Fusion 360 + Mach3 Mill : Getting a deep trail on toolpath, damaging the model

[heitordahoracf]

Hi everybory,

I am getting some issues when I try to mill models on my Mach3 machine (3 axels).

On especific toolpaths generated by scallop strategy, the Z axel seems down more than the desired level leaving a deep trail on the surface.

On Fusion 360 simulation these deep trails doesn't appear, and the toolpaths seems on right way.

Anyone have seen these same problems and could help me, please ?

Find bellow some pictures:

[johnswetz1982]

My guess would be that you have backlash in your Z axis.

[engineguy]

@heitordahoracf 

Can you please upload your Fusion f3d file, go to:-

File > Export > Select f3d format > Save to your computer > Then attach to your reply.

Yes, there is something strange happening, the groove appear to be aligned with lines in the underside of your model as can be seen in the transparent image.

It may be a selection issue but it is best if you can upload a file.

[heitordahoracf]

@engineguy,

Find attached the file.

I though that was some underside lines influence too. But I tried to split the model and do it entire flat on underside, and the issue continued. The grooves wasn`t gone.

[daniel_lyall]

Looking at it where the lines are what may be happening is they are at the same places where the direction changes the cutter will be unloading then reloading as it goes from one direction to the other as it slows right down when it is going around the corner the toolpath needs to have more full contact with fewer direction changes, this is something mach3 has problems with.

I have made a few changes to the toolpath it looks better but not perfect example is attached.

[heitordahoracf]

@daniel_lyall, @engineguy and @johnswetz1982 

Thanks for trying to help me!

The issue wasn`t gone. I have tried to mill the new file, and the grooves just changed it places.

Do don't know why this is happening, but i have tried a lot of parameters and it continue.

Here is a picture of the new grooves that I got with the new file.

[DarthBane55 · Accepted solution]

It kind of looks like there's some deflection, and when the tool changes direction, the deflection changes and it digs in a bit.  Most likely not a Fusion issue but a rigidity one, or too fast for the tool, something like that.  When it changes direction sharply the tool slows down and gets to the correct Z level and it looks like a groove.  Try running the thing twice in a row, see if the grooves are gone after the 2nd time.

[heitordahoracf]

Thanks @DarthBane55,

You were right! The issue was been happening probabily from a material deflection. Decreasing Z steps, doing a thinner clearence with more down layers, before the finishing operation solve the issue with the deep grooves on the material.