Need a method for easy/reliable top/back removal

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Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 2:19 am

Hey nerds, listen up - I have a question :-)
I'm building a mule instrument to try a bunch of stuff with. I threw together a rim set in a few hours and I have a partially complete neck that was a router victim (too ugly to sell, but structurally sound).
Here's the dillio: The rims (pictured below) have wide, solid, laminated liners so I have plenty of purchase to poorly glue the top and back on. I want to take them off and on easily and frequently.
So, by what method does one accomplish this magic?
I've thought of several ideas:
- Shellac seal the entire rimset, including gluing surface, and just glue with titebond or elmers - the plates should just crack-crack-crack off with a palette knife. Dry and cold. No?
- Use a separating paper layer that will yield to the separating powers of the knife? Sounds like a pain to glue up every time.
- Diluted fish glue?
- Million little wood screws and a gasket?? Smoke and a pancake?

Yea ... that's kinda what i got. I realize i'm going to have to cleanup the rims and plates to re-attach if I'm not using screws. I just want them to stay together under string pressure, and separate when I apply the knife.

open for the business of ideas - or experience - bring it
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elm (er ... sumpthin' - wood! they are wood!) rims
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Re: Need a method for easy/reliable top/back removal

Postby Steve Sawyer » Sat Mar 02, 2019 10:35 am

The first thing that came to mind was hot-melt glue. Trouble is, it's hard to get the residue off as it kinda seeps into the pores, but if well sealed, that may not be an issue. It's also a bit "rubbery", so if that would negatively affect whatever you're testing.

The second thought I had was burn-in sticks (the original shellac-based hot melt glue). It's normally used for filling and repair, but might work well as a reversible adhesive.

Both might be tough to get onto such a long linear joint - it will be cooling all the time you're trying to get a bead around the rims.

Fish and hide glue are both chosen because they're reversible. I think you might be onto something with the fish glue thought.

If you were serious about the screw-and-gasket idea, maybe some kind of custom clamp - something along the line of spool clamps, but specific to this application. Weight would be an issue there. Not sure, again, if that would interfere with your testing...
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Re: Need a method for easy/reliable top/back removal

Postby Bob Gramann » Sat Mar 02, 2019 11:00 am

Sounds like some experimenting is in order. HHG yields pretty easily to alcohol and a palette knife. Violin makers dilute HHG to attach the plates to make them easier to remove. I don’t know how that would work with liquid hide glue or with fish glue but it would be worth some experimenting. The one place where I have had trouble removing a HHG glued plate is over the heel block. The larger gluing surface there is hard to dissolve with the alcohol and harder to get the knife under without deforming some wood. You could striate the rim and block surfaces to allow whatever solvent you use to penetrate.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 11:06 am

good thoughts steve.
i will be doing acoustic testing, so i'm trying to avoid rubbery glues - and therefor, i'm no so hot on the melt glue thing.
but what if it were a glass like hot melt glue? i have some burn in sticks i could try it ...
i thought a bit more about the screw-and- gasket thing, and if i were to make a new plate, re-drilling a million through-holes would be a pain. and i would probably have leaks, and the gasket would need to be rubbery...

my wife just suggested glue stick - not sure it will fill gaps.
i need a CRAPPY glue!!!
or 2-sided tape?
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Re: Need a method for easy/reliable top/back removal

Postby Barry Daniels » Sat Mar 02, 2019 11:41 am

In the Somogyi master class I took we made easy removable top braces by placing masking tape on the top where the braces would lie and gluing the braces on top with Titebond. The bond was secure and did not seem to mess with tone but the braces could relatively easily be removed by snapping them off.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 12:26 pm

thanks Barry - that's the type of experience I'm looking for. I figured i'm not the first to need this type of joint, and i'd like to stand on the shoulders of those who came before than do a bunch of experiments.
i could tape the perimeter easy.
anyone else?
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 1:15 pm

by the way, Bob, i plan on minimizing the gluing to the heel block by:
1) on the top, i'm going to install threaded inserts to hold the FB tongue down - so i will glue only the rim and leave the block dry on the top
2) on the back i don't have a solid plan :-) maybe just layer it with tape and glue the plate down
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Re: Need a method for easy/reliable top/back removal

Postby Chris Reed » Sat Mar 02, 2019 1:46 pm

I'd use the paper shim and attach it with hide glue. When the top is removed, a warm damp cloth should pretty much wipe away the paper on the rims, and you don't need to clean all the hide glue off because it will reactivate with fresh glue. I suspect liquid hide glue would work for this, though I use HHG so I've never tried it.

The paper shim shouldn't be too fiddly. Stage 1, glue over-size paper to the rim and allow to dry. Stage 2, trim off excess. Stage 3, glue on the top. With HHG the drying time after stage 1 is just about enough for a cup of tea or coffee, I guess it would be longer with liquid hide glue though.
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Re: Need a method for easy/reliable top/back removal

Postby Peter Wilcox » Sat Mar 02, 2019 2:07 pm

I made a guitar a few years ago that needed frequent back removal. I used the screw-it-on method. The upside was easy removal and replacement. The downside was imperfect acoustic sealing of the joint (though a gasket could probably eliminate that), and I could not find Phillips flat head wood screws of the needed size (#2 I think). It's a PITA to screw and unscrew slot heads without the blade slipping out. Also, I had to wick CA into the holes to keep the lining from splitting.

Just my experience - I wouldn't recommend this. The other suggestions sound better. Some pics show how I did it.

struts-cf3.jpg


back-screws1.jpg


side-view.jpg
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Re: Need a method for easy/reliable top/back removal

Postby Steve Sawyer » Sat Mar 02, 2019 2:35 pm

For paper shims, you might want to try baking parchment. Water-based glues will penetrate it, but the paper itself is impregnated with silicone, so it might separate more easily. And no, the silicone will not rub off affecting finishing.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 3:52 pm

ok people - now we are cooking with gas !

Peter, you confirmed my fears about the millionscrewsandagasket method - no way jose.

I'm testing the tape-one-surface method espoused by our esteemed admin Mr Daniels. See pic. it is a reasonable model of my situation, and seems to be holding quite well. it still needs to dry a bit more then i'll RIP IT APART!!!! :-)

if this is too whimpy, then i'll look into the paper shim thing. i have several materials i could use: baking parchment per Steve, polyester release film (which nothing sticks to - so meh), tracing paper, thick art paper, gawd what else.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 3:53 pm

my pictures are not showing up admin crew. let me try again...

that is elmers glue BTW
Attachments
tapeglue.jpg
do i need a snarky comment?
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Re: Need a method for easy/reliable top/back removal

Postby Clay Schaeffer » Sat Mar 02, 2019 6:48 pm

Hi Chuck,
You might consider using 100% silicone caulk. It is pretty tenacious but as long as you leave enough space to slip a guitar string in the seam you can saw through the joint or cut it loose with a razor knife. Then you scrape off the reside with a sharp chisel.
Hot melt can also work as you can release it with alcohol and light pressure, but may be harder to apply unless you use low temperature glue and remelt it with an iron.
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Re: Need a method for easy/reliable top/back removal

Postby Alan Carruth » Sat Mar 02, 2019 7:23 pm

A friend of mine uses the paper and CA method. I gather that things blow up from time to time, particularly when he uses it with the bridge. I can ask him for details.

Joe Curtin advocates sizing things with weak hide glue, and then sticking them together with CA. CA sticks to protein well, and the hide glue is easy to get apart if you know how.Once he's got everything working the way he wants it's easy to wash away the hide glue and the CA goes with it. Then you can move to more permanent gluing. I don't have much experience with this myself, but consider the source.

I would NOT try fish glue: it's far too tough.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 8:02 pm

elmer's on masking tap gave way very easy. it may work - but it may be marginal. i have a huge gluing area. the rims are 0.3" wide and solid all the way round.
I'm sealing the test surface with shellac right now and will try elmers on that next.

Alan, thanks for the info. i'd rather not use CA. spreading CA all the way round a rim just frightens me on a couple fronts. first of all, i have bad sinuses. and second i've been Brier Rabbit before - with BOTH hands stuck to a guitar body and all the doors out of the shop were closed. looks like i'm in testing mode, so i'll see if either of my first couple trys will work.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 8:07 pm

tell you what - grinding down these giant, solid hardwood rims is a PITA!
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Re: Need a method for easy/reliable top/back removal

Postby Barry Daniels » Sat Mar 02, 2019 8:15 pm

I would use Titebond on the masking tape. It should be considerably stronger than Elmers.
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 9:20 pm

roger that Barry - i'm going to repeat that test right now with titebond. if its better, then i should be over the "marginal" level
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sat Mar 02, 2019 10:45 pm

wait ... there was a table saw and router table under all that dorm stuff?!?!
i WILL get my shop back!!
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Re: Need a method for easy/reliable top/back removal

Postby Chuck Tweedy » Sun Mar 03, 2019 12:19 am

Barry - you win.
I took the test glueup out of the clamps and dropped it on the floor - test 1 - passed. it did not break apart. (dropping it was not intentional BTW - just clumsy)
Then i broke it apart, and the tape came off the "rim" rather than break the glue joint to the tape top.
then i peeled the tape out of the glue and it delaminated the tape's paper (see pic).
This is basically a paper barrier method. as long as the tape's adhesion to the rims is good enough, i'm all set.
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