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Problem milling with Roland JWX 10

Hello, We have two RolandJWX 10 milling machines. One of them is
having a problem where when milling a model the spindle is stepping
down while cutting. Bit starts off cutting level for a few mm. Then
the spindle on the Z axis drops a little and mills at that Z axis
level for a few passes, then drops a little more. After a few more
passes Z drops more. After some more passes the bit starts cutting
into the base plate.We had the parameters set in Modela to not cut
below 5 mm above the base plate. From the side the model looks like
a stair steps into the base plate when it should be 5 mm above the
base plate, level and parallel to the base plate. Any one have any
thoughts on why this is occurring? Models are being created in

Thank You, Roger

Hi Roger,

I don’t know if the Rolands can run on straight G code or not?
(Which post are you using from Rhino?)

If you can do straight G-code, code yourself a big spiral move in X
& Y, all in the same Z level. Let it run (way above the table) and
see where it ends up. If the Z comes down, and you know you didn’t
call for a Z down, then it’s the actuators, or something involved
with the physical movement of the z axis.

If it stays put, it’s something in the post. That at least gives you
a place to start.

For whatever that’s worth.

I would first check the tightness of the cutting tool. If it isn’t
really being gripped properly by the collet it can be dragged to ever
lower positions on each - or after several - passes. If you haven’t
blown out the spindle and maintained the threads on the collet nut,
the nut can seem very tight but is not actually tightening down on
the tool shaft.

Easy to check by using a fine point Sharpy pen to mark the tool
shaft right where it disappears into the collet. After a few passes
on a test workpiece see if the mark has dropped down below the that

I believe that the Z axis on that machine is controlled by a belt.
If the above doesn’t help it might be time to replace the belt.

Les Brown

There are at least three possible causes for this unexpected
dropping in the Z axis. The first is a problem with the program.
Since you’ve got two of these machines, try running the same program
on the other machine. If it cuts normally, then that’s not the issue.
If it doesn’t, look carefully at the program parameters to see what
might be misdirecting the Z axis.

The second possibility is a mechanical problem. Look at the driving
mechanism for the Z axis and inspect it carefully. Slippage can be
caused by a loose pulley or screw in the driving mechanism, or an
insecure attachment to the motor.

The third possibility is an electronic failure. You probably won’t
be able to fix that without expert help, so give Roland tech support
a call, once you’ve eliminated program and mechanical issues as
possible causes.

Andrew Werby