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Giovanni Corazzol

Knives from René Morel's workshop

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I found this interesting article some time ago and saved it in my browser's bookmarks; I would like to ask some questions about Morel's knives since I know that there are some people on this forum who were trained in his shop or personally knew him and so I hope they'll be willing to share some knowledge on this.

René Morel workshop artefacts - the Cozio carteggio

First question is: it seems that Morel was always in search of the best tool steel blanks for his knives. What kind of steel did he use?

The article says that the blade stock was made in the Mirecourt style and it had a roughly triangular cross section.  All luthier's knives that I can find have a rectangular cross section, so why was this feature abandoned? Maybe it would rise production costs too much?

The bridge-cutting knife has another interesting feature that I have never seen before. The blade tip seems to have been ground on the thick side and rounded.

I wonder what is the reason to do that. When I learned bridge cutting from Alessandro Voltini at the Cremona school, he advised us to round the side of the blade a bit in order to ease the cutting action of the knife inside the bridge's kidneys and legs. But, we always kept a straight back and a slightly curved edge.

So, I thought that the purpose of the grinding was that of reducing the thickness of the blade after it was sharpened, to reach into the thinner spaces of the violin bridge even with a thick knife stock blade. Since I have always trouble in sharpening very fine knife points with a stone, because the points bend a little under pressure, I wonder if the grinding was devised as a solution to this problem.

Thank you all for reading and for your comments!

--Giovanni

 

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Hello Giovanni, First off, John Schmidt on MN makes knives and has made the triangular blades you reference.  I have had quite a few and many in our workshop have them as well.  They are about as close as I have seen, and work extremely well.  Rene’ did indeed grind the back of his blade as I have done ever since.  The relief in this area makes for a smoother cut. Rene’ also had his bench knife ground with a relief on the back which is different than the knives Shown in the auction.  The knives in the auction do not look familiar, although I would have easily overlooked them as they are pretty cookie cutter. 

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7 minutes ago, Julian Cossmann Cooke said:

I'd also be interested in knowing which of these tool designs are standard in the trade today.

Julian,

   I do not know if the knives cut this way is standard, they certainly were not when I reached Francais.  I guess a good way to know is what you see at Oberlin....so, does there seem to be a trend?

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31 minutes ago, Jerry Pasewicz said:

Hello Giovanni, First off, John Schmidt on MN makes knives and has made the triangular blades you reference.  I have had quite a few and many in our workshop have them as well.  They are about as close as I have seen, and work extremely well.  Rene’ did indeed grind the back of his blade as I have done ever since.  The relief in this area makes for a smoother cut. Rene’ also had his bench knife ground with a relief on the back which is different than the knives Shown in the auction.  The knives in the auction do not look familiar, although I would have easily overlooked them as they are pretty cookie cutter. 

Jerry,

Thanks.  Jpschmidt44@gmail.com

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15 hours ago, Jerry Pasewicz said:

Julian,

   I do not know if the knives cut this way is standard, they certainly were not when I reached Francais.  I guess a good way to know is what you see at Oberlin....so, does there seem to be a trend?

I don't know if these shapes are "standard" but I have always used ones very similar to these. One thing I will mention is that Rene liked handles which were thicker in the heel of the hand and I made some like that when I worked there. I reverted to a slimmer, flatter shape afterwards. Rene had very wide thick fingered hands. The only thick handle I kept was for my bridge knives because it allows less movement to follow a small radius cut.

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I learned from someone who apprenticed for five years with Rene' Morizot, a former head of the French School in Mirecourt. I was taught to make knives from old straight razors--the wedge shaped ones, not the heavily hollow-ground ones, cause you have to grind the thickness of the razor's spine down to the desired thickness. Bridge knives were made from gravers. The cross section of both would account for a triangular cross section. I wrote an article for the Guild of American Luthiers, very early in the life of that organization, on the knifemaking process. The article is probably in their first Big Red Book. We, myself and the other apprentices, would test a razor's metal quality with a light pass of a small mill file; a higher pitched sound and a sliding feel indicated better quality steel. We'd buy new gravers.

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2 hours ago, Evan Smith said:

Jerry,

You've mentioned using a curved bridge knife on several occasions,

does this represent what you are referring to?

1147089369_Bridgeknife.JPG.58da6de610a0c85d0ca2f7149d2265c3.JPG

It does indeed.  I only use curved knives anymore....for about 28 years.  They are incredibly useful in bow making as well,  especially compared to the big flat knives made from old files that many are taught to use.  

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Chris Burt, thank you for the great idea of using gravers as knife blanks.  I had no idea these existed.  A search shows that they are made in a large array of sizes and steels.  They do not appear to be very expensive.  

Mike D

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Thank you all for your answers. Today I took some time to experiment. I picked up an old "Kogatana" knife blade and tried to reproduce the "Morel bridge knife" pictured above. I started grinding a new bevel by holding the blade square to the wheel, turned the blade and ground the other side (the Kogatana I am speaking about has a central layer of hard steel). The blade got a shape similar to a razor, with a slightly curved edge. I removed the burr and sharpened with my stones, then I returned to the grinder to get a pointed tip and a rounded back.

The knife worked fine but, I think it's not necessary to shape the end to a point. I tried to work on an old bridge with the truncated end; then I tried some cuts with the pointed edge. I prefer the former shape. Probably, it's safer for the most sensitive steel.

I will see if I can find another knife blank to get more familiar with the process. In the meanwhile, I will check for any other advice, which is plentiful and valuable as always here on Maestronet.

knife_1.jpg

knife_2.jpg

knife_3.jpg

knife_4.jpg

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I have saved John Schmidt's address and I will contact him.

I have a last question before leaving this thread: what about using HSS steel as knife blanks?

I found that they are quite hard to grind properly (I have the CAG brand) but they hold an edge well. I now use a narrow CAG knife for purfling; I have a larger one but it takes too much to sharpen and I need to make a new sliding guide for my bench grinder. I cannot sharpen them freehand without overheating. I recently changed my grinding stone and bought a Norton 38A 60 grit stone, and it's the best I have tried so far.

Is there any advantage in HSS over a very good carbon steel? For bowmakers maybe?

 

 

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12 minutes ago, Giovanni Corazzol said:

I have saved John Schmidt's address and I will contact him.

I have a last question before leaving this thread: what about using HSS steel as knife blanks?

I found that they are quite hard to grind properly (I have the CAG brand) but they hold an edge well. I now use a narrow CAG knife for purfling; I have a larger one but it takes too much to sharpen and I need to make a new sliding guide for my bench grinder. I cannot sharpen them freehand without overheating. I recently changed my grinding stone and bought a Norton 38A 60 grit stone, and it's the best I have tried so far.

Is there any advantage in HSS over a very good carbon steel? For bowmakers maybe?

 

 

There are many many types of steel, and methods of heat treatment. Some types are easy to grind and sharpen, yet have superior wear resistance and edge retention. I think John Schmidt has run a lot of samples by actual tradespeople, so you might ask him what he recommends.

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2 hours ago, David Burgess said:

There are many many types of steel, and methods of heat treatment. Some types are easy to grind and sharpen, yet have superior wear resistance and edge retention. I think John Schmidt has run a lot of samples by actual tradespeople, so you might ask him what he recommends.

David, thanks for the opening.  

In my discussions with top violinmakers, they said they did not like high speed steel like M2 because of sharpening difficulty. They very much liked my O1 steel with my hard heat treatment.

But, my tests of a particle metallurgy steel showed this steel to hold an edge 3 times longer ( in length of wood cut) than my O1 blades. To me, this PM steel ( this particular steel which I call PM-X) is easier to sharpen than O1. The mystery is that it’s hardness is only Rockwell 60, whereas my O1 is Rockwell 65. So PM-X is superior.

I fear  that violinmakers  are used to believing that harder is better. 

Welcome to the future.

John

 

John

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40 minutes ago, violins88 said:

David, thanks for the opening.  

In my discussions with top violinmakers, they said they did not like high speed steel like M2 because of sharpening difficulty. They very much liked my O1 steel with my hard heat treatment.

But, my tests of a particle metallurgy steel showed this steel to hold an edge 3 times longer ( in length of wood cut) than my O1 blades. To me, this PM steel ( this particular steel which I call PM-X) is easier to sharpen than O1. The mystery is that it’s hardness is only Rockwell 60, whereas my O1 is Rockwell 65. So PM-X is superior.

I fear  that violinmakers  are used to believing that harder is better. 

Welcome to the future.

John

 

John

The fineness of the microstructure might be a key factor in wear resistance and sharpness.  Powder metallurgy sintering might give smaller grain size than older forging, casting, and heat treatment processes.

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19 minutes ago, Marty Kasprzyk said:

The fineness of the microstructure might be a key factor in wear resistance and sharpness.  Powder metallurgy sintering might give smaller grain size than older forging, casting, and heat treatment processes.

Marty,

agreed. It DOES have smaller grain size.

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5 hours ago, Giovanni Corazzol said:

I have saved John Schmidt's address and I will contact him.

I have a last question before leaving this thread: what about using HSS steel as knife blanks?

I found that they are quite hard to grind properly (I have the CAG brand) but they hold an edge well. I now use a narrow CAG knife for purfling; I have a larger one but it takes too much to sharpen and I need to make a new sliding guide for my bench grinder. I cannot sharpen them freehand without overheating. I recently changed my grinding stone and bought a Norton 38A 60 grit stone, and it's the best I have tried so far.

Is there any advantage in HSS over a very good carbon steel? For bowmakers maybe?

 

 

For bowmakers, maybe HSS is good. I don’t know.

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On 4/10/2019 at 7:56 PM, violins88 said:

David, thanks for the opening.  

In my discussions with top violinmakers, they said they did not like high speed steel like M2 because of sharpening difficulty. They very much liked my O1 steel with my hard heat treatment.

But, my tests of a particle metallurgy steel showed this steel to hold an edge 3 times longer ( in length of wood cut) than my O1 blades. To me, this PM steel ( this particular steel which I call PM-X) is easier to sharpen than O1. The mystery is that it’s hardness is only Rockwell 60, whereas my O1 is Rockwell 65. So PM-X is superior.

I fear  that violinmakers  are used to believing that harder is better. 

Welcome to the future.

John

 

John

I received one of John's PM-X knives a little while ago, and had a chance to give it some serious abuse this morning, installing it in a large handle and making heavy cuts (as heavy as I had the strength to make) on some end-grain ebony. No chipping or bending of the edge (about a 35 degree edge). Still shaved hair afterward. Seems easy to grind and hone, unlike some of the really hard steels.

I'm impressed! So far, it seems much better than any of my other bridge knives. (I specified dimensions for a bridge or ff-hole knife.)

At some point, I might try a steeper angle and see what happens.

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1 hour ago, David Burgess said:

I received one of John's PM-X knives a little while ago, and had a chance to give it some serious abuse this morning, installing it in a large handle and making heavy cuts (as heavy as I had the strength to make) on some end-grain ebony. No chipping or bending of the edge (about a 35 degree edge). Still shaved hair afterward. Seems easy to grind and hone, unlike some of the really hard steels.

I'm impressed! So far, it seems much better than any of my other bridge knives. (I specified dimensions for a bridge or ff-hole knife.)

At some point, I might try a steeper angle and see what happens.

David,

Thanks for the kind words. 

All,.... There will be an article on PM-X steel in the coming edition off The Scroll, a VSA publication coming out in September.

John

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6 hours ago, violins88 said:

David,

Thanks for the kind words.

LOL, you've been here long enough to know that I can be kind, unkind, or anything in between. :lol:

I just call stuff the way I see it. So far, this seems to be one of the best knife blades I have ever used.

With your permission, I can pass the blade along to some other makers/restorers whose  opinions I have learned to highly respect, and see what they think.

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10 hours ago, David Burgess said:

LOL, you've been here long enough to know that I can be kind, unkind, or anything in between. :lol:

I just call stuff the way I see it. So far, this seems to be one of the best knife blades I have ever used.

With your permission, I can pass the blade along to some other makers/restorers whose  opinions I have learned to highly respect, and see what they think.

David,

abso****inglutely you may pass that blade along.

It would be useful if the next recipient of that blade would report back here. All, please remember PM-X steel is not high speed steel and must be “cool ground.”

john

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14 hours ago, David Burgess said:

I received one of John's PM-X knives a little while ago, and had a chance to give it some serious abuse this morning, installing it in a large handle and making heavy cuts (as heavy as I had the strength to make) on some end-grain ebony. No chipping or bending of the edge (about a 35 degree edge). Still shaved hair afterward. Seems easy to grind and hone, unlike some of the really hard steels.

I'm impressed! So far, it seems much better than any of my other bridge knives. (I specified dimensions for a bridge or ff-hole knife.)

At some point, I might try a steeper angle and see what happens.

That’s very interesting.  I might have try something different after using the same knife for decades.

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