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Short scale Eight string?

#41
I actually use the same template for an eight-string and a five-string, since I like my fivers with narrow spacing (17mm or so). I know it's 44mm at the nut end, but I don't remember the body end. It's closer to 2.5" than 3.0", like maybe 2.6"? I'll measure when I get home! (Yes I know I'm mixing metric and English; that's just what I've become comfortable with!)
 
#43
ctmullins said:
I actually use the same template for an eight-string and a five-string, since I like my fivers with narrow spacing (17mm or so). I know it's 44mm at the nut end, but I don't remember the body end. It's closer to 2.5" than 3.0", like maybe 2.6"? I'll measure when I get home! (Yes I know I'm mixing metric and English; that's just what I've become comfortable with!)
Click to expand...

66mm (almost exactly 2.6"!) at the 22nd fret.

The ThunderTwins are a great illustration of this. The PentaBird uses the Schaller five-string roller bridge, and the OctoBird uses the very similar Schaller eight-string bridge.

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#44
Thanks! I think I might go slightly wider at the 22nd, glad to have confirmation, and thanks for those pictures they will help when it comes to nut filing time. Mine will be headless so I am trying to work out how to terminate 8 strings in as little real estate as possible on the head and still have it look orderly. I have some ideas, but I need to do some mock ups.
 
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#45
Man I'm basscrastinating serious honey-dos so far on this vacation. I need to put this stuff down and get my butt in gear on other home stuff.

I laid everything out on the body and neck - doing this 32" scale with no head is weird to me, always good to push the envelope I guess. I think I have everything worked out. I really wish I had the fretboard here! The bass truss rod I got from StewMac is going to fit, but just barely, I probably should have bought a guitar one or something shorter, I wasn't thinking about this being a bolt on when I bought it. I will have to have the adjustment nut up on the headstock, which is going to add to the congestion up there. I drew it up last night, I think I can make it work. I'll mock something up later today or tomorrow.

I planed down the mahogany (it's definitely mahogany) for the body - it's too narrow for a one piece body, I'll probably put a maple or walnut stringer between the two halves:
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I glued up the front yesterday and planed that down today as well. I wasn't very careful about how flat it was when I glued it, no harm done, but it's thinner than I expected it to be:
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And I ran the neck blank through the planer too, just to make it perfect:
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And most excitingly I tapped the side of one of the individual string bridges and added a set screw to hold the string. I had no idea if this was going to work. Success! It looks good and is holding extremely well. I'll have to figure out a way to bring it up to tension, but I see no issues right now. I still have to figure out how to mount these things inside the body and get a hex head bolt for tuning. Changing strings will not be fun, but really how often do you change strings? Once a year is a LOT (for me).
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#46
...and it looks like the idea I had for the other end will work as well. I know this is kind of hard to see. I used a cutoff from the neck planing yesterday, which was not planed, so I cut it by hand, it's really rough, but gets me close to the same thickness as the real neck will be. I also don't have a drill press here at home, so nothing is really straight.
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So I'll need to do another mock up (after I get this popcorn ceiling crap scraped down), but I think this will work. For the final version I'll need to put the brass tube as close to the bottom as possible and I'll have to figure out how to accurately drill that angle and of course everything will need to be straight and a lot more controlled. At least I know the concept works.
 
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#47
I made a better mock up with a hole for the truss rod, again without a drill press so nothing is perfectly straight, but everything lines up pretty good. The hole for the truss rod nut is just a bit lower than it will be in the neck. I'll need to work out a jig to get that angle correct when I drill the holes for the strings. The holes on the edge are going to be stressful, there's not much room, it's going to be a serious bummer if I breakout through the side of the neck. I guess that's enough. I figure even if the strings touch the truss rod nut it's not going to be a big deal. The piece glued on top represents the height of the nut.

(edit - as I'm looking at this I was just thinking, those holes don't have to be lined up to the slots in the nut, I can crowd the holes together in between the edge and the truss rod nut and fan them out after they exit the wood. That would relieve some of my stress in drilling those outer holes.)

(Another edit: I didn't plane or cut this wood to the proper thickness, the line under the brass tube represents where the bottom of the neck blank will be (it's already planed to that thickness). I forgot to leave anything for a volute. I'll have to glue something on there for the volute and I can use that as extra material to add a little interest at the end there.)

20160412_170822_zpse0njp86u.jpg
 
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#48
I laid out everything on the front. As usual there are constant tweaks to get everything in - move the neck up a half inch to get the bridge in place because the tuners are longer than I thought. Oops then the bridge gets moved, oh wait that's where the pickup was going to go, wait there's not enough body left for the neck joint. After a half hour of moving everything around here's where I ended up:
20160413_085643_zpssnyzegyl.jpg


I glued up the billet for the body. I am not sure what happened in the planer yesterday, but the two pieces aren't flat. I brought my dog with me to the shop and she was distracting me, but it's a sanding planer, there's not much I'm doing other than laying the boards on the feed table. There's plenty of room left to adjust, so it shouldn't be a problem. The board had some cup to it, I probably should have propped it up on a board before sending it through the planer, I figured because it was thick enough it would resist the pressure of the planer, apparently not.
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#49
(this is a bit of a duplicate post from something over in the "sourcing headless tuners" thread)

I'm trying to work out how to mount the tuners. The idea is that they are angled up from the back of the bass and accessible from the rear of the bass. The best way I can see to make this happen is to route a pocket from the back off the bass, then glue in a piece of wood that's pre-drilled and angled correctly. I think routing a pocket that is angled would be difficult (if not impossible) as on the deep end of the pocket the edge of the router base will hit the body. I'll have to do some mock ups.

Oh and I cut the body out last night. I'm going to use this as a template to route the billet part of the body. The top ended up being about 5/16" thick, so I should be able to run the bearing around it. I'll use screws in the neck pocket as pins to hold the top in place.
20160414_075336_zpszpvuto16.jpg
 
#50
I had planned on drilling a hole in the end of the headstock for the truss rod nut to stick through, I got it all planned out and ready to go. I made a test using a short cutoff piece from the neck blank. All went well.

This neck piece is too long to sit on the drill press table (it's a free standing drill press) and too short to rest on the floor. I eventually got it all set using a couple of pieces of 4x4 and a bubble level and the drilling went great. Then I tried to put the truss rod in - in order to get the truss rod nut through the end of the blank where the hole is I would have had to made the truss rod channel really wide for a long distance. With the test piece I could just push it in from the end - with the real piece I had to angle the rod in. In the end it seemed like I would end up with a mess so instead I just routed out the whole length of the neck blank after drilling the hole in the end. It looks a little messed up right now, but I will fill this in and you won't be able to see it when I'm done. Depending on how the string holes go I may end up just making a cover for the whole thing anyway, we'll see.
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I had one wiggle in the truss rod route - man I hate that router table, but it's in there nice and snug and flush (note there is some dark parts of the maple up against the walnut, that's not the wiggle!).
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...and finally I used the top as a template to smooth out the rough cut body blank. Looks great! I can see the advantage of making templates, so much easier than getting the the whole body shaped at the same time. I used a Stew-Mac purchased bit for the top 2/3rds and a cheap bit on the bottom 1/3rd. The first bit wasn't long enough to reach all the way to the bottom. Huge difference in those two bits. The expensive one cut cleanly, no burning and it was smooth to push along the wood, the cheap one was way more "chattery" and burned the wood. It looks like I need to get an expensive bottom bearing template bit. I have screws in the neck pocket and where the neck pickup will go as reference points. I'll need to take this top on and off a bunch of times as I build the angled mount for the tuners - someone remind me to put in a wiring route between the pickups before I glue the top on! I know I'm going to forget that and then it will be stress and misery with a drill.
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I will likely carve and indent in the bottom, but I'm going to wait to see how these tuners go and where their heads will end up.

I stupidly ordered the wrong fretboard from LMII. I'll have to call them and see if it's too late, I ordered a four string board when I need a five string board (according to their measurements). If it's even a little oversized I might be ok, I might just let it go and see what it looks like when it gets here. They claim 2.75 width, which is a bit shy of where I was hoping to be at the bottom of the neck.
 
#53
I got the chambering done and started working on the hole for the tuners. I was going back and forth on whether I should just open the whole back up for the tuners and after getting the area drilled out I found that the top had chipped out pretty significantly. I found all the chips and glued them back in. I will likely just open it up all the way, but I wanted the option. We'll see.
2016-04-15%2015.17.25_zpstgewbzdn.jpg
 
#54
I was looking at those chambered holes and thought I should clean them up a little, so I went freehand with the router. Of course the shape of these holes is not critical in any way so the risk was low. After doing the top of the hole freehand I just used a top bearing bit to do the same all the way down the side of the hole. They look at a lot better (even though no one will see them).

Then I got daring. I forgot the template I made for the tuner hole over at my dad's shop, I considered driving back over there, but after the freehand experience I got an idea that I could finish off the tuner hole if I just used a fence on one side at a time. I clamped a fence along each straight line and ran the router along the fence. Not totally freehand, all I needed to do was to watch where I ended each end of the four runs. Once I had the top done, I just used a top bearing bit to extend that down. The hole looks great, very clean.
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Today I'll work on how I will mount the tuners. I think it's going to be a compromise to come up with the best angle for the strings. Since they will be tuned from behind the bridge, they need to slide easily over the bridge or there will be tuning issues, the lower the angle the better. I see that as a combination of the angle of the string as it goes over the bridge and the material and shape of the string saddles. I also need to watch where the heads of the tuning screws will end up. On top of that I also want the strings to come in relatively straight to the string saddles and the spacing of the tuners is going to make that impossible. I think I'm a pretty good at technical drawings, but with stuff that gets overly complex in three dimensions I have to play with it like I'm playing with blocks or legos or something. The other day I was having a hard time visualizing how to even make a mock up. With this hole routed, I can see what I need to do. I'll post up my tests.

I hit a bit of a roadblock yesterday, the parts I'm using as tuners have a 3mm Phillips head screw on them, I need to swap those to hex head and I want to use a longer screw for more adjustment. I guess I only checked one hardware store (but they have a lot of variety) and I could only find 3mm screws with Phillips heads on them. I'll have to do a search, I'll probably end up order a hundred of them :-D The other alternative is to drill out the holes and go to 6-32 screws. I have to check if there's room to do that.
(edit - I found 100 M3x16mm stainless screws on Amazon for $10 - done).
 
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#58
I think I got this tuner thing worked out. I will need to make a route in the top to get them to fit at the correct angle, not a big deal - more router work! My original block was the wrong angle. I started over again with paper, then made a test piece out of pine. I'm not sure why I didn't think of that sooner, pine is pretty easy to work with.

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I need to get going on some other stuff (and maybe a bike ride). I'll tackle this tomorrow.
 
#59
I routed the underside of the top so the tuners will fit in there, I just realized I could have cut the end of the tuner L bracket off too - that screw hole on the end can't be used anyway. Oh well, that's plan B if I need more room. I guess this looks a lot like the other picture I posted above. More wasted electrons.
20160416_171527_zpsyv4ehje4.jpg
 
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#60
Jisch said:
I routed the underside of the top so the tuners will fit in there, I just realized I could have cut the end of the tuner L bracket off too - that screw hole on the end can't be used anyway. Oh well, that's plan B if I need more room. I guess this looks a lot like the other picture I posted above. More wasted electrons...
Click to expand...

Have no fear, in physics, nothing can be created or destroyed. Everything is recycled. Nothing goes to waste.

Unless they've changed that since I last took a physics class 40 years ago.

:meh:
 
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