The Scroll Shop (Ed of H's Shop Thread)

[pauldo]

Arco action is set higher?

Do you sand the bridge up/ down or left/ right?

[edwardofhuncote]

Not so much higher for this guy, Paul, but he needed more arch (radius) in the bridge for playing with the bow. When I originally set this bass up for pizzicato style play, with ropecore tapewound strings, I had cut the bridge to match the arc of the fingerboard, including the Romberg E bevel.
https://en.m.wikipedia.org/wiki/Bernhard_Romberg
(there's your reading assignment for today). So after switching to the chromesteel flatwounds and playing with the bow, if driving the bow hard, he would often be hitting 3 strings at once, as the G, D, and A laid so close the same plane. Giving it a steeper arch creates more separation on them, without too much difference in action. The adjustable bridge was a preference, but lets him tweak that even more to his liking.

When fitting the feet; I scrub them longitudinally... longways, with the grain, to start with. It really matters most that they fit exactly, and make maximum contact with the top. A bit of side-to-side action just to check will sometimes help, sometimes creates a convex surface on the foot. The tops of basses are all unique. Some of them have sunken places right above the soundpost, where the bridge necessarily sits in a 'dished' spot. It's really tough to fit one there. All part of the job. I take all that in when a bass is on my bench.

I just bought a new tool to speed up the process of fitting bridge feet. It's an oscillating spindle sander. This thing will be pre-shaping the bridge feet right off the bandsaw table. I can sand right to a cut line, all while keeping the new bridge back perfectly 90° vertical. I haven't even used it in practice yet, just played with it some... (you can see here how it looks when running on a junk bridge, and at rest on a new one) but I can tell already it's going to save me at least a half-hour, maybe forty-five minutes on each bass. By the time it gets through, there will be very little fitting left to do on the bass itself... just the final fit.

[pauldo]

😎

I have recognized that bevel before.  Now I know the history and the function of it.   Very impressive.

[edwardofhuncote]

Making progress on the KM-11...

Not sure what I expected to see inside... probably lateral bracing or some variation on fan or finger bracing, but I did not expect it would be braced like a miniature flattop guitar. That's exactly what it is though.

The back had been glued and reglued in several places, so it was tough coming off, but I got it with all the kerfing intact. If I had to do it again, I would have sawed it off, especially through the neck and tail blocks. It fits back together nice though.

I've closed the two long cracks in the back, and reglued all the braces. Added some extra backing to those longitudinal splits. They had been open for a very long time, and each individual piece had dried and contracted, so not a perfect, seamless grain fit. I've got a couple more little fill-ins to do, and then we'll glue the back back onto this one tonight... setup tomorrow.

I'm running out to make a house-call today... and look at a Martin D X-series guitar today, that I'm told suffered a fall. These are solid-top guitars with an HPL (High Pressure Laminate) side and back material. I have no idea what to glue that stuff with. It's almost like a wood-grain formica. In conversation, the guy tells me, it was his first guitar, so he really, really, wants to fix it. We'll see what we can do.

More later.

[edwardofhuncote]

As the evening sun sets outside the window over my small workbench... glue is setting on the reassembled Kalamazoo.

I have some reading-up to do on repair of HPL guitars. I accepted this Martin DX-1, partly for the challenge. And Fret Mill Music gave me a classical guitar for a bridge reglue. I might jump it first.

[David Houck]

Looks like a group effort.

[pauldo]

😄

[edwardofhuncote]

Taking a little break from the Scroll Shop today. I worked yesterday afternoon, late into the evening to make up for time missed Friday, and my lack of availability tomorrow.

I got the classical guitar bridge job done, (gang-of-three effort here...) and restrung it for the guys. They hate restringing classical guitars down there. It's tedious and time-consuming, but I kinda' like it. If it was easy, every knucklehead would be doing it. Gluing a classical bridge back on is a little bit trickier. Unlike a steel-string guitar, where my jig has two threaded rods that go through pin holes 1 and 6 to keep the bridge from squirming around under the clamps, the classical bridge doesn't... their strings are tied on, in a slipknot kind of way. So I fit two little guide pins to the underside of the bridge (pieces of wood toothpicks work great for this...) and use cork-lined cauls inside and outside to maximize clamping pressure between the bridge and top. 24 hours of cure time, same as any other.

And the Kalamazoo mandolin is strung up too. I have just a bit of dark brown varnish still drying where I touched up around the edges of the seam where the back is glued on (remember, no binding there...) but I'll rub that out tomorrow before returning it to the store. It's playable, which were my instructions. It could be better if someone bought it and wanted to put more into it. I would just enjoy for what it is, a fun little chording mandolin.

The Martin DX-1 is next... I'll probably jump it Tuesday or Wednesday. I've discovered in addition to the hole in the HPL, it has some more seam separation and it has some loose braces too.

[cozmik_cowboy]

They hate restringing classical guitars down there. It's tedious and time-consuming, but I kinda' like it. If it was easy, every knucklehead would be doing it.

Being an Eagle Scout, I know how to tie a timber hitch in my sleep, so the bridge end is a snap; but slotted headstocks - for whatever kind of strings - are a serious cause of buttockal agony.......

I eagerly await seeing what elegant fix you come up with for that broken piece of counter-top veneer.

Peter

[David Houck]

That's a nice looking classical guitar.

[edwardofhuncote]

It was a pretty nice one, Dave. And a fairly easy repair too. Often I'll triage that kinda' job to the front; something I can get on/off my bench in less than a day, and out the door... that classical guitar for instance, took longer to restring than to actually perform the repair. They do get some cool stuff in at Fret Mill, and enough of a regular clientele that walk in weekly or monthly that Ken's stayed in business for almost 45 years in downtown Roanoke. I like my unofficial 'fixit guy' position there.

I got into the Martin D-X yesterday evening, just some front work. I marked a cutline with a straightedge, and set up the Dremel router base with a downcut spiral carbide bit. Simply traced my cutline as close as possible, and popped out the broken pieces. Followed up with a fine file to true up the straight edge and clean the top of the kerfed lining. I'm stacking layers of veneer with a thicker maple core in opposing directions and making a piece to fit right back over this, hopefully with the grain of the Sapele veneer disguising the original mishap somewhat. I'll need to fabricate some kind of shelf to glue to along the cutline as well... something acting like cleats would in a wood repair. I may even use the broken out pieces for this...

The HPL is basically a formica; a very thin veneer of wood laminated to a base of paper, impregnated with a phenolic resin. So regular Titebond won't do, this will take epoxy or CA to stick. I need to pick up some acetone. In my reading-up on this one, the best advice has been that the HPL won't be affected by acetone, so clean-up will be easy. Again, I have a couple scrap pieces to practice on.

I'm off to see the Sisters of No Mercy first thing this morning, (physical therapy) then up to the Shop.

[edwardofhuncote]

All the loose seams between sides and back are glued-up and tight now. I have loose-fit the patch to the hole. It fits the cutline, and is close to the edge, leaving just a bit to trim off. I still need to devise a way to 'back it up' along the cutline. It will glue to the kerfing just fine. The outer edge of these X-series guitars is a simple 45° bevel. I'll probably do that last.

[jon_jackson]

MUCH nicer than the part you cut out!

[pauldo]

REALLY  appreciate this thread.
So fun how you provide such nice photos documenting your procedure(s).

Thank YOU.

[cozmik_cowboy]

still need to devise a way to 'back it up' along the cutline.

Would I be silly to ask why not a cleat the length of the cut, half its width glued to the original chrome dinette top, leaving the other half to be glued to the patch?
Looking really good thus far.

Peter