#25 Chain Drive Experience ???

[R.C.]

Originally Posted by de_

Hi Rob

Where do you buy the thicker AL #25 sprockets ?

Re the Dark soul tool ( http://www.team221.com/viewproduct.php?id=70 ) I had no idea that it got rid of the masterlink. Thanks

Dave

AM used to sell thicker sprockets with a chamfer. Now they are thinner with no chamfer.

-RC

[Rob Stehlik]

Where do you buy the thicker AL #25 sprockets ?

Unfortunately I don't have a source for aluminum sprockets other than Andymark. I was just pointing out the change in quality in recent years.

I did some hunting around and found some aluminum sprockets with hubs made by Berg. These use set screw hubs and "pin hubs" so it may be best to broach a keyway in them.

www.wmberg.com/catalog/catpage.aspx?url=pdf/B05A107.pdf

I also found some glass reinforced nylon sprockets made by Torque Transmission.

torquetrans.com/roller-chain-sprockets/index.htm

I will give their distributors a call and see what their stock looks like.

These look interesting. Please let us know if you get pricing and availability. We tried using a large nylon sprocket from Mcmaster carr on our intake this year, and had trouble with the chain not engaging properly. The pitch seemed to be off for some reason.

Generally chain "stretching" is every little join on every link wearing.
The reason you see more stretch on #25 is not because it is weaker but is because you have more links per inch to wear down.

This makes a lot of sense. Team 359 uses bike chain which is 0.5" pitch, but much narrower than standard #40 chain. I'd be curious to hear from them how much stretch they see (if any). My understanding is that bike chain is way stronger than #25, but lighter than #35. Unless you could adapt bike sprockets, you would have to make your own. Other than that, it seems to be a great compromise between #25 and #35 chain.

Rob

[Siri]

Sorry to pull up this thread again, but has anyone found a reliable source for chamfered #25 aluminum sprockets? Does anyone know about these RobotShop guys?

[Brandon Zalinsky]

Originally Posted by Siri

Sorry to pull up this thread again, but has anyone found a reliable source for chamfered #25 aluminum sprockets? Does anyone know about these RobotShop guys?

I've never heard of them, but I'd suggest checking McMaster-Carr.

[Siri]

Originally Posted by Flak-Bait

I've never heard of them, but I'd suggest checking McMaster-Carr.

Unfortunately, McMaster has never sold aluminum sprockets. (They're strictly steel/stainless and nylon.)

[Brandon Zalinsky]

Sorry about that, missed the aluminum part of your post. It looks like many of the #25 sprockets on AndyMark are aluminum. Are they not chamfered, or the wrong size, or something?

[Siri]

Originally Posted by Flak-Bait

Sorry about that, missed the aluminum part of your post. It looks like many of the #25 sprockets on AndyMark are aluminum. Are they not chamfered, or the wrong size, or something?

Yes, AM changed their #25s at some point. They're now thinner and no longer chamfered, and we're having systematic issues with CNC notch defects. There was a bunch of talk earlier this month about it, but it was never resolved into a different supplier. We're currently looking either at fixing the bolt pattern and bore on the less expensive RobotShop ones or crossing our fingers and trying to lathe a chamfer on AM's thinner ones. Wondering if anyone found a different solution.

Originally Posted by R.C.

AM is the only person in the market that sells sprockets in #25 in aluminum. Maybe some other supplier might, WCP will in the distant future

Originally Posted by philso

My concern with exchanging the sprockets is that it would just be a waste of time. Since both sprockets had the same "notch" in them, this is indicative of the design or the CNC programming of the sprocket so any replacements would also likely have the same flaw.

Originally Posted by R.C.

AM used to sell thicker sprockets with a chamfer. Now they are thinner with no chamfer.

[Andrew Schreiber]

Originally Posted by Siri

Sorry to pull up this thread again, but has anyone found a reliable source for chamfered #25 aluminum sprockets? Does anyone know about these RobotShop guys?

I've never ordered sprockets from them but I ordered a couple robots kits from them for work. The kits were backordered but other than that arrived fine and worked quite well. Just don't try calling their phone support, it's terrible.

[Madison]

Does anyone happen to know, off-hand, what the change in material thickness on AM sprockets was? I'm looking for the thickness of a sprocket with chamfer versus one without a chamfer.

[msimon785]

I believe the new sprockets are .125" thick. I know they are waterjet.
I'm not sure however how thick the prior ones were.

EDIT: Sorry, I was talking about plate sprockets. Should have been more careful.

[Cory]

Originally Posted by msimon785

I believe the new sprockets are .125" thick. I know they are waterjet.
I'm not sure however how thick the prior ones were.

Waterjet?

There's no way they're waterjet, unless you're talking about plate sprockets. It would make absolutely no sense to waterjet the tooth profile then turn them down to create the hub.

[Joe G.]

I could believe that the larger plate sprockets are waterjet. As far as I know, the smaller sprockets with a hub are still machined, and still have a chambfer.

[Siri]

Originally Posted by Cory

Waterjet?

There's no way they're waterjet, unless you're talking about plate sprockets. It would make absolutely no sense to waterjet the tooth profile then turn them down to create the hub.

Is something wrong with the hubbed sprockets? I'd only had/noticed people discussing issues with the plate versions. (Type A for AndyMark)


And thank you, Andrew. We'll probably get one from them, then.

[Cory]

Originally Posted by Siri

Is something wrong with the hubbed sprockets? I'd only had/noticed people discussing issues with the plate versions. (Type A for AndyMark)


And thank you, Andrew. We'll probably get one from them, then.

Oops. My bad. Poor reading comprehension on my part. Didn't realize which was being discussed.