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Repairing a old Gibson archtop

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.

Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Sat Dec 15, 2012 5:54 pm

Today i asked a luthier in the vicinity about that guitar. He also meant that the neck itself was probably the weakest point and that i should at least install a static trussrod. The stability of the rest was probably sufficient, and opening the back would be hardly possible.

Actually i noticed that the (hard) edges of the additional small bars "come through". I will probably need to add some shaping, especially on the bar on the cutaway side. Now that it actually looks as my mod might basically work additional effort becomes meaningful.
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Re: Repairing a old Gibson archtop

Postby Greg Robinson » Mon Dec 17, 2012 12:00 am

Hi Beate,
Sorry, we ask that you only post images for which you own the copyright on this forum, as otherwise is a violation of copyright law. You are always welcome to post a link to the source of an image (I have converted your inline images to links). Please have a read through the forum rules.
Thanks.
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Mon Dec 17, 2012 12:43 pm

Not a problem. For me inline images are legally fully equivalent to links, which they are also technically. According to German jurisdiction the copyright violation would occur if i had downloaded the foreign pictures to the server.

But of course i am going respect the forum rules. Thank for the hint.
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Re: Repairing a old Gibson archtop

Postby Greg Robinson » Mon Dec 17, 2012 8:54 pm

Thanks Beate, but the forum is not under German jurisdiction. The server is in the United States, and as an international forum, we have to adhere to international copyright law if we are to protect ourselves and the community from potential litigation.
Thanks for your understanding.
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Fri Jan 04, 2013 4:44 pm

Dave Stewart wrote:Never seen older ones, although I've done a few.


Actually also older ones are really rare, but some have been build, e.g. by a German Luthier.

Today i saw a vintage instrument made by
"Heinz Seifert -Vogtland - Archtop Jazz Gitarre - wie Geige mit Schnecke - Unikat" advertized in ebay Germany (You may enter these terms to ebay Germeny (.de) in order to see it).
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Sun Oct 13, 2013 8:53 pm

Just to continue with this one: today i succeeded in restoring the headstock. It is not quite identical to the original one, but its optical impression should come really close:

Headstock_MOP_strings.jpg


I was lucky and got some old celluloid both in black and in pearl. I think i should use smaller knobs on the tuning machines (old Schaller M6), but a lot more important is of course the work on the body: i need to make a new bridge after the guitar has settled again under string tension, and i need to do some work on the pickup holes. I still like the idea to convert them into sound holes - the guitar sounds so much better if these holes are not closed.
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Wed Nov 12, 2014 5:32 pm

Please let me continue with this project and show something which is almost "the result". Unfortunately the structural weakness turned out to be to large for 6 strings. Luckily the fingerboard is so narrow, that 5 strings fit with ideal spacing. Therefore i converted it into a 5 string Tenor with quintic tuning (CGDAE). The headstock reflects the style of the builder of the instrument, the discs covered with pearloid seem to me the closest match to that style, and tailpieces of that style were often used in guitars with that look (I found a few pictures of very similar instruments, just with thicker bodied in the net). I could even get hands on a saddle made from celluloid - the heavy use of that material was typical of the German guitars of that time.

Image

Pickups: maybe some time in the future. I do not urgently need that guitar electrified, more important: the open pickup holes improve the acoustic sound.

I think i'll replace the black disc covering the hole of the 6th tuner with something more suitable, maybe a screw M6x16 made from V2A steel with a flattened and rounded head.

Sound: as to be expected very short sustain, and a warm, somewhat mid emphasized tone, but anyway nice. I will need to experiment a bit with a different bridge and with strings - half rounds instead of the nickel wound flats would probably be better.

In summary it looks that i finally found a rescue for the guitar, and i am pretty happy about that.
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Re: Repairing a old Gibson archtop

Postby Bob Francis » Wed Nov 12, 2014 8:43 pm

Nice work Beate
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Mon Nov 07, 2016 10:53 am

Mhmm, i still feel a bit uncomfortable to continue under the label of the thread i had taken over - i would appreciate having this tread split by a kind soul and my stuff put into something like "restoring an old German Archtop".

But anyway: again, my present work was not successful. The top continued sinking in, and also the glue of the neck joint continued creeping:

Image

I think i should be consequent, open the box remove the crop i built in over the years during my failed attempts to save the guitar and renew everything. A good opportunity to do a full neck reset as well and to align the neck correctly over the pickup holes. My idea is to replace the neck block by a relatively large new block, to extend the bass bars over the neck block and let the bass bars take over the full torsional forces - the top is simply too weak.

Here a quick impression after removing some of the old binding with a knive and chisel:

Image

The step of the inner part of the binding covers about half the thickness of the top. Which means that i removed too much; it should be sufficient just to remove the outer tortoise layer.

Is there a more efficient and especially cleaner way to remove the binding? It is made of celluloid, and it shall be reused.

And how would You open the box? With heat or better "just" cut it of with a thin Japanese (kataba?) saw in order to avoid applying heat to the old laquer and the celluloid?
(I will need a saw at least for the extensions of the neck block i glued in 10 years ago.)
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Re: Repairing a old Gibson archtop

Postby David King » Mon Nov 07, 2016 9:19 pm

Beate,

You might look around for something like this kit for sawing through the binding ledge to get the top off. http://www.ebay.com/itm/7PCS-Circular-W ... 1921206592
Dremel has their own version: https://www.amazon.com/Dremel-670-Mini- ... 00008Z9ZP/
but a smaller blade diameter is advantageous.

I think you'd better count on replacing the binding rather than trying to save it and piece it together later.
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Tue Nov 08, 2016 3:40 pm

Well, i managed to open the box with knife an saw, and i'll try to reuse the binding. I am afraid that new binding on the bottom might be more visible than the old bindings, which came off on really large pieces. I actually do not lose the option to use new binding instead if it turns out to be more appropriate.


Now the whole mess is visible: the problem caused by cutting the bass bars in a top that must have been relatively weak anyway and all the wood i brought into the guitar during my attempts to stabilize it. The picture below does not show the present state: the two large blocks have been removed as well as the tiny bars along the sides of the pickup hole. The tiny rest of the original bass bar beyond the pickup hole has been removed, as well as the support of the disc closing that hole.

Image

My idea is to remove not only the additional wooden blocks (which was really easy) but also the original end block, and to implement a new construction taking over the entire load from the neck. Such a construction might be similar to the parallel bars holding the load of my electric violin, but it leaves me with the problem what to do with the pickup hole.

And here the bass bars. They appear to me having always a bit short toward the heel, and i might have expected trouble even without the cut through them. What do You think? And they do not need to be that high in the central part, don't they?

Image
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Re: Repairing a old Gibson archtop

Postby Brian Evans » Tue Nov 08, 2016 7:46 pm

My thought on this has always been, from the beginning, that it isn't an acoustic guitar so the internal bracing doesn't matter as long as it's strong enough. I would make a full length solid center block, like an ES-335, of solid wood, and mold it to the top and back arch with structural foam or a boat building epoxy with ultra-light filler. That should stabilize the top, and tying the neck and tail blocks into the new center block should take care of the neck moving. Make it a great, cool electric guitar.

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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Tue Nov 08, 2016 9:08 pm

That's of course something i thought about and still frequently do so. Nevertheless it has a surprisingly loud and full acoustic sound, especially compared to a laminated full size archtop, which i liked. That lets me doubt. But You're right. A center block would be easiest.

please let my ideas spin freely...

Maybe a combination would be ideal: a center block ending roughly halfway between the pickups (3 cm across the neck pickup hole?), and then scalloping the old bass bars as far as possible. A good opportunity to learn more about sizing bass bars in archtops, as a preparation for the archtop bass i would like to build...

And no contact of the bar to the bottom except at the neck...
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Re: Repairing a old Gibson archtop

Postby David King » Tue Nov 08, 2016 11:16 pm

What about eliminating the neck pickup and replacing the bass bars full length. A thinner neck pickup should still be able to fit under the strings.
Another option might be a big CF tube that runs from the neck block to the tail block and keeps them rigidly aligned?
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Re: Repairing a old Gibson archtop

Postby Bill Raymond » Wed Nov 09, 2016 1:37 am

I second David's suggestion to replace the bars' full length. You could either put a thinner neck pickup on, or use something like a filtertron that mounts to the bars rather than the Gibson style mount.
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Wed Nov 09, 2016 4:14 am

There is one thing to consider: the neck joint. The heel has roughly the size of the heel of a Höfner Beatles bass. As the height of the rims is only 28 mm, it is actually even smaller. Originally, a violin like joint had been used (like with the Beatles bass), which i changed into a dovetail joint because the old joint opened.

For a dovetail joint, especially such a small one which is under heavy load, the orientation of the grain of the wood in the neck block might be important, won't it?
Would the grain orientation of a typical center block parallel to the long axis of the guitar be usable with a dovetail joint?
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Tue Nov 22, 2016 6:54 pm

[quote="David King"]What about eliminating the neck pickup and replacing the bass bars full length. .../quote]

You are right. That'll probably be the best way. Here the present situation. It would be possible to extend the bars up to the sides if statically necessary. But is that really necessary? I am going to fully close the pickup holes. From the outside the fillings should look like "fake pickups"; i am using apple and will stain that black. The inside should best adapted to match the surface, shouldn't it? Then the joints could be stabilized as usual by tiny blocks of wood, and the bass bars could be entirely replaced by new ones.

Image

The main open problem is the large hole. What about converting it into a soundhole - fitting in a ring of about 1.3 cm width with some decoration matching the style of the guitar?
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Re: Repairing a old Gibson archtop

Postby Beate Ritzert » Tue Dec 20, 2016 7:18 pm

Just because i am happy with what i have reached, two pictures of all those holes closed. Still far from professional precision, but way better than anything before and (with very few exceptions) also better than anything i could achieve before. I am quite happy. The next step is obvious - cleating of all those connections.

The top has become noticeably stiffer, especially at its weakest point immediately above the former neck pickup hole. Anyway it looks as if the braces need to be really stiff (high) in this area. It is really good that i did not remove the neck (for now...). It leaves me the chance to test the stability of the top.

Image

Image
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Sunken arched tops and bracing (was: Repairing a old Gibson archtop)

Postby Beate Ritzert » Thu Dec 29, 2016 6:31 pm

Please let me ask a few questions where i am really unsure in my repair projects. Yes plural, i recently noticed that i have a second guitar which needs work to survive. Again a relatively cheap German archop from the early 60s, full size, in the design of the Isana Elvis Presly played in his German years (Elvis' one was fully carved):

Image

Image

Image

As far as i can judge from the outside, both bars are deformed or even broken (there is, however not rattle, the guitar still plays reasonably, it is "only" unstable under string load ofer long time). The problems are really strong on the bass side. And they are stronger than can be seen in the photos.

On the treble side the top is sunken in the same way as in the thinline i am doing now.
The bars are "old German style" - relatively short but 2.5 high. As it is described in "Jahnel - Die Gitarre und ihr Bau",. The sunken part near the neck is not supported by this type of bracing. In addition the top must have been flat in that region and hence fairly weak.

The problem seems to be old. Even a repair attempt has been made on the heel. My assumption is the this crack is a side effect of the sunken top.

Which means that the guitar must be opened and repaired. At least the bars will probably need to be renewed.

My question - i did not fnd anything in the net nor in my literature:

a) how can i bring the top back into its old shape, especially at the bridge? Which means to increas the arching again. If possible without making a new top... i would prefer to build two bass guitars (an Archtop and a Semihollow) next year and spend as little effort as possible into that one. And, of course, keep as much as possible of the old material intact.

b) If i extend the bars close to the neck block they need to be high in order to take over the load of the strings, won't they? Is there any well established style to scallop them down to typical elevation as, say, documented in Benedetto's book? At least with the high arching of the thinline i discussed here such braces would necessarily end outside the weak zone and give no support where i need it.
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Re: Repairing a old Gibson archtop

Postby Barry Daniels » Thu Dec 29, 2016 8:04 pm

On flattops I have used heat and a little moisture to soften the warped area and then applied flat cauls to clamp the bulge flat. Once it has set for a few days and dried out, then a new brace can be added to prevent future warping. An archtop is much more difficult because you would have to have a proper form to clamp it against. The form may have to be custom made. Obviously the top or back would have to be removed to gain access for the work. A "cheap" archtop may not be worth this amount of work.
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