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1930s Martin 0-18 Major Repair
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10137&t=50720		 Page 1 of 1
Author:  DanKirkland [ Fri Jun 08, 2018 9:14 am ]
Post subject:  1930s Martin 0-18 Major Repair
Title says it all. This will be a little photo journal of getting this thing back together. Just for the sake of documenting it. This will be a fun one.

I had previous asked for advice on getting a stubborn bridge plate off of this guy. Previous "repair" had glued it in with hardcore waterroof titebond (thanks to Mr. Howard for helping make that diagnosis). Top was curved something fierce behind the bridge. Replacement plate was too short and did nothing to keep the top flat. The guitar initially came into my shop for a bridge reset. Upon asking the owner it had been reset about 7 times in a very short span.

I was also concerned because I noticed a gap when I removed the bridge initially. This should not be here.
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I had to remove the back to get at the plate, heating this thing and trying to remove via bent chisel was going nowhere. I decided to very carefully cut out the replacement plate.

Cupped and also not even glued in some areas. The plate extended to the exact edge of the bridge creating a massive bubble right at that tension point in the top. Plus the grain was running perfectly horizontal to the top, that might be "Vintage internet research correct" but that does not mean that it will work This grain just had no strength to resist the pull of the strings.
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Here we uncover the horror that this warped monstrosity was hiding.

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The pieces that came off all had the telltale signs of non-adherence of the glue. Surfaces were just gobbed up with the junk. Turns out that there multiple holes through the top that the bridge plate was supposed to "fill". It didn't work.
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Digging a little further. What do I find but a badly glued scarf fill for the larger portion of the top under the bridge?

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This entire fill just fell apart as I removed the plate. You can see the scarf line. Again there seemed to be no ahesion of the glue.
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And the top. Thank you previous repair guy. You nearly destroyed a very desirable guitar because of your idiocy.
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So the plan for the repair is simple. Thankfully it will be MUCH easier since the back is off already.

Scarf in new spruce for the top. Extend the scarf joint to go below both sides of the bridge.
Fill the gaps in the cross braces to allow better contact with the top.
Glue any loose braces
Patch any and all cracks.
New bridge plate with different grain orientation (diagonal to the top) and extended past the edge of the bridge to help flatten the top.
Put back back on, rebind, touchup finish
re-install bridge, restring clean and done

I was just in a similar situation not too long ago with a 1930s L-0 that had almost the exact same issue. Looking forward to having this one all back together again. It'll a long process, this is the owners main writing/recording guitar. I'm sad to see that it is such a sad state. Honestly if the previous repair guys had just not tried to hide the issues this would not have happened. I tried contacting the previous guy that had this in his shop but have received no response. Oh well, onwards and upwards.

I'll update this as I move along
Author:  Chris Pile [ Fri Jun 08, 2018 10:16 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Wow. Just wow.

Power to you in your efforts, sir.
Author:  SteveSmith [ Fri Jun 08, 2018 1:58 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
What Chris said.

Thanks for taking the time to post the photos, this one is interesting for sure!
Author:  olmorton71 [ Fri Jun 08, 2018 11:50 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Please post photos through out the repair


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Author:  flemsmith [ Sat Jun 09, 2018 9:22 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Wow again....thanks for sharing this. it's gonna be epic.
Author:  DanKirkland [ Thu Jun 21, 2018 12:23 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Been working on this lately. I'll post more pictures later.

The scarf joint for the top patch has been completed.

The patch when in well with a huge amount of glue surface. However I realized that the end portion of the patch is almost directly in line with the edge of the bridge plate.

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My thought is that 20 years down the road from now when the bridge plate wears out again and has to be replaced. That the guy removing the plate might possibly dig into the scarfed patch for the top.

So to counter this and prevent anything catastrophic from happening I am going to overlay the scarfed patch with a paper thin piece of spruce. It'll extend well past the edge of the bridge plate. It should also help to flatten the top quite a bit and reduce the extreme belly. I'll post detailed pics when I have time.
Author:  DanKirkland [ Fri Jun 22, 2018 9:24 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Going back in a time with some of these. Progress is being made.

Cutting the scarfs for the top patch. I decided to extend the edge of the scarf much farther back. The previous repair guy had only had about 1/2" of wood for his scarf on the front side. For this repair we've got nearly a full inch on both sides of the missing top. I like these little violin planes for jobs like these. But these Ibex planes clog alot unless you put a little work into them. C'est la vie.

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Patch is cut, fit to the scarfs, and glued in place.

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Onto making the overlay. The overlay will be as thin as I can make it, I'm using light along with a micrometer to gauge the thickness. Basically I'm going for veneer thickness. This will also give alot of good clean gluing surface for the bridge plate to attach. Thus strengthening the top and helping to reduce the horrible bubble.

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Cut to size, It will be thinned down even further once it's glued in place. The spruce is flexible enough that it molds to the top and gives alot of reinforcement. Should last for a long while.

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Gluing it in place. I used my bridge plate caul to help clamp. On the top of the guitar is a thick piece of acrylic to help flatten the top and give me a good clamping surface. No damage being down to the finish. I used hide glue on everything.

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Once cured the result was immediate with the top. Some arch but none of the extreme doming it had before. When the bridge plate is attached it should flatten out a bit more.

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More to come.
Author:  DanKirkland [ Sat Jun 23, 2018 8:22 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
After thinning the overlay down even further I added the bridge plate. Grain running diagonal as opposed to the horizontal lines from before. I also extended the width to go past the back edge of the bridge to prevent the dome top from returning after some time being strung to tension.

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I re-attached the back. I'm going to have it glued up first and then string to tension before I do any re-binding work. Mostly because if something goes awry it'll be easier to remove the back again and work with the binding already off. I doubt that this will happen but I enjoy covering that base anyway.

The top portion was still in rough shape. Lots of removed top material where the previous bridge resets had occurred. There was a significant "dip" where the top of the finish and the unfinished area sits.

To level out the top I decided to overlay another paper thin layer of spruce to give good gluing surface as well as to preserve the top from further damage. I could have glued the bridge to the wood that was already there with the scarf fill in place, but I do not want to see this guitar again until a long time down the road. I think that it was worth the extra effort. The spruce fill was thinned down and then scored lightly with the grain so that under pressure it "bent" to fill the little gaps between the scarf fill and the little dips in the existing top. I removed as much of the contaminated wood as possible and squared off the recessed portion slightly for the sake of good adhesion.

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Tiny line of spruce is visible. I'll darken it up later. It's more important that there be wood to adhere to than to look absolutely insanely perfect for this instrument.

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Bridge is glued up now. Projection looks good. Thankfully no need for a neck reset in this one. Kind of excited to string this up and give it a test with the repairs that have been done.

More to come after the weekend.
Author:  B. Howard [ Mon Jun 25, 2018 5:25 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
very nice!
Author:  Johny [ Mon Jun 25, 2018 12:34 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
That's great!
Author:  Bobc [ Tue Jun 26, 2018 8:02 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Great work
Author:  mountain whimsy [ Tue Jun 26, 2018 11:43 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Well done!
Author:  DanKirkland [ Wed Jun 27, 2018 4:37 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Bridge glue up went well. Sorry for the blurry pics my phone doesn't want to focus sometimes.

The belly is all but gone and now we just have the nice delicate arch in the top that we are after. In all likelihood this will probably still move and potato chip a little bit. But I've done all I can do at this point. With old guitars, it is what it is.

The tone is much better than when it had a giant hole in the top. I took a little sample on my phone but the quality is pretty low. I might link it later.

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All that's left is to re-attach the binding. Luckily it all came off in one big piece so it's just a matter of regluing it. Essentially it's complete sans the cosmetic issue of the binding.

I am happy with the result. I'm going to let it sit at tension for a week or two before I let the owner know that it's ready. So far so good. The owner I think will be pleased, considering this instrument's past with repair I can only hope that these repairs will outlive the owner or myself. Time will tell.
Author:  Freeman [ Wed Jun 27, 2018 6:24 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Very well done and thanks for the show.
Author:  fingerstyle1978 [ Wed Jun 27, 2018 6:47 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Dude- great job. Well done Sir!!! It's always awesome to see a skilled luthier breathe life back into what probably should have been a lost cause. I haven't done much repair work but this is inspiring.
Author:  nathanpeirson [ Sat Jun 30, 2018 1:53 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Great job and very inspiring. What do you think the tonal difference is now with the extra wood added...anything noticeable?


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Author:  DanKirkland [ Sun Jul 01, 2018 5:54 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
nathanpeirson wrote:
Great job and very inspiring. What do you think the tonal difference is now with the extra wood added...anything noticeable?


Sent from my iPhone using Tapatalk


Thanks for the compliment.

In regards to the tone. Everyone that has heard it compared to what it was likes it. I really don't think it's fair to compare it to what it was previously because it really was not in a decent condition. There was very little wood to wood contact on the top which translates to not alot of transfer of vibration. The other issue with the tone was that the bridge plate was right at the edge of the bridge. So there was truly no resistance to the pull of the strings.

The tone before was not ok, but it was not the fault of the guitar. It was the fault of the previous repair guys using copious amounts of glue to hold the top together instead of wood. Wood always wins in this application.

I didn't mention it before, but the previous repair guy charged my client excess of 500$ to do the repairs. One reason I wanted to go the extra mile is because he had been really screwed on it before. Sometimes you just need to do what you need to do.
Author:  Ruby50 [ Sun Jul 01, 2018 7:16 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Great to see an old instrument brought back. How thick did the thin layer of spruce under the plate and under the bridge end up being?

Ed
Author:  DanKirkland [ Mon Jul 02, 2018 9:04 am ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Ruby50 wrote:
Great to see an old instrument brought back. How thick did the thin layer of spruce under the plate and under the bridge end up being?

Ed


The overlay was about 22 thou when I installed it. Once the glue had dried I thinned it down farther. The edges tapered out to I'm guessing 10 thou. I wasn't insanely precise when doing this.

Before it was installed I just held the overlay up to the light and removed material where it looked thickest. Once in the guitar I flattened it out and then continued forward.
Author:  DanKirkland [ Sat Jul 07, 2018 2:40 pm ]
Post subject:  Re: 1930s Martin 0-18 Major Repair
Update on this one. Client picked it up today. I let it sit at tension from the 27th of June till today. No movement in the top and no budging of the bridge. Seems to be ready for another few decades hopefully.

Client was happy to have it back in good shape.
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