Using Timing Belt Pulleys for full court shooter

[Travis Schuh]

I would strongly encourage you to use the GT2 tooth profile rather than the english series. There has been a lot of design efforts that have gone into improving the tooth profiles to give higher load capacity in a smaller belt, and these advancements are only present in the metric profiles with GT2 being the best. For this reason, we use GT2 or HTD if we can't get GT2 in the size we want. There is a great document on the gates website that outlines the power rating differences, unfortunately it is buried down in there. It is well worth finding and doing the math on the proper sizing, or you run the risk of stripping the teeth off of your belts.

Since McMaster only carries the english profiles, you need to get them from someplace like SDP-SI.

-Travis

[RohitD]

I've been looking at some of the different pulleys, and here's the issue I see.
We can't tap the axle because we don't have the machining capabilities to do so. I've checked on several websites and found that there are no belts that have half inch bores and eight inch bores with the same pitch and numbers of teeth that we need.
With that in mind, are there any other potential options?

[Akash Rastogi]

Originally Posted by Thundagere

I've been looking at some of the different pulleys, and here's the issue I see.
We can't tap the axle because we don't have the machining capabilities to do so. I've checked on several websites and found that there are no belts that have half inch bores and eight inch bores with the same pitch and numbers of teeth that we need.
With that in mind, are there any other potential options?

If you do not have access to a lathe, shoot me a PM. It is quite easy to find machining sponsors or local teams who can help you. Shoot me your location/team number/school name and I can help get you set up.

[nathan_hui]

One option is to build a set of 0.1255" x 0.4996" bushings. The change in diameter is enough that you can put some tiny set screws in the bushing. Barring that, you can machine a pin to go through it.

Another option is to make a shaft saver similar to what RC hobbyists use to attach propellers directly onto motor shafts, such as http://hobbyking.com/hobbyking/store...col let_.html. Some designs hold the shaft using collets, others use set screws. Both can be built with a lathe and a drill press, or you might be able to find COTS ones that fit your specs.

EDIT: Sorry, not shaft saver. Prop Adapter.

[whophil]

There have been some very good suggestions here already. The best ideas unfortunately require a lathe.

To add one more suggestion, (again if you had access to a lathe) you could turn down the 0.5 inch shaft to a more reasonable size for the pulley sizes you are looking at. You wouldn't want to step down the diameter TOO much as there will be a stress concentration and a potential point of failure at the stepdown. At the torque ranges here it may not matter.

As mentioned before SDP-SI.com has a much bigger pulley selection than McMaster.