The Mermaid Bass: First Progress Report

Maybe a year ago I conceived an idea for a 5-string P-bass with a 36” scale and an unconventional body design. I have finally managed to get some work done on earnest, and here is the first picture. (Specifically cleared with the mods for TB-appropriateness). Some discussion of techniques and questions to follow, along with periodic updates.

 

The body started as 1 1/4” x 16” x 24” maple that was leftover from a countertop, so professionally glued up and sanded. It cost $10

The top is laser cut veneers. The pink is holly, dyed with alcohol dye (1/8 drop pink in 1 bottle of white). The rest was figured maple. The hair was done with a mix of orange and black dye, diluted. The tail was diluted black. I was really hoping for the sort of transparent black you see on fancy guitar, but dying and sanding gave a stark grain contrast, and trying to re-dye with even more dilute black to get a black/grey effect failed. At that point I was like “This is 1/42” thick; I have to stop sanding.”

Do first question: how do I get that transparent black flame maple look?

 

Finish at the moment is multiple coats of Minwax Polycrylic, which was the winner of my clearness tests. I brushed, but for the final finish after painting I will find a way to spray and buff to a mirror polish.

 

Veneer technique was tricky, so here is what I did after multiple failures on this and other projects:

After making the drawings, I had the local print shop make a full-size mirror-image. I always put a square of known size on the drawing and instruct them to make the square exactly that size. Then I take a high-quality ruler or calipers to the shop and make sure it is exactly right. 1/16” off on a 2” square is 3/4” off on a 24” drawing!

Then when the pieces are cut, I tape the mirror image drawing to a large board or plywood sheet. I tape clear Cricut transfer tape sticky-side up over that. (There are two kinds of transfer paper from Cricut: regular and extra-sticky. Regular is too weak butsort of works, extra sticky holds great but will damage finishes unless they are well-cured.)

Then I place the pieces of the image down over the mirror-image printout and fit them together. In my experience the will not fit perfectly and some compromise is inevitable (this will be addressed at the routing stage).

Finally, I prepare a substrate by ironing fusible web (from a fabric store) onto it, and then ironing the substrate onto the back of the veneer. I have been using 92 lb watercolor paper as a substrate, but I would imagine a light fabric might also work.

That gives me a veneer image that can be later attached to a body.

 

Details on attaching the veneer to the body and getting the shape right tomorrow.

 

This is what I wanted:

 

Ok, how to attach the veneer to the body? There is a challenge here: the arm cutout needs to be made before you do, but on the other hand, I mentioned that when fitting the pieces of veneer together, they don’t fit perfectly and compromises are made. That means that if you cut the body out before attachment, the fit will be off in places.

I laser-cut a 1/4” plywood router template for the body, and then put an oversized bearing on a 1/2” top-bearing flush-cut Router Bit. This resulted in a body a bit oversize. Then I cut the neck pocket (with plywood template made with CNC) and pickup routs. This is the result:


This allows the veneer to be attached with a margin of varying width that can be trimmed (more later).

It happens I got some tear out than meant I had to use a little bondo before gluing. I like it better than wood filler for the edge because it’s stronger and can be routed successfully.

 

How to attach paper-backed veneer image to the body? I have been working with Titebond Cold Press veneer glue. The main advantage is low fumes and water cleanup. The major disadvantages are warpage (water based) and the need for high clamping pressure. The bottle says 100-250 PSI, or 7-18 TONS for 1 sq ft. That is preposterous, but I can say from experience that only 1-2 PSI will result in warpage and voids. For this project, reasonable amounts of exercise weights can’t assure a good bond.

There is the additional problem of matching the body contour, which would require a special caul.

Vacuum systems can get you 14 PSI. You can buy one for $1,400, or if you have a vacuum pump already, you can buy bags for $100. (You can also make them for less). I went cheaper and bought some Ziploc sweater-storage bags. No doubt a real vacuum system would work better, but this did the job with just 2 spots where the edge lifted a bit and needed remedial glue.

 

Tk help with alignment during gluing, I made some blocks out of HDPE that fit in the pickup rout and neck pocket. They have a sloped edge that leads the plastic bag down gently and presses the edge of the veneer down.

I’m on the road at the moment, which is why my posts are sporadic and weirdly autocorrected, but I will post pictures when I get back. They held the alignment perfectly.

 

To get the oversized body matching the veneer perfectly, given that the veneer doesn’t match the plywood outline template perfectly, I use the top-bearing flush-trim router bit in sections.

I line up the template with a section of the veneer and clamp it down. Then I mark the start and finish points, where the fit becomes bad enough that i want to move the template before cutting further. Then I rout just that section.

For the area between the neck and the tail, after clamping the outline template down, I inserted scrap into the neck pocket to prop the neck drilling template up to level. Then I went in and made the cut. The neck drilling template fit tightly enough that I got away without clamping, just using the force of the router base to hold it down.

Then I flipped it over and used a bottom-bearing flush trim bit to complete the body.

The area near the arm cutout is not flush yet, but I have a plan. I will let you know if it works next week.

 

Looking to the future, the next project is to finish trimming the outline and make the cutouts look clean with some hand work. The round thing in her right hand (giant pearl? The sun?) will be done in abalone and gold MOP.

I have a nice flamed maple board for the neck and a StewMac ebony fingerboard blank. This will be fretless but I’ll add some interesting position markers with shell inlay. There are a few details to finish on the image.

The plan is headless, probably with homemade tuners with ebony/abalone knobs. Similar knobs in the usual p-bass spots for V/T. The pickup rout is sized for Bartolini and there is a cutout from the veneer to go over them.

One thing I am still debating is the paint for the back. The maple is uninteresting, so I’m going back and forth between basic black, like my Fenders, and something fancy and mermaid-y, like seafoam sparkle or shell-pink pearl. Opinions welcome.

 

As promised, here are pics showing the HDPE alignment jigs that I used to make sure the image was properly aligned and stayed that way while the glue set. Later this week I hope to finish up trimming the body and let you know if my trimming idea worked

 

UPDATE: I finally got time to trim the arm cutout area. My method was to make small scroll-saw cuts to project the outline if the top onto the bottom:
Then I tried to align the router template with the cuts:

That didn’t work all that well. But with a bit of belt-sander work everything came out nice:

Then I went to touch up a raged hole left by a dull cutter, and screwed up, leaving the hole still ragged and some ugly rub marks from the router collet.

I half-repaired the damage, but the reality is that a full repair would be a huge amount of work with no guarantee of success.

Next step will be to cut some abalone and MOP for the ball she’s holding, make a neck, and fit electronics.

 

It only took 8 months, but there’s a neck blank now!

 

Hey, don’t smirk at me! I also cut holes for the jack and pots and drilled the connection between the pickup cavity and everything else!

 

And now the neck blank has carbon fiber, a truss rod, and an ebony board glued, radiused, and leveled.


There are inlays to make and install next.

 

Oh, and the back will be seafoam pearl.

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