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Unread 05-02-2007, 09:46
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ZZII 527 ZZII 527 is offline
"Scale Electric Vehicle"
AKA: Shane Colton
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Re: Banebot 56mm gearbox - double D - RELOADED

Quote:
Originally Posted by jskene View Post
With reference to Dr. Brooks' table in the above post of various steel properties, what degree of hardness do we need in the gearbox plate? This will help us decide which metal to start with.

We have access to a waterjet and a computerized furnace, and hope to make some parts. Hopefully we can make several.
Somewhere earlier in the thread, Joe Johnson posted some target hardnesses for different situations:

1 CIM 12:1 or 16:1 - HRC23. Any harder and the shaft becomes the weak link. But this should be enough to handle the torque of one motor in cyclic loads.

2 CIM 12:1 or 16:1 - HRC40 on the carrier and the shaft for the worst-case scenarios. Any harder and the steel may be too brittle.

Also, there are drawings in the first post for a plate/shaft with a square hole/end instead of the double-D, which will help with the stress distribution.

Dr. Brooks' team has made some HRC40 plates and shafts out of 4130 and my team now has two made out of A2 tool steel. I think 4130 or similar is the more appropriate choice, since C40 is almost off the charts low for tool steel. I got it because McMaster carriers 5/32" (4mm) precision-ground stock. Other teams and BaneBots are in the process of making and testing new parts.
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Last edited by ZZII 527 : 05-02-2007 at 10:00.