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I'm not impressed with a very expensive ball mill for contouring. I haven't carved a neck with it yet, just body contours with are shallow and only use the end of the bit where the creed of cut is the lowest.

Any recommendatns for a copy mill tool with round inserts? Dapra? OSG? I got a quote from Mitsubishi and the tool body was $700. I need something priced a little more luthier friendly especially since this is an unproven concept - at least on my mill.

I have a friend who uses two on his neck carving machine but they are spinning at router speeds and cutting hard maple. I'm finding softer woods and mill speeds to be a completely different experience.

Do you have a 10K spindle? The ballnose cutters for aluminum from Ridiculous Carbide and Iscar are both quite good on wood at 10K. That said, I've been tempted at various times to invest in a button insert cutter, too. Inserts are usually interchangeable between manufacturers, they're based on a form factor, and in my limited looking Walter AG made the sharpest ones.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

http://www.toolstoday.com/p-5954-cnc-ball-end-insert-router-bit.aspx
Sheldon,
Is this something that might work for you?

Got a quote back from Dapra and OSG. Dapra's tool body is $500+, OSG's is $360. My dealer said there wasn't a promotion for the tool I was looking at but when googling for a photo for this thread I came across this promotion that includes the PRC tool that I was looking at.

http://www.osgcanada.com/_branding/book ... ROMO2.html

Catalog page is 162

http://www.osgcanada.com/_branding/book ... 191ca.html

The cost of 30 inserts is about equal to the tool body alone. Now we're talking.

Nelson, I haven't tried a neutral rake tool like that. It wouldn't solve the surface speed issue though which is what I think needs to be addressed.

This isn't exactly what you're looking for but the price certainly is good: http://www.toolstoday.com/p-6016-in-tec ... s=10602,0&

I haven't bought one yet but it's on my list to try.

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

Ordered the OSG this morning. I'll know in a week if it was a good idea or not.

Thanks Andy. That one would be good for deeper cuts but for shallow, finishing cuts where most of the work is being done close to the center of the bit the surface speed will still be as slow as a ball mill.

Can't wait to hear about it...that promo goes on a lot longer than a week from now and my tooling guy carries OSG.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

The cutters, tool and holder came in today. First impression was the cutters were nice and sharp and polished to a mirror finish. Ran some test cuts and OMFG!

The difference in the photo is not that noticeable but in real life it's night and day. Both cutters were run at 9000 RPM. The Robb Jack 1" ball was fed at 39ipm climb cut only and the OSG was fed at 140ipm with mixed cut. Even with slow feed and climb cuts the ball still tore the early grain (top photo) while the copy mill was clean and crisp. The only downside is that the copy mill needs to take more passes to get the same scallop depth, but it runs so much faster it's no big deal. Also you have to mill clearance for it to avoid any undercuts. Not a big deal for my purposes.

Edge speed is huge, it's the main reason to use larger cutters IMO. My insert cutter, at effective diameter 3.5", leaves a beautiful finish I wish I could get with anything else!

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Changed the toolpath to parallel finishing to make the most of the diameter of the cutter. The results are even better.

Hey Sheldon....I'm a little fuzzy still.

You said the catalog page is 162 but the page numbers at the bottom of the page pictured are different from the index at the top of the web page.

I'm assuming you bought some configuration of List 78005??

So...what exactly did you pay?

Due to my limited spindle speed and the amount of surfacing I do I've always considered a setup like this but the price has always been prohibitive.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

In Canadian dollars the 30 inserts ran $376. With this promotion you get the tool for free. $368 is the regular price for the tool alone. I went with the 7800503 three insert tool and the 12 mm dia 7811013 inserts. If I was to do it again I might go with the 16 mm inserts. They are not much more $.

OSG's catalog doesn't do these inserts justice. I've included a photo of the tool so that you can see how nicely curved the leading edge of the inserts is.

Did my first test carve on a neck yesterday. You could almost go straight to finish it's that clean.

Setup, Pictures? C'mon you know the deal

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www.morganguitarworks.com
www.morgancustomguitars.com

Neck photos will have to wait until I get more bodies out of the way. Here's a shot of a body contour that's finally locked down and ready to rock. Northern Ash.

OK, I got test neck number two carved. Here's a closeup of the finish and the setup. The two outrigger vacuum tables draw their vacuum from the master table and are hooked up in this photo but wouldn't be normally for this fixture.

I'm really liking the master vacuum table. Indicate the corner in the morning, swap fixtures all day long and only have to adjust for Z.

Pretty sweet! Couple questions:

How do you deal with the shape of the cutter in your CAM software? Is it just used as a form tool with standard 3D machining strategies?

What's the material you're using for your vac fixture? I'm still not satisfied with anything that I've found but I've only tried a couple different materials.

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

The tool is a Corner radius end mill. I orient the tool path to use the flattest, largest radius possible. In all cases so far parallel passes as close to perpendicular to the profile edge as possible. This makes for a lot of Z movement but you can't argue with the surface finish.

The fixture material is 1" phenolic. We get it in half sheets from Synthane Taylor. McMaster has it too at a little higher price. We buy smaller sheets from them. In their catalog it's called Garolite XX.

Cast Aluminum would be the ultimate but phenolic is about all I can afford at this point and it's working well.

Cast Al is outside of my budget too. Don Williams suggested "Paperstone" cutoffs which are apparently some type of phenolic as well. I'll have to try some.

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

http://www.generalplastics.com/products ... ling-board

General Plastic makes this tooling board. I've not used it for tooling yet but I got samples and machined it.

I have no doubt it would be ideal tooling material...the 50 lb. foam.

'Foam' is misleading. This stuff is DENSE, closed cell, material...but the main characteristic is its purported stability...due to its lack of internal stress.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I submitted for a sample months ago and they even called me but then sent nothing! Lousy so-and-so's

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

Ya well...I didn't mention they have a minimum order of one sheet. I don't remember how big it was but I got the impression at the time that it was enough to last the rest of my natural life.

....which is to say that if you get one transaction completed with them it'll be the last one you need to deal with them.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I've got some of those samples. I can't remember where they land pricewise compared to Phenolic. Phenolic's downside is that it's not particularly flat and probably slightly hygroscopic due to the paper. I made a fret leveling block from 3/4" linen based phenolic with a 1/4" layer of glass glued to it. It eventually warped which made me think it absorbed some moisture.

You can get glass filled phenolic, which'll be triple fun to cut. Kevin Ryan (used to, at least) makes his vacuum fixtures from phenolic and he said he faces them off once a year as they expand from moisture absorption.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

It seemed at the time I got the impression it was about 1/10th the cost of aluminum. This is from memory but the price was absolutely $350 for a sheet of it. The sheet size is what I can't remember but I do remember it was 8' long. The width might have been 24" but it could have been 48". I can't really say. It was a very LARGE amount of material.

Though my samples seemed hugely dense...I worried about how the material would hold up to repeated clampings of a tooling plate down to the table on my machine. That worry could be overcome by making ledge clamps that covered a large area. The other thing I couldn't do was rough cut the material in my shop because of its large size.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic