Gates belt theroy questions

[asid61]

Originally Posted by InFlight

That's the Gates specificifation. It would still apply to GT3 and their HTD. The HTD patent is expired, so there's lots of aftermarket HTD belts. How more or less accurate second source suppliers are is unknown. But for as cheap as these belts are now, I wouldn't expect tighter tolerances.

I believe 2791 just runs direct C-C with no center distance addition going off what Chris is Me says. Although the tolerance may be 0.02", realistically it could be much tighter than that.

[AdamHeard]

Not super scientific, but we generally run .005" over on our loaded belt runs. Even that is in the range where it starts to get hard to install in an exact C-C application.

Also.... Theroy Jenkins!

[Chris is me]

Originally Posted by asid61

I believe 2791 just runs direct C-C with no center distance addition going off what Chris is Me says. Although the tolerance may be 0.02", realistically it could be much tighter than that.

Yup, we don't add anything to the center distance and it "just works".

With regards to the specs - the center distance equations are the same. You'll notice the WCP calculator has a field called "center distance adder" that is set to .001 by default - that is where the term comes from. Leaving this at one thou is fine if you want. Doesn't seem to make much difference either way. If you needed to be within one thou of a specific exact distance for belts to work, you wouldn't be able to run them with exact centers anyway because almost nobody holds those tolerances in FRC.

As for the rest of the specs - keep in mind they are referring to mechanisms with far higher runtimes than FRC things. They are very conservative.

[Munchskull]

Thank you for all of the information. Would the pure calculation or adding a few thousandth to the distance yeild a drive that would be less likely to snap a belt?

Also I have heard that mixing different belt with htd5 pulleys can result in less failure than just using HTD 5. Is there any merit to that?

[Chris is me]

Originally Posted by Munchskull

Thank you for all of the information. Would the pure calculation or adding a few thousandth to the distance yeild a drive that would be less likely to snap a belt?

Also I have heard that mixing different belt with htd5 pulleys can result in less failure than just using HTD 5. Is there any merit to that?

Once you add enough distance, you start to over-tension the belt, and you risk failure that way. Once you remove enough distance, you risk ratcheting.

5 thou or less added seems like it would be fine.

Using GT2 belts with HTD pulleys is slightly stronger than HTD / HTD, but weaker than GT2 / GT2. I don't think you need to do this - if your belt strength is marginal enough for this to make the difference you don't have a big enough safety factor.

Remember, 15mm wide for 24T pulleys in a drivetrain.

[Cothron Theiss]

Originally Posted by Munchskull

Also I have heard that mixing different belt with htd5 pulleys can result in less failure than just using HTD 5. Is there any merit to that?

Originally Posted by Chris is me

Using GT2 belts with HTD pulleys is slightly stronger than HTD / HTD, but weaker than GT2 / GT2. I don't think you need to do this - if your belt strength is marginal enough for this to make the difference you don't have a big enough safety factor.

https://www.gates.com/~/media/files/...ure-102005.pdf

This brochure from Gates does a pretty good job of explaining what belts interface with what pulleys. The one thing it doesn't include is the GT3 series of timing belts, which interface with GT2 pulleys.