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i have 3/8 hss 2 flute ball end mill

i want to cut spruce and maple

any suggestions for rpm and feed rates?

i cant find anything from manufacturer

cnc mill? or cnc router? or?
with a ball endmill the actual cutting data is relative the the depth of the cut because of the effective diameter changes as you go deeper into your cut. from near zero at the tip to in your case to .375 at full radius depth.

for some basics start here:
http://www.onsrud.com/xdoc/ChipSoftwood
http://www.onsrud.com/xdoc/ChipHardwood

+.02 -hss tools don't last very long in hardwood (like maple) you might want to step up to carbide or at least a coated tool (TIN or PVD diamond)

stepover 0.0625

doc will vary because its a 3d surface

lets say .25" - .5"

from near zero at the tip to in your case to .375 at full radius depth

If someone is bored, think about what the cutting diameter is at exact center at the atomic level.
Or what is the surface speed at that same point?
Just trying to stir up trouble.

and if the diameter could go negative would be adding material?

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Jim Watts
http://jameswattsguitars.com

...only if it was in a worm hole, Jim....only in a worm hole...

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http://www.PeakeGuitars.com

so am i asking a pissy question or something? did i offend someone?

i am confused by the replies

Hey Jazzhands,

Not the question at all. The guys are already getting stir crazy and full winter hasn't even arrived. To answer your questions, it all depends.

You have to give us a little more specifics.

1. What kind of machine? Mill or router?
2. What kind of spindle?
3. Does the spindle have run out?
4. What kind of spindle speed?

Those are some of the factors that determine cutting feedrate.

Give some specifics and let's start over.

Mike

Naw, they're just cheeky.

Feed at 10000RPM should be about 170IPM. If you're cutting too deep then it might get angry due to low chip clearance.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Sorry about that if you thought I helped to drag your question off into the ditch. Didn't mean to.

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Jim Watts
http://jameswattsguitars.com

Mick, I'm sorry. You have a legitimate question.
This old man just lets his mind wonder sometimes.
Nelson

wish I had your problems. I'm still drying to cut with a sledgehammer and chisel.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

Feeds and speeds depend on many variables -it's one reason I don't like to just spit out numbers to someone without better info on the job at hand. Someone could get hurt or wreck something -not very sporting is it? For example, I could give you reloading data for a .44 mag that worked for me but would probably blow your gun apart. Consult the links I posted for you and start out easy then work it up to a point that's good for you.

You basically start slow - 30 ipm is a good speed to be able to stop the process if something is starting to go awry - and then speed up as your confidence builds. If you see smoke & embers, then you'll either have to slow down the spindle speed or speed up the feed rate. If you get a lot of tear out & chip out, you'll have to either speed up the spindle speed or slow down the feed rate.

Unless you are mass producing parts, I wouldn't worry so much about maximizing individual operations. I'd worry more about setting up a good process (including jigs), getting a nice toolpath & getting clean cuts.

Have fun & post some results when you get them!

Best,
Trev

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http://www.PeakeGuitars.com