Eagle with oval cuts

[Stephen50]

Following is the process I used to create the create the eagle hopefully, next time I won't have the three ovals.

1. Utilizing Aspire 8
2. Downloaded the eagle from Vector Art 3D
3. Rough cut is a new .25 upcut end mill bit
4. Finish cut is a new .125 balloons bit
5. Preview does not show the oval cut
6. Waste Board resurfaced
7. Material is 1" Maple
8. Planed both sides to include sanding
9. Holddown clamps on all corners
10. Three ovals coincide where the rough cut made step downs

Any suggestion on eliminating the oval cuts

[myxpykalix]

"Finish cut is a new .125 balloons bit"
I've never heard of a balloons bit. Is that an endmill or a ballnose bit? You need to use a ballnose bit on the finish pass. Try using a ballnose on the roughing pass also

Are you sure there are no vectors hidden you just don't see?

[srwtlc]

What did you leave for a roughing toolpath machining allowance? An allowance of 0.04 - 0.05 and 3D raster (not Z level) across grain would be good. This allows just enough for the ballnose finish toolpath to clean up.

[Stephen50]

Thanks for your advice changed the parameters and the cribbage board turned out the way I imagined. Thanks again

[scottp55]

Off topic;
Scott W...what did you leave for an allowance on the 1911 grips you made out of the Quilted?
I got some tearout on my shelf that took considerable sanding after using a .5"BN and wondered afterwards if I should have done a roughing pass first, and then a skim pass.
That stuff is softer and has grain going everywhere.
Thanks,
scott

[srwtlc]

Hey Scott,

On the quilted, I did 0.04 allowance, across grain, Z level roughing with a 0.25" downcut endmill and then a 0.125" ballnose with the grain for the finish pass. I didn't necessarily get tear out, but it wasn't the best of finish and did take some sanding to clean up. The quilted is softer and does have a tendancy to tear out a bit, just like any highly figured wood (took on a lot of Tru-Oil too). On some of the others, I did 0.02 for a roughing allowance and did a 3D raster because I used a 0.04" tapered ballnose for the finish pass and it has a much shorter depth of cut. I actually snapped the tip off the 0.04" ballnose in a set that was made from some Brazilian cherry/Jatoba in a spot that had a bit extra material that was too deep for the bit. That's one thing to keep an eye on when using Z level roughing and also if the roughing pass doesn't drop fully over the outside edge and the finish one will. In other words, pay attention to the boundary offset too.

I've got a project under way that when finished and I have time, I want to give one of those 30º bits a try to pull out more detail.

Love the moose!! Kind of a collector of moose stuff. ;-)

[scottp55]

Thank you Very much Scott!
When you do try a 30 engraving, try entering as a VBit vs. calling it out as an engraving with a flat. and preview both.
The program thinks the pointed tip can get in there, but because of the flat it actually exaggerates the detail.
Try entering as both and compare, just remember the VBit preview will look like hash until it's actually cut with the flat.
Good when working smaller stuff.
scott