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Interesting but, I don't see the point in making all that sawdust with that facing tool. Why not just profile the shape to begin with? Seems you could save a ton of time and a ton of bit life.

You could even make your vacuum fixture to hold the scrap so you don't have to worry about it.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Which bit's the interesting part? I'm not heckling, I've just seen so many different ways to machine a body now that I'm not sure what's 'normal' out there now.

I think the facemill was used because there's no shear on the cutter, since that tab under the neck is levered out and might chip out with a spiral cutter. You do get a nicer finish on contours with a larger radius cutter.

The finishing pass is a bottom to top scallop toolpath. It uses constant stepover on the surface rather than an axis, so the scallops are (theoretically) even over the whole surface. It's one of my favourites, but any little jitters in motion show up in the finish so it can cause some heartache if the path isn't proven.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I think he did.

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"Act your age, not your shoe size" - Prince

I re-watched and you're right.

I don't get what Bob means by "there's no shear in the cutter with a facemill". In which direction? Can you elaborate?

p.s., the most interesting question in my opinion is "where are the chips going?"

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

What I found interesting was the use of the face mill which I assume is to clear a large space so that there's no chance of recutting chips on the finish pass. The other thing that I found interesting was the vacuum fixture worked for both the top and back and I assume left and right-handed models. That's a pretty efficient use of fixtures compared to how we do it.

As a tool and die maker, I was trained to never assume a surface was level - and to make a skim pass to make sure it was clean.

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"Act your age, not your shoe size" - Prince

That makes sense if your face mill leaves a better finish than a thickness sander. I'm not sure mine does.

What i thought was interesting was using a face mill to rough profile.

I had thought of using the Safety Planer this way and asked about it in another forum and everyone discouraged it. They said it wasn't designed to spin at the speeds that a router runs at. I wonder what speed he is running it at.

That advice was right. The body of a Safety Planer is cast aluminum, the body of a face mill is made out of pretty tough steel.

So that's not a safety planer in the video? What's a face planer?

It's a face mill....

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"Act your age, not your shoe size" - Prince

A face mill, in most cases, doesn't have any vertical shear so it won't tear out the top or bottom surface of a cut. It's not 'up cut' or 'down cut'.

I think the hand blowing the chips off with an air gun moves to quickly for us to see; the chips that fly into the background stay there for the whole video. I used to have my machine set up to blow off chips with an air blast (M code) every so often so we wouldn't need to clean off the vacuum fixtures between pieces.

Agreed with Chris on the level thing. I always face mill or joint any surface before it goes on a fixture for final machining. Wood rarely agrees to stay flat for long.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services