Official Luthiers Forum!

Hi everyone.

Any pros or cons when using a ball mill or corner radius mill for FB side down neck shaft and heel carving? Any preferences?

I can accommodate a 5/8" mill shaft, so I'm not too concerned about length.

I seem to remember some discussion regarding zero speed at the center of a ball mill being an issue for arched plate carving more compression/burnishing than cutting - is this an issue on mahogany?

Thanks!

Anthony

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Anthony J. Lembo
Lembo Custom Guitars - www.Lemboguitars.com

A bullnose can't cut a concave surface without leaving a flat on the bottom, but that's the only reason you strictly couldn't use one for certain surfaces. A bullnose of a certain diameter is going to have a sharper corner radius than a ball of the same diameter, which is a strike against, and that means more passes to get the same smoothness.

While there is a burnishing in the center of a cut with a ball, there's very little material thickness being compressed as the cutting edges ahead of the center already take most of the material off before the center reaches a given point.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Ball mill are the tool of choice pretty much everywhere I have seen CNC neck carving.

As usual, I'm with Bob on this..!

Trev

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http://www.PeakeGuitars.com

That makes sense. Thanks for your help Bob and Trev!

Constantly second guessing,
Anthony

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Anthony J. Lembo
Lembo Custom Guitars - www.Lemboguitars.com

I hate to sound ignorant, but what is the difference between bull nose and ball?

Thanks,

rlrhett,

Look at these:

http://www.mcmaster.com/#end-mills/=4ko7um
would be an example of a "ball" endmill.


http://www.mcmaster.com/#end-mills/=4ko8gq
would be an example of "bull" nosed endmill.

while these are geared mostly towards metal cutting the concept is the same.

ok, well those links don't seem to work well.

So a ball endmill or cutter has a ball on its end that when it's cutting will produce a half round channel equal to its diameter. ie: 1/2 diameter -1/2 round channel, and a bull nosed cutter or endmill has a specific radius to it's end that is less then full round. When cutting it will produce a square channel with filleted corners. The advantage is that the ball cutter will profile a complex surface with 180 degrees of tangency to that surface.

here's some pics:
http://images.google.com/imgres?imgurl= ... n%26sa%3DX

and...

http://www.made-in-china.com/image/2f0j ... M-010-.jpg

hope all this helped