Z Axis lag - Loosing position

[Allthewatts]

Hey team, so I have converted a Grizzly G0619 to CNC with an Acorn board and StepperOnline drivers. I have fine success, and have made a number of parts now. But I get into situations where I loose my Z position.

My process: I zero the tool to the top of my stock to get and offset. Upon starting the program, the z axis moves up to the tool change position. But at he start of the movement, some times the read out on the computer starts moving, and the axis lags. I end up with the Z position way off (~0.1-0.5in). I cant seem to figure this out, any suggestions?

- Stepper online drivers. CL57T for X and Y, CL86T for Z
I use the following concept: https://www.centroidcnc.com/dealersuppo ... 034.r2.pdf
- I do have proximity switches, and a tool height setter
- The whole electrical system is in an enclosure, though I don't have any EMI reduction methods, so thinking maybe I should add Ferrite rings.

[suntravel]

Connect the CL85T to 5V DB25, it runs more reliable this way.

Uwe

[ShawnM]

Uwe is correct, those are 5v drives and need to be wired to the DB25 for reliable operation. You possibly also need a counter balance on the Z axis as you may be asking too much of the motor and drive combo you installed.

[Allthewatts]

I purchased a db25 breakout and will try that! I'll report back on how it goes.

I've had great success with the large stepper on my z axis, but I'm still using the stock 10tpi acme lead screw. This is also powered with a separate power supply.

I've limited the machine to very slow speeds, as my spindle only goes to 3000 rpm, it's fairly limited all around.

[ShawnM]

The acme lead screw is only adding to the resistance that the Z axis has to endure. A simple gas strut for a counterbalance may be a cheap and easy fix. Let us know how it goes after the drives are wired to the DB25.

[Allthewatts]

Well I installed the DB25 connector, and moved the stepper Logic power over from 24v to 5v per the wiring diagram. I made the necessary adjustment to the external switch on the stepper drivers, and unfortunately no motion at all. So working to troubleshoot this.

[Allthewatts]

okay I have the steppers working off the DB25 now, and all on 5v logic power, and its work.

However the problem persists on the Z axis. I played around for a bit, and I can see it repeatably happen if I move the Z axis around, then Estop, give it a few moments, then try to move the Z axis, it misses around 100 to 500 thou.

Any sugestions?

[tblough]

If the Z-axis moves with power off, then you will lose position. Do you have a brake on the Z-axis motor?

[Ken Rychlik]

I set mine up to force a rehome after estop. E stop is just for emergencies and I seldom use it. The escape button will stop a file without doing the estop.

[Allthewatts]

No brake enabled, but the z axis doesn't move when power is off.

It really is the computer is trying to step and it doesn't seem to respond to the pulses if they are even sent