pic: Team 3266 Sheet Metal Drivetrain

[AdamHeard]

Originally Posted by BurkeHalderman

We buy all our pulleys, pulley stock, and belts from SDP-SI. I agree the pulley stock is really expensive. At $60 for a 200mm bar I questioned if it was worth the cost to make our own hubs. Although the price drops a lot per bar the more you buy, which helps justify spending that kind of money.



I haven't put to much thought into mounting bumpers on this frame since it's just an offseason prototype, but I think what we'll do is something similar to 148's 2011 bumper system; put 1" hex standoffs in the corners and then use a uni-body bumper frame and bolt it to those hex standoffs. I'll CAD this and post a picture of it.

Here is a front view of the bumper frame and hex mount:

$60 for an entire drives worth of pulleys isn't crazy at all.

[BurkeHalderman]

Originally Posted by AdamHeard

$60 for an entire drives worth of pulleys isn't crazy at all.

Well it's actually about $230 total for all the pulley stock needed for the drive as we need 4 200mm bars of pulley stock. I only have experience using small belts on manipulators, nothing to this scale before, so i dont know if that price still a reasonable amount to spend on this drive?

[mman1506]

Originally Posted by BurkeHalderman

Well it's actually about $230 total for all the pulley stock needed for the drive as we need 4 200mm bars of pulley stock. I only have experience using small belts on manipulators, nothing to this scale before, so i dont know if that price still a reasonable amount to spend on this drive?

If you have a CNC you could mill some GT pulley profiles. But 230$ isn't that much for convenience in the scale of things, you can easily spend that amount on pneumatic tires or mechanums.

[AdamHeard]

Originally Posted by BurkeHalderman

Well it's actually about $230 total for all the pulley stock needed for the drive as we need 4 200mm bars of pulley stock. I only have experience using small belts on manipulators, nothing to this scale before, so i dont know if that price still a reasonable amount to spend on this drive?

For that price, I'd buy these pulleys from AM and bolt them to this hub from WCP.

That's $19 per wheel (plus wheel cost) plus tax and shipping. More importantly, it's zero work.

[Chris is me]

This is very similar to 2168's drivetrain this year. Check them out if you can.

I don't think having CIM relief pockets in the belly pan is going to drastically compromise rigidity. Being able to "drop out" the transmission can be really useful. You may want to make the cutouts around that access hole a little less aggressive, and possibly consider an additional cross member if your manipulator won't already serve that purpose. The Andymark Cross Hex stuff that comes with those gearboxes in the kit would be an easy way to add some cross support.

[BurkeHalderman]

Originally Posted by AdamHeard

For that price, I'd buy these pulleys from AM and bolt them to this hub from WCP.

From searching through the forums and reading all the posts about belt drives it was my understanding the GT2 profile and 9mm wide belts were the preferred setup for a FRC application, while the AM pulleys are HTD pulleys made for 15mm wide belts I would like to use the GT2 9mm belts as their smaller but the AM solution is tempting. Do you think the different profiles would have a noticeable difference?

Originally Posted by Chris is me

This is very similar to 2168's drivetrain this year. Check them out if you can.

I don't think having CIM relief pockets in the belly pan is going to drastically compromise rigidity. Being able to "drop out" the transmission can be really useful. You may want to make the cutouts around that access hole a little less aggressive, and possibly consider an additional cross member if your manipulator won't already serve that purpose. The Andymark Cross Hex stuff that comes with those gearboxes in the kit would be an easy way to add some cross support.

It is actually heavily influenced from 2168's 2013 drivetrain. The credit for the pulley hub design belongs to them, and the weight reduction was influenced from their 2011 drivetrain. They were nice enough to send me their 2013 CAD and I learned a lot about sheet metal construction from taking it apart and figuring out how it all went together.

And that is the reason I have the pockets in the belly pan, so the gearboxes can be dropped out of the bottom of the frame for easy maintenance. As far as being a little less aggressive do you mean making the pocketing smaller?

[MetalJacket]

Originally Posted by BurkeHalderman

From searching through the forums and reading all the posts about belt drives it was my understanding the GT2 profile and 9mm wide belts were the preferred setup for a FRC application, while the AM pulleys are HTD pulleys made for 15mm wide belts I would like to use the GT2 9mm belts as their smaller but the AM solution is tempting. Do you think the different profiles would have a noticeable difference?

Given that these are the pulleys that came in the 2013 KoP, I think you'll fine . A team that we work with used the KoP chassis this year and had no problems that I can think of at this time with their drive. The added width is a disadvantage if you want things more compact though.

EDIT - I may have misread your post. If you were suggesting using the 9mm belts on the AM pulleys, I am not knowledgeable enough when it comes to belts to say whether the difference in profiles would have a significant effect although my gut feeling would be to avoid mixing profiles.