Re: typical no-load speed

The application is positioning so there is no problem with holding a
position. I think that belt drive actuators might be my best bet as
far as ebay fodder goes but they don't seem to come up very often.

I have used linear motors:

http://www.copleycontrols.com/motion/motors/ThrustTube/

check them out, the motors themselves are quite cheap and so are the
drives relatively, they do little canbus modules but you can set them
up via an RS232 cable to do step and direction. I used these for an
ultrasonic scanning tank I built and if I just buy the motors they are
almost in my budget for this personal project if I use USdigital
instead of Renishaw linear encoders!

Thanks for the info guys, if anyone has a pair of belt actuators for
sale let me know

Graham






--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turyga1963" <TIntruder@...>
wrote:

>
> Linear motors are really neat. I use them all the time for Laser CNC.
> They are faster and smoother than similar sized screw-driven stages.
> (http://www.aerotech.com/products/stages/linear_stages.html ; the ALS
> 5000 series shown here are typical of what I use daily)
>
> Bear in mind though, that linear motors do not have the position-
> holding power most similar sized screw-type stages have. For optical
> jobs like laser cutting, this is no issue, and for many CNC router
> apps, it probably isn't either, but if you intend to mill metal,
> you'll need a really big and heavy linear motor stage and a heck of a
> power supply to insure it doesn't get pushed out of position when the
> mill takes a bite. (yes, I know it will try to return to the commanded
> position) With power removed, linear stages move with no more drag
> than the slides they run on...much less drag than ballscrews have.
>
> Always a tradeoff, huh?
>
> Tom
>