Greetings.  First time posting here.  Most times I'll find the answer I'm looking for by using the search function, but I'm coming up empty handed on this one.

I have an old steel string suffering from a couple of loose back braces.  None of them are completely loose, only a couple of inches where I can slip a feeler gauge underneath.  What methods do you employ to get the glue in such a tight spot?  Guitar was put together with hide glue, that's what I plan on using for the repair.



Views: 487

Reply to This

Replies to This Discussion

I put tape down on both sides of the brace, then use a small palette knife to get glue in the joint. Popsicle stickes can be braced I the body to push the brace down.

Have you been working with HHG already, Aaron?

I don't much like working through a sound hole because my forearms are big.  I usually end up making some sort of extension to a pallet knife and/ or brushes. I also have a fairly large syringe  with a large gauge needle that can come in handy for delivering glue where I need it. The needle is actually from an old piece of equipment in a medical lab so it was made with a blunt end rather than a sharp point. Good for those of us that are needle cover challenged. It's very good for delivering glue to the general area. If I use it with HHG, I put the glue in the syringe and put that in the water bath with the needle so it's all at working temp for the glue. The tube cools very quickly so it's imperative that I deliver the glue to the location quickly and then use whatever tool I need to distribute it.  It's a real handful to try to do that AND get it clamped quickly so I usually try to avoid using the syringe with HHG.  

One tool my brother used was much the same except it used a very small diameter brass tube about 18 inches long which he purchased  from a hobby shop. The end is flattened and widened. It's actually a pain to use because it  takes so much pressure to move glue through it even if it's thinned a  bit BUT it can work where nothing else will. It's not something I would ever try to use with HHG because I'd have to thin it too much but it will deliver thinned titebond under some fairly tight gaps.

Using HHG for something like this ( hard to reach and NOT quick to clamp) I  always find a way to heat the work area. In the hope that my wife won't read this and "react appropriately", I'll admit to using our heating pad a time or two to heat a broad area so I have better work time. Our heat pad is a pretty high end model with a "moist heat" sleeve over the elemen that's a lot like a heavy felt bag. This really helps distribute the heat. If you use a lower end model heat pad, I recommend that you wrap a towel or something around it. The switch is a "deadman" switch so I either have to hold it down or wrap something around it to keep the heat going. Too long or too hot and it shuts off so I still need to keep an eye on it or the area won't be warm enough when I'm ready.  

How I get glue into the gap depends on the size of the gap and it's location. It's pretty straight forward if the brace is next to the sound hole. As I mentioned earlier I often make up a tool to reach where I need to go from whatever I have around. Thin wall tubing is handy if you need to jam a handle into something. I've use a LOT of old metal hanger wire to make this sort of thing. I used to keep them around after I made them but found that I almost always needed to make something a bit different, longer, shorter, stronger... when I next needed one so I stopped keeping them.  Hanger are not that hard to come by and a I find that a tool made for the specific problem tends to work better.

I strongly recommend that you work out how you are going to brace the repair and test it before you even think about applying glue. When I say test, I mean that you should insure that everything fits AND that you can do it quickly. If you are going to use props, which seems to be what most of us do, be aware that you are going to be putting pressure on the top and back. I learned the hard way that it's possible to cause more damage as you fix things using this method. I got the two inches of brace glued back into place very nicely and discovered that I've popped the opposite end loose in the process. Now, I tend to add props along the length of the brace just to help hold things in place. They don't need to be all that tight, just enough to hold things.

You really don't want more pressure than it takes to hold the brace where it should be held and you should make props that are just long enough and no longer. You may also need to clamp the outside to support the body before you use this method. In fact, I think it more likely that you will need outside support if you DON'T make the props really tight.  For me, that depends on how much pressure is needed to close the gap under the brace. That's another reason to test without glue.  It's not always easy to get a small, short gap to close up properly with just a prop, at least that's been my experience. Sometimes is't the plate that moved, not the brace. You probably need to use a prop to fix this anyway but you'll also need to clamp from the outside for sure. 

Now that I've said all of that, I really do think it's much easier to use a long clamp if the brace is on the top rather than the back. It's usually just easier than trying to work a bunch of props.

I saw a picture somewhere of a very thin pallet knife that had been modified with several slots along the length of it's blade to help hold and distribute glue. I haven't made one of these yet but my next, closed body brace repair may be the catalyst to make such a tool.

I use those green plastic tube that come with D'adarrio bulk strings, they're about 3/8" and you can heat the end a bit and flatten it, that way it gets up to the loose edge of a brace. 

The tubes about 18" long and I would usually use PVA glue because I work alone and I don't have time to apply HHD and then get a clamp on. 

I put one end of the tube in my mouth and draw up about 2 or 3 inches of glue, then I put the other end of the tube next the brace and blow. 

Scoff if you want but it's the only way I could think of to, hold the guitar get the tube in place and apply the glue.

For a back brace cut a U shaped peice of plywood, put one end of the U on top of the brace and then use a wood cam clamp and clamp from the other side of the U over the top to the back of the guitar directly under the side of the U that's on top of the brace. I have picture somewhere I'll try and find it.

Any comments on Stewmac's Brace Gluing Wedge?

Its fifty dollars the green plastic tubes are free and easier to use.

Thanks for all the input, everyone.  Pretty much what I figured, there's no easy way around this one.  The Stewmac gluing wedge looks to be a bit too bulky as I'm dealing with tight gaps.  Fortunately, I have a spare basket case to practice with.

I have been using magnets for a while now, very successfully.

Looking for a faster, less cumbersome way than wedges, weights or other cock-a-mamey schemes. Magnets came to mind but how I could balance a magnet on different shaped braces? It dawned on me that an out-rigger of sorts could work. I experimented a bit with that and also, safely using the powerful magnets.

I already had a glue injector from StewMac and discovered that I could add various Brass tube sizes and shapes to the end of it with some plastic tubing and I came up with this rig. There are a couple of palette knives taped to some dowel rod in the image as well, to get back in there where hands can't go. I make the Brass tubes and extended palette knives as needed for the job.

The hypo tip is just shoved onto the Brass tube but lately I have been using electrical tape to keep that connection from leaking.

Here is a shot of the magnet brace tool, simple to make. The magnets are 1" X 1/8" neodymium magnets, very powerful!

These must be laid out on a table in the correct order and orientation before they are put inside of an instrument. The polarity is set to repel it's neighbor. Stacked magnets provide more pulling power. Label them! Get rid of anything metal that is not necessary for the project at hand!

Glue is applied when every thing is set to go and spread with the palette knife.

Magnets are placed, starting from next to the ribs (usually) and applying them one at a time working towards the center of the instrument. If you can reach in with the magnet in your hand, do that and hold it in place on the brace. With your other hand, put against the back (or top) and slide it under the magnet inside. Then the next and so on. This must be done carefully, we don't want magnets flying around inside of an instrument! If you can't reach where you need to be, I use a heavy bladed palette knife to set the inside magnet and then set the outside magnet, trying to stick it from directly below, rather than sliding it into place. I never try to do more than 3 of these inside an instrument at the same time, difficulty and risk increase. You can see in the image though how close they can be placed. Probably best to limit yourself with one magnet placement until you get a feel for the process.

View of outside magnets with leather to protect the instrument.

Clean up as usual, whetted cloth on some extendy tool.

I typically use Titebond diluted a bit but have also done this with hot hide glue. The trick there is keeping the glue hot. I use a Red infrared lamp for a heat source but the reflective clear plastic and tubing will not heat directly with the Red lamp. This is solved by placing the rig on a sheet of Black plastic laminated board. The Black gets hot and warms up the glue rig. A light bulb inside will warm the interior of the instrument and can be supplemented with a blast of hot air from a hair dryer or by using a Red lamp from outside of the instrument. Hot hide is more effort but completely do-able. The Titebond is much easier and does really well with a joint that's less than clean.

Thanks for the detailed photos and description, Paul.  Pretty nifty.  I just might run with this method.  



Thanks for posting those pictures as well as your clever techniques for keeping things warm. The only suggestion I have is to have magnets with the leather glued to one side. These would be dedicated to being next to the finish (on the outside). Just one less piece to juggle.

Thanks again.

If I wasn't so cheap, I would have enough magnets to dedicate a few more to specific uses, they often come apart for other jobs though. The loose leather is actually no extra bother and I don't feel like I am juggling or need a third hand when using them. The magnets on the little outrigger jigs are stuck on with double stick tape and can come apart too, if I need them for something else. Thanks for your comment.


© 2022   Created by Frank Ford.   Powered by

Badges  |  Report an Issue  |  Terms of Service