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Peter K-G

Purfling groove 2 mm, Really! Because we are taught to do so?

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I can't believe the old masters where as stupid as we are. Why on earth are we cutting 2 mm grooves?

 

First violin I made, shallow groove and channel almost finished first. Did not know "better" at the time:

 

post-37356-0-06465200-1454613570_thumb.jpg

 

I'm not doing a better purfling job today now that I "know" how to:

 

post-37356-0-02105700-1454613759_thumb.jpgpost-37356-0-22198000-1454613878_thumb.jpg

 

 

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Prefer your first attempt, the mitre is better. 

What do you mean about the 2mm ? depth or width ? 

 

 

Depth of course, 2 mm wide purfling would be for a cello maybe  :)

The first image was my very first violin made 1997

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If the Cremonese masters purfled a closed box then they'd likely have finished 99% of the arching first.
That would mean the purfling would be a very shallow groove to cut. 

By examining very worn edges (top shoulder) you could ascertain the sort of depths
they went to. 

On many old instruments (thinking about a Guarneri viola) the purfling can bee seen
proud of the plate, not something you find much on modern ones. 

 

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If the Cremonese masters purfled a closed box then they'd likely have finished 99% of the arching first.

That would mean the purfling would be a very shallow groove to cut. 

 

 

That's my believe too!

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Corner shape on your new one is much better. 
'Over work' is very likely, if related to sales then certainly considering today's market.

You can clearly see the purfling has been inserted after the arching was done
on this Andrea Guarneri from 1664, it sits proud of the plate.
Also very little wear to the corner, look how crisp it is. 

post-24957-0-87657600-1454616900_thumb.jpg

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If I had to hand-cut purfling grooves, I'd sure be getting the arching and channel nearly finished first.  A router bit doesn't care much how shallow or deep it has to cut, so I leave the arching and channel for later.

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My purfling is a tad less than 2 mm tall, so a 2 mm deep groove seems appropriate. What's the issue?  <_<

 

The issue relates to following the protocol outlined in the attached diagram.

This requires a deep purfling groove and relatively deep purfling....

 

post-24896-0-96259600-1454620837_thumb.jpg

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I can't believe the old masters where as stupid as we are. Why on earth are we cutting 2 mm grooves?

 

First violin I made, shallow groove and channel almost finished first. Did not know "better" at the time:

 

attachicon.gif2014-03-31 07.39.20.jpg

 

I'm not doing a better purfling job today now that I "know" how to:

 

attachicon.gifWP_20160203_002.jpgattachicon.gifCornerToday.JPG

Hi Peter,

I find your terms of phrase a bit unfortunate given that Roger has spent decades working on restoring examining and copying the great old Cremonese masters and you have not  :) .

 

It is true that a lot of makers and even good copyists purfle into a nearly finished channel these days. One thing to keep in mind was that these guys are not accustomed to manual labor.  Even craftspeople 50 years ago were accustomed to constant manual labour and had much MUCH stronger hands and forearms than people have today....

 

(Even my own father who was a dairy farmer who went to work at 4 AM would have to milk all his 50 cows by hand if there was a power cut. ( This is a superhuman feat that would probably defy cage fighter training) The hand strength for this is incredible but was normal until recently...even now my father is 70 and is quite thin but he has hands and fore arms like Popeye...shake his hand and his hand will just crush yours from trying to be friendly)

 

I doubt that the  mention of physical effort can prove or disprove Rogers theories..........but Ill put it out there

 

Getting a sore finger from a bit of hard work simply did not happen a few years ago.....The whole body was sore and  pain was taken for granted...

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Apologize, but  Ben's post 7 is also a nice example of the ground stain, only the winter or what is called reed line is dark. Also the grain  is not vertical, indicated by the little smear on one side of the reed line. Apologize.

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You can clearly see the purfling has been inserted after the arching was done

on this Andrea Guarneri from 1664, it sits proud of the plate.

attachicon.gifViola Guarneri, Andrea 1664 ITALY Cremona orange-brown 48.1cm n.jpg

 

I'm not quite as sure that this indicates the sequence, as I don't know how things move around over 352 years.  I do know that the spruce shrinks most in the plate thickness direction, which might tend to raise the purfling over time.  Or if the purfling was hammered and compressed into place, it might want to expand and rise up.  I suppose if you could find tool marks that cross the purfling groove but do NOT show up in the purfling, that would be more convincing.

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I've built violins where my purfling ended up looking like this and I always scrape it flush to the spruce or maple. My ground contains water and it causes the purfling to swell more than the surrounding wood.

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 I still do not understand this thread.

 

That's 'cuz you use a CNC router for purfling grooves.  If you had to hand-cut them, you'd probably prefer to cut 1mm deep grooves rather than 2mm, which would require at least roughing out the channel first (instead of a flat platform).  Roger's method shows cutting the deeper purfling groove into the flat platform.

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I agree with Melvin. Compared with most woodworking jobs, letting the purflings in to a violin is a doddle. In the past everything was done by hand. Imagine sawing out the timbers to build a house by hand, or just cutting the moldings for the skirting boards!

 

With proper tools and a good attitude, purfling isn't so hard, even three millimeters deep. Peter, with respect, you could start with a good knife! The craft knife you show on another thread must make heavy weather of the job. Or you might try the Strad style cutters. They work really well, and the work is done with the whole hand, not just the fingertips.

 

By the way, purfling into the full edge is the method we were given, coming from the school in Cremona. You can't blame Roger. His innovation was to cut the edge channel as he does, not the purfling trench.

 

I think that it's important to have some depth of purfling left after the edge is finished. Too little, and it fails as a protection for the plate, and tends to loosen and fall out too easily.

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If Roger says it, we would all do well to pay attention. I cut my purfling groove by hand and can not see what the big deal is.The very top part of the groove is always a tiny bit sloppy. I want to carve the channel and a little purfling away to get a nice tight pretty fit.

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That's 'cuz you use a CNC router for purfling grooves.  If you had to hand-cut them, you'd probably prefer to cut 1mm deep grooves rather than 2mm, which would require at least roughing out the channel first (instead of a flat platform).  Roger's method shows cutting the deeper purfling groove into the flat platform.

 

Not only is a flat platform involved but one set at a height able to accommodate the fluting profile outside the purfling rising to the outer edge of the plate.  (See Step 6 in diagram.)  This results in having to cut a purfling groove to an approximate depth of 3.0mm.  (See Step 2.)

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I like about 2mm of wood left under the purfling, so if I start with 4.75mm I make my cut 2.75mm deep. Last year I made one where I cut the fluting to about half it's depth before purfling. To be honest I don't remember it being all that much  easier, but it did answer a question I had about the look of the finished job. A very deep channel tends to tighten up very well about the purfling, whereas lots of nice old instruments have a looser look.

 

Again, 'Roger's method' is in the cutting of the fluting, and the shaping of the edges, and the details of how you let in the purflings are perhaps less important.

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The purfling on the Guarneri viola in the NMM does stick out of the channel in places, but is also cut down so it's lower than the rest of the fluting.  In these instances the gouge cuts continue into the fluting/arch inside the purfling, while the corner of the gouge appears to have scored into the outer edge very slightly.  There are also several gouge marks that appear to be one gouge stroke that continue from one side of the purfling channel to the other without affecting the purfling.

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Hi Peter,

I find your terms of phrase a bit unfortunate given that Roger has spent decades working on restoring examining and copying the great old Cremonese masters and you have not  :) .

 

It is true that a lot of makers and even good copyists purfle into a nearly finished channel these days. One thing to keep in mind was that these guys are not accustomed to manual labor.  Even craftspeople 50 years ago were accustomed to constant manual labour and had much MUCH stronger hands and forearms than people have today....

 

(Even my own father who was a dairy farmer who went to work at 4 AM would have to milk all his 50 cows by hand if there was a power cut. ( This is a superhuman feat that would probably defy cage fighter training) The hand strength for this is incredible but was normal until recently...even now my father is 70 and is quite thin but he has hands and fore arms like Popeye...shake his hand and his hand will just crush yours from trying to be friendly)

 

I doubt that the  mention of physical effort can prove or disprove Rogers theories..........but Ill put it out there

 

Getting a sore finger from a bit of hard work simply did not happen a few years ago.....The whole body was sore and  pain was taken for granted...

 

The title was to raise the question. It was absolutely not to disrespect Roger in any way. I'm a great admirer of his work and teaching skills and there is a history to why I asked the question. Roger has taught me on MN how to do edge work (still learning)

 

 
Changed the title
 
Thanks
 
Peter

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