Re: Source for Belts and pulleys
 

Is it possible to design a pulley of any size with just the belt profile?
We made some pulleys of weird sizes out of acrylic for the 2012 season that were light and cheap, but it took some tweaking to get it right.

-Mihir

Re: Source for Belts and pulleys
 

We don't use the belt profile but instead the actual pulley profile.

We use only GT2 5mm x 9mm wide. But you can use other sizes: 2mm/3mm work, 973 used those sizes successfully this year.

-RC

Re: Source for Belts and pulleys
 

Never though about doing hex like that. Makes a lot of sense. And it saves our team kinda a lot in terms of us, if ever switching to hex (hopefully!) the we wouldn't have to buy a broach machine.

Re: Source for Belts and pulleys
 

I've used this method before on other non-FIRST projects that required high precision hex alignment, and it works quite well. The only downside is that you can't go very deep with it on small hex sizes. Typically you don't want to broach very deep anyways, so it's not usually a problem.

That being said, in most cases it's easier to broach. You can hex broach most wheels/hubs for FIRST with just a regular arbor press and some cutting fluid if you're careful, so it tends to require less time than trying to mill it. If you have access to a mill, you most likely have access or room for a press that can broach.

Re: Source for Belts and pulleys
 

I'm surprised there hasn't been any action on this thread since the game was announced and we got the details on the drive parts in the KoP. Maybe it's in another thread that I've missed, but I've searched and haven't seen it.

The KoP contains two 39-tooth aluminum pulleys, 5mm pitch, 30mm wide. The belts are 15mm wide, so the idea (I presume) is to run two belts side by side on each pulley, going to 15mm width pulleys on separate wheels. Not sure I would have designed it that way, because I don't like the belts rubbing where they cross, but I guess it will work.

The part number given in the Drive Base checklist is P39-5M-30 AL. Searching for "pulley" on AndyMark yields the am-2265, which gives more details such as Gates part number 39-5M25SP01. I can't find either part number, or anything like them, on Gates (or McMaster, or anything else). I've found pulleys (or "sprockets") for 5mm HTD belts, but only in 15mm widths.

We're considering using a different size pulley on the gearbox driveshaft, to change the torque/speed characteristics. For now, we'll try to stay close to the original design of two belts coming off the drive pulley, but we may need to change that. AndyMark doesn't sell any other size, and I can't find it anywhere else.

We don't have the ability to make these parts from scratch. We could combine two smaller pulleys, machining off the flanges where needed (but maybe best to leave at least one flange). How to mount these would be a design consideration, but I think we can figure that out.

Any help on finding sources for these parts would be greatly appreciated. Links are especially helpful.

Re: Source for Belts and pulleys
 

http://www.mcmaster.com/ (My favorite site for everything, not always the best for pulleys, though, because they carry mostly steel or plastic)
http://www.bbman.com/products/belts.html (Official Gates distributor)
https://sdp-si.com/eStore/ (Lots of variety especially in timing belt pulleys and belts)

Re: Source for Belts and pulleys
 

Thanks, Patrick. I've checked those sites, and still can't find the 30mm wide pulley like the KoP item. If you've found any, can you give me a link to the actual part (or category, part family, etc.)?

Re: Source for Belts and pulleys
 

Apologies, somehow I missed the 30mm when I read that. Most of those sites carry timing pulley stock, so if you have a lathe you can make pulleys of whatever thickness you'd like.

Re: Source for Belts and pulleys
 

You can get the KoP Belts from Andymark: http://www.andymark.com/product-p/am-2451.htm

Re: Source for Belts and pulleys
 

And some pulleys I made last night: https://sphotos-b.xx.fbcdn.net/hphot...70581742_n.jpg

GT2 24th 9mm wide. 3 of the holes are tapped for adding a flange.