How do our experts support a violin for alignment and accurate measurement?


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Thanks for those who answered my questions about measuring alignment . I am sure those ways can work although since the fitting process involves measuring many times to adjust all of the required specs I prefer the simplest and most repeatable method which for me is the surface plate. 
 

For the OP and other less experienced people I will add that I find it very helpful to have the instrument in my hand supported by my knees, the edge of the bench etc. so that I can tilt or twist it to allow cutting in what ever direction  required to use my knife or chisel effectively and to see where I am cutting. Just my way of doing it but as I mentioned at one time I was setting necks for an entire production shop and even won a “John Henry “ race with the fairly well designed machine which replaced me after I left.

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The difficulty to be aware with surface plates and old instruments is dealing with instruments that have a significant amount of body twist, or are asymmetrical (either made that way, or through significant wear.) 

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45 minutes ago, Jerry Lynn said:

The difficulty to be aware with surface plates and old instruments is dealing with instruments that have a significant amount of body twist, or are asymmetrical (either made that way, or through significant wear.) 

Absolutely.
 

Resetting as opposed to setting necks on new instruments is a very different matter. I still use the surface plate but will temporarily build up edges and make adjustments and compromises as required.

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On 4/7/2021 at 1:09 PM, nathan slobodkin said:

Absolutely.
 

Resetting as opposed to setting necks on new instruments is a very different matter. I still use the surface plate but will temporarily build up edges and make adjustments and compromises as required.

Do you have a surface plate large enough for cello neck assessment?!

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On 4/8/2021 at 9:30 PM, Mark Norfleet said:

Do you have a surface plate large enough for cello neck assessment?!

Yes. I use a granite countertop. Not as accurate as a real surface plate but flat within a quarter of a mm. This method is not perfect but it is pretty good and when I check measurements on instruments coming into the shop I find that there are an awful lot of badly set necks out there.

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Nathan, Even though how to take this measurement seems obvious, I just wanted to check my understanding of this method. I took the fiddles I have to my kitchen island, that has a granite countertop, because that was easier than cleaning up the shop that's got several projects running. The method seems very sensitive. Even fiddles that I think of as having straight necks are measurably off. What I did was shim the violins so the top plate is square to the surface, and then take the height measurement at the center of the nut on one side, then flip to the other side and repeat.  Sound about right?

Thanks,

Jim

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4 hours ago, Jim Bress said:

Nathan, Even though how to take this measurement seems obvious, I just wanted to check my understanding of this method. I took the fiddles I have to my kitchen island, that has a granite countertop, because that was easier than cleaning up the shop that's got several projects running. The method seems very sensitive. Even fiddles that I think of as having straight necks are measurably off. What I did was shim the violins so the top plate is square to the surface, and then take the height measurement at the center of the nut on one side, then flip to the other side and repeat.  Sound about right?

Thanks,

Jim

Jim,

I do think this method is very sensitive and therefore accurate. I am primarily concerned with the relationship of the neck to the top. On instruments which will not sit squarely on all four bout edges I push the body of the fiddle over until one back edge and both top edges are firm on the plate then take my measurements from there. The slight tilt of the instrument does change the measurement slightly and if the instrument is really twisted (usually an old one) I will  compensate for that. This method is not perfect but I think is is much more accurate than eye ball or bent rulers etc. Also very quick. I set the gauge just above the edge of the finger board so I can slide it over the board and then slide the gauge toward the body of the fiddle until it touches. When both sides touch at the same distance from the nut The neck is centered. Because of the taper of the Board even my eye is off by a mm. the actual error off center will be less than a tenth of that.

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53 minutes ago, nathan slobodkin said:

Jim,

I do think this method is very sensitive and therefore accurate. I am primarily concerned with the relationship of the neck to the top. On instruments which will not sit squarely on all four bout edges I push the body of the fiddle over until one back edge and both top edges are firm on the plate then take my measurements from there. The slight tilt of the instrument does change the measurement slightly and if the instrument is really twisted (usually an old one) I will  compensate for that. This method is not perfect but I think is is much more accurate than eye ball or bent rulers etc. Also very quick. I set the gauge just above the edge of the finger board so I can slide it over the board and then slide the gauge toward the body of the fiddle until it touches. When both sides touch at the same distance from the nut The neck is centered. Because of the taper of the Board even my eye is off by a mm. the actual error off center will be less than a tenth of that.

Perfect, thanks. I can see using a height gauge for multiple tasks now that I’ve brought it out of retirement. 

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In my shop we use a sheet of plate glass three feet long and about 5/8" thick for cellos. If there's a slight sag, setting up the two stations (one in each direction) on the same line but in opposite direction goes a long way to cancel the effect of the sag. If you put it permanently, you can even support it underneath to straighten it out, but I've never found that necessary.

If I'm reading Mr Bress' comments correctly, he's skipping the most important step of the process: setting the shims up so that the distance from the purfling to the surface is exactly the same on either side of the upper bout and the lower bouts (separately). This is critical.

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18 minutes ago, Michael Darnton said:

In my shop we use a sheet of plate glass three feet long and about 5/8" thick for cellos. If there's a slight sag, setting up the two stations (one in each direction) on the same line but in opposite direction goes a long way to cancel the effect of the sag. If you put it permanently, you can even support it underneath to straighten it out, but I've never found that necessary.

If I'm reading Mr Bress' comments correctly, he's skipping the most important step of the process: setting the shims up so that the distance from the purfling to the surface is exactly the same on either side of the upper bout and the lower bouts (separately). This is critical.

 Michael,

I think Jim is thinking in terms of new instruments. Are you referring to adding shims to account for edge wear on older instruments?

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Thanks for the added details Michael. As Nathan says, I'm only dealing with new making. I've saved yours and Nathan's notes, and will be using them later this year with my first cello neck set.

Cheers,

Jim

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14 hours ago, Michael Darnton said:

I would never make the assumption that something I did was perfect without checking. Also, I go to the effort of getting the plates square to the surface.

Without checking what? Do you have an efficient way to hold the plate(s) square to the surface? How do you measure that?

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