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Project Silhouette

Smilodon

Smilodon

Feb 18, 2012
1,268
542
Norway
#1
Hello all! :)

I figured it was time to start this log now since I have started working on my next bass project. The planning started a few months ago but I haven't done much until now.

First of all, some specs:

- 34" scale
- 5 Strings
- Neckthrough
- Walnut and maple body and neck
- Ebony fretboard
- 2X EMG 40TW @18V
- EMG BTS
- Headless (But with a headstock...)
- Custom hardware


Here is the basic layout:
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I still haven't figured out where to put the volume and tone knobs yet. The original idea was to partially incorporate the knobs into the bridge, but the bridge ended up looking massive so that idea was ditched.

The design isn't finished, but the design will be pretty much along these lines. (Headstock and cutouts will be altered)

Drawing of the bridge:
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The two small holes between the knobs is to release the bridge lid. An allen key can be pushed into the hole to pop of the lid.
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Layout of the bridge:

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The frame will be made from aluminum and the mechanical parts will be brass and steel. The bridge will be more or less enclosed. The "lid" that will cover the saddles will be aluminum but with a top layer of wood in the same pattern as the neck piece. The lid itself will be held in place by magnets.

Here is the parts made so far:
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Saddles, string anchors and the basic tuning knobs. I'll make some flutes into the knobs for decoration and grip.


This is how everything will be placed. I just need to mill out the bridge frame:
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Saddle pieces:
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The saddles will be held in place by two prongs that will push out from both sides when a needle screw is screwed in from the front of the saddle. (left shows prongs extended)


I had to stop work for today because I managed to break my 3mm mill bit in a stupid mistake. (I started the mill with the bit touching the workpiece. :o ) New bits were already on order, so it's not too big of a deal.

I have never used a mill before, so there are quite a few things to learn. I usually learn things the hard way... :help: I thought the bits I were using were worn out. Turns out that the problem was ever so slight play in the Z axis of the mill which caused chattering. Tightened it up a bit and everything was fine again. :)


Hope you'll all enjoy this thread. Tips, trucks, criticism and suggestions are welcome. I'll probably need it as the build progresses. :hiding:
 
#6
Looks cool.

Nice work on the bridge. And I'm interested to see how your cover and its removal will work. You've never used a mill before? the result looks good! And congratulations if you didn't snap a bit from doing those deep but narrow cuts with too fast a feed. (People who know what I'm talking about definitely know that "Ping!")

The open design of the body and headstock are nice. But I'm worried about the strength of the headstock. Not simply because it is and open design though -- the sharp points of the opening, the ones pointing back towards the body, present a strong stress riser. If that were to receive a blow on the headstock, it is very likely to split by forming two cracks from those hollow internal points back towards the body, through the walnut, just outside the outer maple stripes. It would amount to putting torsional stress on side grain, which is weak in that way. Along with the stress riser factor.
 
#7
Thanks for the feedback, guys! :)

pilotjones said:
Looks cool.

Nice work on the bridge. And I'm interested to see how your cover and its removal will work. You've never used a mill before? the result looks good! And congratulations if you didn't snap a bit from doing those deep but narrow cuts with too fast a feed. (People who know what I'm talking about definitely know that "Ping!")
Click to expand...

Yeah, those deep passes were a bit of a challenge, but not too much of a problem. Patience solves lots of problems. ;) What worries me thought is the cuts into the aluminum block which are going to be even deeper. (but not as narrow, so it should be ok.)

If you look closely on the "posts" on the saddles you can see the "wave" pattern from the bit chattering. I just wish I had discovered that loose Z-axis sooner...

pilotjones said:
The open design of the body and headstock are nice. But I'm worried about the strength of the headstock. Not simply because it is and open design though -- the sharp points of the opening, the ones pointing back towards the body, present a strong stress riser. If that were to receive a blow on the headstock, it is very likely to split by forming two cracks from those hollow internal points back towards the body, through the walnut, just outside the outer maple stripes. It would amount to putting torsional stress on side grain, which is weak in that way. Along with the stress riser factor.
Click to expand...

Yeah, that's what worries me as well. There won't be any stress from the strings, as they will be attached to a block on the "striped" part. (I see now that I forgot do draw that in). The walnut part of the headstock will be two layers of walnut and a center layer of maple.

I will cross laminate the maple to add some strength. My idea was to make a 45 degree lamination of maple that is bookmatched to get the grain looking good from the side. The maple piece will also be the tenon of a mortise and tenon joint. (If that makes sense...) If I can get the materials the same method will be used on the body wings as well. (That's actually my biggest problem at the moment; Sourcing the wood...)
 
#8
Got The frame for the bridge done this weekend.

The entire thing assembled. (But without the top lid):
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This is how the insides look from the bottom.
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The tuning mechanism is tightened all the way to hold the knobs in place. It turns out that the locking mechanism for the saddles work great as well. *Phew* :)

With the base plate fitted:
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Originally the bridge were to be screwed with machine screws from the rear of the body, but I'm considering redoing this and to simply use 3 or 5 wood screws through the base plate. It seems to be stiff enough. (It's only 2mm thick, though...)

Closeup of the edge of the baseplate:
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This was done to add stiffness for the outer bridge "chanels" as there will be no screws to attach the base plate to the bridge frame. As you can see there is a slight height difference between the base plate and the frame. I'll have to sort that out later. I have to either sand it down (Lots of work, and it may not be completely flat afterwards) or i could mill it down. The aluminum in the base plate do NOT like to be milled, though. It's sort of gummy. I may have to work out a system to lubricate the milling bit. (All work have been milled dry so far)


I also redesigned the tuning mechanism slightly:
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I feared that the screw would eat through the aluminium after some use. There was also too much play using just the screw by it self. Using ball bearings will look better as well. (About 0,5mm of the bearing will be visible and look like the shaft)

The new design utilize a ball bearing that the tuning knob "rest" on which give a much larger surface for the knob to rest on. I was hoping to press fit the bearings, but milling round holes precisely is very difficult. The holes the bearings rest in now are about 0.2mm to large. Some epoxy will fix that, though. :)

Half of the bearing is recessed into the bridge frame. I'll make a small recess in the "bottom" of the knob that the other half will rest into. In the end there will be a 0.5mm clearance between the knob and the bridge, and only the edge of the ball bearing will be visible.



So to the bad news:

I just discovered that I need to remove the saddles to be able to change the thickest strings. I'll do some experimenting, but now it looks like I have to redesign the lid to extend all the way to the front of the bridge. :hmm:
 
#14
Thanks. :)


Got a bit more done today.

Baseplate done:
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In the end I decided to go for wood screws (The middle row of holes). I just hope the aluminium is strong enough. If it turns out that id doesn't hold It's easy enough to simply make a new baseplate. The countersunk holes is for the screws holding the plate to the frame.

The square holes is to push the ball end of the string into when changing strings. The routine will be to first tread the string through the front of the bridge. Tighten the tuner all the way, push the ball into the hole and hold it while the tuner is loosened. When the string is released it will pop back into the recess of the tuner.

Bridge lid:
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I know it looks very rough after the milling. It's actually very smooth. The two smaller grooves is the "slopes" to help getting the lid open. The black dots are magnets glued into place.

I did have a bit problem gluing the magnets, though. The first time I wasn't able to push all of the magnets in place because the holes were a bit tight. (The glue sealed the holes, trapping air which pushed the magnets back out.)

When I finally managed to glue everything in place it turned out that I had glues all the magnets the wrong way around. :rollno:

I had to mill them out of the holes. Neodymium magnets generate lots of sparks when milled. :D

The magnets are oriented opposite on the left and right side. This is to make it impossible to attach the lid the wrong way around. (Which would render the opening mechanism useless.)

This is the holes to open the lid.
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Originally they were to be placed between the tuner knobs, but I figured it was much easier to place them on the string side.


Same holes from the inside:
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(Note to self: Remember to tighten up the milling table...)
The holes line up with the grooves in the lid. When a hex key is inserted into the hole the lid simply pop off.

The magnets you can see in this picture doesn't serve much purpose. I drilled them by mistake, but glued in a couple of magnets. I figured they could hold the hex key in place after the lid is opened. ;)


This is how it looks now after assembly.
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I'll post more tomorrow. :)
 
#15
Second round of update for the weekend.


First of all some "behind the scenes stuff. :)

This is my milling setup:
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The picture is from a earlier stage. The clamp you see there is made to be able to mill the ends of the bridge frame since there isn't enough travel on the Z axis to stand the block on end.

The small grooves milled out on the right of the clamping block is to hold the smaller pieces I made earlier. One groove to fit 1/2" square stock and one groove to hold round stock.


Problemsolving..:
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When I milled the lid the aluminium sheet bent ever so slightly. (apparently hard aluminium have some degree of inherent tension). This is the setup I used to get the piece flat again. I knew I kept those pencils for a reason. :smug:


OOPS!
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It doesn't show very well, but that is a broken drill bit. In a "moment of stupidity™" I was drilling some 2mm holes up to 2,5mm (I used a 2mm mill bit to place the holes and a 2,5mm drill bit to open up the holes for threading). For some reason I thought that a hand drill was a good idea. :rollno:


I tried grinding around the hole and use pliers to get the broken bit out, but that didn't work. Time for some extreme measures:
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A makeshift setup to bend the base plate from the frame. I then jammed some washers and hex keys between the base and frame to create enough space for the baseplate to clear the broken bit. I then used a hammer to knock the plate forward to get it out of the grooves along the side.

Incredibly this worked well and I managed to get out the broken bit.

Lucky:
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This time I was doing the same thing on the headpiece (brass). Luckily I had the drill bit a bit loose on the drill chuck. (Drill press this time). I have never seen a drill bit twist like that. Usually they just shatter.

Ok, time for some progress:
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Test run of the headpiece. It's just screwed down to a board. The bottom part will be below the surface on the final product.

I will be shaping the headpiece a bit more. I tried sanding drums in a drill press, but that was a bit too stiff to make a compound arch on the corners. I just couldn't find my soft sanding drum. I did find it when I putting back the tools for the day. :rolleyes: I'll finish it up next weekend I think.

Bottom view of the headpiece:
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6mm grub screws to hold the strings and two 4mm screws to hold the headpiece to the headstock. There will also be a cover plate on the back of the headstock. (I haven't made that one yet)

Milling curves is pretty damn difficult. I'll fine tune them a bit more than they are at the moment.

Plank bass! :smug:
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I just had to give it a test run to see if everything works. Turns out it does. :) I didn't tighten all the strings to full tension simultaneously, though. The board started bending a bit more than I was comfortable with. It had a pretty cool sound, but was a bit difficult to play with 15-20mm action. ;)


This is how the bridge looks with strings:
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I underestimated how little travel was needed to bring the B string up to pitch, though. Everything seems to be working perfectly. :)
 

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