Rohlix Linear Actuator any good?

[kenny1]

Hello...

I picked up something called a Rohlix Linear Actuator. It's basically six ballbearings on a springloaded split metal block, with a .500 dia piece of TGP rod
through its middle. The ballbearings support the rod, and when you spin the TGP
the linear actuator moves back and forth on the rod.

Has anyone ever heard of this? If so, is this accurate enough for say a Y axis drive instead of a ballscrew? It looks very well made, but unfortunately I have no picture of it yet.

Thank you,
Kenny1

[juzwuz]

I saw one of those on ebay once. You can check out the website here for more information:

http://www.zero-max.com/products/rohlix/operation.asp

I didn't bid on it because the comment on Positioning Accuracy didn't seem too good:

"The Roh'lix is a friction drive device and as a result, will show an accumulated error that is, in general, up to 0.002 inches per shaft revolution. Where greater accuracy is required, linear encoders can be used to indicate position."

It sounds like for good accuracy, you'll need some sort of encoder.

[Al_The_Man]

The one application I have come across is DynaBend used to use them on their press-Brake back gauge systems, and they work very well when adjusted correctly, they use them with a linear scale, because they can be prone to slippage if coming up against stop or very high load.
Nevertheless they are very accurate when used with a linear scale.
I have retro-fitted a few of these and got exellent results in this application.
Al.

[RICHARD ZASTROW]

You may want to try www.amacoil.com as well.

[kenny1]

For a minute there I thought I found the perfect Y axis linear mover.

I found the Rohlix website, and they say there is an movement error of roughly .002 per shaft revolution. Also, they say that you can move the Rohlix and the associated shaft will rotate, which is not what I want to happen.

Oh well, looks like back to ballscrews for me.

Thank you,
Kenny1