Official Luthiers Forum!

The glue gelled under my bridge plate before I could get it clamped well.
Should I try to heat the patch to reactivate the glue and re-clamp? Or remove and start over?

All other braces are already on. Not sure what happened. It was butted up to the X and i pushed down on it for a few seconds hoping it would grab (braces usually grab in a couple seconds), but when I put the caul and go bars on it started sliding. TIA!

Also, long time no see! Hope all are well. I haven't been able to log in on Tapatalk for a couple years and it's so much easier to browse on the app...

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Pat

Yes, if it’s still moist, heat it up and reclamp it. If it needs a little moisture, put a drop on the edge and lead it around with your finger. Don’t over do the heat. 130F is enough. You don’t want to undo any of the other joints.

From Romanillos’ book on Torres: Torres used put his plates on with HHG. He’d spread it on the edges, put the pieces together, pour alcohoi along the joints, and light the alcohol to provide the heat to liquify the glue.

Is it in the correct spot butted against the x’s?

Yes, but drifted away from the X 1/32"

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Pat

I don’t like it, but I could live with it considering how forces are applied….

Problem is the thick glue line, like .005"

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Pat

It's hard for me to advise whether to take it off and try again, or just heat it up and stick it down. I would need to be there to see what it looks like. Heating it up and sticking it down works great with hide glue, but there needs to be enough glue to do the job. Otherwise, you are better off pulling it up and trying again.

I can, however, offer some help to avoid the slippy/slidey problem in the future. Get a plastic cutting board and bandsaw it up into some roughly 1" squares. Or, I found a 1" diameter UHMW dowel online somewhere. I slice 1/4" pieces off of that to get roughly the same thing. These act as stops. You get the bridge plate where you want it, and apply a few go-bars so it won't move. Then go-bar some of these little plastic pieces around it, right up against the outer edge in a few spots. Then lift up the bridge plate, apply the glue to the bridge plate, then set it back where it was. Then put on a caul (if you are using one) and go-bars on top. Once you have several go-bars on top of the bridge plate (and caul), it won't move around. Then you can take off the plastic pieces and clean up the squeeze out. I use this for a number of brace gluing operations. Very handy. More setup, but fewer opportunities for problems.

I do the same thing using pieces of scrap plexiglass.

I do this too and almost all of the set up time is reclaimed when you move the go bar holing each block in place over a little bit onto the bridge plate caul. It is like having 4 or 5 go bars pre installed just waiting to be positioned. That saves a some of the stress of getting them all in place before the glue cures.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

One of the best locator/ stops I've ever used came from Beau Hannam. He cuts little slabs from a roll of old school white masking tape and butts them up to an edge as a stop. I've used this method for all sorts of alignment tasks, especially braces and bridges, and it's incredibly effective for alignment and slip-stop. I keep a couple of dozen little blocks of tape in a poly zip bag and re-use them over and over. When the adhesive is no longer tacky, you peal that tape layer off the slab with a blade and have a renewed adhesive surface. Works with all glues and I've yet to glue a single piece of tape to the work. Tape tip starts @2:10
https://www.youtube.com/watch?v=VfCI95jEBpQ

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Measure Twice,

Karl Borum

Well, I wetted, heated it up and clamped. I got rid of the thick glue line. However I couldn't get it pressed up tight to the X, but I think it's good.

Great ideas about the positive stops for next time!

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Pat

For some things, like gluing down a bridge. I find the masking tape stop is not quite positive enough.

As a technique, a range of 1/4" and 1/2" UHMW plastic blocks work well to function as brace or bridge plate jigging. UHMW or MDPE plastics are commonly used for cutting boards and may be cut with standard woodworking tools and blades, and have very low surface energy, so will easily separate from a glued surface.

After dry fitting the X into position, those UHMW jig blocks are go-bar'd down to the dish or building board to facilitate a more leisurely glue-up, with three blocks - one near each end for lateral alignment and a third for fixing one of the brace end locations doing the job. This allows the notch-up leg to be placed and go-bar'd in place before 192g HHG will set up, to be followed by the notch-down brace after clean-up. Trying to do both X braces simultaneously may actually add time to the excessive if either brace seats with a cant reference the plate - grounds to redo the braces.

On bridge glue-up... one technique that seems to work is to dry-fit the bridge, use low tack sign-maker's tape to within 1/16" of the bridge reference surfaces (e.g., front edge and two wing sides for Martin belly bridge), then place 3-4 layers of 3M 3/4" width blue or green tape on that low-tack base layer IN CONTACT with the bridge reference surfaces. This avoids any potential fresh lacquer damage from the medium tack blue tape, avoids the issues with any mis-registration of the bridge due to a softer, slightly rolled bottom edge on some bridges, and those additional layers provide more positive registration than the 1-2 layers often see. Finally, the low-tack/medium tack tape stack is more easily removed for glue cleanup after the bridge is on and clamped than a medium tack base coat.