Repair of Zither (Harp Mandolin) ??????

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Re: Repair of Zither (Harp Mandolin) ??????

Postby Daryl Kosinski » Wed Jul 11, 2018 3:13 pm

Don't give up on it yet.

I have restored a furniture that had family history.

One of the biggest issues is fixing the old repairs.

I once spend many hours with a jewelers loupe and dental picks digging epoxy and gorilla glue out of a "repaired" crack.

Take it all apart fix the fixes or even make a new top and back.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Daryl Kosinski » Wed Jul 11, 2018 3:19 pm

Caley Hand wrote:OK, Based on what I learned, if I were to just build a copy of this Zither, where do I get the wood for it.

What do I use for the front and back soundboards? I have looked, but there do not seem to be any sheets of about 3/16 inch thickness (whats on my Zither), that are at least 15x24 inches. I have found hardwood ply, but I am not sure that ply is something you would use for soundboards. Based on what has been mentioned here, Spruce seems to be the choice.

If anyone has some links to wood sources, that do not break the bank, I would love to explore those. The sides are 1.25 inches wide , and I am guessing 1/2 inch thick to hold those pins in place. and I would need about 6 board feet. From what I have read, Maple seems to be one of the big choices. Caley Ann


If I were you I would find a small cabinet or millwork shop. Stop in with your project and say Can you help me? Show them what you need and you would be surprised at the help you may get. Just replacing the top might be the way to go.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Wed Jul 11, 2018 5:33 pm

Daryl, Not likely to find such where I live, 29Palms, California. Heck, the only trees we have are Joshua Trees, and Palm Trees.

Unless I want to trash the instrument I have, there is no way to remove the back. I tried this morning, and despite every effort, the back would not release. They used some kind of glue that does not react to water or steam and heat. I also tried to use a fine razor saw to separate a corner, to no avail. Whatever glue they used is permanent, and harder than the saw I was using, probably super glue. Thus the thought that it might be easier to just make a new one from scratch. Caley Ann
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Thu Jul 12, 2018 12:23 am

OK, I did not give up, but I took the "Hammer" approach, almost literally. I have accummulated a lot of different things through the years, including a few chisel sets, along with all the things necessary to create razor sharp edges.

So, if I could not remove the back one way, I would use the brute approach. But this approach sacrifices something, the original back, as I had to strip away the back one piece at a time. But I did eventually, and without but one side ding, get the back off. Once that was off, I had to figure out how to remove eight blocks of wood. Yes, there were eight in there. I ended up trying the chisel, but found I would have punched a hole through the front. So I got some vise grips, and took an end of each, and gave a quick twist. That released the grip of the glue on all of them.

Next, was preliminaty cleanup, again with the chisel, and rubber mallet. I had left wood from the back on the side panels, and that had to go. Twas very tedious work, but got it done.

Then I cleaned up the inside as well as I could, again with the chisel, using if primarily as a scraper. I finally did a cleanup sanding on the back sides.

The picture shows it clamped. I am going to leave it this way for a day or so to see if the sides will relax, and allow the cracks to close. If not, at least I can do the repair work from the back. But it may close, as it has a little upon clamping it. I think the wood just needs to relax.

Now I hav to find some kind of wood for a new back. Any suggestions? Byt the way, the wood I took off was very soft and not at all what I would expect. I wonder if 3/16 Spruce would be that way. From what I understand, the front should be Spruce, but the back could be something else. Would a Mahogany ply be OK. I can get that in the size I need. Unfortunately, Spruce would require me to join two panels, and if the seller does not make the edges perfectly straight, then I can't. I do not have the tools. Caley Ann
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Back Removed.JPG
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Chris Reed » Thu Jul 12, 2018 5:26 am

Step 1 would be to remove the back on your zither, to see how it is built inside. And if you do that you might even decide you can fix the old "repairs"! If you can sharpen and use a chisel then you can (very slowly and carefully) shave off all the wood and most of the epoxy. If the epoxy is rock hard, it should soften if you heat it with a hair dryer.

For back removal, get a thin blade. A craft knife or scalpel is good. Heat the join at one corner with a hair dryer and use a damp towel to add moisture to the join. Once the wood is hand hot (careful not to scorch the wood!), gently work the blade into the join. Then keep heating and damping along the join, working the blade along as you go. Don't force it or you'll cut into the wood, just gently twist and lever it along the join. If you can see any back bracing inside this might be a problem if that is notched and glued into the sides - in that case, once the back to side join is open all the way round you need a longer blade, like a long kitchen metal spatula, to work along each brace. Plan to spend an hour, rather than minutes, doing all this, though you might be lucky and the glue just cracks open all round once you have got it started.

If you go carefully and don't force it, you can glue the back on if you want to keep this as a decorative piece (assuming you decide it's not fixable).

Ready thicknessed spruce panels can be bought from model-making shops. They're about 4 inches wide, so you have to glue up several lengths to make a board the right size - this is quite easy using a flat surface like a piece of MDF or laminate-cover chipboard, panel pins and masking tape. You need to hand pick the boards - you want vertical grain (i.e. the end of the board looks like this ||||||||||||||| ).
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Thu Jul 12, 2018 4:02 pm

Chris, The back panel is off.

I have magnetic building boards with all kinds and quantities of magnets. All I will have to do is cover the steel sheet with a plastic sheet, then apply glue to the edges of the boards. Then all I do is start laying magnets along the tops of the boards where the seams are, and using big magnets, clamp and put pressure inward. I've done this before building various models for friends. A magnetic building system is quite effective to use in many building endeavours.

Since it is the back that met its demise, I have ordered Maple to use for it. I purchased two sheets of 12x24x3/16 I've read that Spruce is primarily a sound board, and that Maple is the prefered wood for backs, and sometimes sides of stringed instruments. The only thing is that the place I purchased it, "Scroll Saw Wood", says it is finished on two sides. I am hoping that the sheets are actually square cut on the sides. Not sure of the quality of the wood, but spending $40 for two panels is a lot less than the nearly $200 that most Luthier wood stores are charging. I'm quite sure that the woods they sell are superior, but no one will see what is under the paint. Caley Ann

An additional note: As I mentioned about the previous picture, I have clamped the sides in the hope the monster crack would reduce in size, and it has. I am going to leave it clamped until I install all the cleats needed. I still think that taking the repair Spruce sheet, and cutting so that I get a long piece with grain perpendicular to the crack will be the best approach. I think I need all that surface area glued to insure that monster crack does not reappear. Same for the small one above the sound hole, though that one has completely disappeared since I clamped things.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Thu Jul 12, 2018 11:11 pm

Welllll...!!!! I discovered today that my clamping to get the things to relax, did just that, but not what I was wanting. One of the sides decided to move inward. So I unclamped, and moved the side back into position, applying a little Gorilla Glue.... NOT!!!!....Titebond Hide Glue, and clamped things in a way that brought the two joints back into alignment. Another lesson learned. Do not tighten clamps too much.

I finished my spool clamps, but my problem is that apparently my drill press is not all that good at precision work. The drill bit seemed to find whereever it wanted to drill a hole, and almost never where I carefully found center, and put a center punch. I guess things don't have to be perfect as long as they function for what they are intended, and that will be holding the bottom panel in place while the glue dries. I made 20 clamps, which I hope is enough.
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Spool Clamp.jpg
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Chris Reed » Fri Jul 13, 2018 7:15 am

That spool clamp looks fine to me.

Note that the threads can dent the wood when you apply the clamp (ask me how I found out!), so I'd wrap some tape around it before tightening or put some scraps of cardboard between the threaded part and the wood.

Up to you on the long cleat, but I'd find it easier to apply lots of small cleats in a line. That would let me creep up on aligning the parts, rather than having to get it right in a single go. But if the back is off and you don't like the result, you can always remove your long cleat (hair dryer) and have another go.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Fri Jul 13, 2018 11:22 am

Chris, I already was wondering about the threads on the sides. Thank goodness I have to clean up the sides, and repaint it to bring it back to near orignal condition. I got some paint matched to the colour already there.

I'm just waiting on the wood for the back so I can join the two panels, trace the outline, and cut out a replacement back.

I am still thinking about how I will go about filling the front crack. The wood I am getting is being shipped from China. I had no idea it was there, or I would've ordered from StewMac, and just paid the higher price.. I think I will just keep test fitting the splinter until if is as near perfect as I can get it, then glue it in place. After that, any imperfections can be taken care of with the "TimberMate" wood filler I got. Then I can just try to do art work connecting the graphics on the front, so that it looks fairly close to original. This is my first repair, so I expect to botch some of this work, and thereby learn something.

I just hope that the work I do will produce an instrument that sounds fairly decent. Caley Ann
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Steve Sawyer » Fri Jul 13, 2018 6:21 pm

Caley - an old trick from pattern makers. To keep parts from sliding when clamping a glue-up, put a few grains of kosher salt on the glued surface. The salt bites into the wood, preventing it from sliding. Pattern makers used to use foundry sand as it was readily available, but a tiny pinch of kosher salt works just as well, and won't dull a chisel or router bit if you cut into it later.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Jim McConkey » Fri Jul 13, 2018 11:26 pm

To protect sides from the threads, pick up some 3/8" inner diameter poly-whatever tubing at Home Depot, then cut into pieces a little less than the thickness of your instrument. Place over the threaded rod between the spools. Since the clamps work with everything from fiddles to guitars, I keep a bunch of sizes handy.
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Sun Jul 15, 2018 8:51 pm

I tnink the least troublesome, and least expensive way to keep the bolt threads from doing harm to an instrument is simply to use cardboard. Since I am a cereal eater, cardboard is not something I cannot get, and it is free. I used cardboard to mix my epoxies, when I needed small amounts.

Right now the Zither is on hold, waiting for parts to continue repairs. I have two projects ongoing. The other is my scratch built Kalimba viewtopic.php?f=9&t=5562&start=20
I am almost done with doing the finish on the instrument, and just have the tines to create. Will display a picture in that thread, once things dry. Caley Ann
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Re: Repair of Zither (Harp Mandolin) ??????

Postby Caley Hand » Tue Jul 17, 2018 2:25 pm

I got tired of waiting for stuff from China, so I went ahead with the only wood I had on hand, Basswood 1/16x1/4, and created the splinter suggested to fill the monster gap on the fron panel. I used Titebond Hide Glue as the adhesive. Glued, I inserted the splinter into the crack. I place plastic sheet and a block under that to fit tight on the face of the Zither front panel, then slid the splinter into place. The excess wood protruded from the rear. I just used a sharp chisel to remove the majority of that, and then place another piece of plastic on the back side of the panel, and finally use Neodymn magnets to hold the seam flat. Of course I removed the block of wood from the front. Now I am just waiting for things to dry.

Once that is done, I can then carefully sand the rear of the panel to clean up any excess splinter or glue. I am hoping that with my forcing the splinter to reside in the crack at the front with that wood and plastic, that no glue will, or at least very little, will have seeped onto the front graphics. I should just have to paint over that anyway, to bring the graphics together across the repair. Once dry, and cleaned up, I will post a picture. Right now I do not wish to disturb things while the glue dries. Apparently 24 hours for full cure.
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