Ball spline for linear to rotary motion

[Intermesher]

Does anyone know if there is a manufacturer of 'extremely course ball screws'? Perhaps the device might be considered as a ball spline with twist.

Operationally - Linear motion of the shaft causes the 'block' to rotate. The desire is that 2" of travel will result in 30-degrees of rotation. It should be a precission device and handle a thrust of approximately 500 lbs.

Thanks.

 

[ChrisGW]

Back drive a standard ballscrew - I would go with a high lead screw. Your efficiency drops like a stone but it works.

 

[ChrisGW]

Pardon the blatant reference to my companies website - but this page has charts of the efficiencies. I would go with a ground ballscrew myself to keep the motion as smooth as possible to increase the efficiency.

If you think about it - most people test the smoothness of a ballscrew driven actuator by pushing the top table of the actuator long - which is exactly what you are talking about - linear to rotary. You push the table and it spins the shaft.

Backdrive efficiencies

http://www.thk.com/THKCatalog/THKCat_en/THKD020.html

 

[EnglishMuffin]

My memory may be at fault, but I feel certain somebody makes these - I just can't remember who (I've been trying since yesterday). I think we used one at a company I worked at. I thought it was Helac - but their standard ones just use ordinary helical splines.

 

[EnglishMuffin]

Further thought : Helac do make a similar device which uses a short planetary roller screw - if that's of any interest. I think that's what it was actually, come to think of it. It's used in robotics etc. But they may have done it with ball screws too if you check with them.

 

[Intermesher]

ChrisGW & EnglishMuffin

Thanks for the information