View Full Version : back crack cleats

Mar-07-2004, 7:40pm
I am still working on my old 1916 Gibson A. Not too sure what I am doing but still enjoying it.
I have taken the back off and forced glue into 2 back cracks that are about 3 inches long. It seems pretty stable now but I want to re-inforce it.
Should I put cleats on?-- if so could someone tell me what size to make them and where to situate them. I assume that one on each end of the crack and one in the middle?
I got a hold of some birch that I am planning to make them from. (since the back is birch) I also have some close grain spruce. Which is better?
I have toyed with the idea of fabric re-inforcing but can't find out too much about it.
Do the cleats stiffen up the back enough to affect the sound? I doubt it but am curious about this.
Any info greatly appreciated.

Gail Hester
Mar-08-2004, 2:04am
There was a previous post that may help. Hereís a picture of the cleats on a violin repair, they can also be other shapes such diamond. Be good to that 1916, it would be well worth it to pass it on to an experienced luthier.

http://www.mandolincafe.net/cgi-bin....l=cleat (http://www.mandolincafe.net/cgi-bin/ikonboard.cgi?act=ST;f=7;t=11880;hl=cleat)

Mar-08-2004, 2:50am
Gail thanks for the info. Us westerners are up late tonight.
Don't worry too much about my mandolin. I won't hurt it. I am being very cautious. It is in bad shape already so it is probably not worth it to spend a lot of money on a luthier. It would probably cost more than it's worth.
So far I have cleaned it up a bit; removed the back which was coming off anyway; cut the pickguard pins off which had to be done because they were glued in; removed the top brace, which was also half off; attempted to refit the deteriorated tuners with some spare parts, (not going so good); formed a mold of the top out of plaster of paris to act as a support for when i glue the back back on; fabricated a bunch of L-brackets with tapped holes to use as a jig to pressure the sides back into shape in readiness for the back replacement.
I am very concerned about the actual hide glueing of the back when the time comes. I am fairly optimistic that with patience the sides will go back into position but having never used hide glue before I am afraid that disaster may be looming.
I am considering doing all of the jig building and aligning myself and then taking the whole thing to someone who knows what they are doing for the actual glue job. We'll see.
Not too many people with that kind of experience in my neck of the woods. Mostly guitar guys with 5 gallon buckets of Elmers glue. They don't take mandolins very seriously.
I looked at that link you gave me and it looks like that's what I'll do.
Thanks Gail.

Gail Hester
Mar-08-2004, 4:21am
atetone, sounds like your doing the right things. #My recommendation with hide-glue is use Behlen brand and to mix 12 grams of dried glue to 18 grams of water, allow about 15 minutes to reconstitute. #I let the container, I use a small plastic dunk cup like youíd get a fast food place, hanging in a thermostatically controlled water heater set to about 140 degrees, and I use an electric tea water heater I found at Goodwill. #Apply the glue to both surfaces and have everything ready because you donít have much time and it seems like it takes three sets of hands to get it together and set all of the clamps. #I use pins to help get it together right and ensure the two pieces donít slip (they always slip out of position when you apply the clamps). #I preheat the wood with a hair dryer and some people even use a heating pad to pre-heat the wood so that you have a little extra time. #Hereís a picture of gluing on a back, yes you need this many clamps.

Mar-09-2004, 12:29am
Yikes!!! Gail are you trying to scare me off??http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif
Actually I sort of figured it would look like that. I have ordered 20 of those trigger type clamps because they had a good sale on them, just in case I get brave.
So just how long do you have before the glue sets up, if you pre-heat and all that good stuff?
You might be able to sense that I am getting a little more brave as time goes on. Maybe.

Gail Hester
Mar-09-2004, 1:43am
I actually made all of the cam clamps, because Iím cheap. On the trigger type I just put a piece wood under the jaw so it wood reach over the form to the back. You donít have much time with the glue (probably less than a minute) and it helps to have someone assist. You need to have everything ready and staged before painting the glue on. I paint it on one side and then the other and get it together as fast as I can, you donít want it to gel. The pins help keep it from sliding but you still need to watch it. Put the clamps on like you put lugs on a wheel, filling in as you go, the clamps need to be close together. I leave the clamps on for 24hours. I donít do much with it for a few days as hide glue gets stronger with age. I started using hide glue when I started repairing and building and Iíve had really good luck so far. The nice thing about hide glue is that if it doesnít go together like you want you can get it apart right away, clean if off with a wet rag and start over. Good luck!

Michael Lewis
Mar-09-2004, 1:48am
Atetone, If you wait for warm weather it might be a little easier to deal with the glue, but just warming everything will help a lot. You will have about 30 seconds of open time, meybe a bit more if the planets line up for you, maybe more than a minute in warm weather. Practice going through the process a few times so when it comes time for actually applying the glue you will know better what to do so you don't waste precious seconds of time. I would clamp the neck block area first, then the tail block, then a couple clamps on each side, then fill in with as many clamps as you can fit. The gluing surfaces need to be as perfect as you can make them and must fit together well, success depends on it. You can do this if you think you can.

Apply the glue with a brush (just get a 1" nylon paint brush, they're cheap and will hold a good load of glue) and keep everything warm. If the glue starts to gel before you get it all together just stop and clean off all the parts, let everything dry out and try again. The squeeze out and drips will clean up very nicely with warm water and the brush, then wipe with a cloth or paper towel to remove excess water. If you let the glue dry before clean up you will have a difficult time. Also, if I didn't mention it, keep everything warm.

Mar-09-2004, 2:16am
Great info folks and very much appreciated. I think I am going to give it a whirl. Nothing ventured nothing gained.
I especially like the part where if you mess it up you can just clean it up and try it again.
It will be a while before I can actually get around to doing it but will let you know how it turns out.
Thanks again!