VexPro sprocket wear

[mlantry]

After a season and a half of wear our 15 tooth Vex sprockets that are apart of our drivetrain wore down to nothing at the Bridgewater-Raritan District. The quality of the sprocket was awesome consider we played at a total of 4 districts, at champs, at MAR champs, through offseason events and a lot of driver practice.

[sanddrag]

That's rather concerning. I wouldn't expect that at all. Were they way over tensioned or something?

[Lil' Lavery]

I'm confused. Where these on your competition robot at Bridgewater? Or your practice robot? Did you re-use these sprockets from last year?

[Teched3]

With no lubrication, and aluminum in contact with steel, wear would be expected. Most teams concerned about weight use aluminum, and will easily last a competition season. How did the other sprockets fare? Were they aluminum as well?

Originally Posted by Lil' Lavery

I'm confused. Where these on your competition robot at Bridgewater? Or your practice robot? Did you re-use these sprockets from last year?

OP mentioned using them at MAR Champs and offseasons, so I assume these started their lives in the beginning of the 2013 season.

[Lil' Lavery]

Originally Posted by Andrew Lawrence

OP mentioned using them at MAR Champs and offseasons, so I assume these started their lives in the beginning of the 2013 season.

I gathered that much, but was confused as to how they failed at an event this year. I'm assuming they must have been harvested from last year's robot, but I know better than to assume.

[BBray_T1296]

We used some 34(?) tooth sprockets on our ANSI 25 chain drive last year, and I am not even sure much of the anodizing has been worn off, even after 2 regionals, TRR, and a hundred hours of demoing

[Kevin Sevcik]

I'm guessing poor sprocket alignment? If the sprockets aren't in line with each other, you could get significant wear from the side plates of the chain rubbing against the side of the sprocket. That's about the only way I can think of that you'd get that kind of wear pattern on the sprocket. I assume that once the sprocket was worn thin enough the teeth sheared off and then the sprocket was replaced.

[mlantry]

Originally Posted by Lil' Lavery

I gathered that much, but was confused as to how they failed at an event this year. I'm assuming they must have been harvested from last year's robot, but I know better than to assume.

They were from last year and we reused them and during bridgewater them just wore out bad

[mlantry]

Originally Posted by Kevin Sevcik

I'm guessing poor sprocket alignment? If the sprockets aren't in line with each other, you could get significant wear from the side plates of the chain rubbing against the side of the sprocket. That's about the only way I can think of that you'd get that kind of wear pattern on the sprocket. I assume that once the sprocket was worn thin enough the teeth sheared off and then the sprocket was replaced.

nah we abused them with improper tension and they began to wear excessively from chain skipping the teeth wore down quickly. after we replaced them we were sure to have the chain properly tensioned and lubricated in order to avoid the problem again

[DonRotolo]

Originally Posted by sanddrag

Were they way over tensioned or something?

Matt, still going to argue that the chains aren't too tight?

Sigh. I tried.

These sprockets are in no way faulty, we absolutely abused them beyond reasonable, with chain tension so high the chain actually made a "sproing" sound when plucked, no lubrication at all on dirty, used chain, and a very small diameter (15T) coming off the ball shifter (very high power transmission with about 90 degrees of wrap).

On Team 1676, the adult mentors advise and sometimes cajole, but we don't overrule a student decision (except for safety). Maybe there's some education that happened here. Finally.

sheesh.

[T^2]

Originally Posted by DonRotolo

chain tension so high the chain actually made a "sproing" sound when plucked

Is there anything wrong with keeping chain a tiny bit loose?

[wireties]

Originally Posted by DonRotolo

Matt, still going to argue that the chains aren't too tight?

Sigh. I tried.

These sprockets are in no way faulty, we absolutely abused them beyond reasonable, with chain tension so high the chain actually made a "sproing" sound when plucked, no lubrication at all on dirty, used chain, and a very small diameter (15T) coming off the ball shifter (very high power transmission with about 90 degrees of wrap).

On Team 1676, the adult mentors advise and sometimes cajole, but we don't overrule a student decision (except for safety). Maybe there's some education that happened here. Finally.

sheesh.

Truth.

The chain should move up and down a distance proportional to the length of the chain.

[Botwoon]

Originally Posted by T^2

Is there anything wrong with keeping chain a tiny bit loose?

Cyclists sometimes call it track slack. A loose chain is a fast chain.