How to reduce machining time?

[brodie]

I am trying to make a shallow wooden bowl cut.  It is 6" in diameter and goes from 0 at the perimeter to 3/4" deep at the center.  Tool time is over 15 hours with the bulk of the time being a 3d finish tool path.
Any way to reduce this time?  If not, is it ok to let the machine (and bit) run for that long?

[gerry]

You can certainly run the machine that long.

You can probably reduce your milling time. Is this a 2D or 3D cut? Either way you can do all your roughing with a large bit. I'd either use a 1/2-inch ballnose or a 1/2-inch downcut with a 20% stepover to hog out most of the material. Then do the finish pass with a large or small bit. Make the choice based on how intricate the bowl interior is. If it's a smooth bowl, the a 1/2-inch ball nose with a 6-8% stepover would be fine. This stepover is based on how much sanding you want to do to finish the surface. Personally, I'd use a very small stepover and let the machine do the finish work. 


If you're not sure, post the project here. If it's too big, post it somewhere like free Google Drive, then post the link. Don't forget to make it shareable.

[brodie]

I guess its a 3d cut. I'm using the 3d finishing tool path. I changed the tool from 1/16" tapper ball to 1/4" ball nose spiral and the machine time went significantly down (now about 2.5 hours).
Might have to find a 1/2" ballnose bit to see how much more time it will cut out.
Thanks!

[kokopelli2020]

Another place to look is at the tool database. If you’re using the program’s suggested database, it is a starting point. Knowing your machine parameters and capabilities along with hardness of wood or materials, you might adjust the speed rates and plunges rates a little at a time. Yes a 1/16th bit will take 4x longer or more than a 1/4 inch but you sacrifice detail in doing so. Experiment with simple projects to dial in your machine and take ample notes.

[dustypilot]

Let's talk bit selection. 1/16" would be useful for a very detailed carving. But you are making a smooth sided bowel. As previously mentioned, you could use a 3/8 or 1/2 EM to rough it and then a 1/4" BN with a 20% stepover. Yes, there will be a little sanding but you will cut your carve time by 3/4. I ran a quick test using a 6" depression set to 3/4" in Aspire. A 1/2" roughing bit comes out in 3:51 and the 1/4" BN with a 10% stepover finishes the project in 11 min 28 sec. Big diff

[pedro]

I cut a bowl recess (the inner part) on a 12 inches circle, 1/2 deep in center, in about 3 minutes. I use a 1/2 inch round nose bit with about 50% overlap. The little ripples that I get, I sand them out with a 120 grit orbital sander in about 5 minutes.