Dremel for purfling channel?

Don Harris · #1 06-28-2007, 12:20 PM

Do you builders like using the purfling channel routing jig with a Dremel? The reason I ask is because a violin builder I'm studying with used it for the first time and said he kind of likes the way the traditional approach looks better. I was buying a purfling channel cutter from International Violin and Ken really questioned me on why I didn't want to go with the routing jig. -don

1st Bass · #2 06-28-2007, 12:50 PM

Just bear in mind that the Dremel tool is really made for pretty light cuts--I burned mine up trying to use it for purfling the bass. Probably I was simply trying to go too deep in a single pass.

I got no warning--no smell, no feeling of abnormal heat-- it simply, abruptly ceased to function. You might want to consider the Foredom tool, if you want to go that way. I think it is a lot "gutsier" (if that is a word), and should last longer.

I really regret ruining my Dremel tool-- it was useful for all sorts of tasks, and I don't feel I have the money to just run out and replace it.

**Matthew Tucker** · #3 06-28-2007, 05:05 PM

a cutting marker, knife and pick worked well for me. Next bass, I will leave ALL the purfling until the plates are on and the outline is finalised. I find, in fact, that its easier to inlay the purfling that way too, with the bass well supported.

arnoldschnitzer · #4 06-28-2007, 06:42 PM

I have both a Foredom and Dremel with specially-made purfling bases. I prefer the Dremel because it turns a lot faster and the base I have is more supportive. However, the Dremel is cheaply made and some runout is par for the course. I've also done basses completely with hand tools and I will never go back to that.

Bob Branstetter · #5 06-29-2007, 11:27 AM

I used a Dremel tool with a home made jig for purfling for several years. With the setup I had, I could only cut the purfling channel in the plates before they were attached to the corpus. The photo below shows my jig.

Nick Lloyd and Jeff Bollbach introduced me to the Croen purfling tool a little over a year ago and I've been using it since. The Croen tool attaches to the Foredom tool and allows you to cut the channel after it is attached to the corpus. I've been able to get around the problem Arnold mentioned by hanging the Foredom tool from a movable track which hangs above and over the length of my work bench. The trick with both the Dremel tool and the Foredom tool is to go slow and/or take multiple cuts. Like Arnold, I have no desire to go back to doing it all by hand although a certain amount of hand work is still required at the corners and for intricate patterns.

Don Harris · #6 07-01-2007, 12:33 AM

Thanks for the input. More to think about. Does one use a traditional purfling cutter to get closer in to the corners than a router base can go or just a knife?

1st Bass · #7 07-01-2007, 01:12 AM

Mostly the "purfling cutter" is just used for marking the exact boundaries of the purfling channel-- you still cut the channel with a knife and purfling pick. (you probably already knew that...)

**Matthew Tucker** · #8 07-01-2007, 07:22 AM

Hey Don, why not practice with a marking gauge/cutter and a piece of scrap first before deciding what you need. If this is your first instrument do you really want to shell out for a dremel etc etc for one job which you CAN do by hand, though it does take a wee bit longer? The tools shown in Chandler's book are adequate. Although I have some real purfling cutters I bought a chinese marking gauge for $8, rounded the face on the bandsaw (to get into the corners) and replaced the scriber with a single thin homemade knife blade. It actually works better than the "real" ones I have. And, like Chet said, you only use it for marking the channels and starting the knife cut, and use your knife to deepen the cut to about 1.5-2mm.

1st Bass · #9 07-01-2007, 08:58 AM

You know, I nearly forgot-- my "purfling cutter" which I bought from International Luthiers Supply years ago will not adjust large enough to get the distance from the edge that I wanted for the bass, anyway.

I ended up using a trick Michael Darnton passed along-- he took a cheap set of straight divders, and ground one leg off about a half-inch short, and dulled the end of the long side, then ground a very sharp single bevel (flat on the inside) knife point on the short leg. You adjust it with the screw, using a ruler, then hold it so that the long leg runs along the edge of the plate, and the short, sharp leg scribes the line.

It actually works quite well, and is easier to use than the "real" purfling cutter.

I would definitely second the motion that you practice on scrap, first. Cut some mock corners (the whole C-bout shape would be best, with two corners and a couple tight curves) of spruce or pine or what have you, and practice a lot. You can practice your edgework that way, too.

Paul Schuback recommends fifty practice runs. That sounds like a lot, but the results are worthwhile. He tells me that he did seventeen whole tops, before one was allowed to be put onto an instrument--all the earlier ones were examined minutely, critiqued and burned. Rough way for a fifteen-year-old to learn, but it really shaped his later work.

Don Harris · #10 07-01-2007, 12:50 PM

Good input. I've got a constant internal debate about whether to buy a bunch of power tools that will make things faster and easier but that I would only use occasionally, or to make due with hand tools and enjoy the process (and learn patience). Luckily the purfling cutter I ordered from International Violin was out of stock and didn't ship, so I've got time to weigh my options. I like the modified divider idea. I do have a marking gauge too, but I'm not sure if I want to round off the guide, and I can't visualize how to add a blade to it. I'm definitely planning on practicing a bunch on scrap wood. I've ordered some of the fiber purfling to do that.

I'm wondering how, if you wait to do the purfling after the top and back are on, you deal with graduation thickness when you do the edge fluting. Unless you could be very precise with the gouge cut, you wouldn't know how thin you're getting underneath. Does this make sense?

I'm making the clamping cauls for bending and gluing and waiting on a 1500 watt dimmer to arrive before I start some test bending. I'm going to try to use 3/4" oak dowels through the mold with bungee cords for bending and clamping. I'm doing dry runs and I'm thinking that I can get a lot of lbs of pressure on the joints and it's pretty flexible on which direction the pressure is applied. The dowels and cauls are long enough that the bungee won't touch the heat blanket. I'll post some pics soon.

Bob Branstetter · #11 07-02-2007, 09:03 AM

Quote:

Originally Posted by Don Harris

I'm making the clamping cauls for bending and gluing and waiting on a 1500 watt dimmer to arrive before I start some test bending.

Don - I was under the impression that a dimmer will reduce the temerature of the blanket, but wouldn't actually be variable. Please let us know how this works for you.

Don Harris · #12 07-02-2007, 02:04 PM

I'm anxious to find out if it works too. A local shop that makes dulcimers and ukes that did my resawing and thickness sanding uses a heat blanket with a dimmer and said it works fine. We'll see.

lkbigmac · #13 02-01-2009, 10:31 AM

I bought a dremel from grizzly its not the dremel brand but its the same thing
it was 30.00 dollars i got it on sale for 25.00. its worth a try at a price like that.

fdeck · #14 02-01-2009, 11:12 AM

I own two Dremels, one is about 30 years old, and the other is fairly recent. There is a huge difference in quality. The old one had a speed control that would allow the tool to maintain torque at lower speeds. The new one, if you run it at anything but top speed, grinds to a halt when it is loaded down.

In a former life doing some industrial production, I learned that one can find bits made for milling machines, with the shank diameter required for a Dremel, but in a variety of cutting diameters. They seem to be of a much higher quality than the bits sold by Dremel. I also learned that a blast of compressed air helps cool the bit during cutting.

ctregan · #15 02-01-2009, 01:26 PM

Its hard to get a flat bottom when chipping out the waste by hand.

The power tool method could save days, if not weeks of labour.

If you buy a Foredom, you may find other uses for the tool besides cutting purfling grooves.

**Matthew Tucker** · #16 02-01-2009, 02:17 PM

Quote:

Originally Posted by ctregan

Its hard to get a flat bottom when chipping out the waste by hand.

If you sit there long enough you'll get a flat bottom

robobass · #17 02-03-2009, 02:20 AM

If you use a foredom/dremel type tool and happen to have an air compressor, you may want to get this.

I've never taken one to a bass, but used it for years when I had a prototyping business. The higher rpms/lower torque can be an advantage, and the lightweight air hose is much more convenient than a flex shaft. Kind of loud, though, and definitely not for dentalphobes!

Eric Rene Roy · #18 02-03-2009, 06:30 PM

I found the dremel unusable. The motor is not solid enough in the housing and causes the bit to be erratic. Tom Croen's tool with a Fordem is the only way to go!

Martin Sheridan · #19 02-07-2009, 08:48 PM

I have done it by hand and I've used both Dremel and Bosch.
I used an attachment from Stewart McDonald for the Dremel but it has to be used with the top or back on the bench. The Bosch had one that is designed to be used with the plate on.

It sure is easier to move through the wood with power, but you can't get into the corners and if you're not careful you can screw up in a heart beat.

The last few years I've gone back to doing everything by hand. It's just more satisfying to me for some reason.

It's the final outcome that is most important and how you get there is up to you.

There are those who think we should still be working by candle light, but I've never seen one of them come to my shop in a horse and buggy.

gbaker · #20 02-07-2009, 09:46 PM

Quote:

Originally Posted by lkbigmac

I bought a dremel from grizzly its not the dremel brand but its the same thing
it was 30.00 dollars i got it on sale for 25.00. its worth a try at a price like that.

Yep.

Seems to me, what one spends on a tool depends on how often and how hard one intends to use it. If you are going to use a rotary tool in production every day or even every week then go for the Foredom and enjoy the power and speed afforded. Otherwise scale back from $300 to $30 and don't push it as hard.

I have a no-name Dremel clone ($30 with a bunch of bits and a flex shaft) and it works fine for the occasional rout. I also have a little $25 Harbor Freight 1/4" router/laminate trimmer with clear plastic base and a edge guide (that I modified to be a two point guide) that works better for edge-guided routing. BTW I also have Bosch and Porter Cable heavy routers so it is not a matter of being cheap but rather a matter of spending appropriately to the intended requirement.