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Roger's edge method


Berl Mendenhall
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On my last two I used a single blade and found it a wonderful experience,especially when  compared to knifing the cuts free hand. .the only spot I had any trouble with was around the inside edges of the trench near the corner points, in the  re curve, where, I suspect that if I change the geometry of the inside cutter blade a wee bit things will flow much easier.

 I do confess to a little pre channeling, just a bit as the purfling I have is only 2mm deep. In my next series,I intend to make the purfling myself,so that will or should not be an issue, by then, I also expect to have built a "proper" set of cutters complete with depth stops.

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I have never seen that Roger Hargrave would say "This is how it was done" without being sure. And I take Roger being sure of this, over anyone else.

Plus, I heard a rumor that Dilworth is cutting a channel in half an hour these days too. Do I want those results? You think?

Why is anyone arguing? And not trying to get or make these purfling cutters?

My 2 pennies, worth more or less than exactly 2 pennies.

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I have never seen that Roger Hargrave would say "This is how it was done" without being sure. And I take Roger being sure of this, over anyone else.

Plus, I heard a rumor that Dilworth is cutting a channel in half an hour these days too. Do I want those results? You think?

Why is anyone arguing? And not trying to get or make these purfling cutters?

My 2 pennies, worth more or less than exactly 2 pennies.

I couldn't agree with you more.  My next project will be learning to use the single bladed cutter to cut the purfling channel, instead of just marking and then using a knife.  I can see the benefits of doing it that way, much faster.   

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M

Yes, made em when I was in school donkey's years ago and have used them too!

 

But surely you can see that Strads depth stop would not work, especially on the belly, if the edge were not flat. A narrow edge would simply be crushed. I think Addie posted this pdf last. The copies are mine.

Purfling cutter-Letter.pdf

post-25163-0-43827800-1394652055_thumb.jpg

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Roger has proposed this method of purfling for many years based in part on a tool that we don't know actually came from the workshop of Stradivari (unless it is actually listed in Cozio's inventory). Unlike the forms and templates it bears no stamp, handwriting, or signature linking it directly to Stradivari.

But there are certain features found on many of Stradivari's instruments (we can attribute these features directly to Stradivari because the instruments are genuine) that can lead to a differing interpretation of Cremonese edge work.

One important feature is the occurrence of glue ghosts in the channel.

See this thread:

http://www.maestronet.com/forum/index.php?/topic/323149-glue-stains-on-strads-and-old-cremonese/?hl=%20varnish%20%20bruce%20%20carlson

post-53756-0-76656300-1394654221_thumb.jpg

These ghosts are often irregular in shape and quite large. I interpret this as the channel having been finished prior to the glueing of the purfling.

If you were fortunate enough to visit the Stradivari Exhibition at the Ashmolean last summer you will remember these as a quite predominant feature on the back of the "Maiden".

These glue ghosts, blunt scribe marks on some Cremonese instruments, and some other traits bring me to very different conclusion than Roger.

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I made a couple of these a while ago, and I've purfled three fiddles with them since.

 

As I get used to following the line, and fine tune the shape of the cutters, I find cutting the channels easier and easier. I always cut in from a full 4.75 mm or 5mm edge, and with a slim knife, it took a few hours, and I invariably had a blister on my finger by the end. These take all the hard work out of it.

 

We had a long discussion on all this last year. One issue I have with putting purfling in to an almost finished groove is the lack of depth for the purfling to be held securely. Many old instruments have a very small depth of purfling left in the fiddle, and as anyone who has repaired such things will know, it's much harder to set purfling in a very shallow groove.  The three mm cut is no bother to me.

 

There are, however, features of old fiddles that I don't see much in my own work. Deep down in the groove, the purfling usually fits very snug, as the wood swells around it when it's glued. I can't point to any Cremonese violin in particular, but there's often a looseness to the line at the joint where the knife has spread the wood, and where this has remained after glueing. Curious One pointed to a Del Gesu, where the purfling chisel had slipped right out, and left a cut on the finished surface, and I couldn't imagine how this might have happened  with a three mm groove.

 

I've thought a lot about this since, and I've come to a possible conclusion, which I may try next week, on my next violin. I wonder did Del Gesu make the cut with the deep u shaped gouge, (whose traces can be seen in his corners) almost to depth, before he purfled. This would have made the purfling cutting easier and still left enough edge to support the depth stop of the cutter, while leaving wood on either side to protect the finished edge from glue. It would also explain the toolmarks around the purfling. 

 

So, Roger's method - purfle, deep groove over purfling, finish both sides separately.

 

Another possibility - Deep groove, purfle, finish both sides. I may take my heart in my hands and try it next week.

 

What do you think?

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The only thing difficult to make on those cutters is the threaded blade, and even that doesn't look like to big a deal.  Just have to get some steel, cut some threads, grind it, and temper it.   

I made my cutters from silver steel, and making the thread was a curse, but my die is ancient, and makes a sort of rolled thread, so it seemed to work harden the steel at every pass.

 

Brian Mc Carthy made his blades and brazed on a little threaded rod. 

 

( nice to see your work Berl)

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I made a couple of these a while ago, and I've purfled three fiddles with them since.

 

As I get used to following the line, and fine tune the shape of the cutters, I find cutting the channels easier and easier. I always cut in from a full 4.75 mm or 5mm edge, and with a slim knife, it took a few hours, and I invariably had a blister on my finger by the end. These take all the hard work out of it.

 

We had a long discussion on all this last year. One issue I have with putting purfling in to an almost finished groove is the lack of depth for the purfling to be held securely. Many old instruments have a very small depth of purfling left in the fiddle, and as anyone who has repaired such things will know, it's much harder to set purfling in a very shallow groove.  The three mm cut is no bother to me.

 

There are, however features of old fiddles that I don't see much in my own work. Deep down in the groove, the purfling usually fits very snug, as the wood swells around it when it's glued. I can't point to any Cremonese violin in particular, but there's often a looseness to the line at the joint where the knife has spread the wood, and where this has remained after glueing. Curious One pointed to a Del Gesu, where the purfling chisel had slipped right out, and left a cut on the finished surface, and I couldn't imagine how this might have happened  with a three mm groove.

 

I've thought a lot about this since, and I've come to a possible conclusion, which I may try next week, on my next violin. I wonder did Del Gesu make the cut with the deep u shaped gouge, (whose traces can be seen in his corners) almost to depth, before he purfled. This would have made the purfling cutting easier and still left enough edge to support the depth stop of the cutter, while leaving wood on either side to protect the finished edge from glue. It would also explain the toolmarks around the purfling. 

 

So, Roger's method - purfle, deep groove over purfling, finish both sides separately.

 

Another possibility - Deep groove, purfle, finish both sides. I may take my heart in my hands and try it next week.

 

What do you think?

Yes Conor, that free, simple looseness is exactly what I see. It is hard to describe but easy to recognize. Good luck with your experiment. Let us know how it goes. :^)

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 Another possibility - Deep groove, purfle, finish both sides. I may take my heart in my hands and try it next week.

 

What do you think?

I think it's good, go for it. Curious made a good point that one can make a nice looking groove and miters, but cut it down a couple of millimeters, and you expose something different from what was on the surface.

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 I think Addie posted this pdf last. 

Um, yeah.  I also drew it.   :P

 

In case anyone is wondering, I had a PM with a “museum quality” photo with a scale included, so I know it’s right, except I didn’t flip the outline when I drew the back.   :huh:  This is only one of the pair, the other is slightly different, but not in terms of working.  They are threaded for a set screw on either face of the cutter... I see Roger left that out, since he has a pair (presumably set for outer/inner). 

 

The blade is quite easy, if you have an anvil, die, and a propane torch, and a tool steel rod.  Only the tip really needs to be hardened and tempered, so a propane torch works fine.

 

I haven’t finished mine yet--still working on the graduation punch.

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Conor Russell, on 12 Mar 2014 - 3:23 PM, said:

.."Curious One pointed to a Del Gesu, where the purfling chisel had slipped right out, and left a cut on the finished surface, and I couldn't imagine how this might have happened  with a three mm groove.....I wonder did Del Gesu make the cut with the deep u shaped gouge, (whose traces can be seen in his corners) almost to depth, before he purfled... It would also explain the toolmarks around the purfling."

 

The right lower bout in the back of the 'Ole Bull' has that little flaw too, but not quite as visible as the 'Sainton' , which is above the upper treble corner.  IIRC, the 1738 Kemp has a couple dinky spots on it, too. I rather think the tear out (on either side of the purfling groove) stems from gouging too deeply against the grain; or a dull blade, though some scud/skid marks can be found scattered about on different fiddles and in different places.

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Chris, I just hope this has encouraged people to at least try this.  I think it will make your edge work better.  Lets face it edge work is one of the first things people evaluate when looking at your work. This thread has had it's ups and downs but I still think it has been informative.  People can do it exactly as Roger describes it or do as Davide Sora does it in his videos.  Either way I believe you will be pleasantly surprised.

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Is it possible that the method was changed to suit the wood?

So really hard dense wood that made deep grooves hard work got thinned first, and softer wood saw deeper purfling grooves?

 

Is it possible that Guarneri had a different working method from Strad?

 

Is it possible that decorated instruments were treated differently, by the same maker, from non-decorated instruments?

 

IOW did these folks used their judgement to tackle the situation instead of following the same routine everytime?

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But surely you can see that Strads depth stop would not work, especially on the belly, if the edge were not flat. A narrow edge would simply be crushed. I think Addie posted this pdf last. The copies are mine.

Are these the only purfling cutters that have come to us from the Golden Period?

Do we have other makers cutters?

If we do ... Are they the same?

If the channel is not deep, would all these 'bells n' whistles' be needed?

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Is it possible that the method was changed to suit the wood?

So really hard dense wood that made deep grooves hard work got thinned first, and softer wood saw deeper purfling grooves?

 

Is it possible that Guarneri had a different working method from Strad?

 

Is it possible that decorated instruments were treated differently, by the same maker, from non-decorated instruments?

 

IOW did these folks used their judgement to tackle the situation instead of following the same routine everytime?

Yes, it is very possible that The Amatis and Guarneris had a different technique than Stradivari. Stradivari always seems to me the outsider. Robert Bein used to say he thought Stradivari was "the kind of guy who could have learned violin making in an afternoon".

I don't think he was handed the tradition in the same way as the Guarneris did from Amati. He would have been free to find his own solutions.

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And your point? That the edge was 5mm thick?

 

It is a tool.  From the Strad workshop, as far as we know (via Fiorini).  And it relates to making the plate edges.  Unless I’m mistaken, we’re talking about plate edges...  at least you guys seem to be.  I’m just promoting my free drawings, really.   :rolleyes:

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