Problem cutting MDF

Hi. Trying to cut MDF 15mm with the LR3. It starts ok, but on the first down in the z axis, smokes are produced and the machine has difficulties to move and one y axis is blocked and does not move (video attached).

Any ideas why this is happening?


3mm single flute
0.75mm doc (tried also 1mm)
3mm\s (tried 5mm) Plunge feedrate
8mm\s (xy feedrate)
12k rpm (tried also with 20000)

What bit are you using? It looks like it isn’t cutting well.

You can also adjust the plunge angle. It can move at a 45 degree angle while plunging so the Z doesn’t have to clear the chips while plunging.

The video also looks like it is diving more than 0.75mm?

Check your bit turns in the right direction, with that kind of spindle wrong connection can make it spin counter-clockwise so it would be very hard to cut with lot of burn and smoke.

Very hard to be sure but playing your video at 0.25x speed, i would say your bit does seem to turn counter-clockwise…
I would check for an electrical connection inversion on your spindle.


Bit looks cooked in the video (looking at the direction the smoke is going seems like it’s going CCW). Also you have the bit sticking out so far it looks like it’s barely even in the collet. That depth setting ring should be butted up against the collet.

1 Like