Hello, I am new here, and hopefully have posted this in the right area!

I have a Journeyman 320 with a 'stuttering' problem with the servo drives.

Control: Centurion IV (I have a complete wiring schematic for this machine.)

Each axis (X, Y, and Z) will shudder when jogged in one direction only. The other direction runs smoothly.

This sounds like a power supply or control issue, but I am not a whiz at this stuff, and would appreciate some suggestions.

Any help appreciated.

Thanks, Tom

The machine works normally from a cold start, and this means it was shut completely down, control and all overnight.

I think the problem arises from heat.

The control is a Miltronics Centurion IV, with chip sockets. Perhaps I must go through and reseat all those chips. Make sure there is enough cooling fan action on the mother board. Check all connections.

Open for suggestions.

thanks, Tom

I don't know about your problem, but if you decide to rid yourself of it we could use the Z axis ball screw and nut!

Pat

If they are the older style DC drives based on the Westamp style, these are notorious for aging components and are usually affected by temperature with age.
Bit of a coincidence for all three to get it though.
Al.

Al, thanks. I'll take a closer look to see what the drives are tomorrow. It started acting up the other day again, and only the X axis was affected.

I left the control on all night, and tried jogging all the axes in the morning. Everything ran fine. perhaps it's in the motor drivers rather than the control.

This machine was built in 1983. not bad for an old gal.

On the lighter side, If we can't find a Ballscrew nut for our machine without having to have a rebuild company build a new one, we may consider just parting this machine out. It's a 1982 Journeyman 320 and it's got 3 good Gettys N360 drives on it, along with motors, ect. One of the drives (Z axis)was just rebuilt by Magna Products last month: http://www.magnaproducts.com/ (Before we were aware of the cracked ball screw nut)
Our machine was originally owned by the state of Kansas and put out of service and in storage around '88 to '90 and had been sitting since then. We were told when we purchased it that it had a bad Z axis drive, which possibly caused the Ball screw issue.
I don't know if they changed Drives in 1983 or not but I was just thinking.

Do you have a manual on tuning your drives? We have a factory manual that came with ours that tells a (seemingly) simple way to tune the drives with only a multimeter, but if you don't have N360 drives it won't do you much good.

Pat

Pat, thanks for your help.

I have Gould Servos, Gettys 360 drivers(240AC/12.5 amp)

I do NOT have a the manual for tuning the drives. That would be a good place to start.

Pat, if you don't mind, I'd like to be able to contact you for that tuning section of the manual. I may end up needing parts, but it would make sense to do some PM first, and then go from there.

Thanks, Tom

Tom,
Send me an e-mail to reymac@earthlink.net and I'll scan the page when I get to work tomorrow and send it to you (.jpg if that's okay) The drives can be tuned fairly simply, there may also be a way to tune the signals the computer sends to the drives, I'll look in the book and see. We're right in the middle (at least we were) of swapping in a Galil controller with CamSoft software so since I no longer had the original computer I didn't look in the book to se if there's any computer tuning that can be done on the original computer.
On the Camsoft software you just change what's called the PID (proportional gain setting; integral gain setting; derivative gain setting) to take care of the servo problems like you're having.
The Factory computer would have PID too, I'll have to look in the book to see if it's anything that you can adjust.
On our mill the "Z" Gettys drive axis was acting jerky in both directions similar to what you were describing and I finally tried backing down the proportional gain setting 1 number at a time until it stopped acting up, and now it's as smooth as can be.
Pat

Pat, I received the FAXes for the Servo adjustments. Thank you very much. I'll let you know how it goes.
Tom
I can't tell you how much I appreciate your help.