Torque Limiting Screw - Slip Clutch

[jack3333]

I need a screw assembly with a slip clutch to limit the torque applied to a screw, which applies force to a clamp. The purpose is to limit the clamping force. The screw diameter would be in the range of 3/8". The torque limit would be in the range of 1 ft-lb and should be adjustable. The screw would be hand tightened.

I have searched the web and found slip clutches for power trains, but they are more complex than what I want. Also more expensive. Is there a simple device available commercially to do what I want to do?

I think I can probably design and fabricate one with some advice from this forum, but I would prefer to purchase the part if possible.

Thanks,
Jack

 

[MintJulep]

http://www.wmberg.com

 

[jack3333]

Thanks for the info MintJulep. I'll check that out.

 

[Compositepro]

I would search for "torque limiter". A spring-loaded ball-detent design is common. Many cordless screw drivers have that feature. Or find a manual screwdriver with a torque limit feature. McMaster-Carr carries them.

 

[jack3333]

Thanks for the suggestions, Compositepro. The screwdriver may work for my application.

 

[plasgears]

I used with success an output shaft with compact bellville spring as the slip interface. Smart calibration made the process of mfr look easy.

 

[jack3333]

Thanks, plasgears. I like the belleville spring idea. Do you have any details re your design?

 

[plasgears]

Jack3333,
This was a slip clutch for an output gear in a subfractional gearmotor. The 3/8D threaded shaft had a collar to support the gear axially. On the other side of the gear was the bellville spring with a nut to adjust slip torque. Mfg set the nut at the point of desired slip torque, then the nut was thd locked in place. Addition of moderate heat set the thd lock.
No lube was used. A porous PM gear could have contained a minute charge of oil, if desired. Our PM sintering process included dropping the gear into an oil bath after air quench.

 

[jack3333]

Thanks, Plasgears. That sounds like a nice straightforward design. I think I can make something similar for my application. In my case the handle or knob to tighten the screw will replace the gear. I will need to add a ratchet mechanism so the screw won't slip when it is released.