Jump to content
Maestronet Forums

Pinpricks and Dimples revisited


Torbjörn Zethelius
 Share

Recommended Posts

  • Replies 184
  • Created
  • Last Reply

Top Posters In This Topic

Wouldn't a perfectionist have templates for both 'arching' and 'graduation' or does one not matter as much [to a perfectionist]?

Jim

Do you mean a graduation map? Did Strad use one? I'm sure he must have had some idea of how thick the plates should be and how to graduate them. If he started with the inside carving first then wouldn't he have convex inside arch templates? Are there any of those in his tools or does anyone know?

Link to comment
Share on other sites

All this was covered in detail in M'net some time ago. Strad's graduation devicewas saved and is now at the Cremona museum. Compressions can be seen on the outside of the arch on several cellos and pin marks on the inside. I am convinced that Strad used outside arching.

That said, if inside arching works for you, then by all means use it.

Oded

Link to comment
Share on other sites

All this was covered in detail in M'net some time ago.

sorry I haven't been around long enough to find and read all the old threads. Someone resurected this on and I thought I'd chime in by stating the obvious. :)

Having only made two violins I arched the outside first then thicknessed it symmetrically thicker in the middle thinner towards the edges then adjusted thickness from that base line. Doing it that way seems like the simplest most obvious way. They sound ok to me but I've never heard a good instrument so what do I know. They do sound better than dad's old German factory fiddle though..

Link to comment
Share on other sites

They sound ok to me but I've never heard a good instrument so what do I know. They do sound better than dad's old German factory fiddle though..

[/quote

Yeah/ my experience as well. I've only made seven/ and all of them sound wwwaaayyy better than my great granmas' old German. Something has changed education wize! I built an el Tatto last year Thanks to M Dartons Page.I really enjoy the simplicity of the Tatto. I am going to put a 1mm picth screw for a pin on mine thanks to Ken N

Perhaps the punch was used for both inside and outside work ./ First on a topographic type layout that could have been figured from inside mould dimentions/to achive a rough form. Then from the inside. I find I can drag the point away and leave a line to work to. the planning of arch height could have been done ( I think so) with inside form dimentions .As per Andrew Dippers book .....but probably executed from the outside first/ as we are more concerned with the presenting face and this approche allows the maker to see the nuance of form.

Link to comment
Share on other sites

Trying to think like a 17th century person interested in high production:

Make a "master" arching pattern by starting with a hard piece of wood which is flat and parallel on opposite sides. Carve a negative of your standard arching into one side. Spot glue a roughed plate to the opposite side, and punch away with your thickness punch. Carve until the punch marks are gone. This master could also be made from a finished plate by making a plaster cast.

When the outside arching is done, the "master" could be removed, and the punch used on the inside for thicknessing.

Even Omobono could have made decent archings this way, using Dad's pattern. :lol: And if punch marks have been observed on both sides, this would be one possible explanation.

It could also be done in the opposite order (a convex master for doing the inside first), but it would be more difficult to attach a plate, since the attaching surface (what will be the outside of the plate) presumably wouldn't be flat.

Hey, that might even be a decent approach to use today. :o Maybe it's worth a try.

Link to comment
Share on other sites

Wouldn't a perfectionist have templates for both 'arching' and 'graduation' or does one not matter as much [to a perfectionist]?

Jim

Probably much would depend on the philosophy of the maker.

Still, the question is the right one to ask, from my perspective.

It would depend on whether one had determined that or if there was a correct workable "standard" to follow for either the arch shape or for the thicknessing scheme, or for both.

I see more of a necessity for following a particular (exterior) arch shape (for both aesthetic and for acoustic reasons) and more of a rational for abandoning the idea that one standard thicknessing scheme - as might be followed by using a template - would work for all violins alike.

I didn't start out making violins believing this - but have evolved the idea over time.

In fact, when I started out, I used a light table (my own design) for thicknessing the belly (my little "secret weapon"...) but as I progressed, I realized that - even though it seemed to work well enough, I was often thicknessing around density variations to get the same amount of light to shine through, and I had to watch out for color variations - also - which started me thinking along other lines.

This is simply how I work - it is a useless point to try to convince someone who has another idea that they use and that works for them, that it is the only correct way to go.

Link to comment
Share on other sites

I see more of a necessity for following a particular (exterior) arch shape (for both aesthetic and for acoustic reasons) and more of a rational for abandoning the idea that one standard thicknessing scheme - as might be followed by using a template - would work for all violins alike.

I didn't start out making violins believing this - but have evolved the idea over time.

In fact, when I started making violins, I was absolutely convinced that a standard for thicknessing was crucial. I remember copying and studying every different thickness map I encountered.

Hutchins gave me the idea of tweeking away from geometric "correctness", in order to taylor the response. I can remember how I believed that this was THE key element in violin making.

I have since fallen from grace on this point...

Link to comment
Share on other sites

"Trying to think like a 17th century person interested in high production:

Make a "master" arching pattern by starting with a hard piece of wood which is flat and parallel on opposite sides. Carve a negative of your standard arching into one side. Spot glue a roughed plate to the opposite side, and punch away with your thickness punch. Carve until the punch marks are gone. This master could also be made from a finished plate by making a plaster cast.

When the outside arching is done, the "master" could be removed, and the punch used on the inside for thicknessing."

That might explain the pinprick hole in Del Gesu's instruments in the middle of the back? Vestiges of a mounting screw to hold the plate to such a jig?

Link to comment
Share on other sites

Hutchins gave me the idea of tweeking away from geometric "correctness", in order to taylor the response. I can remember how I believed that this was THE key element in violin making. I have since fallen from grace on this point...

In accordance with simple harmonic motion and Unit Circle principles, geometric "correctness" is a MUST - otherwise the whole cos(t), sin(t), 0-to-2π 'thingy' doesn't happen, i.e., inefficient simple harmonic motion.

IF drawing a circle were the objective, it shouldn't matter where one starts the pencil [at 0º, 45º, or 110.99º?]. All that matters is getting the 360º circle 'perfect'.

For plate carving, it's possible to affix both arching & grad templates to a jig around the perimeter of the plate outline - so carving one or the other 'first' is simply a matter of choice.

Maybe Strad's 'circles' just weren't that perfect to begin with. I dunno.

Jim

Link to comment
Share on other sites

As long as you don't drill thru the plate, you're cool.

Hi Ben - do near misses count? I managed not to go all the way though.

post-98-0-82113400-1296412908_thumb.jpg

I didn't manage to line up the grain perfectly - so I repeated it all over a week or so later. Much in the same place as well. With much the same result. Maybe drilling all the way through would make the repair a little easier. Plugging a blind hole appeared to need more care.

Oh well all experience is good for the soul.

cheers edi

Link to comment
Share on other sites

In fact, when I started out, I used a light table (my own design) for thicknessing the belly (my little "secret weapon"...) but as I progressed, I realized that - even though it seemed to work well enough, I was often thicknessing around density variations to get the same amount of light to shine through, and I had to watch out for color variations - also - which started me thinking along other lines.

Not such a secret after all. That's what I did with my two. Except I used a dim lamp in a dark room rather than a light box.

Link to comment
Share on other sites

Yeah.

I know several other people who have independantly come up with the "lightbox" idea. It did teach me some useful things about plate thicknessing.

Any advice for a beginner on how to advance after the light box stage? I was planning to use that same idea on my 3rd one when I get around to building it...

Link to comment
Share on other sites

Any advice for a beginner on how to advance after the light box stage? I was planning to use that same idea on my 3rd one when I get around to building it...

I can only relate what I do, which is; be very careful and deliberate when arching the outside surface, be very careful and deliberate when arching the outside surface, and, be very careful and deliberate when arching the outside surface. So, spend some time getting it right.

Then I mark the inside perimeter, based on the rib outline, drill depth holes (with a drill press & stop, like Don N posted recently) leaving adequate room along the edge so as not to "squeeze" the plate thickness all the way out to the very edge, which, in my opinion, is a common newb mistake, thinking that removing weight from anywhere is a good thing - then I purfle and work the channel, corners and edgework.

I like to get the entire "live area" of the plate down to just over 3mm - then I mark the center (thickest) point, which for me is either on the C/L under the bridge, or just slightly North...,depending, and use a small thumb plane with a toothed blade and scrapers to finish.

Feeling, tapping (I tap extensively, though there is nothing in particular I'm listening for - just gathering general information) and flexing till finished.

"Finished" is the place where intuition/experience (fingers and ears) tell me when to stop removing wood. For me the *feel* of the plate is of utmost importantce.

No magic.

Any one else care to comment on their procedure?

This (arching & thicknessing plates) is my favorite job in violin making - though varnishing has rather captivated me lately.

Link to comment
Share on other sites

...I mark the inside perimeter, based on the rib outline, drill depth holes (with a drill press & stop, like Don N posted recently) leaving adequate room along the edge so as not to "squeeze" the plate thickness all the way out to the very edge, which, in my opinion, is a common newb mistake, thinking that removing weight from anywhere is a good thing - then I purfle and work the channel, corners and edgework.

I like to get the entire "live area" of the plate down to just over 3mm ...

Any one else care to comment on their procedure?

As a relative beginner, my methods are still evolving, but CT's steps are somewhat close to what I do. I have to remember to do some final exterior scraping after the drillpress/stop step... on my last fiddle, I noticed a gridwork of dimples on the back after I varnished it. I have a new, accurate chuck on the drillpress so the drill runs true and doesn't rattle the plate around, and will use a sharp, split-point carbide drill to minimize the forces.

Another thing to consider is the F-holes and fluting. I get the outside arching close, then graduate inside to ~4mm, then do the F-holes, fluting, and final shaping of the outside, then finish up the graduations inside to a map of dimensions, gradually bringing the thicknss down all over. The stopping point will depend on the stiffness/density of the wood and the character of the sound I want to get. I do track taptones, but only for possible future information; I don't "tune". I also "flex" the plate, but prefer to get actual stiffness numbers rather than trust my "feel". My fingers might go out of calibration over the months between builds, but the scales stay pretty accurate. That also at the moment is for future analysis; I don't have enough data yet to tune to any particular stiffness.

Link to comment
Share on other sites

I have not read all the post's, but my take would be that most of the arching would be done, then the internal graduation, and then a final stage where both are worked "towards" each other where the final shape and thickness are achieved. That's what I do. One must be "flexible" with their building, if one completes the arching in its entirety,puts in the purfling, this leaves no room for marriage. The internal shape MUST now conform to what the outside is doing.IF most outside shaping is done before the internal scooping starts, this gives one a "rough" idea of a "point" to shoot for, once close to the point, one can then go back to the topside and slowly work one then the other, I now purfle and cut the holes, most times, after the plate is final. It would seem to me this "theory" rely's on the fact that the purfling is done before graduation?

Link to comment
Share on other sites

Original blog post: Pinpricks and Dimples

I am still not convinced that Stradivari started his archings from the outside. Quite the contrary. Let's examine the details.

First, let's look at the violin belly. The 'conclusive proof' mentioned above by actonern (here) is flawed because not "most of his instruments left the shop in this state"; this is a rare example. The fact that the marks weren't removed indicates that something other than graduation was going on. If done properly, there wouldn't be any marks remaining or they'd be very scant. Looking closely, it actually seems that some of the cleats were also indented as Mr./Mrs. Somebody was happily chopping away, but that must surely be accidental. :)

We turn our attention to the cello pics. I insert photos of the actual graduation punch (catalog nr 665) below. To understand how the tools were used, we need to examine them closely. We can see that the anvil doesn't fit the dents on the cello. Another indication is that the inside dimensions are too small for a cello (about 57x374 mm*). Stradivari had another graduating tool for cellos which was hand held; (cat nr 664). It is illustrated in Sacconi's book on page 79. It's made of forged iron. It measures* 115 mm at the widest end, 254 mm deep. Neither of these tools correspond to the dents in the cello.

Ok, so what do the actual punch marks look like, according to me? I'm glad that you asked. :)

For those lucky enough to have the latest Strad poster, the march 2010 issue, the very well preserved Stainer viola has many pin pricks on the belly. Yes, that is on the outside folks. They are very small, barely noticeable, as should be expected. Although they are scattered all over, notice in particular there's a row of tiny pin pricks stretching across the upper treble bout. The upper and lower bouts are typical places to find these marks. Holler when you see them. :) Generally speaking it's a bad idea to spot these pin marks in photos, but if the instrument is in a very good condition as here, I think it's alright.

Torbjörn

* My measurements.

post-24030-1267178264.jpg

Hi all, I'm guessing the clear area down left what is, it looks me like a chip off warnish or glue...

Did you noticed varnish on it?

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...