CNC router misbehaving!! Dec 10 (Sat, tomorrow) Class may be cancelled!

Run away! Run away!

The CNC router Speed controller is not responding properly!

When I press F5, the spindle comes up to the set Speed.
When I start the GCode, the spindle speeds up to 24000RPM!
The only thing I can do is Stop the GCode to stop the Speed over run.

Any prior cures for this?
I’ve restarted the hardware & Mach3 both, to no avail.


I know they were messing with the profile to get more accurate speeds. Any chance you have the wrong profile?

It was the default “BigCNC” profile, but I will check again.
The only new one is “TestProfile”.


I would also try using the backup profile. You will need to find it in the Mach 3 folder, rename it something, then try to use it

Good call Coy!

It seems “they” decided to rename the TestProfile as “BigCNC” and BigCNC as “TestProfile”.

When I run “BigCNC” the Speed function runs away.

“TestProfile” seems to behave just fine.

The class is still on!

Thanks for the thought!


Tim mentioned this problem too… he did some sort of calibration on his profile and it went away… try using his profile?

I have a profile stashed on my CPU just for those exact situations :slight_smile:

Thanks all!


Heh just read this one. Sorry for the double reply. I don’t know if it would be worth looking into what I said? No idea if that’s useful anymore :stuck_out_tongue:

I saw your note. Thanks for the info.



Try using the profile “Test”. This was a copy of the original Large CNC file which I then manually calibrated the spindle, I am yet to have the spindle radically speed up on this profile.

I have seen the large CNC profile act up on multiple users as well as myself.