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de afwerking mk4-4++ - blablas has that building itch again

I'm beginning on a new build.... and build thread.

The plan is to make a (left handed) 12 string (4 + 2 octave strings per string), it will once again be based on my mk4 single cut body design.

Most of the CAD-work is already done, the tuner layout, the placement of the bridge and the fret positions.
Sd057Lt.jpg


I've also been working on the headstock shape.
CSK5og3.jpg

Due to the huge amount of tuners I'm limited to working with straight lines, if I try a curve somewhere I run into position problems with them.
I'm really happy with the tuner layout so I'm afraid I'll have to live with these straight lines.

The advantage of these straight edges is that the fabrication of the headstock will be a lot easier. :)


The details I'm pretty sure of:
- 12 strings, 4 + 2 octave strings per string.
- mk4 body design.
- Bolt-on neck.
- 35 inch scale.
- 24 frets, brass nut.
- Two dual action trussrods.
- Schaller 3D-8 bridge (which will need some modifications to be used for twelve strings, and while I'm working on it some other refinements as well).
- 4 Warwick bass tuners en 8 Boston guitar tuners.

Things I need think about in more detail:
- Pickups (two, probably dual coils).
- Electronics (active, but which one).
- Wood: body, top & back, neck & fingerboard.

For the top and back I will use one of these two sets:
Rosewood:
B6vMdOd.jpg
C7Xww7o.jpg

the first one will be the top.

Poplar burl:
shLX8Hx.jpg
llGxzmA.jpg

I'm net yet sure which of these two will be the top.
 
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I'm beginning on a new build.... and build thread.
...
I've also been working on the headstock shape.
mk4-4hs.jpg

Due to the huge amount of tuners I'm limited to working with straight lines, if I try a curve somewhere I run into position problems with them.
I'm really happy with the tuner layout so I'm afraid I'll have to live with these straight lines.
...
That rosewood sure is pretty. Would it darken up with a finish? or would it be left unfinished maybe?


I was thinking about that headstock. I thought there was some possibility of making some curvature in there, without touching your tuner layout.

I tried making a Tele style lefty, but it didn't work with the tuners. Something inspired by a normal righty one cold be like these,
DSC00320-Version2_zpse38fd7f2.jpg


DSC00320-Version2_zpse38fd7f2.jpg

or, if you're willing to extend the overall length somewhat, it could be done with a larger, fuller top bulb.

Reversed for your lefty, you get reverse-Tele types.
1bbd0b45-ca5e-42de-8e2f-b8a0ebb8c0be_zps98bd84dd.jpg


93771ec2-7f11-46c7-bc10-7254610d0142_zps391be525.jpg


The other possibility is to go like most of your other "blablas standard" headstocks--slight concave curves on both sides. There's enough room to make it work.
DSC00316_zps03d9a93c.jpg

And IMO it's so much more elegant than the straight-hacked sides.
 
That rosewood sure is pretty. Would it darken up with a finish? or would it be left unfinished maybe?
Probably, but if I'm using this one I will oil it anyway.



The other possibility is to go like most of your other "blablas standard" headstocks--slight concave curves on both sides. There's enough room to make it work.
DSC00316_zps03d9a93c.jpg

And IMO it's so much more elegant than the straight-hacked sides.
Those Tele designs you did don't work for me, I prefer my headstocks more symmetrical.
I like the last one you did, when I tried this sort of shaping this afternoon I couldn't get it to work, I'll give it another go tomorrow. :thumbsup:
 
IMO 12ers are easier to tune if you use 2 different tuners for the octaves. Easier to figure out which one you're tuning without looking. Schaller makes two quality styles of guitar tuners. These are cheapo Chinese.
P1060352P_zps0e9bec70.jpg


It will be interesting to see your mods for the Schaller bridge. It works fine for me with the slots in the right place.
http://www.talkbass.com/threads/12-string.1078138/
 
Your build gave me the idea that this was exactly the bridge I was looking for. :)
P1060033_zps980aa7fd.jpg

The main mod I want to do is see if I can give these ball ends a nicer fit by slotting the holes they go through, factory standard it's just a round hole I assume?
I'm also going to ad at least two more screw holes for mounting the bridge to the body, for me as a engineer three just feels too risky when twelve strings are pulling on the bridge.
 
Your build gave me the idea that this was exactly the bridge I was looking for. :)
P1060033_zps980aa7fd.jpg

The main mod I want to do is see if I can give these ball ends a nicer fit by slotting the holes they go through, factory standard it's just a round hole I assume?
I'm also going to ad at least two more screw holes for mounting the bridge to the body, for me as a engineer three just feels too risky when twelve strings are pulling on the bridge.

On Top Petersen's aluminum 12 the holes are slightly modded. I didn't see the need since everything works and there's not a lot of extra metal in that area. I'll also be using guitar strings for the high Es as well as the high Gs in the future. What I did have to do was relieve the A string saddle carrier where there was slight interference with one of the high As that caused buzzing. LH setup might cause a similar problem on different strings.

3 screws are perfectly adequate to hold in pine, let alone alder. So no reason to add more IMO. It's possible you might need more in softer wood, there are also holes under the A and D saddles.
I don't like to overdo things, spent too much time around structural engineers in my youth.
 
If there are two holes underneath the A and D saddles I don't need to make extra holes. :cool:

These two extra holes are by the way not showing in the Schaller drawing of this bridge (found somewhere on the Internet, the only place where you can always find what you are looking for, even if it is wrong :D).

So much for 'German Precision'. I was going to use those extra holes but forgot about them after I realized they were unnecessary. Just remembered when I replied. Schaller doesn't supply screws for those, you will need flat heads instead of the oval heads fitted in the other holes.
 
Here's the sketch with the original lines still in, so you can see where the relative changes are.
DSC00323_zps03633168.jpg
I've been doodling around some more with the concave shape and still can't get it to my liking, I come up roughly with the same shape you did, but I don't like the way the tip of the headstock comes out, it just gets too wide, I prefer a slim looking tip, for the time being I'm staying with the straight lines, maybe when I start shaping the headstock I'll give it another go but I don't keep up my hopes too high.
The straight edges don't really bother me by the way, the headstock will already busy enough with all those tuners and strings running over it.
 
What is the total center to center tuner distance on each side of your headstock? Mine is 126mm, same as Hamer. If something works steal it, modify it and make it your own. That's a fundamental designer rule.
12ertuners_zps479729f1.jpg


Yours seems much greater. With a 35" scale, double dual action trussrods and extra length on your headstock, neck dive could be a major problem as well as reach to the far tuners.

The parameters that are highest on my priority list are ergonomics, weight distribution and overall weight. A bass that is uncomfortable or too heavy to play while standing will seriously limit its functionality IMO.

As I say, these are my engineering guidelines. I'm always curious as to what other builders consider of primary importance...besides tone of course.
 
Center to center my distance is 170 mm, I don't like wriggle my fingers around objects when I'm tuning, this is the minimal distance I feel comfortable with.
I hope I compensated the weight gained by this distance enough by making the shape of the headstock more compact.
I also don't expect any real problem with reaching the far tuners, this headstock is roughly 1.5 cm longer than the the one of my previous build, the 35" seven string, and I can reach those without any problems.
I don't know if neck dive is going to be a issue, but considering the fact I go with a single cut body design and the strap button is positioned just beyond the eleventh fret I don't expect a problem.


Meanwhile, I've been working on the body design, I think it's almost there, I'm not yet sure if I'm fully satisfied with the lower horn shape, for now I'm letting sink in this design and see if I want to do a little more reshaping.
m9VRtFd.jpg
 
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I'm going with the rosewood for the top and back due to the simple fact that the poplar burl is to small for this body design.
No problem, the poplar burl will be use for a future mk5 build.

The first parts arrived today.
MnGZc7j.jpg

The rest of the parts I need are also ordered, once these and the wood for the back are in I can start making sawdust.
 
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And today the top for the back arrived at my doorstep.
Bg65bqq.jpg



Decided on the wood I'm going to use for the body, khaya mahogany core, three ply birch accent layer between the mahogany and rosewood and of course the rosewood top and back.

Re-sawed the body core, straightened the edges of all the layers for gluing and very roughly sawed the body shape.
6mTia94.jpg


Re-sawed the top for the headstock from a leftover piece of the top.
D6eGdZ2.jpg
 
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Looks great..! I'm sure this will be -another- amazing build from you :)

Question: Do you use regular wood glue for the rosewood front/back? It looks that way from the pics... I'm asking because some say Rosewood is difficult to glue due to the high oil content and that epoxy is advised. Apparently it can un-glue itself after a few years with regular wood glue. But I don't know if this is exaggerated... I'm curious to hear your thoughts and experiences on this