Hardinge CHNC retrofit- Another one on the way!

Well I don't know whats going on now. I go to work on the lathe today and can not get it to error out whatsoever. Im going to guess that it was the weather? The days it was acting up on were 100 degree plus days, shop was pretty warm. Other than that I don't know why or how it fixed itself?

Well machine is at it again, not sure why. The weird thing is that now as soon as Y errors out, X will start to error out as well. Here is a photo of the PID output, it looks to be working correctly. I think the servo drives may not be responding to the command for some reason? Seems to be pretty inconsistent in where it will error out. PCW, If it were a tachometer how would I test one to verify it is working correctly? Andy I have attached the Hal file. thanks guys.

The PID output is on the top.

Yeah, looks like something just quit working, but its not a total failure
but just looks like its become de-tuned suddenly so PS looks like a suspect

Testing the tachometers will probably require a oscilloscope, and some long back and forth moves to verify that you get a voltage proportional to velocity and no excessive ripple or dropouts.

If its temperature related you might try a gentle application of a hot air gun or hair dryer (safer) to find the sensitive area

Not sure why the Axis f-errored signal is not responding. It does show as a following error in the bottom right corner of Axis. I may have the signals crossed for F-errored axis 1 and 2. Any how I will try to test the tach and power supply this weekend. The whole servo system runs on 90V dc created from a transformer in the cabinet, so I guess I should start there. Thanks again guys.

Hi ak amps are good at acting up if there is excessive ripple in the power supply. I havent messed with a size 50 in a while,but the bigger amps have a +/- 15v supply to run the logic on the amp. Worth looking into. I test tachs by putting them in the spindle of a vmc and program 1000 rpm,check the voltage.
You might consider replacing the now ancient hi aks with something more modern, you will be chasing these gremlins forever unless you completely rebuild the drives at the board level. Even then,you are still using 40 year old technology. You might consider something like a 25a20 from Advanced motion controls, simple and inexpensive,also consider all new cabling, ive chased numerous problems in old cabling.

Well I tested the 15 V supply and main 90V power supply, no problems there. So I moved onto the amp itself, I was measuring some board level voltages on the z-axis amp and fat fingered the probe, and then the fireworks started again Doh! Unfortunately or fortunately, Im not sure yet, the Z axis drive is dead .

Soooo......... the machine is getting new servo amps and motors. 1 kw Yaskawa sigma 5 servos on both X and Y axis. Already bought the motors and cables, still need to get the amps though. I also need to get a new Mesa encoder board. However Im not sure which one will work best with the Yaskawa amps since they can do torque, position or velocity mode. Would pulse and direction be better than analog voltage for a drive signal for any reason? Also since the amps will be closing the position loop, would I need to disable the pid inside linux? The servos have 20 bit encoders so I think I may need to scale them so I don't swamp linux .

You might just consider replacing the amps,I used AMC B25A20 brushed amps,I got off ebay for like 50 bucks each,replace the wiring to the tachs and be done with it. The bigger yaskawa motors wont fit under the x saddle with out some serious modifications and the amount of speed you will gain on such a small machine will be negligible. If you elect to go the yaskawa route,Id direct drive them and modify the enclosure. Im pretty sure you need the PID loop in the control, as I think the encoder is for closing the velocity loop in the amp.You could drive the Yaskawa motors with AMC BE25a20 amps also,which are all over ebay. Ive considered the Yaskawa route for my other Hardinge .as I have the motors and the AMC amps, My motors are size 4,and barely fit.

Thanks for the suggestion Jr, however I think I want to get away from the brushed motors. Besides I already had the motors, and cables, just had to buy the Drives. The sigma 5 stuff is pretty compact, not much larger than the stock motors, and with a lot more torque. Hopefully It wont be too much trouble mounting them on the lathe. Direct driving the axis would be ideal, however would require a little more fab work. I think I may just belt drive them, since that would be the quickest way to get the lathe back up and running. The cables are only 10 feet long, so I hope they are long enough to route properly.

Andy I am using the 7i49 now, I think the 7i33 looks like a good canidate. As for the encoders, they are absolute, however the drive will let you use them as incremental as well as output a quadrature signal.