Flat area clearance tool and residual groove

[H20Diver]

When carving a graphic with large surface areas that need carved out I use the "Flat area clearance tool" and limit the tools depth by clicking the "flat depth" box and assigning a variable.

While the works great I am getting residual surface area which is not being cleared. This material being left when using the flat bottom clearing option hugs the vector line.

While the pictures I have included show this material along the edge of the area being cleared it looks more pronounced in person. (I guess a 2d image can only show so much)

How can I remove all the material when flat bottoming?

Thanks,

Chris

[CRFultz]

Chris do you get the same results with every job?

The clearance tool appears to have gone deeper then it should.
Is the angle and diameter correct for your cutters?
Maybe the Z zero for the clearance tool was off a bit?

[Jerry In Maine]

looks like the same trouble I had when I had my bit angle set a few degrees off (bit was supposed to be 60, was actually 55).

[H20Diver]

Thanks for the reply,

Actually the clearance tool is not going deep enough... what is happening is there is a thin layer being left in the bottom of clearing space. I have the clearing tool cutting first with the v-bit following. The clearing tool does a good job, it is only after the v-bit follows through that the bottom is skewed or that the bottom is not clean so I think it has something to do with the v-bit. Both tools are set up for the proper depth. I have tried both 60 and 90 degree v-bit but there is no difference.

I guess I could play around with varying the angle of the bit. I do not have a flat bottom endmill so I am using a ball nose to flat clearance... could this be it? I will have to get a 1/8" endmill to try this.

Thanks for your help and feedback

[Burchtree]

Yes that sure could be it
Dan

[coop]

i also have had similar issues and found it was relative to my exact z surface position.. so when i need precision cut i have often used the
v bit to clear out the areas
the additional time was not as long as you would think !
for the larger pieces i used a 1.5" v bit because the tip had an inherently larger tip that cleared more material quickly...
and if you eliminate the tool change time and zeroing the surface again
the cutting time was not that different.
you can also calculate both toolpaths with the flat clearance tool and without and simply check either cutting time !
but by using the v carve tool yiu will definatly eliminate any difference in the flat bottom and the bottom of the v tool !

[TReischl]

Zeroing cutters can be a pain. I learned the hard way that materials are not as consistent as we all would have them.

Nowadays, I pick a spot on the material to zero the tools, and they all get zeroed in roughly the same place, that takes care of the material inconsistencies.

I also use a 1/2 inch aluminum bar as my feeler gage. When zeroing, I always approach the bar from the same direction, coming down. This takes care of backlash in the Z.

Having worked early in my career in a machine shop, I should have known this to begin with. . . sheesh.

[H20Diver]

Thanks TReischl,

I also use a 1" aluminum block as a feeler gauge which helps greatly in zeroing the Z.

Coop,

I will try the flat bottom with the vbit and check the machine time. Your right, by using the V-bit that should negate any variance between tool changes when clearing the flat bottom.