Matt7783 - Posted - 03/10/2010:  16:14:17

Hi all, I'm new to the forum and I'd really appreciate any advice on a neck repair I'm planning. I recently was given an old fiddle that my local luthier identified as a low-end Czech instrument. I'm a complete beginner, so I figure this instrument will be acceptable at least while I'm just getting started. It actually sounds alright to my untrained ear. The only problem is that the neck has sunk severely and so the string action is extremely high (like 10+mm at FB end) , making the instrument pretty much unplayable. The bridge is of medium height so i don't think I can solve the problem by lowering the bridge.
I'm on a very tight budget, and so I'd like to repair this myself. If something gets messed up, it's not a big deal (the instrument was bought for next to nothing at an estate sale). From reading this forum and digging around on the web, it seems like the easiest and most cost efficient way to fix the problem would be to put a shim under the fretboard. I haven't been able to find any detailed info on this process so I'm wondering if there is anything special I need to know. I gather that I just take off the fretboard (which shouldn't be hard; it's already coming loose), insert the shim and glue it all back together with hide glue.
I guess my first questions are Does this seem like a good approach, and Do I understand the method correctly? I've seen discussions of neck 'pull-ups,' which sound like they require a degree experience beyond my own. Also, I've seen mention of 'wedges,' but I'm not sure what this entails. If the shim is the way to go, what type of wood would be best? I will probably be getting something from my local building supply store so my options will be limited and I will probably be using something less than ideal. I'm OK with this, as I'm really just looking for something to play around with; playability is of much greater concern than sound. I'm also wondering what the ideal string height is at the end of the neck, as this would make picking the height of the shim much easier.
If anyone can shed some light on any of these questions, it would be greatly appreciated. I'd really love to get the instrument in playable shape. Just playing around with it as it is has really sparked my interest. Thanks in advance,

Matt

2

1

emviolins - Posted - 03/10/2010:  16:26:11

Using the shim method is not the best or correct way to solve your problem. The proper way is to take the neck out and reset it. Not easy for a beginner, talk to your luthier about it.

transplant - Posted - 03/10/2010:  16:28:27

Given the choice between doing a pullup and shimming up the fingerboard, I would go for the pullup. One way or another you have to crack some glue joints or other, and stick them back together. You will need to make some closing clamps-- spool type clamps work perfectly well.

woodwiz - Posted - 03/10/2010:  16:29:09

The shim is wedge shaped from 0 at the nut to whatever thickness you need at the heel to raise the fingerboard sufficiently. More than a couple of millimeters gets very noticeable when you play. We make ours out of ebony - looks better, but we have old bass fingerboards to cut from. You can use maple; it's just more visible.

Cut a taper of the correct angle and cut to length, then shape it til it's only a hair (a few thousandths) wider than the neck. Best to glue it in two stages, since parts want to slip around a lot. You'll need to make cauls for the clamps. Be very careful to keep everything lined up right,

Once the glue is dry, scrape the shim down flush without getting into the fingerboard or neck.

Takes a little patience and an eye for detail.

woodwiz - Posted - 03/10/2010:  16:39:19

Lots of times you don't want to break a perfectly good neck joint (my least favorite part of luthiery), or as on a recent fiddle, there was just too much damage around the neck joint to risk it, sometimes the fiddle is unstable, and sometimes there's not enough overhang for a pullup. There's also the matter of cost. School instruments?

I regard a shim as a temporary, reversible repair that can be undone easily when it comes time to do a proper reset. Most people wouldn't even notice our shims unless they were looking directly at the overstand. We don't do many of them, maybe a couple a year out of about a thousand repair tickets, but sometimes it just makes sense.

We've already done our normal quota for this year.

Edited by - woodwiz on 03/10/2010 16:55:06

Matt7783 - Posted - 03/11/2010:  18:25:11

Thanks for the advice guys. I think I'm going to try the shim and hope that this will at least make the instrument playable. My luthier advised me that the instrument was not worth putting any serious work into, so a full neck reset seems like the wrong way to go. Also, the fiddle doesn't seem very structurally stable, so it's probably best to avoid cracking too many joints. Thanks again for the help!

Matt

rafa - Posted - 03/12/2010:  03:26:40

Hi all, is it ok to use pine shims like at home depot for doorframes and such, will the kind of wood be to soft or affect the sound? Thanks for the great info.

woodwiz - Posted - 03/12/2010:  06:09:33

That would really look bad, and you''d still have to plane the shim down to thickness. those shims are really soft, too. Ebony/s my first choice, if you can find an old fingerboard. Maple second.

hardykefes - Posted - 03/12/2010:  17:41:27

The shim repair is very controversial.It is also known as the "english method" and described in the book "Violin Making as it was, and is" by Heron-Allen. Generally it is an OK method if you don't want to open the box.
You need to consider two aspects if you decide for this method: a) The neck is getting naturally thicker and could become uncomfortable to play. b) the neck is becoming heavier and therefore the resonance frequency of the neck goes down.
A previously fine-tuned violin would need to be re-tuned. The material should be either ebony or maple. I prefer Maple because of the looks from the side.
I personally dislike this method more because I don't like the change in feel of the neck.
The second method could be re-shafting the neck. You would have to brake the neck loose and change the angles by removing or adding material. Often a fine wedge-shaped shim between neck and body will do, but you have to adjust the angle touching the button.
This method is good if the violin top is set evenly all the way around.
The third method is to open the top. Case dependent you can leave the top attached to the neck-block, so only the sides and bottom end block are open. Then re-glue and clamp the bottom block first by measuring the neck angle with a gage.

rafa - Posted - 03/12/2010:  18:08:33

Hey Woodwiz thanks for the info. But where would I get hardwood shims? I`ve asked at a few places. Do I have to plane them myself out of some maple board?
Thanks for the help!

woodwiz - Posted - 03/12/2010:  18:40:16

Rafa, they are something you make. I don't do these very often, but I usually rip a wedge to approximate dimension on the table saw (band saw will do), then use a plane and scraper to do the fitting. Others just glue a block on the neck and shape it in place, risking damage to the peg box.. You need some tool skills to be able to do this.

Hardy, FWIW a shim is the first option listed in Weisshaar's book. I agree that it has its drawbacks, and we do probably 20 or 30 neck resets and pullups for every shim, but sometimes it's the only thing that makes sense. A 2mm shim will raise the projection 4mm, and hardly changes the feel for someone who seldom gets out of first position. IMHO, ebony shims look a LOT better than maple shims. If it's done well there's no visible joint line to draw the eye, and people seldom gauge the thickness of the edge of the fingerboard, or notice the step in the underside of the fingerboard.

rafa - Posted - 03/12/2010:  18:47:26

Hey Woodwiz Thanks a whole lot for the info!

hardykefes - Posted - 03/13/2010:  07:23:54

Thanks woodwiz, I have the Weishaar. Personally I feel even a shim of 1 mm thickness and don't like it. Thanks for your response.