back brace gluing problem

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.
Post Reply
Greg Steil
Posts: 158
Joined: Sat Jan 07, 2012 7:54 pm

back brace gluing problem

Post by Greg Steil »

OK hive mind, ideas please. The problem, loose back braces on Weissenborns(my own build). Very thin body, so the Stew Mac brace jack won't work(too tall) and I can not get my hand very far into the sound hole. Any ideas in how to get the "tool" in there what ever it may be? Thanks.

David King
Posts: 2678
Joined: Sat Jan 07, 2012 10:01 pm
Location: Portland, OR
Contact:

Re: back brace gluing problem

Post by David King »

Perhaps a vinyl ball could be partially inflated inside?

Greg Steil
Posts: 158
Joined: Sat Jan 07, 2012 7:54 pm

Re: back brace gluing problem

Post by Greg Steil »

now thats cool, I had thought of something pneumatic, but figured I'd blow up the guitar. I'll explore that stuff....I love this place.

David King
Posts: 2678
Joined: Sat Jan 07, 2012 10:01 pm
Location: Portland, OR
Contact:

Re: back brace gluing problem

Post by David King »

Actually you might want to experiment with a mylar balloon as it's a low-stretch material and you could achieve a higher pressure more quickly that way but you wouldn't have the convenience of the needle inflator/valve.

Michael Lewis
Posts: 1473
Joined: Thu Jan 12, 2012 1:22 am
Location: Northern California USA
Contact:

Re: back brace gluing problem

Post by Michael Lewis »

Neodymium magnets. StewMac has some, also K&J Magnets. Sometimes American Science and Surplus has some too. K&J has by far the best selection. You might spend some time at frets.com to see how Frank Ford uses them.

Greg Steil
Posts: 158
Joined: Sat Jan 07, 2012 7:54 pm

Re: back brace gluing problem

Post by Greg Steil »

I do have some magnets, and am experimenting with placement tools. I have also developed a couple accessories for the Stew-Mac jacks but they don't fit.

Clay Schaeffer
Posts: 1477
Joined: Fri Jan 06, 2012 12:04 pm

Re: back brace gluing problem

Post by Clay Schaeffer »

You could try wedging a post (like a violin sound post) between the top and brace. Use a pair of hemostats to extend you reach.

User avatar
Ryan Mazzocco
Posts: 576
Joined: Sat Feb 04, 2012 6:01 pm
Location: Joplin, MO
Contact:

Re: back brace gluing problem

Post by Ryan Mazzocco »

Clay Schaeffer wrote:You could try wedging a post (like a violin sound post) between the top and brace. Use a pair of hemostats to extend you reach.
That's what I was thinking. Maybe even use of those violin post setters to do it. It's not that expensive of a tool if you don't have one.

Greg Steil
Posts: 158
Joined: Sat Jan 07, 2012 7:54 pm

Re: back brace gluing problem

Post by Greg Steil »

I have the post setters, and have made two sets of much larger ones for Bass and Cello, and have used long Hemostats as well. Learning as I go I guess. The brace closest to the bottom end is gonna be a real trip. Thanks for all the advice!

John E Giarrizzo
Posts: 139
Joined: Sat Feb 04, 2012 10:17 am

Re: back brace gluing problem

Post by John E Giarrizzo »

Here is what I did on a guitar that I restored. I had to replace a brace.

I used a tapered rectangle of wood with rounded edges. I inserted it at a sight angle until it made contact with the brace and opposite side, then twisted it to apply pressure.
Jeg 100_7070a.jpg

User avatar
Peter Wilcox
Posts: 1159
Joined: Sun Jan 08, 2012 1:31 am
Location: Northeastern California

Re: back brace gluing problem

Post by Peter Wilcox »

I don't know how long your hemostats are, but ring forceps are handy for getting into inaccessible places, and have good clamping pressure. You can even clamp two together for longer reach.

Excellent for removing stuff that falls into the garbage disposal.

http://www.amazon.com/9-1-Locking-Spong ... ing+forcep
Maybe I can't fix it, but I can fix it so no one can fix it

Paul Breen
Posts: 63
Joined: Mon Jan 09, 2012 11:39 am

Re: back brace gluing problem

Post by Paul Breen »

Magnets can work quite well for loose brace repair in difficult places but there is a bit of a learning curve to their SAFE use.

I made these very simple fixtures, with the magnets double stick taped on. I think the image gets the idea across and solves how you get a magnet to balance on top of a brace. The magnets are 1" X 1/8" Neodymium, four used inside and 4 outside is usually enough magnetic pull the get the job done. If you pay attention to the polarity, and you should, you can also use their repulsive power to arrange the fixtures pretty close to a neighbor. You can see I have mine labeled + and - so I can keep track of them once glue has been applied. Clear the deck of anything magnetic in proximity to your project! Lay the magnets out on the bench ready to go in order, organization will help negate the chance of flying magnets. With a sound hole that is large enough to get a hand in there, place the magnet fixture with one hand and hold it in place, then bring the other magnet on the outside to it while grasping it firmly in some protective leather. With an instrument that the sound hole is too small or the brace can't be reached, use something like a steel palette knife, taped to a dowel rod if necessary, and put it into position and hold it there while bringing the outside magnet set into place.

Practice your set up! Do a dry run of both arranging the magnets on the bench and placing them in the instrument. If you have never messed around with Neodymium magnets, play around with them before they ever even get near your bench and get a feel for them. Watch out though, they can raise a blood blister on your fingers before you even know what happened, they are VERY strong! The last thing you want is to have some slip up during placement and have magnets go flying around in an instrument, they can easily crack or break thin instrument wood if not carefully handled.
magnet inside uke.jpg
magnet outside.jpg
magnet fixture.jpg
This is the rig I use to get glue delivered. A Stew Mac glue hypo, some 5/32" brass and vinyl tubing and a hypodermic needle. The Brass tubing is bent/ shaped for the job. I have a good assorted collection of shapes now.

I generally use original Titebond, diluted some with water but have also used it with hot hide glue. The problem with using hide glue in it is keeping it warm enough to not gel. I solved that by using an Infra Red lamp and the glue injector on a small sheet of Black laminated board. Infra Red won't heat up shiny objects but it gets the Black laminate good and hot. Use the injector combined with thin palette knives to get the glue under the loose brace. Have a reaching tool ready with a small bit of rag fixed it that will be dipped in water and used for glue clean up.
Glue rig.jpg
glue rig needle.jpg

Clay Schaeffer
Posts: 1477
Joined: Fri Jan 06, 2012 12:04 pm

Re: back brace gluing problem

Post by Clay Schaeffer »

I like John G.'s idea. It looks less complicated than the "sound post" idea I suggested. I'll have to remember that one.

Post Reply