Milling marks????????

[cnc_works]

Cut some corian today and experienced something I've experienced before, but I'm afraid this customer is expecting a smoother product.

PRT96, geckos, mach3, spindle at 15K rpm, 100ipm, 1/8" ball nose w/.009 stepover.
File is their solidworks file right into Mastercam. The raster is very nice, hardly feel it with thumbnail. Straight fillets aligned exactly parallel or at right angles with raster are smooth, but all other fillets have little gouges in the edges of the letter.

So, it's gotta be in the machine or Mach settings...any ideas?

The photo is of an approx. 1" patch. The little bit of foil is just to help my camera focus.

"IMG]http://www.cncworks.biz/images/omega.jpg[/IMG" (http://www.cncworks.biz/images/omega.jpg)

[supertigre]

A second pass at 90 degrees to the first pass will clean up a fair amount. Doubles the final pass time though.

[cnc_works]

Yeah, I thought of that, but I was at two hours on the first pass for a $100 job. Thanks for the input, though.

[Brady Watson]

Did you do a roughing pass before the 3D pass? Looks like you got some cutter deflection where the background meets the letters. Lines are common on Corian - ask anyone who has cut a lithopane.

It appears that this particular design would benefit from cutting with a 1/16" cutter. It looks like the 1/8" is too big to really separate the letters from the background.

-B

[cnc_works]

Did you do a roughing pass before the 3D pass?

**No Brady, no roughing pass, but the finish path was only 1/16" deep, so not too much stress.**

Looks like you got some cutter deflection where the background meets the letters. Lines are common on Corian - ask anyone who has cut a lithopane.

**Yeah, I've cut miles of corian including lithophanes and, while this shows up some, it is not problematic in lithos. I've noticed this in MDF as well, but it has just not been a problem for most customers...'til now.**

It appears that this particular design would benefit from cutting with a 1/16" cutter. It looks like the 1/8" is too big to really separate the letters from the background.

**I would agree, except that transition parallel or perpendicular looks great. Could you imagine this being some kind of ramping/acceleration problem? And again, cutting time is already maxed out at two hours.**

[gc3]

.004 or less for finish pass with slower speeds

i would look at your settings in mach. vectric forum has good info on corian carvings...look for posts from viktor

if this was in sb control software i would look at ramp rates plus 3d threshold settings

my 2 centavos

[cnc_works]

Thanks so much for all the input.

The progress I've made is primarily only as to what it is not. First of all, it is not machine specific. I ran the same tool path on my smaller, more precision CNC and got the same results. So at this point the only thing there is in common is Mach3...with one slightly possible exception. Both machines have spindles and I know the weight on the smaller CNC's z is probably close to the limit and on my Shopbot the springs just barely keep it neutral when the power goes off, but it would be pretty amazing for the cut pattern between the two machines to be so similar with so many variables unless it was generated by the same thing.

I checked the Solidworks file and could see nothing obvious, though I am far from a SW expert. I closely examined the toolpath lines generated by Mastercam and saw nothing to account for the gouges, fiddled with the gap settings and still no change. So I guess my next step is to post in the Mach forum again and see if anybody has any insight.

Man, it is always that last little bit of performance that is the hardest to track down, eh?