Speed for 1/8 ballnose

[mhoffman8727 (Michael Hoffman)]

Hey everyone hope you’re having a good weekend. Couple questions:

Want to cut a 3d project with a 1/8" ballnose. Cutting into poplar.

I’m using a .25EM to do my 3d roughing pass. Usually when roughing with this I leave an allowance of .02" for 3d roughing… software has it auto set to .04" but I figure why not get the relief closer and push the ballnose to cut faster?

Any idea on feed/speed with a 10% stepover and this .02 I can cut with the 1/8" BN? Something i see that concerns me is when I cut with any BN after roughing, the initial passes the entire diameter of the tool plunges into the wood until a path is created, and then the tool begins its 10% step over. This also happens sometimes as the tool moves through different parts of the project.

Maybe not a concern but I definitely turn my .25BN up to like 170ipm after my 3d roughing. Seems to cut fine but erks me on those initial passes, I have to manually decrease speeds in carbide motion.
Thanks

[WillAdams (William Adams (Carbide 3D))]

The community has some notes on feeds and speeds at: https://wiki.shapeoko.com/index.php/Materials#Wood

Use a technique such as:
https://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm
to test them and work up something suited to your machine and material.

[The_real_janderson (Jonathan Anderson)]

I was just doing a knurled patterns last night with my 1/8" ball endmill in poplar! I was doing a 0.1" stepover at 0.5mm depth and running a CPT=0.001" at 21000 RPM with no problem. Since you are doing such a smaller stepover and smaller depth, I wouldn’t hesitate doing a CPT=0.002-0.003" and perhaps even faster.