Double Bass when do you like to cut the neck mortice?

[Don Harris]

Yet another question... The Chandler book suggests cutting the mortice before the top or back are on. In the luthiers group I'm going to, violin necks are set with the tops and backs on. Would the break angle on the back make it tough to cut the mortice with the back already on? What do you guys do? -don

 

[1st Bass]

I've only done one bass, so take this with the appropriate quantity of salt;

I cut the mortise before attaching the back plate, so I could get the height, angle and everything just right. Once I had it close (just a little high) I marked the heel at the back of the block, and extending up to where the button would go. Then I set the neck aside until the plates were installed.

After the plates were both installed, I cut the heel off close to the line and proceeded to fit it as I would a violin heel, except that I was only concerned with shaving the right amount off the back of the heel to allow it to settle against the button with clamping pressure. I knew the glue would lubricate things quite a bit, and I did not want a loose neck joint.

I heated both the mortise and the heel with a heat gun before applying the hot hide glue, then slathered the glue on, clamped it and double-checked straightness, angles, etc. and let it set up.

It worked well, the neck is straight, and has an acceptable overstand (a little lower than I had planned...I shaved just a tiny bit more off than I should have, on the sides...should have stopped earlier), and a good tight fit.

There are probably perfectly good arguments against doing it this way--hence the disclaimer at the top.

 

[Matthew Tucker]

I did it the same way, pretty much. Much easier to cut the mortice with a saw if the back plate isn't glued on!

Chet did you cut the sides of the mortice at an angle vertically (not along the top of the neck, but as you would a dovetail) or just straight down like I did? I thought about it, and in the end the slight mechanical gain of the angled sides didn't seem worth the trouble so I made them straight. But then, I used a bolt-on neck design. A glued neck might need that extra vertical strength.

Don - what stage are you up to? Still thinking, or has the wood been cut?

 

[1st Bass]

I cut it at the same angle as the increase from nut to neck-heel at the fingerboard, I think-- which is to say, almost straight. Not enough that I would term it a dovetail, anyway.

 

[Don Harris]

Made the mold with a jig saw, rasps and hand planes. Next time I'm getting a table saw... An awful lot of work to get things square.

I've got the blocks in and shaped. Did that with home made curved sole planes. Worked great and fast.

I made the C-bout form with aluminum tubes for cross supports. I'm also going to put some cross supports on the full mold for the upper and lower bouts too. I bent some thin cardboard over the mold to see where it tended to sag and that's where I'll add them. Pretty much just next to the corner blocks.

Got the heat blankets from Omega,(a 10" x 18" and a 10" x 30") and have the bending straps cut. I think I'll use a high wattage dimmer to control the temp. A local guitar maker does that and says it works fine once you figure out where to set it. I've got a "shoot and scan" thermometer, so I think I'll be able to tell what's going on temp-wise.

I joined the top a couple days ago with hide glue and a rubbed joint. I was going to use Titebond, but when the joint turned out so solid I decided not to clamp. I'm really happy with how it turned out. Then I cut out the outline about 22mm oversized and roughed out an arch with the a scrub plane and the home made planes. The gouge seemed harder to control and more likely to cause bruised knuckles. It went a lot faster than I'd anticipated and I really enjoyed getting a feel for carving a top.

Got the rib stock re-sawn and thickness sanded, and I'm not sure how long I should let it climatize before bending. It's well seasoned wood, but after cutting it it seems to be moving a bit.

I'm going to laminate the neck. I've got 1/4" bubinga for the center stripe with thin black veneer on either side and nice 2" thick maple on either side of that. I'm using System 3 epoxy to put it together. Next time I think I'll just pony up for a real neck block as by the time I bought the bubinga and veneers, I'd spent some money, not to mention time, getting the maple surfaced and ready to glue up.

I still need to make my clamping cauls and wire up the dimmer/timer for the heat blankets.

Probably way more than any of you wanted to know, but I'm stoked. I'm loving the process. -don

 

[1st Bass]

"Probably way more than any of you wanted to know, but I'm stoked. I'm loving the process. -don"

I think it's great! I wish I was as productive as you seem to be. Keep enjoying it. Keep posting the progress.