: pic: 4speed1

better talk to 2485 they are experts on making, molding and baking their own carbon fiber (and kevlar) parts.

03-05-2014 17:49

anomalynerd

Re: pic: 4speed1

The composite plates are carbon fiber, kevlar, and a foam core material with epoxy resin.
This was actually one of our first attempts with composite plates where we made a mold for the materials, where now we fabricate the composite plates and then machine them out after.

The gears have to have a 5.8 diametral pitch because we machine them on our cnc mills in shop. The drive system ends up with either 5:1, 10:1, 20:1, or 40:1 gear reduction.

04-05-2014 00:06

asid61

Re: pic: 4speed1

WOW this looks pretty hardcore. It looks like the depth was kept down so you're not realy using space.
What was the motivation behind using 5.8 pitch gears over "normal" 20p, 16p, or 12p gears?

04-05-2014 00:18

Redo91

Re: pic: 4speed1

anomalynerd stated why they make them the way they do.

Emphasis mine.

That said, why not purchase a cutter that will cut the tooth profile of something with a larger DP? You seem to have a machine capable of using one.

04-05-2014 02:03

DampRobot

Re: pic: 4speed1

Might not have an indexing head, or have more of a router setup than a mill setup.

04-05-2014 15:21

Rob Greene

Re: pic: 4speed1

Our team does overbuild many parts. We used the Lewis gear formula and found that 5.8dp would work well with a high factor of safety. We did break multiple 20dp vex gears in this drive system. The gears are very big and we are looking to reduce to a 6.5dp on the next system we build. The other very important factor for these gears is 100% based on the tooling we have at the time of build.

04-05-2014 15:24

Rob Greene

Re: pic: 4speed1

Yes, tooth size was based upon using a 1/8 endmill.