Maslow unit started to rotate as it travelled, then ruined cut

We have the 4.1 Kit at our Sign shop. We built the recommended wooden frame. I had just made a successful cut without issue before I tried making the cut that resulted in an error.
I create my vector in CorelDRAW, export as an SVG, then run it through MakerCAM to get g-code (.nc file.)
I see no issues in the wireframe of my Vector File, and when I load the .nc file into a preview program, the travel path looks correct.

We had to cut some thin polycarbonate for The Royal Canadian Legion to use as a stencil. It said ā€œLest We Forgetā€ at 69.6" x 10.345", well within the 4’ x 8’ bed size.
If you know MakerCAM, it sends your unit on a crazy travel path.
It successfully cut out the ā€œWā€ then went travelling to the ā€œLā€

However, as it was travelling, the unit started rotating as it travelled. My bit wasn’t dragging on the material and nothing was touching the belts. Due to this rotation, I think the belt loosened off of the gear and when that motor tried to turn the gear to keep following the path, there was slack so the unit didn’t move in the proper direction. This ended up ruining my material and project.

At first I thought that maybe some debris had gotten stuck in the gear so the teeth on the belt slipped. I gave it a good clean, grabbed another 4’ x 8’ sheet of material and tried again. It did the exact same thing. Rotate, belt slack, machine kept moving in the wrong direction, ruined my project.

Any ideas on how this happened and how to solve it? Has this happened to you?

We’ve used this machine a small number of times (Maybe 5 times) so it’s very disheartening when every time I have to use it, I’m nervous as hell because my success rate with it is probably 20%. There’s always problems with it.

Kevin Murtland wrote:

However, as it was travelling, the unit started rotating as it travelled. My bit wasn’t dragging on the material and nothing was touching the belts. Due to this rotation, I think the belt loosened off of the gear and when that motor tried to turn the gear to keep following the path, there was slack so the unit didn’t move in the proper direction. This ended up ruining my material and project.

At first I thought that maybe some debris had gotten stuck in the gear so the teeth on the belt slipped. I gave it a good clean, grabbed another 4’ x 8’ sheet of material and tried again. It did the exact same thing. Rotate, belt slack, machine kept moving in the wrong direction, ruined my project.

Any ideas on how this happened and how to solve it? Has this happened to you?

We’ve used this machine a small number of times (Maybe 5 times) so it’s very disheartening when every time I have to use it, I’m nervous as hell because my success rate with it is probably 20%. There’s always problems with it.

if you do an air cut (run the machine without the bit in it) do you have this
problem?

my guess is that when you did the find anchors, you did not have the router all
the way down, or when you restarted the machine it didn’t know where the router
is (Z axis), when you do a full retract/extend, you should also set Z stop (not
just Z home) to make sure the machine knows where it is.

David Lang

I’m not sure if I put the router down all the way to the stock surface before or after connecting to the anchor points. It definitely didn’t drag along the surface though.

Would the Z-axis really affect the X/Y movement that much if the bit is above the surface?

I’ll give the air-cut a try and redo the Z-stop calibration.

Kevin Murtland wrote:

I’m not sure if I put the router down all the way to the stock surface before or after connecting to the anchor points. It definitely didn’t drag along the surface though.

Would the Z-axis really affect the X/Y movement that much if the bit is above the surface?

Yes, the belts need to be longer when the router is higher, if you didn’t have
it down all the way when you did the ā€˜find anchors’ step, then it thinks it
needs to have more belt out than it should.

if it has the wrong idea of it’s height (the Zm number just above the log), then
it can be feeding out more belt than is needed.

David Lang

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