Aluminum sprockets for drive train - several questions

[ChrisH]

Originally Posted by squirrel

How many miles do you put on your robot?

Thanks to some of the added capabilities of the new control system, we are planning to include an odometer in our code. That way we can track repairs etc. by distance traveled and figure out how many tires we will need this year.

Of course, figuring out just what the milage really is is complicated somewhat by our tendencey to spend much of the time driving backwards.

[MrForbes]

I guess you need to ignore the direction signal from the encoders when incrementing to the odometer?

Very neat idea! I wonder what other stuff might be useful to keep track of?

[M. Mellott]

Everyone,

Thank you all very much for your testimonials--it's very helpful to know so many quality teams have used them successfully.

[Elgin Clock]

Chain shouldn't tear up the gears, but if you have something other than a drive train (ie: something that will include a huge load on it - arm, or other such load) your gears could get their teeth torn up...

We made a gear box my first year in FIRST (2001) and by the end of the season, the welds we used to attach the gear to the shaft help up awesome... but left the teeth the weak point, & it resulted in a half-moon shape gear. (The application was just a gear on gear mesh without using any chain & we were lifting full size robots & the goal that year which was about 150 lbs as well, all while putting that gearbox to it's full potential, & obviously past it's limit.)

Would have worked great as a cam, but unfortunately that wasn't our intended application of course.

We have since learned quite a bit about drive trains, & gearboxes & don't have that problem any more. (knock on wood).

[Mr_I]

We've used AndyMark and IFI sprockets for years, with both 25 and 35 chain, and the only real slip we’ve encountered came when the robot took a hit, bent a frame and introduced slack. So the two important lessons are A) have a tensioner system (with lots of room for movement), and B) the tendency to slip is directly proportional to the number of degrees of wrap that the chain makes around the sprockets. Make lots of >150 degree turns and you should be fine.

[AdamHeard]

Originally Posted by Elgin Clock

Chain shouldn't tear up the gears, but if you have something other than a drive train (ie: something that will include a huge load on it - arm, or other such load) your gears could get their teeth torn up...

We made a gear box my first year in FIRST (2001) and by the end of the season, the welds we used to attach the gear to the shaft help up awesome... but left the teeth the weak point, & it resulted in a half-moon shape gear. (The application was just a gear on gear mesh without using any chain & we were lifting full size robots & the goal that year which was about 150 lbs as well, all while putting that gearbox to it's full potential, & obviously past it's limit.)

Would have worked great as a cam, but unfortunately that wasn't our intended application of course.

We have since learned quite a bit about drive trains, & gearboxes & don't have that problem any more. (knock on wood).

Are you referring to gears or sprockets? I can't really determine from what you're saying.

Somewhat related;

I have used 60T #35 Aluminum sprockets on extremely high powered and high reduction arms (As in the final stage of a 2500:1 reduction directly attached to about a 5' arm that was rather heavy [forgot specifics] and held the trackball at the end of that. It also hit the rack when extended at drive speed many times) with no signs of fatigue or tooth wear. I believe this is true of 330 as well.

[EricH]

Originally Posted by AdamHeard

I have used 60T #35 Aluminum sprockets on extremely high powered and high reduction arms (As in the final stage of a 2500:1 reduction directly attached to about a 5' arm that was rather heavy [forgot specifics] and held the trackball at the end of that. It also hit the rack when extended at drive speed many times) with no signs of fatigue or tooth wear. I believe this is true of 330 as well.

True. 330's are custom-made; I don't know the metal. See also 330 2005 and 2007.

We also used some mid-size ones in 2007 for deploying ramps. Those took everything we threw at them and still worked. They were on the outside rear of the robot, virtually unshielded, IIRC.

Aluminum sprockets are a good thing if you use them correctly, in any application. The trick is to use them correctly. (I know 330 has used them in drivetrains and arms for some time. Other things, like tires, have or worn, but not the sprockets.)