Massive Z plunge after space bar stop

[beacon14]

This is the second time this has happened to me. Something wasn't right so I hit the space bar to stop the machine motion (I may have hit the space bar more than once - sometimes it does not stop right away - that's another problem). Once the machine stops, the message window comes up offering me options to Quit, Restart, Insert Move, etc. I select Restart, wait for the router to come back on and get up to speed, press OK to continue the file, and the router plunges STRAIGHT DOWN to the hilt, burying the bit and collet in the workpiece before I can frantically stop it again by mashing the space bar.

What's up with that? Has anyone else experienced this? I'm using Version 3.5.3 but the first time it happened I may have been using an earlier version as it was a few months ago - not really sure about that.

[henrik_o]

I have experienced similar violent z plunges on the added z when we first tested out or Alpha: the culprit was likely electrical noise inside the ctrl box due to the fan wiring for the Colombo. We moved the fan to a separate power supply outside the ctrl box and the problems immediately went away.

Your problem seems different, though, in that it happens after a programmatic event rather than an electrical event (in our case turning on the spindle).

[Brady Watson]

Please take a few minutes to contact ShopBot support when you guys encounter these anomolies. Try to give the conditions that they occured under, and send a copy of your shopbot.cfg and problem.log files so that the software can be improved to prevent these types of things in the future. If nobody reports errors/bugs or anomolies, they'll never be fixed or addressed.

-B

[beacon14]

The first time I figured either I was dreaming or had done something wrong - but twice is not a coincidence - I'll contact them on Tuesday.

Good point Brady

[myxpykalix]

My symptoms were a bit similar in that after hitting spacebar to stop file it would raise up and because it apparently lost its Z setting it would want to raise up too high and top out and router would just fall down, not plunge. That doesn't happen too often though.

[henrik_o]

Brady,

Yes, even though we solved this one on our own we did contact Shopbot and discussed the fix. I completely agree that strange behaviour like this should be reported to Shopbot even if a fix is devised on the fly.

[beacon14]

Another poster with the same question reminded me to follow up on this thread.

Scott at Shopbot suspects it is a communications problem as the space bar interrupts active communications between the computer and the machine. I added a dedicated USB 2.0 hub as has been suggested elsewhere on this forum and have not had a repeat since. I still visually check the bit height after a space bar or an "S" stop just to be sure.