stepper or drive problem?

[Appalachiatools]

I had an incident yesterday where my X axis stepper lost it's "grip" so to speak. That is it lost its orientation by a number of steps and it wasn't "locked" when not in motion. The ball rod could be turned somewhat easily when the motor should have been holding it in place. I have Superior Elect. SLO-SYN stepper motors with Superior MD808 drives. This happened after the CNC had been running for a while and my Z had dropped down a couple of thousands. I had to stop the program and re-wind the code to start over, when doing this I noticed the X had also lost...or gained a few hundredths. I have occasionally had this problem with my Z dropping a couple of thousands during a large file which puts a line across my work piece. I have also had the same problem with my X on rare occasion and only on large files. Could this be the drives or steppers? Could heat be a factor? I have been meaning to build a temp controlled, positive pressure box to house my computer, power supply and drives but still have them sitting on top of my CNC in the heat...and dust of my shop. Just a note...I have the jog set up extremely slow for zero-ing out for set up. Could this be causing me problems? Any advice or opinions would be appreciated. Anyone also know of a good source for these drives and steppers? I can't afford down time and would like to keep some on hand as spares. Thanks.

--Rick

[TarHeelTom]

I've had similar problems on a table top mill, have not yet found the answer.

Your drivers are still listed, and Superior still makes steppers, and list lots of them on their web site. You might want to give them a call..

Their web site does give specific precautions on keeping the working temperature on the drivers down, mentions adding heat sinks and increasing air flow.

You can buy digital readout aquarium thermometers for well under $20. Be interesting to clip one to the heat dissipation area on the drive in question and see what its operating temperature is.

Tom

[Appalachiatools]

Thanks for the reply. I'm going to shut down and get my computer and drives out of the elements of my shop (heat & dust) before I do any real damage. I found a wire which came disconnected to the motor which caused my problem but I still have the problem of my Z dropping a few thousands when running a large file and on rare occasion my X as well (usually when doing a raster cut along the X axis). I think the heat might be causing this.

--Rick

[TarHeelTom]

The answer might be as simple as adding a fan to move some air across the driver boxes.

Tom

[jschmitt]

. I found a wire which came disconnected to the motor which caused my problem but I still have the problem of my Z dropping a few thousands when running a large file and on rare occasion my X as well (usually when doing a raster cut along the X axis). I think the heat might be causing this.

--Rick

The z problem could be as simple as the tool slipping down in the collet

[Appalachiatools]

I am going to build a temp controlled box with positive air flow to house my computer, power supply and drives. I'm also going to shield my power supply from my drives a little better and give a little more distance. I thought of the tool slipping in the collet and have it as tight as I dare. When I put it all together and got it up and running (it bought it in pieces and not all were there), I didn't quite finish the wiring and set up. (finalized). Thanks.

--Rick