Bohm Waldzither re-build

[dave17120]

I needed something to keep me visiting the cafe more regularly..... other than the syntillating conversation of the members that is...... I have a Puglisi restoration half done, but I've had to lay it aside for the moment because of pressure of work. So, I decided I'd post photos of a friend's waldzither that I am restoring... not exactly a zook, but many seem to retuned that way.

So, here is the beast in question..... a nice Bohm waldzither from the pre-1918 era (with the GR 4 6825 number on the label) its similar to a type 2, though the decoration is different..... photos shortly.

Cheers, Dave

[dave17120]

This is the waldzither in question.....



.... the basic problems are typical of many similar instruments... the back has shrunk and come away from the sides in places, where it has been heavily reglued. It has also sparated somewhat from the centre-line purfling. There are loose struts inside, both on the top and bottom, and there is a very long split in the side panel, where the worst of the loose struts have had a wedge inserted between them at some point to try and hold them apart.
Finally, the head has a badly repaired split, there is a shrinkage crack running down the centre of the top, and the top itself has sunk under the bridge position.
The back will need to come off to address these problems......

More later.... Dave

[Tavy]

Lots to keep you busy there Dave!

Worth it though - these are great sounding instruments once they're in proper shape,

Keep us informed, John.

[dave17120]

Welll, here are the problems in a little more detail once the back was taken of.... not so easy in itself...

The back struts are detached in the areas marked by the arrows, the top struts similarly, but also shown are the split down the middle, (now filled...) and the split head.

Difficult to see, but perhaps the most serious, is the split almost the whole length of the one side, I think caused by the wedges.

More soon, as I have already started on the restoration work..... Dave

[dave17120]

I decided to start on the back first, as there seemed to be a lot of work to do there.
Its a two-piece back in mahogany I think, joined down the centre with a strip of dogtooth purfling. Inside, I guess because of the purfling, the join has a re-enforcement strip glued in, in-between the back struts. The problem was that while the re-enforcement strip was still all in place, the back had actually shrunk away from the purfling, in some places on one side, in some places on the other. So the strip was severely compromised, although still glued in place.

I decided to remove it and fit a new piece (identical) when I rebuilt the back...

And here it is dis-assembled....

[dave17120]

Once in pieces, I removed the centre purfling, and fitted new after cleaning up the two edges....
The purfling was first glued to one side, then with battens to hold the back flat, glued to the other.
Once together again, the back cleaned up nicely, and next I will refit the braces.

[Eddie Sheehy]

Looking good there Dave. I've still got that Bohm-style Waldzither I bought off you a while back - the one with the Celtic design on the top. I lost the tuner socket so I make do with needle-nose pliers. I keep the instrument in Ireland and play it when I visit.

[Tavy]

Looking good there Dave. I've still got that Bohm-style Waldzither I bought off you a while back - the one with the Celtic design on the top. I lost the tuner socket so I make do with needle-nose pliers. I keep the instrument in Ireland and play it when I visit.

Eddie, I wouldn't use pliers for tuning these - the tuning machines are quite "bendable" and if you twist them out of shape you're in trouble! For a replacement tuning key, try a clock winding key - they come in all possible sizes - I think a 4mm socket worked for me, but check your machines to see what they need - they only cost a couple of $$'s too

[dave17120]

Hi Eddy, I agree with Tavy, you can pick up clock keys on ebay fairly cheaply, but the size of the nuts on the top of the tuning barrels does vary, so check it first....... I've found 4mm 4.5mmm and 5mm ones.

Hope that zither is standing up to everything ok...... Dave

[dave17120]

Time to tackle the split in the side.... it runs most of the way around the one side, but fortunately, no-one has tried to re-glue it, and there are no bits missing, so it is relativel simple to repair.
Some glue worked into the crack and clamped up was stage one, and once that was set, then a re-enforcement inside with a fabric strip. Once gone, I think the integrity of the side is suspect thereafter, especially as its only just 2mm thick, so I prefer to re-enforce...

[dave17120]

Next step was to start addressing the problems of the top, notably where it had sunk under the bridge, and where the struts had burst out of thier seatings on the one side.....
Photos below show the damp pad in place to 'soften' the wood under the bridge area, a bridge plate being glued in to re-enforce the area, and the ends of the loose struts being glued down again.
The finished result can be seen in photo 01o........ more soon, Dave

[dave17120]

While the side was being sorted out, I managed to get the struts fitted to the back again, having cleaned off all the old glue.... the problem here is always to try and apply pressure all along the strut so it ALL glues down well...

I forgot to take a photo of this one when it was all clamped up, so the photo of the struts clamped up is another Bohm I'm working on to demonstrate the set-up. Ends clamped and lots of pressure in the middle of the strut, which has in fact a curved foot.

Once all re-assembled it looks fine, but as seen in the 3rd photo, what with the original shrinkage, and the small amounts of wood taken off the centre to make good gluing edges, the back is now rather small, and doesn't reach the linings all the way round.

Next step then is to fit new linings..... I'll get banding shortly.....

[dave17120]

The solution to the slightly small back is to add more linings in the interior..... in the photos you can see the new supplementary linings first pinned in after bending while they dry, and then glued with slots cut to receive the struts......

[dave17120]

Right, the back is now back on...... two photos show the back being glued, clamped up, and then once the clamps were removed. The next step is to fit new purfling and edging around the outside. It will then be solid enough to strip off the old varnish, and start the prepping process for the new...... have to wait for a nice day for that though!! Need to do it outside, as the old varnish is somewhat toxic!
More soon, Dave

[Tavy]

Right, the back is now back on...... two photos show the back being glued, clamped up, and then once the clamps were removed. The next step is to fit new purfling and edging around the outside. It will then be solid enough to strip off the old varnish, and start the prepping process for the new...... have to wait for a nice day for that though!! Need to do it outside, as the old varnish is somewhat toxic!
More soon, Dave

Did the Boem's have the same dreadful harder-than-hell nitro that the Pluckthum's had? If so I wish you the best of luck in getting it off!

[dave17120]

Don't know yet, I just fitted the purfling this morning. Got to do the binding first, then strip it!!

I don't exactly know what the varnich is...... its the stuff that comes off as a yellowish powder and smells distinctly.... but I couldn't say what of!? Cyano-acryllic perhaps.... not an expert at identifying old varnishes.....

[brunello97]

Don't know yet, I just fitted the purfling this morning. Got to do the binding first, then strip it!!

I don't exactly know what the varnich is...... its the stuff that comes off as a yellowish powder and smells distinctly.... but I couldn't say what of!? Cyano-acryllic perhaps.... not an expert at identifying old varnishes.....

Always fun to look over your cyber-shoulder, Dave. Thanks for posting this thread.

BTW What are you using to strip the old finish?

Mick

[dave17120]

......to strip the old finish?...... a scraper and sandpaper. I did a test last year with a mandolin top, much softer then most of the rest of an instrument obviously, and using this method, I lost less than a fifth of a mm of thickness..... so I think an instrument can stand it once in its life....

[dave17120]

..... and here is the purfling in question, all now installed. Tomorrow I hope to be able to do the binding..... I hope I have something wide enough, as the slightly reduced size of the back, (that necessitated extra lings...) also means that the space each side for binding is somewhat wider than originally the case.

[dave17120]

Well the edging is now done, after a slight problem.
The purfling was fitted, but at certain points, the gap between the edge of the purfling and the edge of the instrument was deeper than the edging. So.... I was obliged to fit another row of purfling to take up the gap.
The heel end I did slightly differently to the original, as I find the purfling and edging around such a tight exposed curve, not altogether simple to do, or robust.

Now just waiting for a nice day to get outside and remove the old varnish.

[dave17120]

Well, the sun is shining here, it reached 20*C outside , so I managed to avoid more gardening, and sand back the old varnish on the waldzither today.
It took me over an hour with sandpaper and a scraper, but its now done....... I have some small repairs to make, before I prep for varnishing (a bit of the old edging came away, and there are one or two fissures around the old head split, but nothing serious.)

Once prepared, I shall varnish with Tru-oil... its hard and light, easy to apply, and I've always had good results with it. More later...

[dave17120]

Having a weekend catching up on IT stuff, and realised I never finished off this thread... Oooops!!!

Well the waldzither was finished off and strung and sounds good to me, even though I don't play in that tuning, so here are some photos of the finished article....

[Tavy]

Looking good Dave, is that TruOil?

[dave17120]

Yes John, Tru-oil, but I had to seal and pore fill first with a shellac based sanding sealer...... pores on that were just so open!!
What do you use to finish yours off? Dave.

[Tavy]

Yes John, Tru-oil, but I had to seal and pore fill first with a shellac based sanding sealer...... pores on that were just so open!!
What do you use to finish yours off? Dave.

My waldzither was straight TruOil, but currently I'm using straight shellac for all my instruments, IMO you can't beat it for looks.