[MichaelOsceola]

Not sure if this is a Mastercam issue, CNC issue or what, but I'm at a dead end figuring it out.

Most of my sheets are a very dense polystyrene with thin MDF glued to both sides, total thickness just under 1.125". Sheets cut fine all the time, the router bit does not go into the spoilboard at all.

I am also, less frequently, cutting similair sheets where one side has a solid surface material instead of MDF, total thickness @ 1.25". On these sheets, the bit almost always wants to cut way too deep, and goes into the spoilboard nearly an 1/8".

I've compared the G code of the files and don't see anything that would cause this. I've quadruple checked my thicknesses in the Mastercam drawings and with micrometers on the actual sheets, and they match. The router bit is tight and not moving.

After cutting a sheet that goes too deep, I can immediately go to the other material without the solid surface, and again it cuts fine, does not go into the spoilboard.

Any suggestions on what to try to fix this?

[Jim Dawson]

It sounds like your Z axis is being pulled down by the cutting forces. Without more information about your machine, we can only guess at the cause. Maybe a downcut cutter would help, but I'm not sure how well that would work in foam. Maybe slow the feed rate and see what happens.

[MichaelOsceola]

Jim, thanks for the response.

The CNC is a Thermwood M43-510. We generally use standard compression bits to route. We have tried different feed rates. Nothing seems to help.

Also, when we originally started routing the material that is the problem, this wasn't happening. It has mostly been over the last month that this issue has cropped up and seems to have gotten worse the more we run them.

I am considering going back through a couple of the files, deleting all of the toolpaths, and starting over to see if it does any good. I figure it can't hurt at this point.

[Jim Dawson]

That is a substantial machine. (I have an older one, not sure of the model, no identifying marks on the machine at all) I'm going to guess that this is a mechanical problem. Is there a brake on the Z axis motor? If so, some of them are adjustable to compensate for wear. Is your machine equipped with servos or steppers?

[cadcam]

That is a substantial machine. (I have an older one, not sure of the model, no identifying marks on the machine at all) I'm going to guess that this is a mechanical problem. Is there a brake on the Z axis motor? If so, some of them are adjustable to compensate for wear. Is your machine equipped with servos or steppers?

I,can safely say if was working and not now it is not mastercam but the machine. Contact thermwood. They can also look your mastercam file. As they are a Mastercam reseller to.
I would try talking to Bret over there.

[Claude Boudreau]

Does your Z=0 on top of material changed after that job?