Full or Scooped?

[FiddleBasher]

Having read quite extensively internet articles on the subject of arching, and at times becoming bewildered. Can someone explain what full arching looks like when compared to scooped arching. I imagine full is carving straight up from the purfling, while scooped you carve inwards from the purfling a particular distance before going upwards. Also would this apply only in the C bout area? A simple sketch would convey the idea, unfortunately I cannot seem to find anything in my searches. 

[David Burgess]

2 hours ago, FiddleBasher said:

I imagine full is carving straight up from the purfling, while scooped you carve inwards from the purfling a particular distance before going upwards

Scooped could even describe going down from the purfling, before going up.

2 hours ago, FiddleBasher said:

Also would this apply only in the C bout area?

Usually not, but maybe in some instances. Terms like this have no precise and universally-agreed definitions, so I wouldn't waste too much time on that one.

[FiddleBasher]

2 hours ago, David Burgess said:

Scooped could even describe going down from the purfling, before going up.

Usually not, but maybe in some instances. Terms like this have no precise and universally-agreed definitions, so I wouldn't waste too much time on that one.

Thank you for the advice David I won't waste any more time on this one. 

[violins88]

I saw a viola here in Wellington that looked like it was blown up like a balloon. I assume that would be called full,

[Dennis J]

It does, at least with smoothly contoured arching profiles, particularly the upper and lower bout ones. And higher arching there can accentuate that. The centre bout arch needs to be about as full as practical.

In the photo I have drawn in pencil what is a possible at the upper and lower bouts. It is no more than about 1 mm, and most of that is achieved by making the scoop a little shallower. That involves moving the inflection points closer to the plate edge. And that in itself will have little impact on the corner cross-arch inflection point locations. Inflection point positions on each arch are the blue dots. Those corner locations have by far the largest recurve components.

[Brad Dorsey]

13 hours ago, violins88 said:

I saw a viola…that looked like it was blown up like a balloon. I assume that would be called full,

I would call it spherical.

[Wood Butcher]

The arching drawings above, look strange to me.

[David Burgess]

1 hour ago, Wood Butcher said:

The arching drawings above, look strange to me.

Better not let Dennis hear you say that!

[MikeC]

2 hours ago, Wood Butcher said:

The arching drawings above, look strange to me.

Because there's not enough recurve maybe.  At least to my eye, but what do I know, I'm just a backyard hacker.  

Just finishing the arching of a back plate using templates from the Titian.  I'm starting to get a vision of what a good arch looks like but with the inexperience of only two builds there's still a lot of learning to do.  

Browsing through the laser scans at luthiers library and old curtate cycloid threads here, you start to get a feel for what a good shape looks like.  

Full or scooped.  I found a youtube video of someone making a fiddle for the ship Tally Ho.  That's what I would see as very full arching.  Even looked arched into the corners.  Like blown up like a balloon.  Reminded me of my first VSO back in 1985.   it was a mess.  Wish I still had a picture of it to show what not to do.  

[Dennis J]

Having spent a huge amount of time over the past few years I know the underling geometry I use to design arching profiles is absolutely correct. It is quite flexible as far as recurve is concerned but there is a limit as to how far in from the edge the inflection points can be at the upper and lower bouts. If they are too far in from the edge there it is not possible to create a smoothly integrated transition from the upper convex curve into the edge scoop.  Because the inflection points at the upper and lower bouts have to be at or near edge height (to blend into the scoop at the upper and lower block areas) there is a limit as to how far in from the edge an inflection point can be. If anyone doubts that try drawing a smooth, convex arch profile with a very wide recurve, especially the lower bout one.

[LCF]

Scoopiness to me means a large radius to the concave parts of the arching with a good flow into the convex parts.  I think the archings shown in the Amati Alard drawings from the Ashmolean which you can see in these preview pics, are the epitome of scoopiness.

 

https://shop.ashmolean.org/products/15-violin-alard-by-n-amati-print

 

I've never compared them to cycloid shapes but it would be interesting to do that.

 

[Dennis J]

What I see in those drawings is a fairly high arch for the top. The convex part of the centre bout arch is fairly narrow with a wide recurve as are the upper and lower bout arches. So the corner bout arches subsequently have large concave elements. But overall it looks to me to be geometrically what I would expect. Large radiuses like this have to become almost flat to merge into the perimeter scoop.

The central convex element is even narrower for the lower back height and seems to match the top geometry.

[David Burgess]

7 hours ago, Dennis J said:

Having spent a huge amount of time over the past few years I know the underling geometry I use to design arching profiles is absolutely correct.

And there you have it, irrefutable proof.

7 hours ago, LCF said:

Scoopiness to me means a large radius to the concave parts of the arching with a good flow into the convex parts.  I think the archings shown in the Amati Alard drawings from the Ashmolean which you can see in these preview pics, are the epitome of scoopiness.

https://shop.ashmolean.org/products/15-violin-alard-by-n-amati-print

I'd call that one a "super-duper-scooper".

FiddleBasher, I'd suggest the archings of one of the Strads on that Ashmolean site as being worth emulating, at least as a starting point, rather than Dennis's.

[nathan slobodkin]

4 hours ago, David Burgess said:

And there you have it, irrefutable proof.

I'd call that one a "super-duper-scooper".

FiddleBasher, I'd suggest the archings of one of the Strads on that Ashmolean site as being worth emulating, at least as a starting point, rather than Dennis's.

Yeah,,,,

[Dennis J]

I'm surprised that the critics of what I post can't point out where my approach to designing arching layouts which can be used to make templates is wrong. If they understood the geometry behind what I do they would be able to put on paper what I have done. I'm sure early makers would have known about what I have laid out.

[Mark Norfleet]

9 minutes ago, Dennis J said:

I'm surprised that the critics of what I post can't point out where my approach to designing arching layouts which can be used to make templates is wrong. If they understood the geometry behind what I do they would be able to put on paper what I have done. I'm sure early makers would have known about what I have laid out.

You don’t know that they cannot, just that they haven’t.

[FiddleBasher]

6 hours ago, David Burgess said:

And there you have it, irrefutable proof.

I'd call that one a "super-duper-scooper".

FiddleBasher, I'd suggest the archings of one of the Strads on that Ashmolean site as being worth emulating, at least as a starting point, rather than Dennis's.

Thank you for the advice i'll do that.

[FiddleBasher]

The Ashmolean drawings, are they full size reproductions?

[GerardM]

How do the Ashmolean posters compare to the Strad Posters?

Apologies did a search and it’s been discussed here before. 

Edited July 7, 2024 by GerardM

[Wood Butcher]

The ones I have seen are line drawings. There are no pictures, like with a Strad poster.

[David Burgess]

4 hours ago, Dennis J said:

I'm surprised that the critics of what I post can't point out where my approach to designing arching layouts which can be used to make templates is wrong. If they understood the geometry behind what I do they would be able to put on paper what I have done.

How you've done what you've done isn't what's important. What matters is results.
Yes, you can make templates. So what? Anybody can.

[Dennis J]

The OP's original question was about the difference between a full and scooped arching. I've pointed out that the difference is not much when you look at arching profiles. The simple fact is that there is only a small amount of variation possible although it can be visually significant.

I'm not suggesting that an aspiring maker try to construct a full scale geometric plan like I have to design arching templates although  it would  give them the ability to design any sort of arching. It involves drafting tools like a large compass, long ruler and large sheet of paper. It's not something that can be done on a PC. Things commonly used by early makers to design violins by the way.

Templates have to be based on inflection points consistent with a particular outline shape  and specified inflection point positions. And a long arch pattern is the starting point which is needed to fix heights at cross-arch template positions. The long arch is not tied to any violin geometry that I can see but the cross-arch ones are. The position of the inflection points (distance from the plate edge) at the upper and lower bout is delineated by the same geometry that defines the general convergence of the strings, fingerboard and neck of the violin. That results in the distance of those points from the plate edge being greater at the lower bout than the upper bout.

No point in making templates which don't fit that sort of criteria.

Edited July 8, 2024 by Dennis J
Addition

[David Burgess]

17 hours ago, Dennis J said:

Templates have to be based on inflection points consistent with a particular outline shape  and specified inflection point positions. And a long arch pattern is the starting point which is needed to fix heights at cross-arch template positions. The long arch is not tied to any violin geometry that I can see but the cross-arch ones are. The position of the inflection points (distance from the plate edge) at the upper and lower bout is delineated by the same geometry that defines the general convergence of the strings, fingerboard and neck of the violin.

No point in making templates which don't fit that sort of criteria.

Nah. Arching profile shapes can be drawn freehand. Or copied from an instrument which one considers to be successful visually/tonally. Or one can make a top or back with an arching that pleases them, using only visual cues (such as oblique lighting) and then make templates from that, should they want templates for future reference.

The last method is mostly what I've used. I'm not as hung up as you seem to be on coming up with a "paint by the numbers" system, or in claiming that some system I happen to prefer is the only correct one.

[Andreas Preuss]

18 hours ago, Dennis J said:

The OP's original question was about the difference between a full and scooped arching. I've pointed out that the difference is not much when you look at arching profiles. The simple fact is that there is only a small amount of variation possible although it can be visually significant.

True.

On 7/7/2024 at 4:40 PM, Dennis J said:

I'm sure early makers would have known about what I have laid out.

I wouldn’t be sure. 
 

However ideas shouldn’t be right because ‘early makers would have known’, but rather because an idea is good and functional to what it is supposed to perform.

On 7/7/2024 at 2:45 AM, Dennis J said:

Having spent a huge amount of time over the past few years I know the underling geometry I use to design arching profiles is absolutely correct. It is quite flexible as far as recurve is concerned but there is a limit as to how far in from the edge the inflection points can be at the upper and lower bouts. If they are too far in from the edge there it is not possible to create a smoothly integrated transition from the upper convex curve into the edge scoop.  Because the inflection points at the upper and lower bouts have to be at or near edge height (to blend into the scoop at the upper and lower block areas) there is a limit as to how far in from the edge an inflection point can be. If anyone doubts that try drawing a smooth, convex arch profile with a very wide recurve, especially the lower bout one.

‘Is absolutely correct’. 
 

This statement sounds like ‘there is absolutely no other way to make a correct arching’. 
 

What I would like to ask is if you have done experiments with a ‘correct’ arching versus a ‘wrong’ arching where you could see what is right and wrong, presumably in respect of sound characteristics. If I had done this experiment I had made for example two back plates to be exchanged and two top plates.
 

Without trying to diminish your achievements, I am a bit sceptic about your statement ‘absolutely correct’. My scepticism comes from my experience copying instruments where I was facing situations to copy an arching I would consider as ‘wrong’. (That was a violin by Enrico Ceruti) But in the end the sound was surprisingly good which made me massively rethink the ‘right’ and ‘wrong’ I was convinced of. 

[Deo Lawson]

I have an instrument for which I made two tops, one very full and one very scooped. Thicknessing the same.

The scooped one is sweeter, richer, more responsive, just all around better. The full arching was louder, but required constant vigilant force in the right hand and had a limited range of tone colours because of that.

I would argue it's important to have smooth, flowing contours, both for aesthetic and acoustic reasons. A scoop actually softens the boundary between the edge and the arching, on both sides of the plate. I think hard angles or changes in direction have the effect of restricting vibrations to certain modes, like the dents in a steelpan.