THK KR46 actuators with mystery American Precision steppers

[peter_kd5bwt]

Hi all,
I'm quite new to the whole CNC world (though not new to real-time software control of other things), but I'm in the process of converting an X2 mini-mill over. Along the way I came across a good deal on these two THK KR46 linear actuators with ballscrews at a local surplus house, and they came with stepper motors and working limit switches. I'm not really sure what to do with them yet, but it only makes sense to get some familiarity controlling and configuring them before I get in to the meat of the real project, so I'm going to test them out with my Geckos.

Thus, I have a few questions. I have made some fairly thorough attempts to search for these answers but haven't come up with anything yet.

1) The motors don't have voltage or current limits stamped on them. All they say is "MODEL MT232-06" from American Precision Industries, Inc, with what appears to be a manufacture date of 10/95. They have the standard 8-pin 0.100" header, and I've tested them with an ohmmeter; the windings are 1-5, 2-6, 3-7, and 4-8 and each one has approx 0.7ohms of resistance. They're standard Nema23 size, but without voltage or current limits I'm not really sure where to start.
Here's a photo of the motor label: http://www.flickr.com/photos/80823736@N00/294997110/

Assuming that I can't find any better information on the motors, can anyone suggest a decent place to start for voltage and current limit settings? I'm not going to pushing much load with these at first, so I was just going to go with 2A/30V as a starting point unless you'll have better suggestions. I have access to a wide range of test equipment so if there are any other easy ways to divine recommended limits I could try those out. The controller I'm using is a Gecko 202, and the power supply is TBD.

2) The actuators aren't the cleanest, but they slide easily from one end to the other with minimal force and I don't hear any grinding. I have no idea if they've been dropped or anything and haven't indicated them yet, but they look nice. Can anyone suggest a fun project to make with these to experiment around with while I get comfortable? Is there any reasonable way you could use one of these on an X2 CNC conversion? I could imagine putting a larger motor and doing the vertical axis with one, but that's about it.

Relatively detailed photos of the motors and actuators are here:
http://www.flickr.com/photos/80823736@N00/

Thanks!
Peter
Melbourne, FL

[juzwuz]

http://www.cnczone.com/forums/showth...light=thk+kr46

Looks like a good find to me. Check out the above link to get an idea for a cnc router with thk actuators. I've got a couple of THK KR46 actuators that I'm hoping to make into a cnc router one of these days. Sorry I can't help with the mystery stepper motors but you could always get some brand new stepper motors off of ebay for relatively cheap (280 oz-in for $39, 400 oz-in for $54). Are your actuators 10mm or 20mm lead? How much did you pay?

[peter_kd5bwt]

Thanks -- surprisingly, I didn't find or notice wisp's that thread in my searches, and I appreciate you sharing it.

I will be picking up some new steppers for use with the X2 Mill conversion, so I might just do that earlier. The actuators appear to be 20mm lead, which I interpret to mean 20mm of linear motion for 360 degrees of rotation on the screw. They're definitely coarser threads than the screw on the vertical axis of wisp's router.

I gambled and paid an uneducated $60/each (they were asking $75 each) for them. What I was looking for was a smaller step motor / ballscrew assembly out of a printer or something to get some familiarity with the domain and such before messing with something I've put together. As someone with some mechanical skills but no professional training I've often found that spending some time with a professionally assembled device helps me do it better on my own. This was my sequence with manual control of the mill:
1) Want to make a part; realize you need to be able to mill to do it.
2) Research ad nausem. Purchase an X2 mill kit. Mostly assemble it.
3) Make part, but deal with all sorts of sloppiness.
4) Wander over to the machine shop at work (I'm lucky here.) Find someone who's willing to share part of a lunch break showing you the Bridgeport they've been making parts on for 15 years. Move the controls on said machine, and feel the slop in the vise. Watch him take a pile of metal weighing more than vise I'm using in a matter of minutes. Compare to what you have at home.
5) Completely strip the X2 and deal with most of the little problems. It's still not like what you've seen, but it's a lot further toward that end of the scale and it's now possible to make reasonable parts.

Back to the KR46s -- do they stamp the complete model number (with ballscrew grade, etc) on them anywhere, or is this something that can be easily determined?

-Peter

[juzwuz]

http://www.tos-world.com/TOSUS/HTML/pdf/spl0030.pdf

I'd look through this catalog and match the various dimensions. The only thing I couldn't figure out is the precision (normal vs high grade) with a rolled ballscrew. If you have a ground ballscrew then it is the precision grade actuator. I've seen those new on ebay for $600. Normal precision can go for up to $400. You could probably sell them for at least $200 so I'd say $60 is a good buy. The 20mm lead is kinda coarse but I guess it depends on what you want to do with the actuators. I'm still trying to figure out the stepper motor electronics on my Taig mill before I tackle the THK KR46 router build.