Official Luthiers Forum!

I recently accidentally dropped an uncompleted guitar. My reflex was to catch it with my foot before it hit the floor. I was a few milliseconds late and hit it with my toe on the lower edge of the back. I guess you could say I was lucky in that I didn't break any pieces out of the back. However, the cracks radiate out an inch or more from the point of contact. The problem is that one of the cracks has its edges overlapping the wrong way. I think if I could push it from the inside I could get the crack to overlap properly and then glue a piece of veneer to the inside clamping it with rare-earth magnets. Unfortunately, I can't reach the cracked area from the inside of the guitar because my arm just isn't long enough.

I'm wondering it anyone has had a similar problem and found a way to pop the the edges of the crack back out to a normal position. Here are a couple of pics: the first is the complete back, with the break near the bottom edge about 4 inches to the right of the center strip; the second is a closeup of the break itself. You will note that the crack extending from lower left to upper right appears very light in color - this is the "inside" edge of the crack.





All input will be appreciated.

Thanks,
Max

_________________
Max Bishop
Brighton, Michigan

I am going to say that I would remove binding and remove back and repair completely or replace . The reason I say that is " Question" ? are you ever going to be happy with it if you don't ?

Sorry for the accident , however I think we have all been on the side of that problem

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

It's in a bad position, being so deep into the lower bout. If it isn't a Guitar for sale I think I'd remove the Back and repair it. Hard to say without seeing it in person. You should be able to make that all but disappear. Nice wood.
You see far worse.

Take a look at the StewMac scissor jack. I think with sufficient cauls you can push out the back without damaging the top.

^
Agree. I reckon you can get e edges to align, squeeze some glue in, and get a near invisible repair. I don't think internal cleats will be needed.

I'm sure some more repair oriented folks will be along for more thorough advice...

Perhaps you can use magnets to clamp the pieces back together, and then wick thinned hide glue into the cracks to close it. Did you crack any braces? That is the first thing I'd check.

You can attempt to clamp it by taping a magnet to a stick and reach in that way. It will not be a clean fix unless you remove the back, fix it, and replace it. Finishing touch up will also be required and it will not be easy to do for a tinted/yellowed finish. It may be better to refinish if this is a guitar for sale.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Colour touch up shouldn't present a problem.( lol ) Not mine BTW! And yes these are before/after photo's, not the other way around.

How do you do a color touch up like this? I have tried without success to make it invisible, and decided it wasn't possible without a refinish.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

That is really good work Michael.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

It's not mine!
That is an extremely high level of repair/restoration. The instrument would have to be worth an awful lot to justify such a repair cost. Either that or it would have great sentimental value. The guy who posted those pictures also posted another Violin with fairly extensive woodworm damage. it was equally impressive.
I worked with a couple of school trained Violin repairers/makers in the '90's. They weren't doing that level of repair but some of the work they did was incredibly good. Touch up on Violins is normally done with spirit varnish and a very, very fine artists brush. It's almost like pointillism, little tiny dots. Getting the colour right is the hard bit. They tend to use the natural shellac colours, Lac dye, Alkanet, Dye woods, Madder etc. There's a whole range that they use. In combinations they can cover the range. It takes a lot of practice to get good at that kind of touch up. It's really very specialist work. No way would they refinish the entire Back. That kind of thing would be considered a mortal sin in the Violin world!

If I had an instrument so extensively damaged, I would just refinish the back. It is much easier to shade the back, and make it blend between different sections (between back and side) than it is to blend it in the same area where even minute difference can be VERY obvious. That kind of damage would require refinishing to cover all the repair anyways.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

You are wrong Tai. They very, very rarely refinish Violins. Any expert restorer would hang his head in shame if he did that.
Back when I was working with those Violin repairers a guy came in with a Violin. He had ripped a very large band of Varnish off the soundboard because he had applied some sort of stick on pick up. Unfortunately it wasn't his violin. He had it loaned to him by a music conservatoire, he was one very worried young man. He came to collect it a couple of weeks later. He honestly could not find the varnish repair, no matter how hard he looked. I saw them do it. No refinish, not even remotely.

Regarding the finish, the accident happened before the finishing was complete. I have two coats of brushed varnish on the top and 5 on the back and sides. Consequently, once I have the repair completed I plan to put at least one more coat on the back (possibly two) and sides before leveling the whole thing and applying a final thin coat, final sanding and buffing. I will be using the same varnish as has been used on the instrument to this point, so I hope that color matching won't be as tough as the violin repairs referenced. BTW, the wood is Lawson Cypress from Oregon. Beautiful stuff!

Max

_________________
Max Bishop
Brighton, Michigan

In one of Sloane's books, he uses a L or dogleg-shaped jack to apply leverage when gluing such cracks. Would that be helpful? I could upload a photo when I get to the house.

Glenn,

Yeah, the photo would be most helpful. It sounds like an idea I had. So, I would like to see it.

Thanks,
Max

_________________
Max Bishop
Brighton, Michigan

bump

_________________
Max Bishop
Brighton, Michigan

Sorry, I forgot to take the pic last night. I was googling for it but no luck yet.

Hi ya Max.

If you want to bring it by we would be happy to take a peek and discuss how you might approach the repair.

I've been using rare earth magnets for about 8 years now and they work great once you understand the shortcomings and dangers. I made a very simple tool, a stick with a recess that carries one magnet into the bowels of the instrument manipulating from the sound hole. The stick is about 8" long and has that recess to carry one magnet. It was also named as a tool by my shop mates and that name cannot be repeated on this forum....

I use the stick and by having a protective caul on the outside and manipulating my position of the outside magnet the inside magnet "launches" out of the stick and into position right were I want it. I try to slide the stick into place with top contact so that that "launch" is more of a repositioning than an actual rare earth projectile inside the box...

Removal is simply sliding the top side magnet off the caul/instrument and the inside magnet falls loose (provided that we put waxed paper on it..... don't ask me how I learned this...)

The magnets that we use, the 3/4" ones are powerful enough to flatten a pucker... and do a great job of keeping things level.

Anyway if you want to bring it by we are happy to help - always!

Hi Hesh,

Great to hear from you. I would love to drop by. Is there is there a day or time that is better than another for you?

Thanks,
Max

_________________
Max Bishop
Brighton, Michigan

Bump

_________________
Max Bishop
Brighton, Michigan

Max. It's a bit like a Shepherds crook but not quite. Just a very simple wooden device. It acts like a lever, You push the end down and the other end pushes up. It just has to be the right shape (and length). You put a wooden block on the soundboard and the pivot point rests on it. It's the see saw principle.

You can also make static jacks that are already sized and notched. The notches utilize existing braces and lock on and each jack is sized for the needed length. This is a common approach that has been done for likely over a century. When a brace is not handy for the jack interior cauls for the jack to bear on are a good idea.

The jack with handle that Michael is trying to describe appears in one of the big red books, has also been used for all of time, and needs to be specifically sized for the instrument. For example the mando ones are too short for guitars, etc. The down side is that because it is a lever, basically, that important feedback that keeps one from exerting too much force and crack say a top further is not present.... Careful Will Robinson.

Max - Yes, I'm in all day Thursday and Friday and I missed you last time so let's catch up too. As far as I know Dave will be in all day Thursday so that's a good day to visit if it works for you?

Here it is:



Hope that helps.

Glenn

A better shot in use: