Bottom "chipping" in pocketing HDU...

[paco]

I have this issue when I do pocketing (area clearing) in HDU that the last wall removed is actually chipped instead of being cut like the rest since it's only about 1/16-1/8" thick (horizontaly); I've tryed different approach (from inside to outside, outside to inside, climb vs conventional, raster way...) but none had proved effective... the problem is that when this happen, a small chip is removed/breaked from the bottom which kind of damage the smoothness of the finish. Here some pics that demonstrate this...

5137
5138
I'm pretty sure one of you had encounter this before...? What can be done to avoid this? Is there a cutter that had proved better for this issue?
Thanks in advance.

[joe]

Paco,

I also have had this to happen when clearing away deliclate area's. Must be that HDU has little tensil stregnth. This seems to happen most on 15lb foam. Everwood 15lb doesn't seem to have as much chipping.

Joe
www.normansignco.com (http://www.normansignco.com)

[paco]

Joe-
Had you find a strategie to avoid this issue?
I thought of a finishing bottom cleaning removing only 0.016 to 0.032" but this will prolong the process thus making the jobs higher price for the customer which I would like to avoid... in the example I first demonstrate, I only removed 0.125" thick!?!?!? I do machine it quite fast (5-6"/sec.) but that's what praticle in a such soft material... I did'nt see any difference using a spiral up tool bit...
Any thought "Botters"?

[joe]

P.

I would suggest slowing down the cut. How much overlap are you doing? I think your materials are at fault and not your machining.

Do you have an option to use another brand of HDU for a test? I know 18lb is much more expensive but you have to weigh this against cutting time.

J

[paco]

I may Joe... unless I decided to do this "finishing pass"...!?
I do the "pocketing" (area clearing) with three tool size (this is when I have quite large area to clear); 1/2, 1/4 then 1/8" and they take about 35-40% of their diameter each stepover... Most of the time, it's the customer's material...
Still, thanks for joining!