Foreman elite with PWNCNC 220v spindle sudden plunge

I got my foreman elite finally setup and squared. Squaring was problematic and it was difficult to avoid ending up with a parallelogram.

BUT, the real issue occurred when I went to flatten the spoilboard I used a proven toolpath (one that a friend used) and as it was going along it suddenly starting ramping down in depth rapidly. By the time I stopped it (I was standing next to the controller) it had ramped down to 3/8 of inch!! I was only taking of .015 inch off.

I was using a 220v Pwncnc spindle plugged into a separate circuit from my 220v cyclone dust collector in another room so there should not have any interference there.

Either the Masso went wacky or I suspect there may have been some EMI that affected the spindle.

Suggestions of what went wrong?

First - be careful running other people’s code, it may not do what you think it should or have a different starting point than what you set.

It is possible you have a loose grub screw on the connection between the Z axis stepper and the ball screw.

I would suggest running the program again with the Z zero point set several inches above the waste board and the spindle turned off to see how it behaves. See if there is a commanded move lower in the Z height as it runs - this would be reflected on the Masso controller screen, you will see the Z value change. If the axis moves lower yet the Z value stays the same on the readout then you should look for a mechanical issue.

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I marked lines on top of the spoilboard to see where it was cutting. Ran the program successfully a first time without issues. The lines revealed a low spot that I had not discovered putting a straight edge on the spoilboard. So. I zeroed on the low spot measured it’s depth with calipers adjusted the depth of cut and reran. This is when is suddenly ramped down from .015 to about 3/8" in space of about an inch.

I will check the connections as you mentioned.

Did you hit the cycle start button more than once? Sounds like the same thing that happened on my Foreman the first time I tried to surface the spoilboard.


I didn’t think I did but I wouldn’t swear to it. What effect would pushing it twice have? If it does have an effect that does not seem right.

Well, the picture I posted was the result of my first attempt to do anything on my Foreman. I sort of assumed that hitting the equivalent of play would be the same as doing so on an original series machine. Didn’t realize that I had to wait quite a while after pressing the cycle start and anything actually happening. Pretty sure I pressed it many times, thinking my new machine didn’t work.

In my case, the result was that while spinning at 12k rpm, my machine plunged a 2" surfacing bit into the spoilboard at at least 100 in/min. It would have gone through, had it not overloaded and tripped a 2.2kW vfd and just split the lower half of the mdf…

Dan, always press rewind before hitting cycle start. Once you hit cycle start, wait 15 seconds as the masso is spinning up the spindle, then it will start the program.

Well, I’ve figured that part out by now.

This exact same thing just happened to me as well - I’m on a makita though. I have everything grounded, on a separate circuit, and even completed a dry run using the masso. I rewound the steps to the beginning and hit go. The router started up, it got into X/Y position, and then rapid plunged straight down into the piece and broke my bit. I made the toolpath myself and have been doing hobby cnc for going on 3 years.