Broken Neck - 1/4 size plywood

robobass · #1 11-30-2007, 12:51 PM

I'm planning to make a rather nefarious repair.
A student of mine lost her head

It's a 1/4 size plywood of the very cheapest sort. It has a diagonal split from under the nut to about Bb, so I've got about 3" of surface to work with. I told her I'd glue it up myself. Everything fits together well and no pieces are missing. I'm no bass luthier, but a craftsman and good at things like making clamping jigs. I'm just planning to hide glue and that's that. I think it will be strong enough, as it's a very short string length. Anyone have a problem? Should I go with epoxy? The mother wants me to use a screw. I don't think it's necessary.

Thanks for any advice,
Robobass

Darren Molnar · #2 11-30-2007, 01:15 PM

Hide glue will be the strongest bond, no epoxy needed, or wanted there. I think you're right on track, robo. I think, given that it is a low priced small student bass, you're idea is about the only one to try. If it fails, i might consider putting a biscuit in there, to increase the gluing surface area. But try you're way first.Screws never work out well.

Jake deVilliers · #3 11-30-2007, 06:44 PM

+1

Glue & clamps is all that little bass needs. Well, a neck with better grain orientation maybe, but that's not going to happen, is it?

forester · #4 12-02-2007, 06:28 PM

epoxy..accurglass to be more specific...there i said it

let the nut kickin' begin..onetime fix on a cheap student 1/4. hide on the FB. any doubts..Pop FB after neck sets..dowel..replace. my 2..

i like the pic. you can see the ambrosia stain.

jimmyduded · #5 12-02-2007, 06:49 PM

just to give my 2 cents, every bass ive seen with this problem has had to have a neck replaced, string tension on a neck is alot more force then one might imagine and being a 1/4(dont quote me) I would imagine have a smaller neck which puts it at a greater risk, if the glue doesnt hold the bass could be toast due to the low cost(like totaling a car) so If i were you I would just beware the family does not blame you for anything you do that they do not understand

jimmyduded · #6 12-02-2007, 06:51 PM

by the way I just spent 5 minutes trying to figure out what i was staring at, the carved out part of the scroll looked like it was inverted so I thought it was a block of wood, silly me

Bob Branstetter · #7 12-03-2007, 09:07 AM

Does anyone know of a reliable source for 1/4 bass necks and fingerboards in the US? One local school district bought a bunch of S. Korean made S&R 1/4 size basses and they have had a lot of trouble with neck warpage as well as more than normal breakage. I've tried all of my usual suppliers and none stocked 1/4 carved necks and/or 1/4 ebony fingerboards. I'm currently waiting for a 1/4 ebony fingerboard that had to imported (my thanks to Anton Krutz for adding it to his big fingerboard order) to arrive. A US supplier would certainly make things easier.

I agree with jimmyduded that because of the relatively small gluing surface and the great tension exerted on these little 1/4 necks, the repairs frequently fail and a neck replacement is the only long term solution.

jlehmberg · #8 12-03-2007, 10:24 AM

I snapped my neck in a similar place back in May. The luthier here just used epoxy--no pins or anything, and so far it's been great. From what I understand, the fingerboard is what really supports most of the tension, right? I'm guessing that this bass will be outgrown before the repair fails, if ever. By the way, what is the conventional wisdom about epoxy vs. hide glue for various repairs?

Darren Molnar · #9 12-03-2007, 11:19 AM

Talking glue amongst instrument makers has been known to start fist fights. So I'll only give my opinion here and won't bother defending it here after.

Hide glue is the only needed and wanted glue in instrument repairs and building. The bond between hide glue and wood is stronger than the wood itself. Hide glue has a shear strength of over ten thousand pounds per square inch, so imagine hanging a jeep off of the end of that repaired neck that started that post.The wood would fail first.

Hide glue does not fatique. Hide glue does not creep. (dimensionally stable, not elastic)
Hide glue is environmentaly friendly, in both the manufacture, and use of it compared to epoxies. Hide glue is reversible. Hide glue doesn't give you cancer.

Modern adhesives offer no strength benifit. they are not stronger than hide glue to any useful degree.

Using hide glue is a skill like any other aspect of repairing or making. You have to learn how to apply it right.You have to use it fresh and hot. once you learn to use it properly, you see that you can trust it, and have no reason to try any thing else. It has been in use since the age of the pyramids. Modern adhesives have no track record back more than sixty years or so.

For the most part epoxies and the like are favored by peolple new to the craft, and haven't learned how to use glue properly. They believe the marketing hype that any thing new or modern must be superior. Which in this case is bullox. ( that should generate some comments

)

Remember that craxy glue ad, where a guy is suspended in the air,hanging from a one square inch crazy glue bond? What was he, two hundred pounds?. So imagine the same test, with a wooden beam, bonded with hide glue to a one inch wooden block. You could hang him and fifty of his closest buddies off of that. if the wood doesn't fail first.

Now, casien glue, on the other hand,,,,,,,

Darren Molnar · #10 12-03-2007, 11:43 AM

The dowel idea and the neck graft sugestion are both superior ways to repair this break.
But there is a point where the cost of a good repair isn't justified on a " 1/4 sized plywood of the very cheapest sort. "

It takes the same amount of time to neckgraft a strad, as it does to neck graft a BSO, do we charge less for one, and more for the other? Interesting topic.

Jake deVilliers · #11 12-03-2007, 12:27 PM

Epoxy and aliphatic resin glues are only useful for gluing contaminated joints, like if the owner or his uncle tries to fix the break. :/

Hide glue in a fresh break is very strong and stable through a wide range of temperatures. Hot glue and hot gluing surfaces make it easy.

Unlike Bob and jimmydude, I think that break will repair well with just glue and clamps. There is plenty of surface area. It looks like the neck broke from some kind of percussion.

Bob Branstetter · #12 12-03-2007, 12:42 PM

Quote:

Originally Posted by Darren Molnar

The dowel idea and the neck graft sugestion are both superior ways to repair this break.
But there is a point where the cost of a good repair isn't justified on a " 1/4 sized plywood of the very cheapest sort. "

It takes the same amount of time to neckgraft a strad, as it does to neck graft a BSO, do we charge less for one, and more for the other? Interesting topic.

The last time I did a doublebass neck/scroll graft, I found that I could have bought a entire neck with a machine carved scroll for little more than my cost for a good quality maple neck grafting block. When you figure in labor, it quickly becomes apparent that in most cases it just isn't cost effective to do neck grafts on most mass produced factory basses. I doubt if there are very many owners of these basses who would be willing to spend an extra $1000 or more to have a graft done on their existing scroll instead of a replacement with a machine made neck and scroll. I also doubt if there would be any difference (between a graft and a replacement) in the resale value if the luthier did the work properly. A repaired broken neck on the other hand, always decreases the resale value. With a plywood 1/4 size, a graft isn't even a consideration assuming you can find a replacement machine carved neck.

jimmyduded · #13 12-03-2007, 01:24 PM

I agree 100 percent with bob, the price of materials is low but cost of time for a good graft is worth far more than the bass is im sure, seems like its totaled because if bob cant even get a 1/4 neck with all of his connections it will most likely be a challenging feat, try the repair(cant hurt) but dont be surprised if the bass is less than up to par with any standards

Bob Branstetter · #14 12-03-2007, 01:34 PM

Quote:

Originally Posted by Jake deVilliers

Unlike Bob and jimmydude, I think that break will repair well with just glue and clamps. There is plenty of surface area. It looks like the neck broke from some kind of percussion.

Jake - I've done a lot of school district work over the years and I would agree with you if you are talking about 3/4 basses. However, one of the reasons I'm looking for a source for 1/4 necks is because of repair failures both of mine and from other shops that I've had to redo. IMO, there is NOT plenty of surface area. Truthfully, If replacing the neck is not an option, I would rather have the work go to some other shop. If you were closer, I'de send them to you.

Kids don't treat these little instruments gently and most of them aren't made from very good wood to begin with!

Believe it or not, I'm leaving now to give an estimate on another broken school district S&R 1/4 size bass neck.

jimmyduded · #15 12-03-2007, 01:42 PM

haha, yes its true about the lack of respect, my school has 7 kay basses, only 4 work because of kids neglect for caring about them

Jake deVilliers · #16 12-03-2007, 02:01 PM

+1 on the kids!

I just repaired a school 1/2 size with a very similar break, but further up and with less of a shear angle. For that one I put a couple of dowels down through the nut surface because of the small gluing surface and its good and strong.

In the kids' defense, in that case and the one presented by robobass, the grain in the neck could hardly have been less suitable for making the neck out of......

Bob Branstetter · #17 12-03-2007, 02:51 PM

Perhaps a little clarification is in order. I don't mean to give the impression that all repairs on these 1/4 size necks are going to break again as soon as you've finished. In my experience, they usually will last for a year or more before they fail. That may be good enough if you were just trying to dump it on some unsuspecting grade school parent from out of town, but that is not a long term fix as far as I'm concerned. For a luthier shop owner, it would be wise to inform the owner that you can't guarantee that it will be a permanent fix. At least you've got a little CYA for down the road.

forester · #18 12-03-2007, 09:13 PM

i'm not looking for a beat down ..i appreciate the zeal to keep and encourage tradition. i for sure am new to the craft and therefore have limited experience and limited skills. we use those unmentionable binders for reconstruction purposes on shattered instruments that have compound breaks, missing pieces and require build up. instrument triage...bare in mind these are "disposable instruments" cousins' to the one pictured. i call it putting lipstick on a pig

but it works and keeps the instrument out of the chipper and puts it back into the hands of the budding prodigy.(at this play level that is what it's all about)

Kevin Hsieh · #19 12-03-2007, 09:37 PM

forester, your students are lucky.

my old high school doesn't even try to fix the broken basses. I have a couple with sunken plates, one with a giant hole through the rib and a couple with cracked tops, bridges, and open seams. they issue these to our aspiring bassists... it's a miracle that they don't quit upon looking at these monsters

forester · #20 12-03-2007, 10:30 PM

thanx kh. i used to live by the "no fiddle left behind" policy but later got overwhelmed. i have 30min.tops for violin,viola....bass and cello 1hr +/- all sizes.
bridge,sp,strings, clean/adjust,any glue ups etc.
true test is when i can play it a child can play it

run these numbers.. 8 of us doing 16 instr/per man/per/day
x 200 working days yr. and i'm still having fun!