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Strad arching templates?


rszemeti

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Hi,

I have started my first attempt at a violin using the drawings on "makingtheviolin.com"  .. I cut a mould according to the pattern supplied (I have a CNC I don't mind using for moulds and templates, but all work on the instrument is by hand) ... the mould looks fine, I built the blocks and ribs without trouble and cut the frontplate.

I cut a set of arching templates in aluminium according to the drawings ... and here's where it goes wrong.  I used the "long"  template to establish the arch profile down the centre of the front plate, no problems here. I then started with the various "across templates" ... the issue became apparent at the "waist" template, at the narrowest part of the C bouts.  The arching template when correct at the centre of the arch is still about 3mm above the "platform" at the edges ... checking the drawings for the arching templates, if you align the centre heights of the across templates with the relevant positions on the "long" template, the end points at the edges are not all in the same plane.

I have lost confidence in these templates.   Is there a better source of arching templates for a strad style violin I can cut out?  Idealy in some sort fo format I can get into my CNC and produce a set for myself in aluminium or acryllic.

 

20231124_011637_resize.thumb.jpg.98b54912296818c05c60b0c4f8796a70.jpg

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It could be that your edge thickness at the centre bout is too low. It is not unusual for edge thickness at the centre bout to be made thicker than the upper and lower bouts. Personally I think it is preferable aesthetically and it also will add strength to the middle bout. Having said that I would say a 3 mm difference of thickness is a bit much, 2 mm is about right. That could mean a centre bout edge thickness about 5 mm at the waist and 3 mm at the upper and lower bout ends.

So I would say your templates could be quite OK.

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I went through exactly the same process, using the arch templates from makingtheviolin.com for my first violin & is still use them (with some tweaking) as a general guide.   These templates are OK.  

Looking at your picture, I think the long arch is still too high.  The ends of the template should sit down below the edge of the plate, in the purfling chanel.  Your arch appears to end up higher than the edge. 

Are you able to measure the total arch height; the thickness at the highest point of the plate?  It should be something like 16mm at this stage.

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1 minute ago, David Stiles said:

I went through exactly the same process, using the arch templates from makingtheviolin.com for my first violin & is still use them (with some tweaking) as a general guide.   These templates are OK.  

Looking at your picture, I think the long arch is still too high.  The ends of the template should sit down below the edge of the plate, in the purfling chanel.  Your arch appears to end up higher than the edge. 

Are you able to measure the total arch height; the thickness at the highest point of the plate?  It should be something like 16mm at this stage.

 

That's a good point. Templates with a full recurve incorporating the purfling channel area can't sit properly until the final stages. I cut the sub edge part of templates I've made away. Completing the arching after getting the upper part accurate is no problem at all.

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It's not hard to see why arching templates aren't popular. Those sold are just about useless as far as practicality goes. But the solution is easy. Anyone can fairly easily make a long arch template that works. It is just a matter of deciding what sort of long arch profile is best after deciding what the maximum height should be. The possible variations are fairly extensive especially for the back plate. 

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Just for reference, here is what I get when I overlay the templates, with the centres of each "across" template lined up with the correct point on the long template in green, the cross templates in blue.  The red horizontal line is through the end points of the long template.   As you can see, some of the cross templates end above the red line, some below.   violin_arching.thumb.png.75930d2687e412e33263fff48c249c3e.png

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19 hours ago, rszemeti said:

Hi,

I have started my first attempt at a violin using the drawings on "makingtheviolin.com"  .. I cut a mould according to the pattern supplied (I have a CNC I don't mind using for moulds and templates, but all work on the instrument is by hand) ... the mould looks fine, I built the blocks and ribs without trouble and cut the frontplate.

I cut a set of arching templates in aluminium according to the drawings ... and here's where it goes wrong.  I used the "long"  template to establish the arch profile down the centre of the front plate, no problems here. I then started with the various "across templates" ... the issue became apparent at the "waist" template, at the narrowest part of the C bouts.  The arching template when correct at the centre of the arch is still about 3mm above the "platform" at the edges ... checking the drawings for the arching templates, if you align the centre heights of the across templates with the relevant positions on the "long" template, the end points at the edges are not all in the same plane.

I have lost confidence in these templates.   Is there a better source of arching templates for a strad style violin I can cut out?  Idealy in some sort fo format I can get into my CNC and produce a set for myself in aluminium or acryllic.

 

20231124_011637_resize.thumb.jpg.98b54912296818c05c60b0c4f8796a70.jpg

Maybe this is one of the reasons why all experienced makers here , recommend using , posters … or another good reliable source 

I heard so many  of the templates are not that accurate 

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28 minutes ago, Arsalan said:

I heard so many  of the templates are not that accurate

Even some of the posters are not accurate.

If OP has experience with CNC he should be able to check the drawings in his 3D software. ANy errors would show during 3D modelling of the arches.

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15 hours ago, David Stiles said:

Are you able to measure the total arch height; the thickness at the highest point of the plate?  It should be something like 16mm at this stage.

 

I've done more work since that photo while waiting for som purfling to show up (the supplier told me he had to cut it in half to get it in the packaging tube, I said OK if you have to .. and I just got it .. the 800mm pieces cut down to 400mm ... and sent in a 900mm tube. I guess the brains of the outfit was not in that day) It's 16.5mm at the highest point now.

20231128_132152_resize.thumb.jpg.325dbb08f9589d337ee400d0eec3b0d0.jpg

Heres the long template, there is about 0.5/0.75mm gap at the ends so I can rework the plate a little flatter yet.

20231128_132209_resize.thumb.jpg.6645c3b9a29440253fffd3c25777460d.jpg

 

And here is the "cross" template ... as you can see it is never going to be right ...

 

20231128_132247_resize.thumb.jpg.876f200b75202591a289be25c120bfc5.jpg

 

4 hours ago, HoGo said:

Even some of the posters are not accurate.

If OP has experience with CNC he should be able to check the drawings in his 3D software. ANy errors would show during 3D modelling of the arches.

I can check it in 2D, no problem, and that was my point, there are errors, some of the across templates have too high an arch to match the long template, some too shallow.   It sounds like there is no concensus on this anyway, and people make their own adjustments, I'll just adjust the templates for consistent platform height, no problem then. Scaling the arche to match the long template is not an issue if it is generally accepted they are often slightly wrong.

I was just hoping for an accurate set to avoid another source of error, which for a newbie is always a good idea.

 

4 hours ago, Arsalan said:

Maybe this is one of the reasons why all experienced makers here , recommend using , posters … or another good re liable source 

I heard so many  of the templates are not that accurate 

 Yes, indeed, and that is what I was asking for ...a good reliable source ... if you know of one, or a good PDF poster I can buy with arching templates, just let me know ...

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Looks like you already cut way too much from the center arch. The concave areas are very wide and the arch looks pinched to my eye. The channeling in the centerbout areas is very narrow and almost immediately turns into arch while you carved wide platforms and from there you carved smooth transition into arch by removal of wood further from edge. To me the the template looks closer to "standard" arch than what you accomplished.

Makers use templates to guide the convex shape of arch only and the rest is done by connecting it to the edges when the purfling is done and channel excavated.

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One thing one should keep in mind when drawing instruments or working after drawings that were taken from old instruments is that there are deformations in the whole body that can be significant in instruments that are more than 2-300 years old. the whole body bends like a bow under load of strings and arch height measured along top may be lower than arch measured across. In bouts you can see many forms of distortion and perfectly exact cross templates don't necessarily match heights of long arch template.

I've done extensive work in drawing musical instruments from CT scans and differences between height of cross and long arches on 1923 Gibson mandolin were almost 1mm, and that was mandolin scanned without strings so some of the forces were not in action.

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3 hours ago, rszemeti said:

And here is the "cross" template ... as you can see it is never going to be right ...

20231128_132247_resize.thumb.jpg.876f200b75202591a289be25c120bfc5.jpg

Are you sure you printed the cross template at the correct scale? I've never tried to print them from the Makingtheviolin.com site, but it seems a bit undersized to me.

I have a different approach, I don't make templates, I use a profilometer if I want to compare with the curves of other instruments or posters, I usually only measure the central radius, which in your arch seems very tight. If you wish you can watch this video: https://www.youtube.com/watch?v=rH82AxfDhPQ&list=PLaxadm6POX7Hqti7L6LWsHk_G-xkqjGIG&index=8

The poster you see in the video is that of the Titian 1715, the archings are deformed as usual and slightly low for my tastes, but not too much and it is a good starting point for the shape of the curves.

Here you see one of my radius gauges in action, the shadow completes the picture:

DSC_8169GXXIV2017Radiustop.thumb.jpg.ee13e824143ac3ee31a359f7f07119df.jpg

If you want you can read this article where I show my way of making the archings, perhaps not the simplest approach and perhaps not exactly for beginners, but that's what I do.

https://davidesora.altervista.org/wp-content/uploads/2021/02/Davide-Sora-Archings-article-published-in-MVA-newsletter-2017.pdf

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First watch Davide Sora's video, it's awesome!  

and then... 

C bout appears to be cut in too far from the edges. The first thing you should do is trim some more off the top of the plate so that the long arch template fits. That should help get the C bout lower and closer fit to the template. 

Don't worry to much about the overall height, just don't go too low like 12mm like I did on an early plate which I had to scrap.  :D   

Then get the upper and lower bout templates fit as well as you can.

I use half templates, they seem to work out better for me.  It gives some freedom to fudge things a bit.  

My first one started out a bit peanutty in the middle like that but I was able to work it out.   

 

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8 hours ago, rszemeti said:

I've done more work since that photo while waiting for som purfling to show up (the supplier told me he had to cut it in half to get it in the packaging tube, I said OK if you have to .. and I just got it .. the 800mm pieces cut down to 400mm ... and sent in a 900mm tube. I guess the brains of the outfit was not in that day) It's 16.5mm at the highest point now.

20231128_132152_resize.thumb.jpg.325dbb08f9589d337ee400d0eec3b0d0.jpg

Heres the long template, there is about 0.5/0.75mm gap at the ends so I can rework the plate a little flatter yet.

20231128_132209_resize.thumb.jpg.6645c3b9a29440253fffd3c25777460d.jpg

 

And here is the "cross" template ... as you can see it is never going to be right ...

 

20231128_132247_resize.thumb.jpg.876f200b75202591a289be25c120bfc5.jpg

 

I can check it in 2D, no problem, and that was my point, there are errors, some of the across templates have too high an arch to match the long template, some too shallow.   It sounds like there is no concensus on this anyway, and people make their own adjustments, I'll just adjust the templates for consistent platform height, no problem then. Scaling the arche to match the long template is not an issue if it is generally accepted they are often slightly wrong.

I was just hoping for an accurate set to avoid another source of error, which for a newbie is always a good idea.

 

 Yes, indeed, and that is what I was asking for ...a good reliable source ... if you know of one, or a good PDF poster I can buy with arching templates, just let me know ...

Is it the first violin you are making ? 
have you made instruments before ? 

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8 hours ago, rszemeti said:

I've done more work since that photo while waiting for som purfling to show up (the supplier told me he had to cut it in half to get it in the packaging tube, I said OK if you have to .. and I just got it .. the 800mm pieces cut down to 400mm ... and sent in a 900mm tube. I guess the brains of the outfit was not in that day) It's 16.5mm at the highest point now.

20231128_132152_resize.thumb.jpg.325dbb08f9589d337ee400d0eec3b0d0.jpg

Heres the long template, there is about 0.5/0.75mm gap at the ends so I can rework the plate a little flatter yet.

20231128_132209_resize.thumb.jpg.6645c3b9a29440253fffd3c25777460d.jpg

 

And here is the "cross" template ... as you can see it is never going to be right ...

 

20231128_132247_resize.thumb.jpg.876f200b75202591a289be25c120bfc5.jpg

 

I can check it in 2D, no problem, and that was my point, there are errors, some of the across templates have too high an arch to match the long template, some too shallow.   It sounds like there is no concensus on this anyway, and people make their own adjustments, I'll just adjust the templates for consistent platform height, no problem then. Scaling the arche to match the long template is not an issue if it is generally accepted they are often slightly wrong.

I was just hoping for an accurate set to avoid another source of error, which for a newbie is always a good idea.

 

 Yes, indeed, and that is what I was asking for ...a good reliable source ... if you know of one, or a good PDF poster I can buy with arching templates, just let me know ...

I also recommend using profile guage to check the arching and find out which area to shave more …. Try it specially for the first instruments it help a lot 

for me better than templates 

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Well to me it looks as if the templates aren't the problem because they appear to not be full length, or width in the case of the cross-arch one, so that takes the edge height out of the equation.

As Davide's photo shows a template made having that edge scoop would not sit on a flat edge. It also shows how tight the recurve is approaching the edge. And how the convexity of the arch reaches almost the full width of the waist.

And, going by the way your templates sit, the gaps at the ends can be reduced just about completely by reducing the height of the arch. But it would have to be quite a lot at the centre bout because you have cut into the convex upper part or sides of the arch too much. And doing so would of course alter the shape of the long arch. But I wouldn't see that as a major problem if the height or depth finished about 14 mm. So don't worry about the templates, it could be your best option.

Edited by Dennis J
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I quickly checked the drawings in Illustrator and found no problem.

The higghest spot of central cross arch measures ~19,4mm (which is quite tall) and the long arch at the same spot matches it.

On the drawing of the top templates I measured height from bottom of channel to top of arch and there is slight difference with the cross arch being slightly lower than long arch (by about 0.5-1mm) which corresponds to typical difference of thicker edges at the center bouts versus edges at lower/upper bouts.

So I reckon the problem was in OP's printing which is not always to real scale.

PS: I think most folks would consider 19.4mm top arch a bit too much so if you are at 19+ by following the long arch template, you can still safely remove 3-4 mm and get reasonable arch shape closer to normal (don't remove any wood from the areas near edges).

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There are two sets of drawings on the "making the violin" web, one shows the outside profiles of plates from underside of edges and the other shows just final templates from bottom of the channel to top. Other than the higer-than-typical arch height they do agree well enough with each other. I wouldn't comment if they (based upon cycloids) are good or wrong for tone.

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11 hours ago, HoGo said:

There are two sets of drawings on the "making the violin" web, one shows the outside profiles of plates from underside of edges and the other shows just final templates from bottom of the channel to top. Other than the higer-than-typical arch height they do agree well enough with each other. I wouldn't comment if they (based upon cycloids) are good or wrong for tone.

I don't know how you measured 19mm earlier, perhaps Illustrator is not a good package for making measurements, the actual height of the arching on the long template is 12mm.

If you think they agree with each other, perhaps you can help me understand this. 

Here is the drawing of the long arch, with the positions of the templates used on "making the violin" .. I have used a trusted CAD package to add height information:

arch1.thumb.png.146149d86f1c995261eb4e3ade449042.png

So for example, we can see the first template position (please note, on making the violin.com they are not at "fifths", but at specified locations) the height at the first position is 9.4mm ... I would expect the "across" template to also have a height of 9.4mm at this point.

Here are the heights of the "across" templates

arch2.thumb.png.9011c6104cd321bb46decf85599a4b3f.png

So for example, in position one we should have a height of 9.4mm according to the "long" template, but we have a height of 9.0mm, so the across template is 0.4mm too shallow at this point.   The differences range from -0.6mm to +1.2mm  to maintain a consistent edge height.

I have also attached a PDF.   Of course, maybe I am misunderstanding something fundamental, for example, maybe the edge thickness changes by 1.8mm around the instrument, but my reading of the instructions was it should be carefully cut to a cosntant 4.2mm

I have also included a PDF, if I made an error, perhaps you can find it and help me understand.

erratum: postion 3 shuld read +0.5mm, not 0.6mm, typo.

Arching_errors.pdf

Edited by rszemeti
Minor numerical
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On 11/28/2023 at 5:43 PM, Davide Sora said:

Are you sure you printed the cross template at the correct scale? I've never tried to print them from the Makingtheviolin.com site, but it seems a bit undersized to me.

...

If you want you can read this article where I show my way of making the archings, perhaps not the simplest approach and perhaps not exactly for beginners, but that's what I do.

https://davidesora.altervista.org/wp-content/uploads/2021/02/Davide-Sora-Archings-article-published-in-MVA-newsletter-2017.pdf

Thanks David, I have watched your videos for many hours, I shall review again. 

I did not print the templates, I imported the drawings directly into a CNC package and cut the templates on a precision router, they will be +-0.1mm maximum from the drawings.

I compared the "c bout" profile to the pencil drawings and, it does match quite well in shape if I correct the height by a simple scaling.

What I plan to do is scale the heights of the arch templates to match the long template. It is difficult to always understand what people mean by "arch height" as some people seem to talk about it from the plate base and others from the edge thickness, but to me, the long template seems about correct (12mm height, + 4.2mm edge thickness = 16.2mm)  so I am going to take that one as "good" and adjust the others to match. 

I don't think the plate is far off, I still have some extra height in the long template to work with, It is always better to have some more wood to remove than

The other difference is you have used "fifths" for the template positions, where as the "making the violin" website appears to have used their own specific position.  I will study your drawings more carefully and see if I can make some templates that match and check my plate at the "fifths" positions.

I have a PDF that explains the errors a little better.  I shall try correcting them to match the long template.

I appreciate your PDF, I think the "radius" templates are too difficult for me at this point, maybe on my second instrument .. I have some nice wood from Pahler I will use for that.

Arching_errors.pdf

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I checked again the files, namely the #3 and #4 on this page:

http://www.makingtheviolin.com/Arching

and found no real problem. Illustartor is not CAD but these files are svg's so they are not presumably drafted in professional CAD either (so I wouldn't expect any rocket science precision) and Illustrator is good enough for this simple check. The problem is that Illustartor doesn't convert them in correct scale so my numbers were slightly enlarged (sorry I didn't check top length, I just compared the arch heights within the drawing against each other).

You really should have a close look at the figure #3 especially at the channeling. You'll see the small green rectangles that show how deep channel the cycloids produce and you can clearly see that there are differences between the real channel and the "reconstruction using CC" It's hard to see it in the preview that you see in browser but when you zoom in you'll see that the displacement of the CC's from real channels is varying among the crossections (the central has noticeably less deep channel) while the arch height between central and the next crossection doesn't differ that much which creates difference in the final template height. Actually you can see the numbers at the crossectins that tell you the parameters of the CC, the central is h11.4 while the next one is h11.5... that is height from bottom of the CC and the thickness of plate at the channel (green rectangle) is 3 mm at upper/lower bouts and 4mm at center bout.

The templates figure #4 is exactly the same drawing with most unimportant lines removed so you cannot see that the bottoms of the CC's don't align in the same plane like you did in your sketch.

PS: the svg's import into AI scled up by 25% so I needed to scale down to 80% to get real size.

 

 

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