Official Luthiers Forum!

Ever seen anything like this before? Do these things have tail blocks? Owner complained of cracking sounds, tuning problems. Do they typically have tail blocks? Looks like this one doesn’t, or it came off.

There have been several very good articles in American Lutherie about restoring old plywood basses (and I think there was a GAL seminar). I could look thru my stack if you don't find a bass guy here (if I find the articles you could contact the authors to see what you are dealing with)

Yes, they have end blocks, very much like an acoustic guitar.

I've got one I'm repairing for a buddy right now (cheap plywood upright bass). I had to take the back off to get in, make a new block, and now just need to reglue everything.

Plywood? This is a fairly new bass. Company that made it is now defunct. I’ll get their name. You seem to think it’s made of plywood? Based on the crack pattern?

The top and back are typically plywood, unless it is an expensive carved bass. The end pin fits into a tapered hole in the tail block. That looks strange, something has happened to the tail block, take the pin out and see what is there.

It's possible that the end block broke loose (crappy glue/jointing job) But yes they HAVE to have a good end block to function correctly. If you think of the way they are constructed, if the end block is not as tight/strong as a submarine's hatch then the tuning problems will become unbearable and you risk causing some serious deformation issues.

Luckily basses/cellos/violins are used to being disassembled so removing the (edited) top on these is much more enjoyable than on a guitar.

There are articles in AL 107, 109, 110 on building or repairing double basses and a picture of the ribs for one on the cover of 121. All the pictures and the GAL plans show end blocks.

I called it plywood because that is the term I hear - my understanding is that most of basses were laminated tops and backs. However I have no first hand experience so I could be wrong.

The owner of the bass said its from King Doublebass (defunct). Said it was built with Gorilla Glue (really??). He feels that in its current form, its a loss. So that removing the back is an option. I've never messed with Gorilla Glue. Thoughts? And, how do you get back off?

If it's constructed with gorilla glue then that does complicate things. I don't know of a surefire solvent but maybe you could try acetone? Have you verified that it actually is constructed with gorilla glue?

In looking at what I wrote, what I should've said was that the TOP is what you should take off. This is routine in maintaining/repairing any violin family instrument. I apologize for the mistake.

Watch from 2:38 to 3:10 and you can get an idea of how to remove the top.

https://www.youtube.com/watch?v=g9XlMWDZqnc

Now IF the gorilla glue can be dissolved/worked with I would simply use a series of pallet knives and work from both sides down simultaneously. Keep in mind that part of the function of the "edge" of a violin top is to hide the areas where the top has been removed/scarred in repair work. It really is routine so it's not that invasive of a job.

What I've done for hide glue assembled instruments is use a soldering iron as a spot steamer to weaken the glue joint. Just work down the edge leaving the separating knife in the joint as a spacer to apply light pressure. You really shouldn't have to "saw" the top off.

It's a BIG job so I hope you're ready to have him compensate you accordingly for your work, to give you an idea, a local shop near me charges around 450 to do a top reglue (and that's just to remove and reglue the top not including any interior repair work). So you need to be charging appropriately otherwise you're going to dig yourself into a very deep and frustrating hole.

All of this though is meaningless if the instrument was indeed made with gorilla glue. I really doubt that's the case but you should try to find out before you go any farther into this thing.

May I suggest contacting James Condino www.kaybassrepair.com He talks about Kay, King and American Standard double basses in his AL articles - seems to take them apart pretty easily. Since he taught seminars at the 2011 GAL on repairing these critters I'm guessing that he will share his secrets.

James is much more likely to answer a phone call than an email, and he is about the best there is with basses. His last GAL article is about repairing a damaged endpin.

_________________
A man hears what he wants to hear, and disreguards the rest. Paul Simon

The one I worked on was plywood - not certain about this one, but its very common for affordable basses.

I used a hot separation knife to remove the back (love that violins/cellos/basses were designed to have these come off easily - No binding!)
Then its easy to see what what has happened with the tail block.

The one I've been working on had what looked like reject lumber from the big box store used as a tail block - very poorly fit, and not surprising that it broke loose when someone dropped it on its end pin.

I traced the radius for the end block from the edge of the back. I just used a compass (kind with a pencil) to get my radius offset. Taped paper inside the removed back, set the compass to the correct width and traced the radius. I'll try to post some photos, as I'm not doing a very good job explaining.

The most challenging part is refitting and clamping the new tailblock in place.

Unstringing it, removing the endpin, and looking inside is the place to start.

Sent from my SM-J727V using Tapatalk

It will be at my house tonight for inspection. I did talk with James Condino. Very helpful guy.