25 series chain skipping

[MrForbes]

Originally Posted by philso

We tension the chain by sliding the gearbox and tightening the mounting screws. The chain will deflect about 1/8 inch when "pushed firmly" half way between the two sprockets.

Did you try loosening it just a little bit? I think it should move about 1/8" when touched lightly, not firmly.

[Mr. Van]

I second the squeezed link opinion. If the chain is reluctant to bend freely at each roller, it will extend off of the sprocket. I think this would be even more pronounced at the high speeds you are dealing with.

- Mr. Van
Coach, Robodox

[philso]

Thanks for the quick replies.

The links did not look "squeezed", if I recall correctly. The parts of the chain that were climbing the sprocket teeth were not near the master link where the chain was broken.

We will try varying the chain tension on second robot.

Thanks.

Phil

[jspatz1]

AndyMark has apparently stopped tapering and deburing the teeth on their #25 sprockets. They used to include a gentle taper on both sides of the tooth, which should be standard for any chain sprocket, and were tumbled to removed burs and sharp edges. Now they seem to be shipped straight from the cutting operation with no taper, and have sharp edges. They are also now made with thinner .090 material despite being described as .125. We add the taper to both sides of the teeth by gently rotating on a sander, and soften all edges with a wire wheel. This makes a big difference in the sprockets running smoothly, and makes them more tolerant to misalignment.

[Madison]

Originally Posted by jspatz1

AndyMark has apparently stopped tapering and deburing the teeth on their #25 sprockets. They used to include a gentle taper on both sides of the tooth, which should be standard for any chain sprocket, and were tumbled to removed burs and sharp edges. Now they seem to be shipped straight from the cutting operation with no taper, and have sharp edges. They are also now made with thinner .090 material despite being described as .125. We add the taper to both sides of the teeth by gently rotating on a sander, and soften all edges with a wire wheel. This makes a big difference in the sprockets running smoothly, and makes them more tolerant to misalignment.

Additionally, we've run into some trouble with the tooth profile on some sprockets being a bit off such that you cannot wrap chain around the whole sprocket. Somewhere, the pitch is off just enough to make the chain unable to fit.

I think that may be the likely culprit here.

[sanddrag]

We have a virtually identical setup on our shooter and have not had a problem. I say improper chain tension or defective sprocket or chain. Have you checked the chain for any bound up links that do not pivot freely?