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Bridge removal on classical guitar - easier than I expected
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Author:  mkellyvrod [ Sat Mar 01, 2014 7:09 pm ]
Post subject:  Bridge removal on classical guitar - easier than I expected
Screw up #?. oops_sign When I went to string up one of my latest, the outside treble string was too close to edge of the fingerboard. After inspection, it appears that my bridge was off center by 1/16" (0.06 inches; 1.6 mm). After consulting previous posts on this forum and the internet, rather than play with string spacing at the nut, bridge removal seemed like the right thing to do (actually paying attention in the first place was the right thing to do). So I opted for the hot iron, heat up a palet knife, and work under the bridge slowly to loosen the glue (titebond) method. I acutally followed the hot knife with a second knife to insure bridge didn't re-attach. Took 2 glasses of wine and less than 10 minutes to get the bridge off. Better than I hoped. I would recommend this approach, and would not recommend placing iron on the bridge to heat bridge up and then work knife under bridge. It would be better on the finish and on the tie back block to not try and heat entire bridge from above by placing iron directly on bridge (don't ask how I know) idunno . Use the iron simply to heat the blade of the palet knive; it's quick. After removal I found some fibers from the WRC top attached to bridge, but I take that as an indication that the glue bond was good. A little clean up and I'll be putting the bridge back on more carefully. Have some finish to repair, but it was not damaged by this 2nd attempt.
Author:  Hesh [ Sun Mar 02, 2014 8:16 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
We have to do bridge reglues frequently and likely a couple a week.

No iron for us and we instead use a 250W heat lamp in a smaller, dedicated fixture that we can hold right over the bridge and move it around some from end to end to get the wings to release.

It's super important with the heat lamp to make sure to do a few things as well:

1) Make a snug fitting shield for the top that consists of regular cardboard with thick aluminum foil, shiny side out..., over the top of the shield. The cut-out for the bridge is very nearly the exact size and shape as the bridge, so in our case we have likely 20 dedicated shields or more. Once the shield is over the bridge small strips of the reflective tape used for duct work seal the edges to prevent the finish from getting any direct exposure to the heat lamp.

2) Never, never, never leave the heat lamp unattended when in use and in my case I won't even leave it plugged in even if off unless I am standing right there.

Anyway with shield in place and heat lamp on top of the bridge we heat up the bridge moving the lamp every so often from wing to wing until we see a bit of smoke, smell the rosewood, maybe some oils coming to the top of the bridge as well in the case of BRW. The lamp bulb is very close to the bridge, perhaps 1/2".

Then off with the shield and then we use the pallet knives.

Other important aspects are to note the runout direction for the top in advance of heating the bridge and then with this noted we initially approach the bridge with the pallet knives exploiting the existing runout in an effort to lay loose fibers back down and not lift them.

The new large, wide bridge removal tool from Stew-Mac is the cat's arse IMO and I love the thing. It does a great job and has less possibility of digging into the top.

Anyway with a bit of patience this method will remove a bridge in a very clean manner leaving lots of old glue visible for the subsequent bridge patch clean-up and likely expansion since virtually no-one that I know including and especially the factories remove as much finish as they should from under the bridge.

Additional notes: There is a "feel" to bridge removals that one develops over time. You learn that when using the knives if you encounter much resistance the stinkin bridge is NOT hot enough. What you want to feel is the glue becoming a gummy mess giving way to the pallet knife with some resistance but not too much. If you hear crackling the bridge is either not hot enough, you have the knife in wood fibers, or both.

Finish damage very rarely happens with this method and in fact I can't remember the last time that it did. The heat lamp is also pretty fast with only a few minutes needed (perhaps less than one glass of wine.... ;) ) for the initial session to get hot enough. I typically will heat and reheat a few times until the bridge is completely free of the top.

And again determining runout direction will make your removal much cleaner in terms of not removing wood fibers. I usually note it in advance and then stick a small piece of masking tape on the stinkin guitar with an arrow indicating runout direction for that side of the top. Of course the other side is the opposite.
Author:  Hesh [ Sun Mar 02, 2014 8:30 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
I'm not in our shop in the city this morning being home so I only have a few examples of shields here to take a photo of. Here's one for Martin style bridges:
Author:  MaxBishop [ Sun Mar 02, 2014 9:15 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
Way cool, Heshie. Thanks for sharing the technique. I'm sure I'll get to try this sooner or later. Look forward to seeing you and others at the get-together later this month.

Best regards,
Max
Author:  wbergman [ Sun Mar 02, 2014 10:14 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
My Kohno 30 had the bridge glued about 1/16" off center. This is a really expensive classical guitar. I did not even notice it for many years, but it does cause a problem for me in pulling the high-e string off the board. Yuris Zeltins plugged the string holes and redrilled the bridge to get the strings aligned. Of course, you can see that the bridge is not centered, but the playing problem is solved.

On another guitar, I had the saddled notched, like the nut, to align the strings differently.
Author:  Clay S. [ Sun Mar 02, 2014 10:20 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
" Yuris Zeltins plugged the string holes and redrilled the bridge to get the strings aligned."

Now that multiple holes per string are in voguemaybe he could have just drilled a few more holes. laughing6-hehe
Author:  mkellyvrod [ Sun Mar 02, 2014 4:11 pm ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
Thanks for the suggestions everyone. Wbergman, I thought about notching the saddle and might have done so if in your shoes, but the guitar already has its flaws, and I needed to teach myself a couple of lessons.
Author:  wbergman [ Mon Mar 03, 2014 7:04 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
Hesh,

Seems like a lot of heat and maybe the glue joints below (center seam, bridge underplate, braces) might be compromised. Have you ever noticed a problem with any of those areas as a result of the heat?

I have never removed a bridge, so I am no expert.
Author:  Hesh [ Mon Mar 03, 2014 7:41 am ]
Post subject:  Re: Bridge removal on classical guitar - easier than I expec
wbergman wrote:
Hesh,

Seems like a lot of heat and maybe the glue joints below (center seam, bridge underplate, braces) might be compromised. Have you ever noticed a problem with any of those areas as a result of the heat?

I have never removed a bridge, so I am no expert.


Good question!

No issues for us ever using this method. Each heating session with someone standing right there is only a matter of seconds. The first session may be a minute or so, I am looking for some smoke, smell, and perhaps some oils too with BRW. After the first session for me at least the glue is rarely as gummy as I want it to feel so I typically will reheat or, more accurately apply additional heat.

The shield protects the guitar top and the top stays around room temperature.

We are not heating the bridge to the point that it falls off but instead heating the glue joint beneath the bridge until the glue gets gummy and then comes the pallet knives.

We use the same procedure for fretboard extensions when doing resets too. Works great, no damage to finish or anything else, and you get to smell the smells of a baking guitar too.... :( :D

Like many things it's pretty safe provided that you remain right there.... always and when you do this a few times you start to get a feel for what to expect. We likely have removed hundreds of bridges and extensions with this method and so far no damage ever associated with how we heat. You can still damage finish with the pallet knives if you are not careful and keen to maintain your knives keeping them clean of old glue and inspecting for bent edges.

On my site is an old toot for how I used to do this with a dedicated iron but once I started using the heat lamp I never looked back - way better, faster, safer method in my view.
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