MIMF

This is an old Kay upright bass from the 60s. It had been badly and improperly repaired in the past by someone who did not have experience. The neck joint was messed up and there were signs that the top and sides were being stressed by a number of neck joint issues under a load of wishful thinking wood glue on the surface. I was going to be a big job and the client decided to only have me fabricate an adjustable bridge although was informed that the instrument was in the process of self destructing. Last week a young student in our shop accidentally/clumsily knocked the instrument over and although the bass wasn't strung, it suffered a death blow to what was left of the neck joint. The neck block split in two. the joint on one half of the dovetail mostly let go while the other half separated from the side and top. The heel of the neck fractured the back/heel cap from the back along with the first one inch of the top. To prevent additional damage, I used to heat to separate what was left of connection to the side and separated the neck from the body. At this point, the neck block has about three maybe four fractures. There is minor damage to one of the sides. The neck itself is totally okay and I've cleaned up the dovetail and sepatated the fingerboard which was partially separated already. I'm going to remove what is left of the heel block from the bpdy and see if there is enough of it left to attempt repair on it otherwise I'll need to fabricate an entire new heel block which would be a challenge for me. The shop owner is going to deal with the client. At this point I'm just gathering information.

A lot depends on what condition the neck block is in. If the cracks are clean and fresh they can be glued with hot hide glue, then refit the neck. If the neck block has been previously repaired you may need to replace at lease part of it. Fitting a new neck block is a rather involved repair. Chalk fitting comes in handy for the mating surfaces you can't see.

Is the back off? The button can be replaced with a new one incorporating a swallow tail into the inside of the back.

Get hold of the violin repair book by Hans Weisshaar and Margaret Shipman, you may request it from your local library or buy it for your own library, but it costs several hundred dollars. This book has clear drawings and explanations of most, if not all, repairs likely to be needed on violin family instruments.

Can I use mahogany as a neck block? I'm concerned about strength and stress. There isn't a lot of wood at the sides of the dovetail. The original actually looks like poplar but it may be a poor quality of something else. Mahogany is my favorite wood to carve. Suggestions? I've got the top off as the plys are separated and the top generally needs a lot of attention. I have the neck block also cleanly removed. Its quite a mess but reconstructive efforts have given me an accurate model to copy. I can't reuse the neck block -- too messy from other past repairs.

The neck itself is in perfect condition with the fingerboard removed. I've leveled the maple neck top and planed the underside of the fingerboard. The fingerboard surface has been cleaned up, refined and totally flat. I'll put in the desirable relief when I see how it reacts to string tension.

I've replaced the broken neck block on my own 1953 Kay bass. It actually wasn't that hard of a job. I don't remember what I used for the neck neck block, but I think I may have laminated some spruce and built it of that....

I'll look around for photos; I know I took some during the process, but it was many years ago.

Willow would be the traditional wood, it's light, easy to carve and extremely tough/hard to split. That said it's impossible to find. I'd say a mahogany is fine but overkill, alder, cottonwood would be fine too. I'd suggest gluing a 1/2" sheet of baltic birch plywood to the inside to help prevent it from splitting in the future.

International Violin has willow end and point blocks for violin and 'cello; perhaps they could provide willow blocks for bass also, if requested?

Most of the basses I've looked inside used whatever the maker could find in the scrap pile, mostly spruce. When those neck blocks fail it's often with catastrophic results.

Apparently willow makes the best charcoal for black powder so I suspect some of it goes to that. If anyone ever sees a willow getting the ax they would do well to grab a round or two, split them into quarters and dip the ends for their fiddle maker friends and relations.
It was also very popular for artificial limbs.

Awesome educational stuff. I'm very grateful.

James Condino @ kay bass repair is the plywood maven. You should check out his website (kaybassrepair.com) if nothing else.