Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: mdr01amr03 on October 20, 2025, 12:19:12 PM
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Let's say I am starting a wood craving on my AVID Pro 4'x4' with Mach 4 and for the first minute or two I would like to watch the bit and how it's doing on the wood so I can make sure things are ok. Then, once I make sure everything is good and I'm liking what is going on so I want to put my dust collector boot on so I don't have to stand there with a shop vac or get shavings all over the place. I need to hold the feed, then stop the spindle and move it up in the Z direction to make room for the boot brush and then resume the cycle.
When I hit hold feed, then stop the spindle, all my jogging options are greyed out so I can't move it to get the dust boot on. Moreover, if someone that reads this is able to provide the magic pill for me, obviously after I do this and turn the spindle back on, I'll want to resume the cycle so the spindle goes back to the place it left off and continue the carving. Is this possible?
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Hi,
it is not as simple as you might imagine to do as you want. The reasoning goes something like this:
Mach4 can have ONLY one motion master active at any given time. When you start a Gcode job then the Gcode Interpreter is the motion master, and that motion master
is the ONLY source of motion commands. If, while the job is active, you spin the MPG, nothing happens, because the MPG is associated with the screen chunk, and is NOT the
motion master and therefore can have no effect on the motion of the machine. If you <Feedhold>, even if you stop the spindle, the Gcode job is STILL the motion master, its just
paused. The MPG is still unable to effect motion of the machine.
The only way the MPG can effect machine motion is for the Gcode job to be discontinued, whereon the Gcode interpreter will release its status as motion master, and thus the MPG (screen chunk)
can assume motion master status.
Officially the only way you can do as you want, is not just to <Feedhold> but <Stop> the Gcode job, whereon you can jog around to your hearts content and then RESUME the GCode job
by using the <Run From Here> functionality. I personally hate RunFromHere, and usually restart the job from the start.......but if you get 100% familiar with the RunFromHere procedure
its OK. You may even be able to automate it or at least parts of it........but first you must be 110% on the RunFromHere procedure or you will crash, not once or twice but repeatedly until
you are 110%....ask me how I know!
Craig