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Ken_N

String angle/neck set

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Sorry, I still haven't figured this out. The last couple days I've triged out a bunch of different combination's of nut location, neck step, and elevation. I kept the nut within 4mm of "zero". I kept the step for just under 5 to just over 6.5. I figured out both for a straight belly, where the rib height at the neck is the same as the corners, and for the Ole Bull, where there is a 3mm drop. With those constraints in place the elevation went from 26-27.5 on the straight one, and 24.5-26 on the Ole Bull. The angle varied from 157-158 degrees for both.

This is one area that is like voodoo for me. It seems to be a consensus that 157 is bad, 159 is great. But 159 can't be made, at least on paper in 2d.

Any thoughts?

Ken

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Sorry, I still haven't figured this out. The last couple days I've triged out a bunch of different combination's of nut location, neck step, and elevation. I kept the nut within 4mm of "zero". I kept the step for just under 5 to just over 6.5. I figured out both for a straight belly, where the rib height at the neck is the same as the corners, and for the Ole Bull, where there is a 3mm drop. With those constraints in place the elevation went from 26-27.5 on the straight one, and 24.5-26 on the Ole Bull. The angle varied from 157-158 degrees for both.

This is one area that is like voodoo for me. It seems to be a consensus that 157 is bad, 159 is great. But 159 can't be made, at least on paper in 2d.

Any thoughts?

Ken

...............................................

Ken, what is the end game here? Are you trying to work out the Ole Bull or just make sense of the 'rules'.

I don't understand the concept of keeping the 'nut within 4mm of zero'...what is that? ( sorry I am not meaning to be cheeky but do not understand that) the 26mm elevation is often quoted but is very low unless you have an 18 +mm arch. Saddle height is also important.

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I was content before just throwing it together. Guess I wanted to follow the "rules". I was figuring with 16mm for the belly, and the saddle is 7. As the elevation gets higher, the string angle gets lower. If you move the nut up higher the neck step goes too high. Unless the fingerboard is not really set in stone. Do you get the fingerboard to work, and then do some "magic" on the sides so it looks "right"? Maybe I'm doing something wrong here? Just spent an hour trying to scan and downsize a sketch. Don't know why it was so big, or why it is crashing my computer, but here it is big and not tilted so you can see what I was doing.

I want to be done with this and do some real stuff!

Ken

uploaded and then disappeared! Now the upload manager is gone!

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Sorry, I still haven't figured this out. The last couple days I've triged out a bunch of different combination's of nut location, neck step, and elevation. I kept the nut within 4mm of "zero".

I didn't know what you meant by this either, at first. Are you talking about having a line drawn from the top-gluing surface of the rib plane intersect the nut at some particular place? If so, I don't pay any attention to this when setting a neck, because I don't think it matters much.

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Yeah David, it was the imaginary line from the glue surface. I see after doing this that it can be anywhere. But when you're playing with the elevation and trying to keep the neck set in range (5-7mm, is that important?), the nut placement will not vary too much from zero,plus or minus 4 or so. The thing I was finding was that with a belly that arches down to the neck the string angle comes out less than 157 degrees just by trying to keep the neck set below 7mm. I you go to 8mm step you can get it up to 157 degrees, as it drops so does the string angle.

Maybe a low string angle is all your gonna get.

The neck heel I just cut when I figure it out. The mortise I cut 2mm deeper at the bottom than the top. All of that stuff is easy once you know what angle you want the neck at. The bridge I just set at 3.6mm above the elevation for string clearance. See if this works for my sketch.

Ken

post-23466-1258651251_thumb.jpg

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It seems to be a consensus that 157 is bad, 159 is great. But 159 can't be made, at least on paper in 2d.

Any thoughts?

Ken

Don't worry about pleasing the 'Masses'. Consensus is what gets politicians elected!!! :)

If you need to raise the nut location relative to the rib plane, and go with a high saddle, then don't worry about it, as no player will ever complain about his nut not being inline with the rib frame line.

I could not get your picture to load, but that is because the forum does not like Windows XP very much!

Who does though! :)

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The position of the nut is a flashing red flag that something's not right somewhere. It's a useful measurement if you know how to use it and integrate it into your neck setting process, but it's not the only way to get the job done. It's the easiest visual tag of a problem neckset, but there are other numbers to manipulate, and if they're right, it will be right, automatically.

The specific location of your problem is that you are taking 3mm off the height of the upper block relative to the rest of the ribs, as you have drawn it, but with 6.5mm of appui, you've only added back .5mm of that missing 3mm. Until recent years, the idea was always to take the taper on the back, often over the whole length of the body, rather than just from the upper corners, so the relationship of the top and appui weren't affected by rib heights, in theory. In order to fully compensate for taking the taper off the front, and taking so much, too, you'd have to make the appui 9mm just to get it back to the normal 6mm of someone who takes the taper on the back side of the ribs (especially if this is considered relative to a whole-body taper--some might argue that tapering on the back does affect the top, and the effect is probably indefinite, so let's not think about that too hard. :-)

Then with twisted up old violins, there's another wrench in the works, and that is that often the body sags downwards in the middle from the forces on it over hundreds of years. If the corners and center (an thus the platform the bridge sits on) are lower than the ends by, say 1mm, you need a 28mm pitch to put the top of the bridge equal to height (and angle) of an unwarped violin with a 27mm pitch. such a body sag, with normal pitch might equal 1 or 2mm of additional appui, if it's bad enough. Then, to be to equal that in a new violin, you'd need to boost YOUR appui from 9mm to 10 or 11mm to get the same string angle as an old, warped violin, which just isn't going to happen, I think.

In short, I think tapering your body 3mm, all on the front, and all from the upper corners up, is a bad idea.

I think there are still a couple of empty slots in my summer workshop. You should sign up and come and get the full neck set lecture. :-)

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Thanks Stradofear. I'm sure I can pull something off. Even using a straight top I can't get anything near 159 degrees on paper. I looked at all my posters and none have as much taper as the Ole Bull, but the Allard del Gesu is the closest. Some, like Maggini have little or no taper. I know I read in one of the papers by Roger Hargrave that a instrument had the taper hastily cut on the belly side of the ribs. Since not all of the del Gesu instruments have the taper, (do they?) and it doesn't seem to be planned, what was the reason for it? Was he tuning it from the outside and thought the belly needed more "oomph"? Was it a new thing that he did that worked with the neck/fingerboard he made, and now we don't know what it was? Was it something some hack repairman did? I couldn't help the last one, I think Hargrave said no to that.

Ken

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Looking at the measurements in the Biddulph books, there's quite a bit of apparent randomness going on with the Ole Bull rib heights. On one upper rib, there's a 2mm drop in height in about three inches! I don't know if it was him/her, or someone later, but I wouldn't spend a whole lot of time replicating them. Rather, try to get something going that actually has a chance of being sensible and working.

Roger H was talking about a particular Strad's rib taper. It's rare that you get an indication of what the maker was doing, clearly, after 300 years, and he found that indication of rib height on one Strad, and extrapolated a reasonable story of what Stradivari might have been doing. Del Gesu: not many clues there to go by. It doesn't appear that the erratic rib heights on the Ole Bull were very intentional, regardless of who's to blame for them.

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I think there are still a couple of empty slots in my summer workshop. You should sign up and come and get the full neck set lecture. :-)

*sigh*

I'd pay for that DVD.

Someone should record events like this - for those of us with serious travel problems.

It'd be sorta like the VSA transcripts, but much more dramatic - like a violin makers reality show.

Dog, the Violin Maker...

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In short, I think tapering your body 3mm, all on the front, and all from the upper corners up, is a bad idea.

I think there are still a couple of empty slots in my summer workshop. You should sign up and come and get the full neck set lecture. :-)

Would you consider abandoning the goal of 159 degrees for say 158 degrees?

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158 is do-able. With a little finesse, maybe a set up in between baroque and modern, I should be able to hide the high step too. What kind of elevation do people like? I see Melvin thinks 26 is low, but any time I've seen them noted on a poster they are 25-26mm (a Strad on Luthiers Library was 23 I think), and The Art of Violin Making says about 25mm. But then I'll read a lot of people saying 27 is standard, and they don't like low bridges. But a lower bridge is one of the easiest ways to get the flatter sting angle everyone covets. Nothing is going in the same direction.

Ken

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Hi Ken,

I think part of the problem is that your drawing is too simplified. For example, if you extend the line of the strings behind the bridge on an actual violin you'll find that it's much higher than the height of the saddle alone. Cheers,

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Has anyone measured the amount of deflection (if there's any) happening when tapering the top part of the ribs ? Does that have any incidence on fingerboard projection height ?

Wasn't it Sacconi who mentioned tapering in his book, together with the compass arcs present on strad's moulds ? Or did I badly understand Stradofear's comment about Roger Hargrave ?

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Sacconi noted the tapering, but assumed it was on the back, as on a bass. Hargrave found evidence on an instrument that the taper was taken from the front, presented in a STRAD magazine article a decade or more ago.

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Hi Ken,

I think part of the problem is that your drawing is too simplified. For example, if you extend the line of the strings behind the bridge on an actual violin you'll find that it's much higher than the height of the saddle alone. Cheers,

I finally got someone to send me your diagram, and I see that you did not draw in the tailpiece.

This diagram might help you tosee that the tailpiece will affect the angle.

Side View Diagram from Strobel

Draw on your diagram a tailpiece, or make a cutout of the tailpiece, and insert it in your diagram, and then see how much things change.

Also on the Strobel diagram extend the strings behind the bridge, with a ruler, and you will see how high they are above the saddle.

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I glued the neck on yesterday. I didn't pay any attention to the elevation because I decided to make it kind of one step up from a baroque set up, not so flat of a neck, and not so big of a fingerboard wedge, maybe 5mm, and the elevation would be controlled by the fingerboard later. I gave it a 2.5mm or so neck set. Checking it out today I only need a 3mm wedge on a fingerboard to get it up to a 27 elevation, and that should get about a 158 degree string angle. Wasted a more than a day doing all that figuring., and it was wrong. I say just do it.

Ken

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Here's Ken's sketch at a smaller file size. I used Paint.NET, a freebie image editor to cut it down. We still have plenty of people on a dial up connection and large files are a pain.

post-2210-1259618949.jpg

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I need to think about that, sorry. I've only had DSL (the slowest..cheapest they offer) for less than two years. I still remember.

I have found that the original makers had it easier. Put the neck on and you can plane a wedge until your projection is right.

Ken

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