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5-String Carl Thompson inspired bass


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Not a massive amount to post from the sum of this week's efforts. I have a Seymour Duncan SMB-5A on order, plus the stainless steel fretwire arrived from Peter Schneyder's wonderful store in Germany. I decided to sack off the self-binding on the basis that I adjusted the radius from 16" to 12". This is quite tight from a 5-string bass however I'd like to see how a rounder board turns out. The neck profile was shaped in using a combination of the oscillating belt sander, spindle sander, rasp, spokeshave, cabinet scraper and random orbital sander. The fingerboard has been sanded up to 400 grit which might seem quite low on the face of it, however Wenge is so coarse that anything above 400-600 shows very little return. Instead of buffed the hell out of the board with Scotchbrite. Once the frets have been dressed I intend on buffing the entire board up further.

The body has had the rear stringing holes drilled through the back of the fishtail to be mated up with the holes through from the top. I will be having a brass insert machined to fit into the fishtail, so I should really get around to routing that recess. I also decided to sack off the Neutrik locking jack in favour of a simple stereo barrel jack. The body at 30mm thick is not entirely safe to be boring a 24mm diameter jackhole in and this should have been done far earlier in the build, perhaps when the body was still a blank. These things happen.

The tuners have been drilled back out, the nut location cleaned up and other bits and pieces generally finessed. You can see my wonderfully simple Oak fret bender in the photos. Two small plastic castors, an M8 bolt, three washers and two Nyloc nuts. This will be made to be adjustable one day however for the moment it bends wire a little tighter than 12" which is what is important.


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neck12.jpg

Oh yes. Since I can't seem to kick the tutor into gear to get my radius sanding bars cut on the CNC I hand sanded the radius. After dialling in the radius across the entire board, I checked for straightness and adjusted the board using two pieces of jointed Birch with 80 and 120 grit paper glued on. There were a couple of high spots which would translate back through to the finished fretwork, and I much prefer to spend the time having a perfectly straight radiused board instead of dialling it back out through fret levelling.

I also slashed my finger open on the sharp ends of the fretwire. Bass 1 - Pro 0.

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Not much of an update, but checking in nonetheless. Most of this week has been tied up with stock preparation on other non-guitar related projects and desk work. Bleh.

I did however manage to finesse my 5mm plywood templates for the front control cavity. These were transferred them through to some thicker stock I pulled from the scrap for this purpose. The easiest way to do this was on the overhead pin router.

Similarly I thicknessed the width of a random stick of Pine to the same width as the pickup (which also arrived this week) cut it into two short and two long pieces, then screwed it together to make an outline for the pickup template, then transferred this through to stock on the pin router also. I love that machine. Coincidentally, the radius of the pickup corners is 0.25"/12.7mm and the pin on the overhead router is 12mm. If I am lucky I might be able to come across a 13mm bit on a 12mm shank for cutting the cavity....although it is a weird number....

Here's the body having the main cavity routed in. The template was stuck on the rear of the body with 3M "pressure-sensitive" double-sided tape and located using a line marked both front and back corresponding to the top line of the cavity. The majority of the wood was hogged using a 20mm drill bit in the press:
bodywork17.jpg

Once the bridge arrives I intend to write an entire article on it, including installation and "designing it in" to a plan. It goes without saying that a product review will be on the cards also since there is precious little information the Hipshot D bridge out there on the net right now.

The cavity cover might end up being made from an offcut of ebony Paperstone which will likely match the headstock far better than plastic.

Next jobs are to cut the 2.0mm recess for the cavity cover and an angled recess for the pickup that allows it to sit at the correct height from the strings whilst screwing it securely to the body.

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Some good progress and news to report today! The bridge arrived from Hipshot, which can be a tense moment mid-build. Having designed this instrument out from the CAD design including specifications from both Seymour Duncan and Hipshot, having the physical items there to confirm measurements feels totally different to working them from a "theoretical" standpoint. Thankfully everything is on the nose as it should be. The only discrepancy perhaps might be the intonation range of the bridge as this was not provided in the Hipshot specs. I'll document and review this bridge thoroughly in a dedicated article! It truly is a beautiful piece of hardware which I can't wait to have fitted on this bass.

Firstly, I checked the pickup template I made yesterday from spec for fit. A little lengthening of the cutout was necessary, however this wasn't a difficult job. Since the neck requires a 1.5° angle, the pickup requires this also. I worked out with a little trig the amount I would need to raise one end compared to the other, ran a cutoff through the thickness sander and screwed it to the other end of the pickup template. Instant 1.5° template angle. This was attached to the rear of the body with double-sided tape again, aligning the template with the centreline back and front.

bodywork18.jpg


Pickup cavity, first routing pass. Everything was done in clockwise circles to ensure I was cutting against the direction of cut. Easily confused, this. Additionally, I cut less than half the cutter's diameter to prevent the bit deciding to climb cut.

bodywork19.jpg


Pickup test fit. The recess was made to within half a mm of what I planned out. The side of the pickup casing was notched on the underside to allow the pickup wire to leave the cavity without hanging up on the underside of the pickup casing. Firstly, I marked the pickup screwhole location (made this mistake before) and marked up where the wire needed to run to the cavity and when the casing would need notching. Using an incannel gouge a lightly angled recess was cut to the edge of the cavity in line with the wire run, and the hole drilled through using a small hand drill. The pickup casing was notched with a craft knife. The pickup now sits flush to the bottom of the cavity. Very very tight to the body!

bodywork20.jpg


The state of play as of lunchtime today. By this point I had dropped in an additional recess to the electronics cavity of 2mm to accommodate the cover, which itself was thicknessed to 3.0mm. A light bevel was added to the cover so everything is now "tight tight tight!", to quote Jesse Tuco Salamanca. I feel that the jack socket run is a little long for your average barrel jack so I'll be adding a recess here. That should also help to reduce the whacking huge surface area left unused after my decision to change from the locking Neutrik jack to the standard barrel jack.

bodywork21.jpg


Next week the bridge will be located, the neck glued in and final shaping of the heel transition completed. I would guess that this will be finished before the end of next week. It might not be oiled up, however I would like to think I can bring her home for the autumn break. Everything is working out perfectly so far.

Edited by Prostheta
- Breaking Bad trivia reference
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Okay, so lets jump forward in time somewhat. The neck pocket was routed and the neck fitted using a similar method to the "Myka jig" which I should really build rather than tossing together a routing template from scrap birch. Still, it works which is the important thing. Spent far too long finessing the neck transition and blending into the bevels. Currently halfway through sanding at 240 grit on the body, however I still need to work on the neck profile and headstock before bringing them up through the grits. My Tru-Oil hasn't arrived yet so I hope I haven't hit a crappy eBay seller on that one.

Don't suppose anybody knows of a reasonable source of Tru-Oil in Finland?

bodywork22.jpg

bodywork23.jpg

I should be working up to about 800 grit depending on my patience; normally my weak point in any project. The finishing post is pretty much in sight....

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Very nice, looking forward to the next update!

BTW, regarding the Tru-oil, I have the same problem in my part of the world, so I decided to try to mix my own. I found some recipes on the net, and used my father-in-law's vast knowledge of finishing, since that's his trade. It's 1:1:1 lineseed oil, turpentine and varnish, but he suggested to use a bit more turpentine, 1:1.3:1, but I have yet to try it. Anyway, the materials for a large batch shouldn't cost me more than 10 eur, so it might be worth looking into. After that I'll apply beeswax paste, also homemade. Should be interesting.

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Thanks - I have some Tru-Oil on the way and have sources in Finland now. I might try rolling my own when I have the luxury of being able to experiment with recipes, however for this build I would rather stick to things tried and tested within my experience. Still, sounds like a fun idea....perhaps I might do this on the guitar stand I really really need to be building....!

In other news, the bass was brought home for autumn break. A nut has been cut plus the bass was strung up with an old set to check geometry, etc. The neck pocket could have done with being a couple of mm deeper yet. I didn't have a long enough template cutter available this week and I made a personal promise to myself to have the neck fitted so I could move on with the proper build when I return to study. This has meant that the pickup sits too low when rammed to the body as originally intended so the rubber strips have been fitted underneath. No big deal. The bridge also needed raising a couple of mm or so rather than it being rammed against the body also. Again, no big deal since the original plan was designed to put these items at their minimum fitment heights to get the maximum use of their adjustment ranges.

The bass plays very well despite not having been given any kind of proper setup or fret levelling as of yet. Just basic intonation and string height. The pickup is wired directly to the recessed barrel jack so will sound far better when not loaded in this manner. Pre-amp PCBs are not here yet, but no problem. Forgot to bring the cavity cover and truss rod cover home so I am unable to install them right now, but since the Tru-Oil isn't here either the bass will be on hold for a while.

I learnt exactly what I wanted to learn from this prototype which I will take forward onto the proper "Night Rainbow". That is, that the super-thin 30mm body could be taken down up to another 5mm or so however it would leave major issues with locating a jack socket (perhaps not a barrel jack), batteries, etc. The neck joint could easily work with a 25mm thick body. On that basis I will keep the 30mm thickness for the final build. Very pleased with that bit.

The location of the bridge and recessed tailpiece work very well feels good to me and my playing style. There is plenty of room to dig in if I want, plus the pickup works nicely as an anchoring point. I'd like to experiment with using a ramp between the neck and the pickup on the NR build, whether it be secured using recessed Nd mags or whatever.

Not 100% sure about the stainless steel fretwire. The bass in its unfinished state plays with some strange overtones through the pickup, so whether that is anything to do with the pickup, fretwire or whatever I am not sure. I'll fault find this out when the pre-amp is here and I do the full fret dress and setup. Taming the treble will easily smooth this out. SS is a PITA on many levels despite being better than nickel-silver stuff so I will likely stick to EVO and equivalents. From hereonin if it indeed causes these strange sound overtones. The usual "tonewood" non-discussion can be blown straight out of the water too; despite this bass having been built with "warm" woods the sound is still bright acoustically and amped up. The propagation of sound is slow however, which is in line with Mahogany-like woods such as Sapele and is pretty much what I expected.

I pulled a couple of really nice flamed Birch boards out yesterday which I think will work really nicely when hollowed. The original idea of a straight gloss black finish on the NR is likely to be changed to trans black or some finish that will leave the back and neck black with the front inky black with the movement of the flaming still visible. The formation of the figuring is quite wild and "cloud-y" which suits my idea well. I wonder if there is such a thing as trans black paint that looks like petrol on water....? Allan?

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Thanks Luis. All it took was a set of blistered fingers from far too much sanding. It is somewhat difficult to feel the high/low points with sore fingers. :unsure:

Definitely worth the time and effort though, and realistically that's all it requires. There is certainly no "magic bullet" for dialling in bevels like these other than working with the grain, using small wooden blocks to prevent sanding in soft spots and checking a million times over. I can fully appreciate why Carl's instruments fetch high prices given the sheer amount of time poured just into this part of the work.

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Nver nice work!

I really like the neck joint carve and bevel around it. Looks very crisp.

I've been gone a couple of days and am just seeing this.....and I find a agree with K completely. I love smooth neck transitions. They look great and feel better. Very nice attention to detail Carl.

SR

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wow, this is turning out great! Can't wait to see it with the finish on.

Prostheta, so did you find a good source for TruOil in Europe? The homebrew option also sounds interesting, though somehow I thought TruOil is tung oil+varnish and linseed oil+varnish is Danish Oil. But maybe I got it backwards. What exaclty is "varnish" in that case?

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I did thanks. I have a bottle coming from the UK (I think, since it is very late) however it is available here in Pori but at €17 for 30ml....no idea what "varnish" means exactly but since I'm not going to experiment with homebrewing finishes it doesn't matter much to me whichever way. ;-) I was in one of the local art stores this week and was almost tempted to buy a pigment to tint the oil....nah....

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Hey man-I contacted Hipshot like you suggested and have a 6 string bridge in black being made. 19mm is as narrow as they can go- which I was hoping for a bit tighter as well- but we will see how it goes. I have a project idea I have been sitting on for some time now because of not finding a 6 string bass TOM type bridge- thanks again for the suggestion.

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  • 1 month later...

To bring this one back up to speed....after the coarse work had all been done (shaped, low grit sanding) I test fit all the hardware, had it strung up for a couple of weeks and tweaked the setup. It was then stripped back and has been in for finish sanding today with a bit of headstock shaping modification. The first flood coat of Tru-Oil went on today!

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