Progress pix

[Michael Darnton]

I made a rough measure of the heights of top and back--they're around 18mm right now. I'll be zeroing in on everything later.

I didn't show it, but when I leveled the ribs I did the taper at the same time, flattening one side, and then making the taper from the upper blocks upwards on the other. I do a lot of that by eye, now, and use the flattened inside of the back as a measuring surface.

[Victor J. Colon]

Michael

Where did you find that nice rotary file for the drillpress? I have tried to do the same with a router bit,but the speed is not fast enough...no luck. I'll really apreciate the provider of that equipment. I've been looking around for a similar tool. Maybe I am not looking hard enough:-( . By the way keep us up to date..!

Cordially

Vic

[Michael Darnton]

It came from a machinists' supply place. Buy a good one--there are bad ones, too.

[administrator]

Ain't technology great?

Where have we ever been able to see something like this...in progress yet?

Thanks, Michael, for sharing this with us!

[fiddlecollector]

Michael i`m glad to see you don`t leave that straight area across the top and bottom of the inside .You go up somewhat into either side of the top and bottom blocks.Do you know where that strange idea of leaving excess material on either end came from.I know its supposed to add strength but i don`t see why its necessary .

Modern Italians??

I have never seen it inside any old violin,ive opened but it seems that modern makers (even in Johnson and Courtnall)seem to like doing it all the time(are they not confident in there making or something,i personally don`t like the look of it at all.

[Michael Darnton]

The idea comes from Sacconi's book, but I don't know anyone who's ever seen it done as starkly as modern makers do it. A friend who's done major restorations on a LOT of Strads says that he can see something a bit like that once in a while, but only an impression, not a harsh line as Sacconi indicates. I like to keep the platforms away from the ends of the bar, myself.

[MANFIO]

Michael, what kind of distribution of thickness in the back are you going to use on this viola?

[David Tseng]

Michael, may I ask 2 questions: 1. why the edge of corners are the thickest? (tonal, structural, or esthetic? or just because Tony did that, we have to follow suit). 2. What do you mean by the distribution of weight on back?

[Michael Darnton]

It isn't just the corners that are thicker. Actually much of the edge has changes in it. I do it because Tony and many other good Italian makers did it, and I can appreciate why, and think it's attractive. It's totally visual, like many violin things.

There are a number of different subtle ways to graduate a back that have the effect of changing balance of mass or flexibility from one area to another. One example of this is Sacconi's strategy of making the upper bout of a violin back 2.4mm, and the lower bout 2.6mmm--why that way, not another?? There are all sorts of questions you can make up about graduation if you start thinking about it, rather than just using the assumptions you've always held dear.

[jmasters]

I have been following the pix and really like them. But once or twice I almost reached up to brush the shavings from the edge ... once to see the entire corner of the back with purfling.

Can I assume that you fit the C-bout first with a rather stubby angle and then use the outer bout pieces for the elongation and beesting? (if "No", could you elaborate ?)

I saw your graduating "guillotine" in the manner of Strad sketched before. You know about it, but I will point out for the others that a drill press can rough out a pattern of thicknesses, even archings. I have an old one with a positive stop which is a screw on a 1/16" thread. A quarter turn is 1/64" so that I started early on working in English units. I have not seen such a drillpress recently, the new ones have friction clutches which I do not trust. Anyway, I had a vertical finger (no, not that one) concentric with a sharp drill that would drill to within a certain distance while holding the plate on the finger. It is not hard to hold the plate normal to the finger.

For a conversion, 1/64" is .4mm to within a percent or so.

[Michael Darnton]

I cut the beesting first, from the outer bouts and get those pieces firmly in place just the way I want them. Then they never come out again. Next, I fit one end of the c-bout to jam in there and complete the corner. Then I work on the other end of the c-bout section, progressively shortening it and adjusting the fit until the fit is good and the purfling is just a bit too long to fit in easily--but if I jam it in, both ends are pushed securely home. Then I pull out the c-bout section, flow glue in the groove, and replace it. As I push the purfling home, towards the corner, the glue flows into and around the corner, gluing the tips of the outer bouts. Then I carefully lift the outer bouts without distrubing the corners, flow in glue, and put them back.

The important part of this is fitting the c-bout tight so that pushing it into the groove pushes the corners up into the ends, and clamps the miter closed.

[jmasters]

Thanks, very helpful and I will try it. I cut the C-s first and then bouts with a long taper. This I can also jam in. I join the bouts on the back with a scarf joint overlapping in the horizontal plane. This gives almost a mm of forgivness. This I do parallel to the grain on the wide parts of the bouts. Good way to use scrap peices. Sometimes it stabs me in the back, but I just move on and try better next time. The top has no problem here of course. I remove all 6 peices for a back and lay them out. Then I glue the center bouts first. A pencil mark across the maple and purfling allows me a good refit.

I don't know what your cutter is... MSC sells solid carbide up-cut spiral mills in increments of .005" A .050" gives a slip fit dry and firm fit wet with glue. For viola, I use .060" These are not very expensive, very well made and sharpened.

[David Tseng]

I can see in the pix, the corner is thick, it decreases slightly but increases again toward the center of C. I've read about the optical illusion theory and Roger Hargrave's gouging theory, but I could never appreciate it myself. I force myself to do the way Tony did.

The graduation of back is a problem. We don't know what kind of strategy those good makers of 18th C. used to determine the distribution of weight or stiffness.

[Seth_Leigh]

David, it was my impression that Hargrave's gouging theory was an attempt to explain how Tony did it. You are saying that Tony did it differently than Hargrave. So how do you think Tony did it? I'm curious. I rather liked Hargrave's article. It made a whole hell of a lot of sense to me.

[jmasters]

Likely the old makers were less up tight about a lot of things. I would like to put in a vote for people to take more risks and try more things. Perhaps even try working faster and seeing what that can teach them. Copying less and thinking more.

Tony and Joe are dead. You can look and see what you like in their work, however. And no, I am not saying to be original for the sake of it. I myself am conservative in trying to make what is accepted by tradition.

Strategies of back graduations? Don't you expect that it was completely empirical? How about making a stout violin in the white and play it a while. Then start scraping the back and see what happens? At the same time, you might ease out the f-holes a bit here and there. Many of our local hillbillies are prone to do the f-hole bit.

[Michael Darnton]

I never much cared for that particular Hargrave theory. It trips my credibility alarm.

I lap the purfling at the ends of the back over a long distance--more than an inch. That's not traditional--it's from my guitar making days--but the joint is completely invisible to most people, and even to me about half the time. Only feather the bottom piece, very carefully, in a scoop, and let the top one ramp up over it out of the groove. Put a clamp where the *bottom* of the ramp starts, to push the top piece down into the groove there, and let the spring tension of the top piece take care of clamping it the rest of the way out.

[fiddlecollector]

Michael ,have you tried Hargraves idea ,i think it works rather well once you determine the initial edge thicknesses.It also for some reason leaves a much cleaner ,elegant look to the chanelling which is hard to explain.

[Cliff Green]

I've been making my back upper and lower bout purfling one piece on violins and violas. Did the masters use one piece purfling or scarf a joint?

[Michael Darnton]

Just a blunt cut. Nothing fancy.

[Craig Tucker]

Cliff:

"I've been making my back upper and lower bout purfling one piece on violins and violas. Did the masters use one piece purfling or scarf a joint?"

I used to do this thinking that it was a cleaner look, but eventually I realized that the since the corners were the most critical part of the purfling, If you insert the one piece cc bout purfling first, the upper and lower bout purflings need the corners inserted first also in order to get corner miters EXACTLY right - then, it IS much easier to join the purfling at the center joint (or where ever - it really doesn't matter where) on the upper and lower bouts. I used to waste a lot of purfling attempting to get the length of the one piece EXACTLY right for the corners to work EXACTLY right.

John:

"I don't know what your cutter is... MSC sells solid carbide up-cut spiral mills in increments of .005" A .050" gives a slip fit dry and firm fit wet with glue. For viola, I use .060" These are not very expensive, very well made and sharpened."

I use a RobbJack # SR-2-047 two flute miniture end mill. It gives a fairly tight fit period. I'm thinking about changing to an .049.

[Michael Darnton]

I use HSS cutters, up-cut. I tried carbide, and found it too brittle and not as sharp. It's been a while, though--perhaps they've improved them. Cutters are one of those things I don't have a strong feeling on. Basically, you're just making a hole in a material that's softer than any cutter you'll find in that size was designed for--I use the cheapest ones I can buy.

[Craig Tucker]

I've looked through the catalog several times and there is no claim that I can see about what these end mills are made out of, there is a brief description of which metals & plastics they will cut through and what their intended application is, I suspect that they are carbide.

They are rather brittle and prone to break if one isn't careful to let the cutter cut at it's own speed, or if you tweek the router mid cut the cutter will snap off fairly easy also.

Still, they cut a clean, even channel.

They run right around $13.00 each.

I would switch for a lower cost cutter if I could find one - as long as it cut well.

[Michael Darnton]

If they break, they're probably carbide. In 16 years I've never broken a HSS cutter, but when I was in the W.H. Lee shop we bought six carbide ones and they were all broken within a week.

The ones I use are on page 2335 of the mcmaster.com online catalogue, at the bottom of the page on the left. I use both 3/64" and 1/16" sizes. That's 1.2mm and 1.6mm. They're about $11 for double-ended cutters--$5.50 per bit, then.

[Cliff Green]

Thanks Michael and CT for the opinions on 1 and 2 piece purfling. I've been using 2 piece for cellos with no joint problems. I guess I've just been too purist for violins to add another joint.

Michael, with all the great pictures and questions being asked and answered, your violin building book should be one step closer.

[David Tseng]

I use carbide bits, one of them (1.2mm) has been used more than 10 years and it stays sharp as ever. They are very cheap (average 20 cents each) and sold in one of the store here. All of them are thrown-out from electronic industry. All have 1/8" shank and a plastics ring on it, all kinds of cutting edges and tips in inch and metric units. The one I use has right-hand spiral and the edges are toothed. The carbide bits can operate at high rpm without burning. I also bought 2 brand new bits from the factory, MegaTools located a short distance from my in-laws house in L.A. area. I have over 100 pieces in a box and use the shank to make carbide scraper burnishers as gifts for friends.