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Dennis J

Arching Method

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I'm making a new set of arching guides using the same outline pattern as in previous posts. This time with lower long arch heights, 15 mm and 14.2 mm.

Here is a rundown of the way I go about making a layout based on Double String Length lines to provide the measurements needed to make arching templates. It's only necessary to do one side of the pattern but I do both.

1. Fix an A1 sheet of paper to a board so that you can accurately draw verticals.

2. Draw a centreline down the length of the paper.

3. Using the centreline draw the violin outline along with the usual cross-arch positions along its length. I also include one at the bridge position.

4. Use a long ruler to mark a point on the centreline 660 mm from the bridge location. That is Double String Length, 2 x 330 mm.

5. Mark points on the lower cross-arch line 47 mm from the centreline. This measurement is not set in stone, but it can't be too close to the pattern edge.

6. Using the long ruler draw lines connecting the 660 mm point and the 47 mm locations.

7. Use a compass to make verticals to the DSL lines between the points at which they cross the upper and lower cross-arch positions.

8. The verticals can then be used to draw arcs tangent to the DSL lines. I've used a measurement of 79 mm from the centreline on the lower bout cross-arch line. The radius of the arc will locate all of the inflection points on the horizontal axis.

9. A baseline can be drawn on each arc to complete the plan layout.

10. Now the base length of right angle triangles can be measured at each cross-arch position along the arc. With that measurement, along with the selected angle of elevation (6 deg. for the top plate and 5 deg. for the back), an inflection point height can be calculated. That figure is added to the nominal edge height selected (4.5 mm) to give the height of the inflection point above the base of the plates.

Aluminium blanks are marked out using calipers and a vernier gauge as in the cardboard tests shown in the pics. I've only shown the waist and lower corner arching on the cardboard tests. These two arching positions are the most critical to get right. If they work the other archings will work well too.

I use a fine point pen to mark the arching curve on the anodised aluminium blanks. It shows up well and can be wiped out easily with alcohol. As long as the line passes through the inflection point and looks right use a jeweller's saw to cut out excess metal, keeping about 1-2 mm from the line. Then use a fairly coarse half-round file to develop the curve, still keeping well away from the line. Then check the filed section for symmetry by laying it down on a sheet of paper, marking the line of the curve and then flipping it over to line up with the centre line which is marked on both sides of each blank.

When this central area is right use needle files to develop each end of the arch checking for symmetry all the time. I've got some sections of large diameter plastic pipes which ban be used to smooth out the convex curves. I finish each guide with a burnisher.

Filing the arching shape is actually easier than trying to draw one. Complying with the four points that define the compound curve -- The central height, the inflection point, the bottom of the channel line, and the termination at edge/crest height, a very accurate template can be made. As I've said in previous posts I use a nominal edge height for calculating the inflection point height for each cross arch, but I mark out the templates to allow for a slightly thicker than normal edge when marking out the edge/crest height on each template. That is 4.5 for the uppermost and lowest arches, 4.8 mm for the corner ones, and 5.0 for the waist and bridge position ones.

In previous posts I laid out different ways of doing this and I wouldn't rule anything out. But I think having the arcs tangent to the DSL lines is probably the best way to go.

I think that's about it. Believe me, making these templates is not terribly difficult. When you know how to go about it that is. I hope it is of some benefit to serious makers.

 

 

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Dennis,

I have followed your various threads with interest. You have clearly devised a workable method. I hope that you will take this gentle criticism in the spirit that it is intended. To my mind, your system seems unnecessarily overwrought. I am generally of the opinion that the simplest solution is the best, for the sake of efficiency (a concern for me because new making is my sole occupation) and for the sake of the appearance of fluidity and effortlessness that fine sculpture offers the senses. 

While I believe that your arching technique is overall sound, I think it's important to attempt to put yourself in the shoes of semi-literate 16th century Italians. What tools did they have? What level of mathematical knowledge did they possess? My friend and colleague @David Beard has explored this extensively and put forth one possible reconstruction of the Cremonese working method that is very simple and compelling. Other luthiers, such as Roger Hargrave have written at length along this lines also. I am sure that you have made a thorough examination of the existing literature, but on the off chance you aren't familiar with their works, I believe you would enjoy reading them, if for no other reason than to compare them with your own approach at the bench. 

My best, sincerely,

J

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An arching method and a method of creating arching templates are different things.  While you’ve worked out a seemingly very workable method of creating arching templates, the actual arching method is still lacking.  Most golden period instruments show a very clear tooling progression.  It seems like you have a solid method for the design, but that’s only half the battle.  

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I'll take your comment "workable method" as a plus Jackson. But I think it's a bit rough to describe 16th century Italians as semi-literate ignoramuses. I'm sure the Amati family of luthiers were quite capable mathematicians and geometers. And I'm sure they would have had a very good understanding of arching geometry.

 

 

 

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2 hours ago, Dennis J said:

And I'm sure they would have had a very good understanding of arching geometry.

Understanding geometry and using it in a detailed way are different things.  I find the complete lack of arching templates from that time to be an indication that they might have leaned more on the sculpture side of things.  Certainly all of those carvings from that active period didn't use templates for every part of the sculpture, although some general proportions could have been used at the start.

I find it perfectly plausable (and even most likely) that the old arching methods were developed over time and handed down from master to apprentice, and not fixed by templates.  I have a perfectly good understanding of geometry and math, but find it easier and faster (and more satisfying) to get the shape I want without templates.  Now that I'm starting to use CNC, it is necessary to specify the arching in a rigid mathematical way... but that only gets most of the wood off, and I still finesse the shape by hand and eye to get what I really want.

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3 hours ago, Dennis J said:

I'll take your comment "workable method" as a plus Jackson. But I think it's a bit rough to describe 16th century Italians as semi-literate ignoramuses. I'm sure the Amati family of luthiers were quite capable mathematicians and geometers. And I'm sure they would have had a very good understanding of arching geometry.

 

 

 

I did not use the term 'ignoramus', nor do I think it applies. It's well established that literacy rates, among men alone, were staggeringly low by modern standards in Renaissance Europe. One doesn't have to know how to read or write to be intelligent and skilled.  But literacy does affect the transmission of knowledge, and so I turn to Don Noon's reply to agree with the instructional model he hints at.

Lastly, while this is a perennial hot button issue here, I too would like to point to the lack of extant templates and say that they are not needed and frankly cause the work to go so much slower in my experience than punching guide marks and just removing everything that doesn't look like an arch. 

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I'm not trying to prove that early makers used arching templates. But if they did they probably would have made them out of paper much like I have done with the test pieces in the pic.

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49 minutes ago, Dennis J said:

I'm not trying to prove that early makers used arching templates. But if they did they probably would have made them out of paper much like I have done with the test pieces in the pic.

My old books say to copy an arch one needs to lay on edge a thin leaf of wood across the bout as level as possible and gently scribe across the surface of the arch to be copied thus leaving an identical scribe mark on the wood - do not scratch the violin varnish with the point of the scribe.

One of the books say for the long arch copying one should use the radius of three lengths of the fiddle they want to copy - I haven't tried that one yet.

Maybe Dennis J. missed out on Mr. Kelly"s tutorial some time ago on making the discs and hole placement for template making?

 

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There seems to be some sort of misunderstanding here about this whole issue. What I have proposed here is simply a way to make arching templates. I'm not trying to be critical of other approaches to arching. For instance David Beard's way of handling arching seems perfectly sensible to me. But, as he says, it is a way to handle arching without templates.

My method revolves around the location of the inflection point between two curves. There is a nexus between the vertical and horizontal axis in relation to the edge of the plate regarding the location of that point.

If it is set too high or close to the edge of the plate, particularly at the waist cross-arch location, making a smooth compound curve out of those two curving elements is not possible. With the settings of the angle of elevation and arc radius in the layout I've shown I've tried to maximise the convex component of the arching shape there. If I had the inflection point any higher I don't think a smooth compound curve would be possible. I love the way it works and I can't see anything wrong with the results produced.

 

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My issue with arching templates, and templates in general, is that one tends to work towards the template rather than the piece. This can be a good, even necessary, thing in the process of making. I think a workable mold and rib structure is dependent on an accurate template. I need my scroll templates to set me on the right path, but after a certain point, I don't. Do I need a template for the pegbox? No, but it saves me time not having to lay-out the thing for every instrument.
I think arching is of such a fundamental importance to an instrument that I would not trust it to a set of templates. The arching is where the woodworking skill, intuition, and artistry all come together. It is the best/most fun part of violin making. The loosest, most fuck- it part. And as such requires the most skill to execute well. When we make an instrument we are sculptors and wood carvers, not carpenters. We should keep that in mind.
That being said, there are a lot of very fine makers that use arching templates, and I say more power to them. It's just not for me.

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I'm inclined to confine my artistic endeavours to drawing and sculpture. One thing I have learned in all of this is how finely balanced arching shapes are. I know many makers are capable of producing very attractive arching contours, but are they the ideal shape required for this musical instrument?

 

 

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25 minutes ago, Dennis J said:

but are they the ideal shape required for this musical instrument?

I think you'll find we are capable of making these ideal shapes, which is why we can make a living. 

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If you like to copy arches with "templates", I think it's much better to draw them on paper and compare with this type of tool (this is a bad tool, there are much better ones)

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11 hours ago, Dennis J said:

but are they the ideal shape required for this musical instrument?

If there is one exact ideal sound and all wood was exactly the same, then there might be an "ideal" arching shape.

The fact that there are all kinds of great violins with a variety of archings and different sounds kinda puts the kibosh on the "ideal" idea.

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16 minutes ago, Don Noon said:

If there is one exact ideal sound and all wood was exactly the same, then there might be an "ideal" arching shape.

The fact that there are all kinds of great violins with a variety of archings and different sounds kinda puts the kibosh on the "ideal" idea.

Yup! Why does it take a NASA engineer to expose so many of the foibles in fiddlemaking thought?

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1 minute ago, David Burgess said:

Yup! Why does it take a NASA engineer to expose so many of the foibles in fiddlemaking thought?

Outsider/non-traditional perspectives help refresh any field. Thanks, Don!

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23 hours ago, uncle duke said:

One of the books say for the long arch copying one should use the radius of three lengths of the fiddle they want to copy - I haven't tried that one yet.

So running out a tape measure to around 1064 mm on a concrete floor I came up with a 15 mm height - wasn't very precise, used an unpointed piece of chalk and the tape measure slipped a little bit - it'll work in a pinch, even haphazardly.    

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38 minutes ago, David Burgess said:

Yup! Why does it take a NASA engineer to expose so many of the foibles in fiddlemaking thought?

I guess because he is used to looking for facts and knowledge, combined with a lifetime of testing theories, day in day out.

This is compared to airy fairy theories, dreamt up after reading rambling books written by people who could hardly play, and were clueless as to how violins actually work, waffling on about tone after drinking too much sherry in front of the fire. Bizarre theories about what happens to wood, weird arching fantasies, strange full moon capers in the woods with a tuning fork, varnish with unicorn tears in, visited by the ghost of Stradivari...

If we got rid of all the crackpot theories, there would be little to talk about in many cases.

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18 hours ago, arglebargle said:

My issue with arching templates, and templates in general, is that one tends to work towards the template rather than the piece. This can be a good, even necessary, thing in the process of making. I think a workable mold and rib structure is dependent on an accurate template. I need my scroll templates to set me on the right path, but after a certain point, I don't. Do I need a template for the pegbox? No, but it saves me time not having to lay-out the thing for every instrument.
I think arching is of such a fundamental importance to an instrument that I would not trust it to a set of templates. The arching is where the woodworking skill, intuition, and artistry all come together. It is the best/most fun part of violin making. The loosest, most fuck- it part. And as such requires the most skill to execute well. When we make an instrument we are sculptors and wood carvers, not carpenters. We should keep that in mind.
That being said, there are a lot of very fine makers that use arching templates, and I say more power to them. It's just not for me.

Nicely put, agreed.

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Well, so much for what I thought was the best explanation of the arching concept I've  developed.

I get the impression that some makers think it's a crime to even use arching templates.

My posts have attracted a lot of interest because many aspiring luthiers don't have a clue as to how they might go about arching violin plates.

I've simply shown a way to solve that problem. Time consuming but very rewarding.

 

 

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Maybe there actually is an ideal sound and an ideal arching that goes along with it.  Think of the theory behind a VSA tone competition, but on a scale massive enough that you could call the result an ideal

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20 minutes ago, Michael_Molnar said:

My issue with templates is that they don’t tell me how to blend the surfaces between the templates. Therein lies the rub.

It's possible to calibrate any number of templates at any drawn cross-arch position between the uppermost and lowest ends of the arc on the layout. When the cross-arch line is drawn all the necessary measurements --- edge of plate, highest point of the arch (taken from the long arch), inflection point height (calculation from length of triangle baseline), inflection point position on the horizontal axis located at the edge of the arc,  and bottom of the channel. The arching finishes just inside the plate edge of course. All of those inflection points flow together to produce the inflection surface.

 

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Dennis,

I feel terrible because despite my best intentions I seem to have initiated a 'pile-on'. I want to commend you for what took a lot of effort to provide guidance for yourself and others in the arching process. There are so many paths to a good result in this business, and have been for a long time. Please don't be discouraged. I have made my personal feelings on templates clear, but want to reiterate that I have no contempt whatsoever for those that use them. I have only admiration for fine luthiers regardless of their system. I invite you or anyone else to come spend a week in my shop and we can share ideas and techniques. I'm here to learn and want to keep an open mind always. 

 

J

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