MIMF

Up next on my bench is a '73 Martin D-18 that has been poorly modified. Besides a poor refinish, a set of pots was added for a saddle transducer. Originally, I thought it would be no big deal to pull the pots and plug the holes in the top with some matching spruce and a little touchup. I also knew that a refret and neck reset will be necessary. But then I looked inside and much to my horror, I found that installation of the pots created a lot of brace damage. One of the pot holes was directly on top of a finger brace which got knocked off and relocated to a new location. But the real issue is the X-brace, which falls between the two pots, was completely notched out down to the soundboard. The installer put in a sister brace next to the X-brace in an attempt to re-strengthen the area.

I could not get a very good photo with my phone of the notched X-brace but when I get my new boroscope tomorrow I will rectify that. But I an unsure of how to fix the damage. I will certainly remove the sister brace. But I can't REPLACE the X-brace. And splicing in a new section would be problematic. I am definitely open for suggestions on this one, but let's wait for better photos so you can better see what's going on.

Since major work is going to be required I am also considering taking the '70s era bracing down a bit and replacing the humongous bridge plate with a vintage era size one. My client has given me carte blanche on this one because he inherited it from his brother.

How well did the sister brace work? Does the top distort under tension? How does it sound? In other words, if it works, consider leaving it.

How much harder would it be to just retop it or take the top off and rebrace it. After all, it will never be original.

I’m glad it’s on your bench and not mine.

The sister brace just looks so wrong. And it definitely introduces a huge stress riser. However, the top is not distorted at that location so the sister is apparently working. There is a pretty good bulge behind the bridge though, even with the huge bridge plate.

Retopping it? Hadn't really considered it but that would probably save a ton of work in the long run and would look much better. The finish on the old top looks really wrong and there are some severely worn places. You got me thinking Bob. Since a neck reset is needed that would be the time to retop if I go that direction.

I can't wait to see how you decide to approach all of these elements. Keep posting progress!

I would consider removing the back and then re-bracing the top... I have re-topped guitars before, but I would think of that as a last resort. while 74 wasn't the best of years from Martin, that guitar has had 47 years of playing time on, while re-bracing will have an effect re-topping would be a new guitar.

The top has a number of serious issues. Here are better shots of the braces. Both of the pots fell directly on top of a brace; one being the lower leg of the X-brace.

Tom, that is an approach worth consideration. The top could be saved, but it sure is ugly.

Barry wrote:
"My client has given me carte blanche on this one because he inherited it from his brother."

If his brother is still around it might not matter how much you change the appearance, if he has gone on to greener pastures it might make a difference.
Ultimately I think what the client wants is what he gets. If I don't agree with it he gets it from someone else! But I don't do a lot of repair work for other people, so that is easy for me to say.

After a prolonged lag, I am working on it again. I have decided to save the top by taking off the back for access. The binding on the back had come loose at some point in the past and reglued so it was not a pristine joint. The back came off pretty clean except for one patch that wanted to stay glued to the headblock.

Here is a better view of the scene of the crime.

I think I will need to pull and replace the bridge plate because it is severely warped.

I am a bit unsure about how to fix the x-brace. Either a graft or complete replacement are the options.

I don’t have the skill to make a decent scarf joint in that x-brace arm with the sides attached. If you pull it off, please tell us how you did it. The only downside that I can see to retopping it is not having the top with a couple of plugs in it. Guitars with stories are often more fun.

My client wanted to keep it as original as possible, scars and all. Here is a shot showing the warpage in the bridge plate. So an hour with a chisel, scraper to remove the sister brace, and a half hour with my bridge plate removal tools got me this. It is SO much easier to remove a bridge plate when you can see what you are doing.

I think I will try the brace graft first and if that doesn't work we will re-evaluate. But first I will be plugging the holes. I am feeling a bit better about this project.

I like to try new techniques from time to time and here is a new one for me that worked well. The quarter size chip of the back that stuck to the headblock needed to be leveled and reattached. The chip was still partially attached and I didn't want to break it free. There were some splinters that were hindering the chip from being reinserted into position. I tried to remove them but was somewhat unsuccessful at that. I have used CA in the past to reattach chips like this because it does two things: secure the piece as well as provide a finish repair. The CA I have used in the past, however, had the problem of bleeding through wax paper and getting stuck to the clamping caul. So I tried GluBoost thin and it behaved well with the wax paper. I placed the back into a 15' radius dish, saturated the area with CA (including a couple of nearby small cracks) and clamped the heck out of it. I am very happy with the results. The chip is very level with the rest of the back and the finish cracks are well hid. Just need to scrape and sand a bit and it should be nearly invisible except for one small spot that will need a bit of stain.

In order to flatten the dome in the top I need to remove the bridge. Since the bridge is so chewed up I will be replacing it so my method is to take off most of it with a router then heat the remainder. This usually gives a quicker and cleaner removal. I heat up my bridge plate iron with a torch and go to town with a putty knife, which in this case is a new one from Rockler that is a nice small size, ideal for this job. I still got a big spruce chip tear out and will remove it with a razor blade and reglue it with HHG.

I am. I’m waiting to see how you repair the brace. I did like your router bridge removal.

Thanks Bob. I am sorry to not be able to show you that cause I ended up removing the entire x-brace. A 3" long section on each x-brace was detached from the top. Normally, I would reglue and go on, but in combination to the missing section, the condition of the top, and the unglued areas being partially blocked with dried glue I thought it necessary to pull the x-braces and start off with a clean slate. It won't be a great amount of work. Maybe took me 3 hours. You can see where someone previously tried to repair the top by smearing glue along the braces.

I’m glad that you were able to remove the X. Now, the repair is straightforward and success is almost guaranteed. I like that you could save the top.

Need to catch up here. Got the holes plugged. Installed a new X-Brace which I had never done on a semi-closed box before. My concern was getting the end of the braces tucked under the lining. After excavating the old brace ends and a little bit of the adjacent lining, I made the new braces and pivoted them into place, one at a time. Then I made small blocks of mahogany to plug the gaps in the lining. This worked out nicely. A new bridge plate of course and a PMTE brace for insurance.