Jump to content
Maestronet Forums

No need for arching templates!


violins88
 Share

Recommended Posts

This morning I was scraping a violin back. The rough gouging completed, channel cut according to David Sora, purfling installed.  Now the final shaping begins. As in the roughing out part, where I sometimes watch my hands as they use the gouge, as if I don't have to think about what to do next. My hands know.

 

Now it's the scraping part. Sitting on a chair, holding the plate at the correct angle so that the morning sun shows me the shape of the surface. Again, my hands seem to know what to do with the scraper.

 

How do I know the what the shape is supposed to be? The arches in the drawing of course. But I do not make templates of the arches, but rather just measure the height of each arch in the middle, at the half distance from the centerline, and at the channel. All totaled, there are 5 arches, each with 5 points, so 25 points total.

 

It occurs to me that we don't need arch drawings, as long as the above 25 points are measured accrately,.because as I shape the plate, the sunlight suggests to me where to scrape. Hills and valleys are smoothly merged.

 

 

So..... do we need template drawings?

 

I think a whole plate can be specified with 25 points. 

 

Comments appreciated. Thanks.

Link to comment
Share on other sites

  • Replies 680
  • Created
  • Last Reply

Top Posters In This Topic

I guess you call it shadow light.  if you don't care to use daylight. there  is a bulb with a mirrored top that you stand vertically on your workbench and does the same thing. I have one but don't use it. The problem with it is, if you don't  know all the tricks to get a smooth surface and you set your plate to shadow-light it, it is no longer a glossy smooth surface, just valleys and hills.

Link to comment
Share on other sites

I guess you call it shadow light.  if you don't care to use daylight. there  is a bulb with a mirrored top that you stand vertically on your workbench and does the same thing. I have one but don't use it. The problem with it is, if you don't  know all the tricks to get a smooth surface and you set your plate to shadow-light it, it is no longer a glossy smooth surface, just valleys and hills.

If you have a point source and shade it with a straight line, it works. Not as well as the Sun, but still works.

Link to comment
Share on other sites

I never trust an arching template that I didn't take with my own hands from the instrument..

.Always check arching profiles etc against the given measurements just in case something went wrong during printing. Easy to correct with a scanner and lap top these days.

 

In theory a competent luthier who can recognize a Cremonese arching should be able to carve one just by eye but it might not be that simple. :(

Link to comment
Share on other sites

I guess you call it shadow light.  if you don't care to use daylight. there  is a bulb with a mirrored top that you stand vertically on your workbench and does the same thing. I have one but don't use it. The problem with it is, if you don't  know all the tricks to get a smooth surface and you set your plate to shadow-light it, it is no longer a glossy smooth surface, just valleys and hills.

Fred, didn't you once think the longitudinal and cross arches were merely the simple shapes of bent sticks? 

Link to comment
Share on other sites

This morning I was scraping a violin back. The rough gouging completed, channel cut according to David Sora, purfling installed.  Now the final shaping begins. As in the roughing out part, where I sometimes watch my hands as they use the gouge, as if I don't have to think about what to do next. My hands know.

 

Now it's the scraping part. Sitting on a chair, holding the plate at the correct angle so that the morning sun shows me the shape of the surface. Again, my hands seem to know what to do with the scraper.

 

How do I know the what the shape is supposed to be? The arches in the drawing of course. But I do not make templates of the arches, but rather just measure the height of each arch in the middle, at the half distance from the centerline, and at the channel. All totaled, there are 5 arches, each with 5 points, so 25 points total.

 

It occurs to me that we don't need arch drawings, as long as the above 25 points are measured accrately,.because as I shape the plate, the sunlight suggests to me where to scrape. Hills and valleys are smoothly merged.

 

 

So..... do we need template drawings?

 

I think a whole plate can be specified with 25 points. 

 

Comments appreciated. Thanks.

 

I tried to use this system in early times, but with practice I learned to visualize the arc as a whole without measuring too much.

25 points are a lot, and measuring them on a curved surface makes it difficult to maintain the accuracy so I abandoned.

Now I measure only the sixth (long arch) in 7 simmetrical points for reference, connecting by eye the level of the channel at the edges to the central long arch with the appropriate concave and convex seamlessly curves "stored" in my head and hands.

I try to see the shape and symmetry also by drawing four level curves (five for the top) , but I do the most of the work basically by eye and tactile sensation.

 

So......do we need template drawings?

 

No, provided you have the ability to mentally visualize the shape of the arching you want to do, not an easy task.......

Otherwise might help.

 

Davide

Link to comment
Share on other sites

Whether to use templates or not depends on how sophisticated we decide the very best violins are, and how well we can duplicate them with our eye if we want to.  Beginners, IMO, are wasting time NOT to use templates of good examples and follow them at least until they feel safe without "training wheels."  (Sure, we have to compensate for distortions and the like, and the exact original condition may always be in doubt;  but it's better than nothing.)

 

There's plenty to argue about whether there are some things found in all great violins in spite of the noticeable variations in most of them.  Some say yes, some say no.  Some don't have an opinion.  

Link to comment
Share on other sites

Whether to use templates or not depends on how sophisticated we decide the very best violins are, and how well we can duplicate them with our eye if we want to.  Beginners, IMO, are wasting time NOT to use templates of good examples and follow them at least until they feel safe without "training wheels."  (Sure, we have to compensate for distortions and the like, and the exact original condition may always be in doubt;  but it's better than nothing.)

 

There's plenty to argue about whether there are some things found in all great violins in spite of the noticeable variations in most of them.  Some say yes, some say no.  Some don't have an opinion.  

I certainly refer to arching templets that I have made of an instrument that I am copying. I don't follow them slavishly but shadow and light can sometimes be misleading ( or forgiving of one's preconceptions) even if one is directly copying an instrument that is on one's bench or a plaster cast.

One trick I use to compare an arch I am working on  to a plaster cast is to carefully and quickly  coat the wood with white masking tape. This makes it much easier to see the arch.

Link to comment
Share on other sites

I have done both , currently on the violas I am doing it without, we'll see how they come out ,I am using the method outlined By F. Dennis, utilizing ratios of the arch height as guide points   . I can see plus and minus to both methods . Certainly for a beginner who is starting out without the guidance of an instructor , arch templates will help one get in the ball park quicker , but they are not a magic bullet. I found that when using the templates that an 'all over' approach worked better than trying to carve each arch to position then fairing the surface between them, rather I would try to bring the whole surface down at approximately equal rates . Low angle light is great for finding hump bumps and shallow dips, I also use my arching caliper a lot to help judge symmetry and flow of the curves , especially around the quarter bouts as they / I have a tendency to leave them rather full.

Link to comment
Share on other sites

Hi Marty- my templates were made using bent sticks which follow a catenary. Once you get the hang of it  they are easy to make. The cross arches are determined by the long arch you select. As I mentioned in another post, checking a month or so later the inst's I checked had significant changes to the cross template I checked. Also, many years ago my neighbor Roelof Weertmann who got me into making, gave me a drawing of archings of  a top Cremona inst where the distortion from constant tight sound posts would make one think there was an  error in copying. Maybe the secret is don't make it precise.

Link to comment
Share on other sites

Hi Marty- my templates were made using bent sticks which follow a catenary. Once you get the hang of it  they are easy to make. The cross arches are determined by the long arch you select. As I mentioned in another post, checking a month or so later the inst's I checked had significant changes to the cross template I checked. Also, many years ago my neighbor Roelof Weertmann who got me into making, gave me a drawing of archings of  a top Cremona inst where the distortion from constant tight sound posts would make one think there was an  error in copying. Maybe the secret is don't make it precise.

You might like

Torbjörn Zethelius

 

He teaches the use of Chains to do the inside arching, and then the outside arching.

Link to comment
Share on other sites

I guess you call it shadow light.  if you don't care to use daylight. there  is a bulb with a mirrored top that you stand vertically on your workbench and does the same thing. I have one but don't use it. The problem with it is, if you don't  know all the tricks to get a smooth surface and you set your plate to shadow-light it, it is no longer a glossy smooth surface, just valleys and hills.

I would like to learn more about this lamp, Fred. I now use an adjustable lamp to cast the shadow, but I want something better. Sometimes I get the morning sun in through the window, which is perfect.

 

I scrape my plates (No sanding)  and use shadows to guide me. Yes, the shadows expose all the warts, but then I can remove them. Well, that's the theory anyhow.

 

Mike

Link to comment
Share on other sites

I thought the Cremonese secret is in the varnish. :D

This reminds me of the joke which I believe was in "the Simpsons."  Homer and Apu (sp?) risk life and limb to climb a great peak because it is said that on the top lives a great guru who can tell them the meaning of life.

 

So they finally make it and sure enough there is the guru, sitting there all peaceful in the lotus position, with his eyes closed.  Homer asks, "Oh great one, what is the meaning of life?

 

"Life is a bubbling fountain."

 

Homer says in a questioning tone, "It IS?"

 

The guru looks shocked and his eyes pop wide open for the first time in years, and he cries, "You mean, it ISN'T?"

 

 

Applying that to violins  Stradivari says, "The secret, young man, is varnish."

Link to comment
Share on other sites

Hello

I am, in a sense, a self made maker.

 I went one year to a luthier shop asking for: "how do you make this". I stood one hour and half and paid the class. She had not any pupils. Now she like to teach. May be another way to earn money.

So I learned a lot working alone at home and reading a lot.

For me, templates are usefull. I made a lot of errors working by eye and discovered what it worth about templates.

 I recently made some templates but what I use to do is to work on one side of y the plate and then copy with a hand copier (seems to a comb) the other side.

The long arch is made by eye.

I confess that I am not happy with  my central part of the belly. I guess I have to work with good templates after all.

Regards 

Tango

Link to comment
Share on other sites

While working with intuition, practice, and vision seems a requirement for violins, the underlying design is a thing of great beauty.  Personally, I am highly attracted to Denis's work on Renaissance layout methods, and influenced by my time staring at the vaulted structures in various places.  I ran across this rather nice exposition:

 

http://www-classes.usc.edu/architecture/structures/Arch213B/lectures/06-arch.pdf which some here might enjoy.

 

A problem we face is that we are always designing a complex arched system, with its implied ribs and hinge zones and system of force transfer.  The neck block tries to rotate towards the bridge and loads this structure, for example.  Turn the violin scroll up and take a look, consider the rib structure from upper corner blocks to neck block.  As an arch, the keystone is taking a good deal of load at an angle along the axis of the arch.  So there's a shell on each side, one in tension (back) and one in compression down (the longitudinal arch).  But there is also the spreading force at the widest part of the bout taken up by the cross arching.  If I wanted to transfer more of this load to the wide part of the arch, I'd put a compression beam from the neck block (keystone) to some point on the rib arch.  Well, that is part of what the shell does.  So the load has to be considered as spreading out from the neck block, with some resisted by the bending of the top wood itself and some transferred to the bending of the ribs.  This gets baffling after a little bit.  But I suspect that relatively minor looking variations have an effect on the functioning of the arch, and likely an effect on the sound.

That is why I want to understand arching in fiddles, which I doubt is an achievable goal, and develop/learn and use a consistent system for generating/carving arches that always act about the same.  Then the other variables become a little more open to investigation.

 

Aspects I hadn't considered much in my previous bout of violinmaking were the existence of embedded ribs and hinge zones, and the key importance of diagonal and fan type arches within the shell structure.  

 

Aspects that really complicate my thinking are the bass bar, the two point bridge load, and the sound post.  Having long slices in the top doesn't make things all that clear either!

 

Just food for thought, and that outline was quite compelling. 

Link to comment
Share on other sites

A problem we face is that we are always designing a complex arched system, with its implied ribs and hinge zones and system of force transfer.  

 

The static forces are of some concern, but as long as there is some sortof arch, it seems to survive OK.  To me, the far larger problem with the arched system is how it behaves across the vibration spectrum.  Curved surfaces interact with material properties in complex ways to create something that behaves in very different ways depending on frequency.   That's much more interesting than static forces.

Link to comment
Share on other sites

Agreed, but don't the static forces present in the plate impact that vibration?  More important to me in considering the design is that if there are features that impact the static and dynamic response then I wish to be consistent in their application.  Without consistent application then understanding of the impact of changes is muddied and the possibility of control of such changes reduced.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...