Not sure what to call this...

[dehrlich]

Ok this is a strange problem, and it happens almost every time. I'm running some blocks that use a 1/2" straight bit to cut some slots. When running through the bits for the project at the beginning, where it gets the length for all the bits is when the problem occurs. I load the bit and of course the first thing the machine does is spin the bit briefly while homing. Problem is the head lowers down towards the squaring plate with the bit still spinning slowly, and it ends up running the bit into something and clunk! I just know one day I'm going to find a big chip out of the carbide cutters. Any way to prevent this? Ideas? BTW I'm using a 1/2" rock chuck if that matters.

[fwharris]

Seems to be a common problem with the rock chuck users. I believe some are pressing the stop button as the truck is moving over to the touch point. After the bit stops spinning they hit the continue to proceed.

[lawrence]

That's what I do... I had the same problem so now I just pause the spin on every carve (and move my bit plate out by hand... I think it may be time to service my machine :) )

Lawrence

[spalted]

Interesting, I'm running the rock and never had this happen.

Has it been only larger diameter bits that have been a problem? I don't recall ever using a bit over 3/16" in mine.

Just wondering if the extra rotating mass has more momentum, and that keeps the bit spinning just a little longer?

[henry1]

The rock,, the bit can't be more than 1 in long out from the sleeve if longer problem happen and could be also the cut motor brush are due

[dehrlich]

Yes I thought of this last night, pausing the machine. And I agree with the mass of the bit may be the problem, never happens with anything else. The other problem is the Z axis stall, seems to be random but it happens with the length of the bit. Just one of those things I imagine. Even with the quirks, it's a damn site better than the old quick chuck!

[CarverJerry]

Check your cut motor hours, sounds like its time to change the brushes, this same thing happened to me and it drilled a hole in the plate on the keypad side when it bobbed down. After changing the brushes it hasn't done it again. The common number of hours is around 250. But I do like others are doing, I just open the clear door after it spins up and starts to move towards the keypad then hit the continue button once the spindle has stopped, then it just continues doing it's job.

[Smoken D]

Spinning bit heading towards the board tracking sensor and the photo's show what will happen. Once you drill through the tracking sensor you will not be able to do thickness measurements and get that error. I also have the rock but do not know if that is the problem. On my machine even with only a few hours on new motor brushes, it will do this. As others have stated, I just pause the machine when the rock moves over towards the pad side. Works for me.:D

[bergerud]

I have posted a few times with my theory as to the cause of this. I believe it is that the C1 capacitor on the X termination board has been zapped by the back emf caused when the cover is opened to stop the cut motor. It is the purpose of this capacitor to "handle" this back emf so that the triac turns of and stops the motor. After the capacitor has been burned through, the motor takes longer to stop. The motor actually gets power longer.

I am waiting for someone with this problem to switch out the X termination board (or the C1 capacitor) to test the theory.

[Ton80]

Had this problem for a while myself. Now I just stop the machine like others. If you ever have a bit cut the plastic tab where the bit touches down just use a little adhesive caulk and place a dime there. I read that somewhere on this forum and have done this myself.

Seems like an easy fix regardless of what the ultimate cause is. Of the sensor reads bit rotation don't move the z truck. Right? Hmm wonder if it will ever happen.


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