Bridge Removal

[Will Reyer]

Bridge Removal 11/21/18

Hadn't done this before. Guys like Parchem, Herman, Bagwill are light-years ahead of me.

Still don't know where I got off into the weeds, as guitar 6 uses same geometry as the previous 4, but the bridge had to come off. Need one higher.

Consulted with my friend and mentor here, Kjell, a repairman for Elderly Instruments and an excellent luthier in his own right. Said they used a heat lamp. Sent inquiries as well to a couple luthiers at the forum, and others. Bagwill said “knock it off” per Don Teeter but didn't feel up to practicing that.

Well, this is a “use what you got” deal down on the farm here. Had a brooder lamp with a 60 watt incandescent bulb. Had several old bridge blanks from earlier when I was deciding on final form. Picked one of cherry, glued it on a scrap of 6mm underlayment plywood with Titebond, which I use to glue bridges, to practice removing.

In the garage was a Dollar Store rusty putty knife that was too flexible to scrape the fireboxes of our pellet stoves. Filed radii on the corners, and filed the business end thinner, sanded off the rust and down to 600 grit to get the blade smooth to avoid scratching soundboard finish, per Kjell's instructions. He'd said the knife had to come in flat right on top of the soundboard.

Cut a square out of corrugated cardboard, sprayed it with photo adhesive, and covered it with aluminum foil. Made bridge-shaped cutout, and set on practice mockup. 60 watt bulb might have worked but I didn't have patience for that long a process, so removed that bulb after trying. Installed a 150 watt bulb which equaled the brooder lamp sticker for largest wattage permissible. Bulb protruded a length equal to the aluminum shade on the brooder lamp, so spaced it off of the foil-faced corrugated cardboard surrounding the bridge with 3 pieces of 1/2” plywood.

After a couple 5 minute tentative heats, I left the lamp on for 6 minutes, smoke rising from the lamp shade vent holes from burning cherry, and slid the putty knife under the bridge and lifted it off.

So the method works, now to do the real thing.

I made a 10” square of corrugated cardboard foil-faced, with a very close-fit cutout for the bridge on #6. Set this on the soundboard. On top of this I set a guitar body shaped foil-faced cardboard. Two plys of foil-faced corrugated cardboard. On top of that I set a 11” square of scrap 3/4” plywood that I had bandsawed a 7-1/2” diameter hole in. This plywood cutout was a standoff to keep the bulb off of touching the wood of the bridge, and to surround the interface of lamp shade all the way around to keep heat in.

Kjell had said to cut around the silhouette of the bridge with an Exacto knife before heating to make sure fibers weren't going to be pulled off the soundboard beyond the silhouette of the bridge. Did so.

One 7-minute heat let me start the putty knife on 3 sides of the bridge. A second 8-minute heat let me remove it, Thanksgiving coming early. Still not out of the woods, but 3 years work isn't junk yet.

[John Parchem]

Well I learned something from your post. A good idea.

"Kjell had said to cut around the silhouette of the bridge with an Exacto knife before heating to make sure fibers weren't going to be pulled off the soundboard beyond the silhouette of the bridge. Did so."

I have had small tears in the past that needed to be repaired.

[Will Reyer]

And John, he was careful to point out to me the hopefully obvious, i.e.:
"Cut from the corners toward the middle, so you don't slip and cut too far'

[Herman]

Well done Will,
The trick is not to get the bridge off, but to let the rest intact.
And you did, so congrets!!
As we say: "There are several ways to get to Rome."
Herman

[Eric_K]

I"m late to this, but I had a guitar come back last year that needed the bridge removed. I used an RC covering iron to heat a StewMac bridge removal spatula. It worked very well.

Picture of it going back on, none of it coming off