Second cut not precise...

Hello, I am doing some cutting tests and I wonder why this happened:

  • First I made a cut in a wood of 40mm x 6mm with a 3mm bit and 2mm depth.
[attachment file=121453]
  • Second I made a two perpendicular cuts of same sizes on the extremes of the first cut.
[attachment file=121454]
  • The result I was expecting would be:
[attachment file=121455]
  • I got this in the wood:
First cut should be 40mm x 6mm and comes in the wood as 37.09mm x 4.26

Second cut should be 40mm x 6mm each one and comes in the wood as 38.45 x 3.36

[attachment file=121456]

My steps were: I made the first cut then home X,Y & Z and start the second cut without move the wood position.

note the second cuts does not intercept the first cut, there is a wall of approximately 2mm

What I am doing wrong? Is there a problem with my MPCNC?

When I build my MPCNC I pay attention in the measures and the recommendation from Ryan about that and right now the measures are the same in both sides. like in this picture below from Ryan website.

[attachment file=121457]






  1. The pattern I would expect, since you’re cutting a square hole with a round bit, woild be to leave some material in between, but right in the middle, cut through exactly.

  2. The alignment between the two cuts looks ok.

  3. You’re not cutting well, and you’re leaving a lot of material. This could be some flex in the machine, spindle, going too fast, not enough rpm, or a dull bit. Can you load up some HD foam and try it again? That should remove all the load and split the problem space up.

1 Like

Cutting specs and speeds, router, and bit that you use? That looks pretty far off from normal.

1 Like

Hi Ryan, I am using this spec in Fusion to make the g-code, the router is MakitaRT0700CX4 I set speed to 3500rpm

[attachment file=121578]

[attachment file=121579]

[attachment file=121580]


[attachment file=121581]

[attachment file=121582]

Hi Jeffe3b, I will buy some foam and test, that is a good idea… Let you know.

You really should start with Estlcam. From a glance at your settings (too many to check them all) You are plunging too fast moving a bit too fast and you are (90%) slotting from some reason. I promise you will benefit greatly from starting with estlcam and we can actually hep with settings. Fusion has soo many setting no one can possible check your work without spending a ton of time in your actual project file.

1 Like

You have “stock to leave” checked and filled in at .5 mm, therefore, that cut operation will leave .5mm all around for a finishing pass, that’s probably why it’s not a complete cut.

The makita’s lowest speed is 10k RPM, do you mean 3.5 on the dial?

1 Like

Hi Aaron, yes 3.5 on the dial. I though was 3500rpm. is it too much?

The dial is unloaded speeds, once it hits the material, it will slow down a bit.

[attachment file=121719]