Problem I have never encountered before

How To Machining
1

I am working on a job (rush of course) and the machine is giving me issues I have never experienced before.

I have a ProXXL with a 65mm spindle/ VFD from PWNCNC. In my project I am cutting some letters out of 3/4” MDF. The customer wants a crest in the middle of the letter so I am using the prism toolpath from Vectric with a 150 degree v bit from IDC.

I knew that there would be a slight “ledge” around the outer portion that the edge of the v bit would have to cut. The first letter was going ok but then when it got to the outer portion and started on that it didn’t make it far before bogging down and stopping.

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So I reset everything and created a pocket toolpath offset from the actual letters for a 1/4 clearing bit so that the edge of the V would not engage it.

Started that path and it got part way through one letter and choked again. I reset everything, recycled the power and tried again. Same thing. And the really bad thing is that CM decides it isn’t connected to the cutter anymore but the spindle is still going.

I reset everything again and slowed the toolpath and dropped the DOC to .8 and started. It finally finished that letter and then same thing on the next.

Each time I have to hit the manual stop on the VFD controller. Even then the display on the controller which usually reads 0.0 when there is nothing going on was showing something around 400 indicating that it was getting some input voltage but. It enough to start spinning.

As I was typing this I had CM in the state that it stopped showing not connected to the cutter. I had manually hit the VFD stop. The control panel was showing 75 this time but then started increasing and got to the point that the spindle started.
I hit the stop button and after a few seconds it started to increase the numbers and then stayed spinning again. It did it multiple times until I turned of the CNC and then the panel went to the 0.0 normal state. That makes me nervous about errant signals making the spindle start when not expected. I know there were some comments in a recent thread where folks thought the chance of that was non existent. Well, I just turned the ProXXL back on without doing anything to CM and the VFD control panel immediately started increasing up to 70. And is now bouncing all over the place. Something in the machine controller is passing a signal through to the VFD.

This is MDF, not plastic, it isn’t dry here, I have never had static disconnects before. Did I fry/damage something with that VBit when it bogged down?

The cuts with the V were beautiful until it stopped. The cuts with the 201 are ugly on the edges but that is not really part of the finished project so I didn’t care. This is an ancient piece of MDF I had in the shop for many years.

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image3024×4032 3.05 MB

Here is the V, you can see the vertical edge which I had hoped would handle the lip but not.

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IMG_85954032×3024 1.3 MB

I don’t know what to try at this point.

Here is a video showing the behavior of the voltage to the VFD bouncing around.

And I am days away from selling this and getting a 5.1Pro. Now I may have to replace something on this first.

2

USB connections get jostled ?

3

And another video showing that CM won’t connect to the machine now. That could be because the bit is buried in a piece of MDF and it’s failing to raise for some reason.

4

I sort of checked them all but will go through it again. I even disconnected the jog dial in case there was some issue with a signal from that

5

Checked all the connections outside and inside the control box. Powered up and the same thing. No lights in the box except for a little blue/white one at the back.

6

I can disconnect the line into the VFD controller and check for voltage at the connector but I am not sure which pins to check and don’t want to make it worse. I will reach out to PWNCNC on that.

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IMG_86053024×4032 1.17 MB

7

Power down, unplug from the wall, wait 30 minutes or so.

Reboot the computer, check for updates, &c.

While waiting, with the power off and the machine disconnected, slowly and gently move it to the top of motion (turning the leadscrew/ballscrew), then the other axes to the center of motion, then move the Z-axis all the way to the bottom, then back up to the middle — verify nothing is mechanically interfering or binding.

If things don’t connect then, you may need a new controller, but check in w/ support first.

8

I’m out for a few hours, will check when I get back.
No updates on the computer, it’s a Pi.

I didnt know that there was a way to raise the Z manually. I figured I would have to pull the spindle out so that I could get the bit out of the board.

9

After some additional experimenting the folks at support and I came to the conclusion that the control board was bad. I ordered a new one. It arrived Friday and I installed and tested it. All is well now.

Out of curiosity, what happens on the board when the bit bogs down and stops. I mean is extra voltage being sent to the board or something?

Actually, I am not sure if the bit actually stopped or the gantry quit moving. I was in too much of a hurry to shut it down to do a proper analysis of the situation.

10

I would think the control board would deliver more amperage to the motor to maintain the RPM it’s set to. This may stress the control board components and lead to an early end.

11

I didn’t think that the board had any idea what the spindle and steppers were actually doing, only what it asked them to do.

12

Well then that makes two of us.