One piece black walnut crotch headless 6 string

[T_Bone_TL]

I think one major difference between low end and high end hardware in this realm is standard threads .vs. superfine threads of some sort, given the "straight-pull" nature of the beast - but I'm not sure of any handy source OTHER than cutting your own to get/make super-fine threads.

Well, I did manage to spot some $32/each Micrometer adjustment screws (100 threads per inch) at Newport, and my experience of Newport is that if you track down where they get stuff from and mark it up for the science market it usually costs a lot less.

McMaster has 3/16 - 100 and 1/4" - 80 taps. They don't seem to have dies to match, but they do have setscrews and plastic-head thumbscrews in those sizes, and threaded inserts in those sizes. They also have 1/4"-100 setscrews, but no inserts or taps at that size.

 

[Slidlow]

Very fine threads is what is needed for best tuning accuracy with this kind of design.

 

[Jeff Siddall]

Must resist urge to buy carbide thread mill...

Even so, readily available mills looks like they only go to 0.45 mm (56 TPI). That definitely qualifies as very fine, but I am sure that the odds of me cutting good threads approach zero long before I get to 80 or 100 TPI.

 

[MPU]

I see one problem with your tuner; the nut and at the same time the string can turn when tuning. How are you planning to prevent that? Maybe rails for each nut?

 

[Jeff Siddall]

I see one problem with your tuner; the nut and at the same time the string can turn when tuning. How are you planning to prevent that? Maybe rails for each nut?

Yeah, the final version will be mounted on a 2" aluminum base with a top cap to hold the dome nuts flat

 

[Reedt2000]

Wow, every piece of this build fascinates me, Sub'd

 

[ctmullins]

The motorhead in me says “just put a small smear of axle grease on those threads....”

 

[Jeff Siddall]

The motorhead in me says “just put a small smear of axle grease on those threads....”

Hah! Did that right away actually, but it didn't make much difference. And to be honest, it's not bad, just not as smooth as a quality worm gear tuner. I suspect (but am not positive) that finer threads would make a corresponding improvement in smoothness.

 

[Reedt2000]

From another thread...


Here are a couple of pictures of all the major components:
Tuners:
View attachment 4020184

Saddle and headpiece:
View attachment 4020186

Yes, all off-the-shelf parts, though I wouldn't expect to find most of this at your average hardware store!

• Dome nuts are M10x1.5
• Thread reducer goes to M5x0.8
• Thumb screws are 25 mm long, 14 mm diameter head (considering some 16 mm also)
• Bearings are F5-12M (5 mm ID, 12 mm OD, 4 mm thick)
• Saddle screws are M3x0.5, 10 mm diameter head
• Saddle base is 7 mm tall, 10 mm diameter
• Base plate will be 2 x about 0.75" aluminum angle
• Headpiece screw spacing is 9.5 mm (i.e.: J-bass spacing)

Regarding depth, it will be built on a 2" wide base plate plus the thumbscrews and bearing, or about 2.25" total. Only marginally bigger than a normal bass bridge, though the saddles are not integrated in this design.

I was surprised about how little elongation there is from a floppy string to a tuned string. Only about 7 mm for low string by my measurements, or just over 1/4". This design has about 17 mm of adjustment range.

This should allow standard long scale strings (shown) to work on this bass (35" scale). Yay!
View attachment 4020187

Also, some disclaimers...

The saddle design, consisting of a knurled screw on knurled base, has not been fully tested. The mock up doesn't really have any break angle to speak of. In the final implementation, the body of the bass (where tuners will be mounted) will be angled 10 degrees. This will give the the saddles a proper break angle and also significant down force (> 20 N or about 5 lbf). I believe this will be enough to keep them from sliding on the body when being played, but this is still TBD. I might end up needing a removable adhesive or something like to help keep them planted that if they move too readily. The saddle position will control both the intonation and string spacing so those need to stay put!

As I mentioned, the turning action isn't as smooth as I would like, though it is certainly usable. I might play with different metals and see if I can improve it. I would go to a bigger diameter thumbscrew but then the threads start to get too coarse for fine tuning. 0.8 mm per turn seems like a good place.

The whole thing, bridge, headpiece and saddles, cost less than $80 CAD (about $60 US), and will have a custom look -- hopefully in a good way!

I'd love to see this in more detail. Looks like there was a design pic earlier in the thread but it doesn't display anymore. After buying a pretty expensive headless bridge myself, the idea of building one for cheap is pretty attractive

 

[Jeff Siddall]

I'd love to see this in more detail. Looks like there was a design pic earlier in the thread but it doesn't display anymore. After buying a pretty expensive headless bridge myself, the idea of building one for cheap is pretty attractive

Yeah, TB is strange with trying to re-use pictures, or even upload the same picture twice. Invariably it doesn't display.

Anyway, have a look at this post for some pictures of the main part of the assembled tuner. Don't get too excited, this was just a proof of concept:
What's On Your Workbench?

 

[Jeff Siddall]

One year ago I thicknessed the "one piece" and I just rechecked it today: It is within about a mm of flat along the full length so it isn't going anywhere significant just sitting around. I recently got a spool of carbon fiber tow so the next step will be to route some channels into the top of the neck and cast some CF reinforcement into them. I will also fill all the small cracks in the crotch with epoxy at the same time.

After that, cut the perimeter and carve forearm and belly cuts then the back of the neck.

Hopefully it won't go sideways after removing the remaining wood!

 

[Slidlow]

One year ago I thicknessed the "one piece" and I just rechecked it today: It is within about a mm of flat along the full length so it isn't going anywhere significant just sitting around. I recently got a spool of carbon fiber tow so the next step will be to route some channels into the top of the neck and cast some CF reinforcement into them. I will also fill all the small cracks in the crotch with epoxy at the same time.

After that, cut the perimeter and carve forearm and belly cuts then the back of the neck.

Hopefully it won't go sideways after removing the remaining wood!

Pictures?

 

[Jeff Siddall]

Pictures?

No, I didn't take another picture, but it still looks exactly like it did when I planed it back in post #19.

 

[Jeff Siddall]

Since I have a bunch of slabs of suitably thick maple on hand, I got to thinking that it might be a good idea to do a test run of the one piece build process using hard maple to build a 4 string version first:

That paper template is strategically placed on the board to avoid all the existing checking, though I fear that over the next year the checking might get worse to the point of making the board entirely unusable. Only time will tell, which of course will only further delay the walnut bass.

Still, increasing the chances of success with the crotch walnut seems like a worthwhile path. If/when I start the maple build I will post the pics in this thread.

Maybe this will be a 2 for 1 thread

Or maybe 0 for 2

Really hoping for the former!

 

[Slidlow]

Cut your slab down closer to the template, seal the edges and wrap the whole thing in saran warp to slow the drying. Took me 4-5 years to bring a slab of ebony down to a workable size but maple should be quicker.

 

[Jeff Siddall]

Due to concerns of neck stability with the crotch walnut I am planning to go with dual double action truss rods plus triple CF reinforcements. The CF will be cast into the neck so each piece of CF will be a different depth to fit with the neck profile:

 

[JayGunn]

If it were my bass project I would consider doing it just as you show, except using the 3mm wide CF bars. At the first fret it seems like there isn't enough wood between all the hardware, and reducing width is less of a stiffness loss, of course, than reducing depth.

And actually I'd also taper the bars not to come so close to the back of the neck at the 1st fret as well. Don't want a sand-through!

 

[Jeff Siddall]

If it were my bass project I would consider doing it just as you show, except using the 3mm wide CF bars. At the first fret it seems like there isn't enough wood between all the hardware, and reducing width is less of a stiffness loss, of course, than reducing depth.

And actually I'd also taper the bars not to come so close to the back of the neck at the 1st fret as well. Don't want a sand-through!

Thanks for the suggestions!

I think I will stick with the 1/4" CF slots mostly because it makes routing the slots easier if they are all a single width, but also because it will get tricky pushing the wet CF tow into the slots if they are too narrow. Also, I don't particularly need any wood between the hardware since it is weaker than the CF.

I do agree that sand-through is a possibility with the current layout. I can't reduce the thickness of the truss rods, which are less than 2 mm from the outside of the neck, but making it even easier to mess up by running the CF even closer than that probably isn't a great idea. If I reduced the depth of the CF slots by even 1 mm it would put them at least 2 mm from the surface which I think I can manage without sanding through.

Other alternatives include recessing the truss rods into the fretboard (something I need to get good at for at least one of my other builds) or thickening the neck a mm or two.

Hmmm...

 

[JayGunn]

Got it. One thought is that if you're putting tow in the bottom, might it be a good idea to rout the slots with a 1/4" round nose bit? Avoid the sharp corners and slightly reduce the chance of a sand through(?) Would only work if you put in 1/8" or more depth in the form of tow so the carbon bar stock would stay above the radius. Hope that makes sense.

Anyway I am eager to see how it turns out. Bruce has made a lot of converts I suspect, including me, with his ultra clear discourse on the tow method he uses. I'm planning to try it out next time myself, on bass #3 or #4, both of which are on hold at the moment.

 

[Slidlow]

Plus 1 on using round bits. I finish all my truss rod slots with a round bit.