Help on Speeds and Feeds 1/2 Ball nose

[Mike Caul]

Can anyone give me a starting point on speeds and feeds for 1/2" Ball nose, 4 flute end mill? I have a 1hp spindle on a Desktop. I have only used 1/4" end mills thus far, but have a project that needs a 1/2 inch ball. It's not a 2.5d, I just need a round bottom on a pocketing tool path. I'm going to do a first cut in pine and if all goes well I probably use maple for the finished project. Thanks

[dlcw]

Last time I used a 1/2" ballnose was on alder. I was running a 2.2HP spindle on a PRSAlpha 96x60. My spindle speed was around 14K. My feed rate was around 6IPS. I was taking a 1/8" on each pass. Prior to that, I also used it on some seat bottoms to create a contoured seats in hickory. My spindle speed was 14K and feed rate was around 4IPS. I was taking 3/32" on each pass. Haven't used the bit in about 6 years so my numbers might not work with you machine.

[Mike Caul]

Thanks Don, There are many differences in our machines. My machine tops out at 4ips, but thanks for your help.

[scottp55]

I pretty much only use 2F .5" ballnose with the Fluting toolpath(and sometimes 3D) for bowl shapes and troughs...and not production by any means.
Generally my lines for Fluting toolpath approximate a stepover of 6-8%
Very conservative pass depth of 1/2Diameter.
Generally run 15-17K, and depending on wood and results 1-2IPS, and .3-.5 IPS on Plunge(3D it's usually 1.5,1.5,17K)
Should get you in the ballpark, but Pine won't be a good comparison to Sugar Maple.

[Mike Caul]

Thanks Scott. I was hoping you might read my ad. If anyone knows anything about a Desktop with a spindle it's you. Thanks again, you've given me a good starting point.
Mike

[scottp55]

No problem Mike.
Best finish(almost no sand like shown) for a pocket seems to be one final finish pass(just adjust pass depth to leave the amount) is between .002-.005".
You could use the pocket allowance and a slightly shallower cut toolpath and much bigger stepover to hog it out....
And then a second full depth skim cut with no allowance and then actual depth, if doing quantities and didn't want to change bits....That worked for me on one item we made.

Only 4 flute I have is a .125", 1" CEL made for Carvewright by Drillman1 that I used when doing tight Nesting. It liked doing the cutouts at 1/2D pass depth at 2.4-2.6, .5, 9.5K
and REALLY preferred a conventional cut! And those setting worked fine for cutting out from Cherry to Cocobolo.
4F drove me half crazy trying to keep it cool until I kept dropping rpms, and she settled down.
Don't use that often now, but using that bit for .8-.95" material for 5+ yrs.

[Mike Caul]

Thanks Scott. I'll take your advice on the pocketing and watch the RPMs on the 4 flute.