View Single Post
  #12   Spotlight this post!  
Unread 05-09-2012, 12:44
trilogy2826's Avatar
trilogy2826 trilogy2826 is offline
Mentor - 2826
AKA: Jake Fischer
FRC #2826 (Wave Robotics)
Team Role: Mentor
 
Join Date: Nov 2008
Rookie Year: 2006
Location: Oshkosh, WI
Posts: 113
trilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond reputetrilogy2826 has a reputation beyond repute
Re: Timing belt in drive success

Quote:
Originally Posted by AdamHeard View Post
We cut off of the sdp-si CAD.
Thanks for the point in the right direction. I was assuming (why do I keep doing that) that the Gates proprietary profile for GT-2 would not stray past their walls. I did an overlay of the SDP/SI 24T and the Gates 24T and they are indeed different in tooth geometry. Not much, but just enough to heed Gates warning about not using the CAD to machine.

We will be running a batch using low-voltage EDM, which will (I believe) give the most accurate resolution and accuracy. I am hoping the smoothness spec can still be met with this technique. We will probably be teflon coating these. so it should not matter. If you want to trade an EDM for a milled sprocket sometime, let me know and we can compare/contrast.


Also, if you don't go down the Shaker sprocket route and want to add flanges, what is your technique? Our current method is to laser a flange, press in the flange angle guide, and bolt it to the sprocket. If there is a way to do this without post machining the sprocket, that would be handy.

Quote:
Originally Posted by IndySam View Post
Hmmm, we may have to try and waterjet some as an experiment. Being able to cut the profile and the hex might be a huge savings in time and cost.

Wonder if we could cut them out of 1/4 stock and stack them.
We tried the following techniques in the 2011 and 2012 offseason to manufacture sprockets and gears:

1. Laminate plates riveted, glued or bolted together to a consistent thickness: Laser and waterjet 0.04, 0.08, 0.125 and 0.25 6061 AL and Steel. Result: Any thickness over 0.08 resulted in a kerf that ended up damaging the belt. 0.04 and 0.08 cut accurately, especially in steel, but the multiple laminations required for a given thickness were difficult to align, even with a complex process and a custom jig. Moreover, the laminations presented a "roughness" that drastically decreased the life of the belt. Overall, not recommended.

For what it's worth, this technique has worked very well for us in gear manufacture from small to large (thanks 148 for the inspiration)

2. EDM the sprocket profile to the desired thickness. Works great with gears and I will be trying them on GT-2 belts in the next couple weeks

I would like to do a cost/benefit analysis of make VS buy and machine Vs EDM... eventually.