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Gluing/Regluing a Bridge With HHG- Tutorial
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Author:  Hesh [ Fri Jun 10, 2022 11:13 am ]
Post subject:  Gluing/Regluing a Bridge With HHG- Tutorial
Putting this in the building forum because it's very applicable to new builds and gluing the bridge on as well AND the repair tutorial forum is now full of spam from the spammer last week.

Here's how Dave Collins and I reglue countless bridges every year. Did this one at 3:00 AM this morning since I work nights these days and thought that you might find it interesting.

The guitar today is a Blueridge with a narrow, pyramid bridge that is lifting on the back edge where they typically lift.
Author:  Hesh [ Fri Jun 10, 2022 11:17 am ]
Post subject:  Re: Regluing a Bridge - Tutorial
We use a 250 watt heat lamp for softening up the glue on bridges, fret board extensions, etc. ALWAYS stay right there if you use a heat lamp and have a fire extinguisher charged and ready. We have never had an issue, just don't walk away and answer a phone.....

I heat things well and then begin with the pallet knives also reading runout. I will do a separate toot on this if you want at a later date. What I really want to show you is how you too can glue on your bridges in 15 seconds or less with HHG and have all clamps set. This is rare sharing of the money shot in how we reglue a bridge.

Please note cardboard shield with foil to deflect heat away from the guitar.
Author:  Hesh [ Fri Jun 10, 2022 11:20 am ]
Post subject:  Re: Regluing a Bridge - Tutorial
The bridge came off pretty clean but the real value in this pic is look what a ****** job Blueridge does of clearing finish under the bridge. They left around 35% of the possible gluing area with finish over it with the back side being the worst example of this. That's why this bridge lifted IME with perhaps a little help from RH swings.
Author:  Hesh [ Fri Jun 10, 2022 11:22 am ]
Post subject:  Re: Regluing a Bridge - Tutorial
I clean up the bridge patch, expand the gluing area greatly scoring to near the bridge perimeter, never to the bridge perimeter and then remove all old glue and freshly scrape the patch and bridge bottom.

Once the patch is expanded, scraped and clean and the bridge bottom is also clean and freshly scraped I trial fit. I want my bridges to sit down everywhere with zero gaps with only light finger pressure.

We do rabbit the bridge bottom at times but this one did not need it so I didn't do it and you likely do not have the special tooling to rabbit a bridge bottom so it's optional and not shown here. If the finish is thin, the patch is in good shape and did not shed fibers it's a candidate to not rabbit.

Why we do not clear finish to the actual bridge perimeter is it does not look great, the glue line may show AND if it ever has to be reglued again it will look even worse. Old school Luthiers often do clear to the perimeter and may push back here, push away this works great for us.

Notice the masking tape well that I made from two layers of tape. This permits me when the HHG is out to preposition, slap it down and it falls exactly into place and then snug the clamps very quickly. The well in combination with the next pics are the money shot here.
Author:  Hesh [ Fri Jun 10, 2022 11:45 am ]
Post subject:  Re: Regluing a Bridge - Tutorial
Study these three pics well and your life may change for the better :)

This is a Dave Collins innovation and permits us to preposition the bridge and clamps so that when we slather on the glue you can have the clamps snugged in only seconds and the bridge is perfectly located and stays in place.

Feel free to ask questions. This starts with a dry run and when the bridge is clamped I add the scrap blocks pictured, the tape and now we can back away the bridge caul adjustors and remove the caul and bridge for later rapid placement. The clamps stay prepositioned which is the game changer here that makes gluing on a bridge with HHG be it a repair or new build accurate, fast and drama free, just how I like it and why I'm not married. :)

In the box is a bridge plate caul being held in place with the Ibex clamp.

I preheat the bridge in the microwave until it's pretty hot and then slather on the HHG, plop the bridge, crank the clamp and wing adjustors and I'm done for 24 hours until the HHG cures. Easy peezy and I hope this helps folks here on the OLF out. Timed myself this AM and from glue application to the clamps snugged was 9 seconds.

When the clamps are snugged you can pull the tape and this will also remove in one felled swoop 75% of the squeeze out which is pretty cool too. I clean up around it with the clamps in place and have no access issues with this method making clean up with hot water from the glue pot easy.

We may leave the clamps for 24 hours or remove at 4 hours, seems to make no difference in the results.

This is a Dave Collins innovation and it's also unique we have never seen anyone else do this with the Ibex, tape, blocks etc. So please attribute to Dave if you pass this on? And no we do not own 3M stock hence the use of their tape, lots of it. :)

Thanks guys (men and women) and feel free to ask questions.
Author:  SteveSmith [ Fri Jun 10, 2022 1:29 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Martin size 0. If you use multiple clamps you can still do the same thing, just not quite as elegant.

Hesh, this is from before I went through your setup class.

Attachment:
bridge reglue small.jpg
Author:  jfmckenna [ Fri Jun 10, 2022 2:05 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Clever idea with the tape.
Author:  Terence Kennedy [ Fri Jun 10, 2022 5:16 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Thanks Hesh!!

Good to see you are getting good results with that StewMac clamping system. Probably because of such careful fitting.
I always worried about the screw down wing clamps relieving pressure on the central clamp. I think they do on a marginally fitted bridge that requires some force to seat the wings.

Same with the tape dam. Being a stewer and fretter about any unexpected movement I have always drilled two tiny holes in the saddle slot for 1.4mm brads.

I have adopted the positioning of clamps technique from your previous posts. Works great.

I also owe you one for the idea of using the little StewMac Dremel base for creating a rabit on the bridge. I have used it for years.
Author:  joshnothing [ Fri Jun 10, 2022 6:06 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Thanks for this Hesh.

I agree especially about the undesirability of clearing finish all the way to bridge perimeter. I reglued a bridge on an LG1 recently where a previous repairman had cleared all the way to perimeter. When a bridge pops loose due environmental factors, heat etc, if may lift fibers or maybe there’s a small blob of dried hard titebond along the edge that was missed in cleanup. When the bridge lifts or tilts these things can disturb or slightly chip the delicate finish edge a little - no problem if that edge slightly tucked under the bridge. But unsightly if the finish edge is visible at the limit of the bridge footprint. In the case of this LG1 it chipped at multiple places along the front edge of the bridge, necessitating some color matching of the sunburst top and new lacquer. This hits the customer directly in the wallet and turns a 24hr repair into a 10-14 day wait for nitro cure and buffing.
Author:  joshnothing [ Fri Jun 10, 2022 6:08 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Terence Kennedy wrote:
Thanks Hesh!!

Same with the tape dam. Being a stewer and fretter about any unexpected movement I have always drilled two tiny holes in the saddle slot for 1.4mm brads.


I had no luck with the tape dam with titebond but have found it to work flawlessly for hhg, probably because the initial tack is better.
Author:  Hesh [ Fri Jun 10, 2022 6:45 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Terence Kennedy wrote:
Thanks Hesh!!

Good to see you are getting good results with that StewMac clamping system. Probably because of such careful fitting.
I always worried about the screw down wing clamps relieving pressure on the central clamp. I think they do on a marginally fitted bridge that requires some force to seat the wings.

Same with the tape dam. Being a stewer and fretter about any unexpected movement I have always drilled two tiny holes in the saddle slot for 1.4mm brads.

I have adopted the positioning of clamps technique from your previous posts. Works great.

I also owe you one for the idea of using the little StewMac Dremel base for creating a rabit on the bridge. I have used it for years.


Terry you are very welcome.

Please feel free to post some of your pics here too since you took bridge gluing into some very refined processes.

You are absolutely right there seems to be an inverse clamping relationship between the the wings and the Ibex adjustors. All I've ever been able to figure out to do is just back off the wings a tad and tighten the center a tad a few times and equalize things, hopefully. :)

When I was building I did the pins too and it worked great.
Author:  Hesh [ Fri Jun 10, 2022 6:51 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
joshnothing wrote:
Thanks for this Hesh.

I agree especially about the undesirability of clearing finish all the way to bridge perimeter. I reglued a bridge on an LG1 recently where a previous repairman had cleared all the way to perimeter. When a bridge pops loose due environmental factors, heat etc, if may lift fibers or maybe there’s a small blob of dried hard titebond along the edge that was missed in cleanup. When the bridge lifts or tilts these things can disturb or slightly chip the delicate finish edge a little - no problem if that edge slightly tucked under the bridge. But unsightly if the finish edge is visible at the limit of the bridge footprint. In the case of this LG1 it chipped at multiple places along the front edge of the bridge, necessitating some color matching of the sunburst top and new lacquer. This hits the customer directly in the wallet and turns a 24hr repair into a 10-14 day wait for nitro cure and buffing.


Exactly and we call that "scope creep" and a few other things I can't say here especially the burst matching.... That sucks.

I don't think it's necessary either when a bridge is properly glued with HHG and the patch, bridge, glue and Luthier are well prepared.

I've never done a perimeter style bridge glue and I think it would scare the heck out of me scribing it. I'm nervous enough with the exacto maybe .030" inside the perimeter.
Author:  StevenWheeler [ Fri Jun 10, 2022 8:17 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Hey Hesh,
When did you switch from three clamps to one with the Stew Mac thing?
Author:  Hesh [ Fri Jun 10, 2022 10:43 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
StevenWheeler wrote:
Hey Hesh,
When did you switch from three clamps to one with the Stew Mac thing?


We only use additional clamps if the fit is not ideal. Get a great fit and three are not necessary. I like light finger pressure and it's down everywhere in terms of the fit I work for. Single edge razor blades are great for dialing in the fit of a bridge.
Author:  Barry Daniels [ Sun Jun 12, 2022 10:38 am ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
This technique works really well. Saves time and prevents fumbling around, possibly scratching the guitar.

Thanks Hesh. This was very timely for me. I have a couple of more re-glues coming up.
Author:  joshnothing [ Sun Jun 12, 2022 5:36 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Barry, are those the stewmac composite clamps? What are your thoughts on them?
Author:  Barry Daniels [ Sun Jun 12, 2022 8:58 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Yep, Stew Mac. They are a bit more flexible than I like. Work OK on the wings but probably not enough on the body of the bridge, unless you had a perfect fit.
Author:  joshnothing [ Mon Jun 13, 2022 6:59 am ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Thanks, that’s helpful.
Author:  Woodie G [ Sat Jun 18, 2022 12:50 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Issues with the SM bridge clamping caul are uneven clamping pressure (too much/too little clamping pressure on wings or body) and a design that fails to address clamping of the sometimes huge belly that is clear of the clamped area. To address these issues, we modified the caul to index two of the Ibex/Shop Fox C-frame aluminum clamps, decoupled the wing clamping process from the body with two additional clamps on the wings plus a couple of caul blocks outboard of the bridge plate caul, and a fifth clamp with shaped caul where needed to clamp the belly separately.

Attachment:
4_Clamp_Bridge.jpg


Attachment:
Center_Clamp_Bridge.JPG


Our prep was similar to Mr. Breakstone's approach sans the tape lateral bracing... low-tack sign tape mask, blue tape dam, etc. In terms of step-by step:

1. Modify the bridge clamping caul with shallow depressions roughly two inches apart and centered to index the c-frame Ibex/Shop Fox clamps (with plastic pads removed, the now-visible ball end of the shaft fits nicely in the milled recesses)

2. Where the bridge wings extend beyond the X braces, add a caul block on each side outboard of the central bridge plate caul. This block is padded out with a spruce scrape of bridge plate thickness so that it creates an additional surface for the 6" Klemmsia cam clamps to register on inside the body.

3. Where needed, a shaped caul is made so that an additional 6" Klemmsia cam clamp can clamp the extended belly. Older guitars often see some distortion behind the bridge, and this additional clamp allows closure of that glue line. At my time at Greenridge, we saw a number of deep belly/narrow-winged bridges which held on the wings but failed in the belly area due to failure of the builder or repairer to close the joint behind the bridge clamping caul.

4. In terms of actual glue-up:

- Do a dry clamp-up before committing to glue-up... if the clamps won't fit, relieve the bar edges of the Klemmsias as needed. As with many things in life, order of operation matters, so...

- Outboard cam clamps and Ibex/Shop Fox go into the soundhole prior to glue-up (use cork sheet to allow the Ibex/Shop Fox clamps to rest comfortably on the top... use low-tack tape on the soundhole edges if needed.

- Prep the bridge clamping caul so that the wing screws and pressure pads are a turn or two clear of contact with the wings

- Wet out the bridge patch with 315g HHG, then the bottom of the heated bridge

- Bridge goes on with patch jigged by the tape dam, and Center_Clampstored heat remelts any gelling glue on the patch

- Close the joint with the Ibex/Shop Fox clamps, running them down to near max hand-tight, but ensuring the wing clamp pads are just barely in contact with the wings

- Rotate the now tightened Ibex/Shop Fox clamps as needed to get the Klemmsia wing clamps over the threaded wing knob/ interior cauls, then tighten. These clamps decouple the wing clamping screws on the bridge clamping caul, so avoid placing a cross-grain bending load at the bridge wings, and ensure a better, more consistent glue line.

- If needed, add the shaped caul to the belly are behind the bridge clamping caul using some double stick fiberglass scrim carpet tape, then spread the Ibex/Shop Fox clamps so as to allow the final Klemmsia to be inserted in the soundhole and pressure applied wit the cam clamp. New guitars seldom need this additional clamping, but old LG-1's always seem to benefit.

- Resist the urge to clean up immediately... let the glue gel. With a bridge heated to 160 deg F, that can be a good 10-15 minutes, obviating the biggest drawback to higher gram strength high glue - gelling of the glue line before joint closure.
Author:  joshnothing [ Sat Jun 18, 2022 5:37 pm ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Great tips Woodie, thanks.

I don’t like the two weird little rubber/urethane pads in the center part of the current SM caul, because of their small contact area but also because the most common reglues I do are on Maton guitars, which have catalysed nitro finished bridges, and the rubber/urethane that SM uses eats the finish. I have removed these pads and replaced them with a much larger patch of thick cork.
Author:  Woodie G [ Sun Jun 19, 2022 10:19 am ]
Post subject:  Re: Gluing/Regluing a Bridge With HHG- Tutorial
Yes... I like the neoprene rubber/cork composite padding on the previous bridge clamping caul... neoprene seems to do well with most solvent finishes, and those pads clean up with a little hot water after use.
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