Set screw torque value in aluminum?

[nv10er]

Curious if a torque value has been established as a good rule of thumb for the set screws in the aluminum pulleys on these old machines. Looking at the fixed sheave set screws on the speed changer I’m restoring, they have the least amount of aluminum casting around the screws I’ve seen yet.

When tightening these screws, I always hold the short side of the supplied Allen wrench with thumb and two fingers to avoid over tightening, as I have a tendency to do. But I’m wondering if anyone has come up with an inch-pound torque value for these screws to ensure proper tightness without placing undue stress on the pulley casting.

[chapmanruss]

I don't know of any. When originally assembled at the factory they may have had an "inch-pound torque value" but since they said repairs to the Floating Pulley Assembly is a factory job, they probably never released that information publicly. Assembling it as you described is probably a safe way to avoid over-tightening those set screws.

[edma194]

These two documents from NASA concerning screw fastener torque guidelines may be useful to establish some general guidelines. To know exactly requires specific load and material data that we may not be able to determine.

Installation Torque Tables for Noncritical Applications: https://ntrs.nasa.gov/api/citations/201 ... 003491.pdf
Torque Limits for Threaded Fasteners Used in Space Vehicles and Support Equipment: https://standards.nasa.gov/sites/defaul ... -486-B.pdf

[BuckeyeDennis]

These two documents from NASA concerning screw fastener torque guidelines may be useful to establish some general guidelines. To know exactly requires specific load and material data that we may not be able to determine.

Installation Torque Tables for Noncritical Applications: https://ntrs.nasa.gov/api/citations/201 ... 003491.pdf
Torque Limits for Threaded Fasteners Used in Space Vehicles and Support Equipment: https://standards.nasa.gov/sites/defaul ... -486-B.pdf

Great find, Ed! Those documents are going straight into my own engineering reference library.

[edma194]

Great find, Ed! Those documents are going straight into my own engineering reference library.

Hope you can make good use of them. I assume cast aluminum parts like most pulleys would have the characteristics of 6061 aluminum. PowerPro parts might be something like 7075.

I haven't had much need for these tables lately since I stopped work on my orbital launch vehicle to concentrate on a time machine

[nv10er]

These two documents from NASA concerning screw fastener torque guidelines may be useful to establish some general guidelines. To know exactly requires specific load and material data that we may not be able to determine.

Installation Torque Tables for Noncritical Applications: https://ntrs.nasa.gov/api/citations/201 ... 003491.pdf
Torque Limits for Threaded Fasteners Used in Space Vehicles and Support Equipment: https://standards.nasa.gov/sites/defaul ... -486-B.pdf

Great find, Ed! Those documents are going straight into my own engineering reference library.

Yes, indeed. Thank you for providing this information, it is helpful!