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Yup, I understand bearing forces, etc. But, I want to take soft aluminum and carve router guides (clamped on to the body). I have one of those big powermatic drill presses. If it is possible and advisable, what bits do I use?

If not advisable.. then fine.

Mike,
I am not sure what you want to do. " carve router guides (clamped on to the body)"
Can you elaborate ?
You can easily work aluminum with regular carbide tipped woodworking tooling. A bar of soap rubbed on the cutter will help as will wearing a face sheild. Don't wear a fleece jacket. DAMHIK "The hot aluminum chips will melt in and you will never get it out." You can cut it with a router, table saw, chop saw and you could mill it on your drill press. Depending on what you want to do 2 flute end mills will work fine. I would want a milling table though. As with any operation you need a safe way to hold the work and when milling a controled way to advance the work into the tooling. A better picture of what you want to do and I could get more specific.
Link

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Cut to size.....Beat to fit.....Paint to match.

It's fine, so long as you understand the quill is not going to hold the tightest X-Y tolerances, and that using a press regularly for this may take it's toll on the machine. Don't be surprised by a bit of chatter. A standard straight or spiral router bit will work fine on most aluminum, or an endmill of course. Spiral cut will give you a cleaner edge, but straight will get the job done. High cutter speed and medium feed rate will do you well on a drill press, and shallow passes will help keep it cleaner if you get excessive chatter.

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Eschew obfuscation, espouse elucidation.

If you start getting a lot of chatter, don't be surprised if the quill falls out.

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Steve Smith
"Music is what feelings sound like"

I generally find it more expedient to cut aluminum with a band saw, or just a jewlers saw if it is a small piece, and then clean up with files. You are not going to get the ultimate in precision using a drill press as a mill, so the benefits of milling are somewhat lost.

If i had a big drill press like yours, i would probably try it anyways though...

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Jordan Aceto
Ithaca, NY

I want a guide to cut a purfling channel between the hardwood and soft top wood. So a template guide clamped to the body in the shape of that mult-curve would b idea for the bosch colt. NOW it just hit me. It does not need to be made out of metal. But, that sharp point will be a problem unless the bit is very small diameter with means more passes... this is no good. Ideas?

I would find it to be much less work to just cut the purfling channel with a knife and purfling pick.

You are going to have to do some knife work anyways at the point, if i am understanding what you are going for correctly.

I bet it will look very cool, no matter how you do it.

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Jordan Aceto
Ithaca, NY

Now I see what you are doing. Yes you could and would be better off making a template out of 1/2" baltic ply and run a router with a template guide. Most of the template guides are just under 1/2" although I have had to grind a few down a bit. The template has to be perfect, no bumps or dips. The little point you could easily finish with a sharp chisel. You should do a test run on something to see how far away from the little point you have to stop and get the feel of it.
A steady hand and lots of concentration are needed to do this with a template on one side only. Any slip off of the template and your grove is spoiled. It does help to run a smaller bit first so that on your final pass with the full sized bit the bit is not fully engaged.
Link

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Cut to size.....Beat to fit.....Paint to match.

I agree with Jordon, this looks like a job made for a knife and purfling chisel. Sure make a template, you'll need two of course one for each side of the purfling, I'd probably use clear plastic so I could see the work, then have at it with knife and chisel. Far more controlled and probably much quicker.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Colin,
How would you perfect two templates ? The only way I can see to do it accurately would be to make a master of the inside curve and route two templates at once with the dia. of the router bit creating the inside and out side of the tempate. If you could do that then it would be very safe to use a router with a template guide as you would have the inside and outside and no way to slip. The only isssue at that point would be tear out but with small bits is minimal.
With a single template maybe a knife with two blades or maybe a knife with some kind of stand off to ride the template on the inside with the knife on the outside. Is there such a animal. I can't see making two templates by hand and getting the channel of even width the whole way. I know it can be done as I have seen work that was done way before routers with nice inlayed curves etc. How to keep the channel width consistent ?
Link

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Cut to size.....Beat to fit.....Paint to match.

I think this is one to avoid overthinking/overjigging. Sharpen up your instrument makers knife, practice making nice cuts on scrap spruce and go at it. You could probably just make one template to guide a knife, for the side of the cut closer to the body, and use already established line where the hardwood begins as the other wall of the channel.

I would just do it free hand, the trick is to go way slower than you think you should. Even working slowly free hand will probably be quicker than planning out a jig, thinking about how to make it, screwing up the first one, trying again... etc etc.

If you go the way of the knife, a sizing of thin hide glue makes it much easier to cut a nice curve in spruce. You want to harden up the soft summer growth so that the knife doesnt want to dive in every time you cross a grain line.

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Jordan Aceto
Ithaca, NY

Quickies:

1-Yep, acrylic (clear, really hard) or polyethylene (not clear, much easier to machine) are both better choices than aluminum unless you're making permanent fixturing or you have a real mill. Even then, I'll use acrylic when I don't want to get coolant in my mill (because I have to clean all of it out before I can cut wood again!).

2-If you were cutting aluminum, I'd use the drill press to cut a patten of relief holes and then use a bandsaw or a hand saw followed by files. Probably faster, and no chance of hurting your drill press.

3-If I didn't have the Fadal, then I'd be going at it with a scalpel as others have said. On the other hand, if you don't trust your bladework completely you're much safer taking three tries at making a guide than missing your first and only shot at cutting the channel freehand!

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Maybe I am getting this wrong, but say I transfer the curves to a piece of acrylic. Then, once cut, you have both of the templates?? Anyways, I just bought some really nice, small (2mm, 4mm) 2 cherries gouges at SMC (among other things) so I am on my way.

Mike

Remember.... the chuck is usually held on with a Morse taper and no bolt.
A milling machine chuck is held on with a morse taper and a big bolt....

So... when drilling, most of the force the Drill chuck sees is pushing it back up into the drill....
tightening on the taper.

Milling is completely different, though -- where most of the force is side loads...
and you can eve have significant loads pulling the cutter down into the work...
*ESPECIALLY* with Aluminum.... but Brass is the worst for being Grabby.

The caution is that the chuck can unexpectedly disassemble off the drill
from the side loads and chatter. Happened to me last week while trying to
"Cheat" and make a hole a little bigger.

That being said.... zillions of people do it.
Cumpiano and Natelson's book shows directions for milling bridges
saddle slots on a drill press.....

Good luck

John

I did a similar purfling on by last bandura. I decided to cut it with a knife and chisel it out. It was pretty tough to get perfect and as you can tell from the shots, it's not perfect but it's concealed pretty well. I cut the rest of the purfling channels with an ibex purfling cutter and that went pretty well. The biggest revelation (which was obvious as soon as I did it and I was kind of embarrassed that I didn't think of this before since I've seen it in other applications) was that you need different templates for each "side" of the purfling. i.e. if you're using a router, the differences in inside and outside radii will take care of themselves. If you're using a knife and a template, you've got to either have two templates or some sort of offset for your knife.

I ended up using a single template and sort of fudging it to get it to look even - hence some of the gaps.

I'm probably not going to have this type of purfling on my next instrument but if I go back to it I'll probably use a knife and chisels again.

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

Gaps? C'mon, that looks totally great.

Old school tecniques for old school results!

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Jordan Aceto
Ithaca, NY

Well thanks Jordan, but there are some gaps there, I just did a surprisingly good job of filling them to match the top. They're kind of hard to see in the photo but look closely. Just wanted to pass along a word of caution.

One other thing I just remembered, the channels seemed to grow as I made them deeper, probably from poor knife technique. Be careful when doing that.

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

Here is a nifty tool, if you are that type. I made a purfling pick out of a little file. It is thin enough that it fits in the channel nicely, and i left the teeth on the sides so that when you need to widen the channel you just give it a little rub.

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Jordan Aceto
Ithaca, NY

Where's the template you cut the first curves from? You could probably cut the shape with a hardboard template and exacto or carvers knife and clean it out with a dermel like doing an inlay. Or if you are going to repeat this and want the line to be 1/8" wide buy the Whiteside Inlay router kit and make a template.

Chris, I wish I was smart enough to have thought about that in advance. I did not. the drawings were the template, but the actual pieces are not precisely matched to the drawings after installation.

live and learn

Mike

I would like to add to this crucial fact of the chuck being held on by taper with no bolt... I just today brought my son back from the hospital after the chuck wobbled off the taper from some ill advised side loading with an unbalanced piece of work that he was trying to machine with a file. The chuck shattered the base knuckle of his right index finger requiring surgery and steel pins, as well as number of other less serious fractures and a lot of abrasion. Granted, it was working with metal and the proper tool would have been a lathe or milling machine, but if the chuck comes off because of chatter or wobble, it doesn't generally just fall off... it flies off with a lot of force. Be careful out there...
Don Fera