Tips for gluing hard to reach Brace

[Matt Haugen]

I just picked up an old Regal parlor that is missing the furthest back back brace. I made a brace and it is ready to go in, but I am having trouble figuring a good way to put pressure on the brace once it is in place. I know about the stew mac scissor clamp, (I have a story about this below) but that sure is a lot of money. I then thought I would try coiling up some thin metal, holding it tight in a coil and then letting it unravel inside of the body over the brace. I figure the pressure of the metal unraveling would push the brace tight against the back of the guitar. Anyways, I just wanted to post this to see how others go about gluing braces back down on a guitar repair.

The side note I wanted to post is that a while back I was gluing a brace and I came up with a drawing of a small jack, like a scaled down car jack. I told my wife that this would be a great tool for gluing braces inside of guitars. One of the ideas that she actually liked. Anyways, I did nothing about it and about a month after I showed her this drawing I received a catalog from Stew Mac with their scissor jack on the cover. Funny how things like that happen.

Anyways, any thoughts or processes are welcome. Thank you all.

[John]

I use magnets all the time, but I haven't used this approach...nice one Paul. I'll throw my hat in anyway.

Take 2" of a 1/2" dowel drill and 1/8" hole in the end about an 1 1/2" deep, drop a pickup spring into it and then cut an 1/8" piece of dowel to fit in the hole. It's a spring loaded piston that works like a little gobar. I use these to hold a bridge caul in place for a bridge reglue. But they're useful for lots of things and the bottom piece can be a block instead of a 1/2" dowel of course.

The other approach I use for back braces is to cut a U shaped piece of 3/4" plywood so that the bottom of it goes against the top of the brace being glued and the top of it is outside the soundhole allowing you to clamp from over the top to the back. Use an appropriate caul on the back of the guitar to protect it.

I once tried inflating a small beach ball inside a guitar to hold up a hard to reach brace.....I don't recommend it. Although I have used up some brain power trying to figure out a way to make a jack that used air.

One other thing if you're having trouble getting the glue under a brace and working the syringe at the same time......took me years to figure this out.....take the tube off of the syringe put it in your mouth and blow. 

Oh yeah and a second one other thing. Clamping the neck fingerboard down on top of your gobar deck so you can work through the soudhole from underneath is sometimes advantageous. 

 

[Mark Pollock]

I've had a thought in the back of my mind about something like this, and just figured out what I was visualizing - you know those old cables that you could attach to your camera to take a picture without jitter? It would have a plunger at one end, and a metal rod would come out the other side when you pressed the plunger. I wonder how something like that, with a little locking knob on the plunger, would work to make a kind of remote jack for inside a guitar. I'll ponder this.

[onewent]

The beach ball inside a guitar body sparked a memory.  Brainstorming the same thing, I bought a child's size sphygmomanometer..the blood pressure thingie..and it's easily pumped up inside a guitar body.  But it needs some kind of box to make it a useful luthiers jack, and I got pretty good at using other techniques to hold braces and bridge plate cauls.  I ran this by the Stu Mac rep at a luthiers convention once, and he remarked that they're working on something similar in R&D.  Tom

[Chris Rochow]

I think we all have a few Irwin clamps...but have you seen the "Mini-clamp" they have?  The pad surface is just  15mm X 20mm.  What I have done is 'reverse the clamp.   You have to remove the end (has a pin in it), and slide it off. Do with the other pad also...now you have both 'grip pads' reversed and facing away from each other....cut the excess guide bar off.... I use about 3.5 "  or so.  

Now all you have to do is line up the clamp to the glued brace...and squeeze the handle to expand the clamp to the pressure you would like.  See photo for a better explanation.  :)

[Mark Pollock]

That - is - BRILLIANT!!!

[Paul Breen]

That looks useful for some applications that come to mind Chris, thanks for sharing.

The limitation though is sound hole size and top to back depth. I fixed a brace in a vintage Regal Ukulele yesterday with an 1 5/8" diameter sound hole and 2" deep body, the magnet thingy worked great.

The guitar shown my previous pictures is a Gibson factory made Epiphone FT30 Caballero. These things where assemble with a foaming urethane adhesive. The bonding strength of this non reversible stuff is questionable and if you get one of these come across your bench, it is almost a sure bet something will be loose inside. Pushing against one part to put pressure in another place, like Chris's clamp idea could potentially pop something else loose in instruments built with this kind of glue. The magnets work well because no stress is created in other parts of the instrument, just where it is needed.

[Chris Rochow]

You are very right Paul, the tiny clamp can, and does, put pressure at the "other end"...but I overcome that by just simply using a caul to distribute the pressure evenly around at the opposite end. It really does not take all that much pressure. These 'mini clamps' of Irwin are just that..MINI...fits through any sound hole I've run across with no problem. I got mine at Home Depot.
It does take a little practice...but well worth it !

[Paul Breen]

Hi Chris, I didn't mean to come off like I'm trying to steer folks away from your clamp idea. It's a great idea and I fully intend to modify a couple of my mini clamps like you have done. Looks like a useful repair tool for most acoustic guitars but you would need to find a teeny weeny mini clamp to fit inside of a ukulele.

[Mark Pollock]

And a teeny weenie arm. If they ever invent a prosthetic arm with about six elbows and no more than 1" think, but deep enough to go to the bottom of a guitar, and able to reach through f-holes, with small eyeballs on the end so we can see what we are working on, and... let's just say I'll be first in line. Even if it attaches to my forehead permanently.

[John]

I've used a webcam inside a guitar before but because of computer placement it was awkward, I've considered dedicating an old laptop and webcam to the Endpinoscopy procedure. Now if there was a little tiny remote control front end loader.......

[onewent]

Here's another idea/modification that sprang out of a hard to reach, stubborn brace need.  I took a stumac turnbuckle jack, drilled a hole for a small rod to pass through, angled the plastic end and covered it w/ cork.  The little handle allows me to reach way inside a guitar and jack a loose brace (you know those stubborn ones that just won't close).  With one hand, I can use the little handle for a half turn, then slide it through to make it longer on the other side again, and continue to expand the jack using that method.  Using just the turnbuckle, and having ones arm twisted in an unnatural way, didn't allow me to really crank the brace flush.  With clamping pressure on the outside to support the top and back, I can crank any stubborn brace tip flush with the back.  I can even leave the jack in place, under mild pressure, while I spatula some hhg under the tip, and jack it up immediately after glue application.  This has saved me a lot of time making brace jacks that are often hard to use anyway.  Tom