will it work?

[mark c]

Hello all,
I have a Seig Micro mill with extended travels that I bought on E-Bay that is driving me crazy! It had a servo system installed that is just doesn't seem to work very well.
I'd like to replace it with the 200 oz in kit from Hobby Cnc. Will this work well with this unit and have oomph to drive it? I replaced the original leadscrews with precision 3/8-12 acme rod & delrin nuts. The servo system seemed too sensitive and would just stop for no apparent reason. All I could get was 36 IPM from it and I had to turn down tha accel rates in Mach 3 to get it to run decently.
The last straw was tonight, I ran a 3D program all the way thru, ran fine, took over an hour. Ran it again, stopped after 15 min or so, Mach 3 was fine, just running along fine, but as happens all to often, the cutter is stopped in the work.
The guy I bought it from said to buy a faster computer, so I did. No change.
Anyhow, sorry for the wordy post, will the Hobby 200 oz in kit be able to drive this mill, mostly milling aluminum, with decent feedrates & rapids?

Thanks
Mark

[mark c]

Anybody out there using a comparable mill with the 200 oz in steppers?

[KTP]

post some more details on what type of servos and drivers you have. Why do the servos not work? Are they underpowered or maybe your cables are flakey?

[dneisler]

I had 200 oz. on a micro mill, it really needs a little more on Z unless you counter weight it, or something. Best I was getting was abou 15 IPM rapids on XY, and about 5 Reliable on Z. This was with factory screws though.

[mark c]

The servos are Pitmans. the specs I have are: 5.9 gear reduction ratio, 30.3 VDC rated voltage, 834 no load speed, 9.5 oz in continous torque, 61.8 oz in peak torque.
the drive, I don't know. It was included as a package. The updated machine is at:
http://cgi.ebay.com/4-Axis-CNC-Mill-...QQcmdZViewItem

The drive unit shown above is a newer unit than mine, the TL500.
I have added 3/8-10 precision acme screws & delrin nuts. Everything runs smooth by hand. Sometimes it stops when not cutting anything, sometimes when making a rapid move. I think the drive unit is just way too sensitive or servos too wimpy.
As an aside, I have used it a lot in the past few days, NO PROBLEMS. I had adjusted the motor tuning slightly. But this has happened before, I can run it hard for a while; I think everything is OK, then it glitches again. So I really don't know what I have going on here. I just don't know that I can trust it.

Thanks for reading my rants.
If you have any ideas/suggestions I would like to hear them

Thanks

[KTP]

Ah, I am familiar with those Pittman motors...I have a few from an old robotics project. They usually have fairly nice HP encoders, like a HEDS9100 and a 500 line encoder wheel. I would not have thought to use them on a mill though, because they are geared and the gears have some amount of slop. Perhaps the slop is not as bad as I thought (as I sit here and twist one of the shafts...I haven't looked at them in 3+ years). I am pretty sure the continuous torque rating you quoted was for the ungeared motor section. Geared 5.9:1 they probably have at least 40-50oz-in cont. torque. Sounds like a problem might be with your drive and not the motors...