Bridge gluing

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Joseph Jones
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Bridge gluing

Post by Joseph Jones » Thu Oct 25, 2018 10:13 pm

Hi all, just wondering what methods you use to glue a bridge.
How do you keep the pin holes clean and free of glue? or what would you use to clamp it?

I ask this because I am repairing a lifted bridge, I’ve pulled off completely before thinking how I would put it back on.😬
DFBEF316-6C43-4887-9106-FB013790F0DE.jpeg

Your advice would be much appreciated.

Regards, Joseph

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Thu Oct 25, 2018 10:54 pm

X bracing, and three ply.

Forgot to mention that.

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Fri Oct 26, 2018 7:35 am

I generally glue the bridge on and then clear out holes with a drill bit once glue is set. I normally have gutter bolts through the two outer holes that engage with a gluing caul under the bridge plate so those two holes are usually glue free.
Martin

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Mark McLean
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Re: Bridge gluing

Post by Mark McLean » Fri Oct 26, 2018 9:34 am

You need to be fussing about with clamps and checking that it is staying in position - so cleaning out the holes is not going to be a priority at the time. Do it like Martin said and clean that later (pin hole reamer is my recommendation).

You have an issue with some of the top ply coming off outside of the bridge footprint. That is likely to leave a noticable defect in the finish once it is glued back, but you might get lucky and have it sit down nicely. A tip for bridge removal next time would be to use heat to soften the glue and work a thin palate knife all the way around the edge to try to get clean separation. But sometimes it just comes off ugly!

You need long throat bridge clamps, and at least 2 or 3 of them. Nothing else really does this job (unless you want to get into vacuum clamping). Various brands are available (Fox, Ibex) from various online sellers (StewMac, LMI, Amazon, eBay). You also need to make a scrap wood caul to go inside against the bridge plate, shaped like the bridge plate so that it fits between the X-braces. This is what the clamps push against on the inside. You need to cover this caul with something that stops glue squeeze-out from permanently gluing the caul inside your guitar. Kitchen baking paper (greaseproof paper) works for that.

Another problem is that the glue makes the bridge slip around on the top of the guitar as you fiddle with the clamps. You need it to go in EXACTLY the right place. I use the trick of a couple of 1.5mm nails (panel pins) as locating pins; others may advise other variations on this theme. You drill 2 small holes through the bottom of the saddle slot (so they will be invisible later) using a 1.5 or 2mm drill bit. Check that your panel pins can slide through these holes, but with a fairly snug fit. Locate the bridge in the correct position (dry fit, no glue) and clamp it there (good opportunity for a practice run with the clamps). Check measurements, and then place your panel pins in the pre-drilled holes and bang them into the soundboard (yes, at this point you are literally hammering some nails into your guitar!). When they are firmly embedded in the soundboard and bridge plate, cut the heads off the nails using a fret cutter or big-ass pliers. Now it should be possible to remove the clamps and lift the bridge off, leaving the locating pins embedded in the top. You now have a method of placing the bridge back in the exact same position when you want to glue it, and the pins will stop it from floating around.

Titebond Original is your go-to glue. Hot hide glue even better, but more complex. There will be some squeeze-out to clean up after clamping. Keep it clamped at least 8 hours. Wait 24 hours before you remove the locating pins with pliers, ream out the pin holes and string it up.
If you haven't done this before I suggest looking at some Youtube videos before you start. I am sure Robbie O'Brien or John Hall have done ones that would walk you through it. Good luck.......

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Mark McLean
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Re: Bridge gluing

Post by Mark McLean » Fri Oct 26, 2018 10:10 am

Take a look at the pictorial tute by Simso also

http://www.mirwa.com.au/HTS_Bridge_Removal.html

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Fri Oct 26, 2018 1:31 pm

Thanks so much guys.

I’ll keep you updated on how it goes.

Regards, Joseph

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Fri Oct 26, 2018 3:42 pm

For gluing up my bridges I make up a caul from HDPE plastic chopping board (glue wont stick to it). I feed a couple of gutter screws through the outer bridge pin holes and through the caul and bolt the whole lot together with a couple of nuts. the two gutter screws hold the bridge on location and apply a bit of clamping pressure. I generally use 2 or 3 long bridge throat clamps as well.
Martin

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Tue Dec 04, 2018 11:32 pm

Here’s part of the update I promised, took a while as we were in the process of moving house.

I’ve used Titebond III for the glue and put pins thru the bridge and top into a plywood block cut to fit in the bracing.
Three 200mm clamps hold it well, with bubble wrap that came with my reamer to stop scratching.
7C350B5E-715A-456A-96AF-F23DBCD93961.jpeg
915DBE46-F84E-4237-A98D-470A8A648EF3.jpeg
Joseph

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Thu Dec 06, 2018 8:10 pm

Well, glue up was a success.(apart from that chipped soundboard😡)
Baking paper came off as if it was never glued, and I was surprised at the performance of my new reamer from eBay, especially being unbranded and $16!!
35738894-0D86-44A7-84B3-849AB5BA06E8.jpeg
CD4B4B93-3E96-4C2E-9C60-5D68225AE6C9.jpeg
Joseph

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Thu Dec 06, 2018 8:13 pm

What's the go with that extra hole aft of the six pin holes??
Martin

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Thu Dec 06, 2018 9:41 pm

Don’t quite follow you there Martin.

Joseph

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Thu Dec 06, 2018 10:58 pm

First photo showing the top and bridge. There's an extra hole through the soundboard aft of the bridge pin holes
7C350B5E-715A-456A-96AF-F23DBCD93961.jpeg
7C350B5E-715A-456A-96AF-F23DBCD93961.jpeg (88.35 KiB) Viewed 497 times
Joseph Jones wrote:
Thu Dec 06, 2018 9:41 pm
Don’t quite follow you there Martin.

Joseph
Martin

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Fri Dec 07, 2018 12:14 am

Yeah I have no idea that would be for, it is a whisker bigger than the pin holes.....
But I don’t know enough about guitars to think that that was abnormal in the first place as this is only my first luthiery related job.

Joseph

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Fri Dec 07, 2018 12:18 am

Maybe it was going to be the soundhole and they decided to use the other end, that’s as far as my thinking takes me.

Joseph

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Mark McLean
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Re: Bridge gluing

Post by Mark McLean » Fri Dec 07, 2018 7:18 am

It might have been a locating pin. Any sign of a pice of dowel that used to be in that spot? Some makers also used a bolt to secure the aft side of the bridge.

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Sun Dec 09, 2018 7:31 pm

What do I do if I’ve reamed the pin holes too far?😬
(Sarcastic question of coarse!😰)

Joseph

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Sun Dec 09, 2018 7:53 pm

Don't do anything until you've strung up the guitar and fitted the string ends and pins. Are you using slotted or unslotted pins? If using unslotted pins have you cut bridge pin hole slots yet? If you cut the string slots on the shallow side you might still get a tight fit once the string and pin are in.
Joseph Jones wrote:
Sun Dec 09, 2018 7:31 pm
What do I do if I’ve reamed the pin holes too far?😬
(Sarcastic question of coarse!😰)

Joseph
Martin

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Sun Dec 09, 2018 8:08 pm

This was actually a repair job: the owner of the guitar kept it in the laundry and the bridge lifted a bit, causing the pins to pop out.
Slotted pins, and they only just pop when it’s almost tuned. Is counter-drilling the pin heads an option?

Joseph

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kiwigeo
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Re: Bridge gluing

Post by kiwigeo » Mon Dec 10, 2018 7:47 am

Not quite sure what you mean by counter drilling the pin heads.

Are there any string slots cut in the bridge holes? If not you could try cutting string slots and using a set of non slotted pins. I use non slotted pins and hole slots on all of my builds.
Joseph Jones wrote:
Sun Dec 09, 2018 8:08 pm
This was actually a repair job: the owner of the guitar kept it in the laundry and the bridge lifted a bit, causing the pins to pop out.
Slotted pins, and they only just pop when it’s almost tuned. Is counter-drilling the pin heads an option?

Joseph
Martin

Joseph Jones
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Re: Bridge gluing

Post by Joseph Jones » Mon Dec 10, 2018 9:12 am

The rims of the pins sit on the top of the bridge, so I thought counter-drilling might correct that.

There are no string slots in the bridge so unslotted pins would work..... I’ll give it a go!

Joseph

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