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More Fun with the Modelo Uno: Forward and Lateral Motion

By the way, it was cheapest to buy a 10’ length. VC Metals charges by the cut, so no cuts = less money. I cut my roughly 1/32” - 1/16” thick. That pretty much leaves me with lifetime supply of fret markers.

I use 3/8" round 6061 bar stock all the time here. I'll buy/trade the excess 9 feet from you.
 
The neck looks good. What about Osage Orange for the fretboard? From what I understand about it, should be plenty hard enough. It’s typically not as dark as Padauk but it is domestic and you can find some pieces with interesting colors.

I’ve heard that about Osage Orange, but from what I have gleaned from the internet and from samples they have my local Woodcraft, it’s starts at this super-awesome radioactive orange and eventually fades to a pretty plain-looking pale hardwood.

I’ve been curious about mesquite. Apparently it grows like a weed and it’s super hard wood. It looks like it has a nice color, but they don’t really seem to really harvest it commercially. Again, they sometimes have small pieces at Woodcraft. I dunno - if I ever go to Texas, maybe I’ll invest in a nice, clean slab, buy a band saw and cut it down into fretboards.
 
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Sure! I’ll bring some by. I think I have some other sizes of 6061 bar stock I can give you as well.

Also, I have my little Barker milling machine all set up specifically to make thin accurate slices of bar stock. Save your elbow from the hacksaw. I'll slice you a bunch of discs in exchange for the leftover bar stock.

(In case any of you are wondering, FreekMagnet Laboratories, Inc. is only a few blocks from the Secret Underground Lab.)
 
I’ve been thinking about fretboards the last day or two. I know I’ve posted this picture before, but I’m thinking I might look into trying out some Richlite sometime.

Richlite_Fretboard_Colours_1024x1024.jpg


Those multicolored textures are a bit much, but the red color is pretty swanky and the blue could look stunning on the right guitar. Interesting colors that are stable over time? Now we’re talking. I’d have to set up a fret slotting rig and radius them myself, but that ain’t too bad.

Now if only they came in white...
 
I carved the neck out.

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It went down pretty fast. I faceted it with the Shinto rasp and rounded it out with a half-round file last night.

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I thought I had a lot of work to do when I got home today, but I just had a couple of spots to flatten out. After doing that, I scraped the whole thing smooth with a round scraper card.

I wanted to do something a little different this time; on my last few neck carves, I’ve just done a straight C profile from top to bottom. These necks have always felt a little flat to me starting up around the 12th fret. This time I made the top part more of a semi-boat profile and kept the part down by the 1st fret pretty much the same:

img_6582.jpg


I think it worked - the bottom end feels firm and supportive and the top end (12th fret) feels really fast. It’ll be great for those double hammer-ons and lightning slap licks I never do. We’ll see how it feels once I get some strings on it.

When I brought my last build over to Bruce’s shop, he suggested making a larger volute:

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So there’s the larger volute. I think it looks pretty good.

And lastly, here’s the contoured neck heel:

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It looks OK. I gotta do some fine tuning in the both the neck and body. I think once it’s finished, it’ll look good. I had to fill in a bit on the corner of the neck with epoxy - I got a little carried away with the half-round. I’m not worried about it - I’m planning on staining the neck black with transparent dye anyway. I don’t think the filler will show. The heel/neck combo has a good feel, but I’m still lukewarm about how it looks. I’ll refrain from making a judgement until after I finish shaping and sanding them both. Again, the carved heel will really help for those blazing arpeggio runs I never do.

Some thoughts:

I think the neck profile was a huge success. My necks have been getting thinner and I think that is a good thing. This laminated neck will be nice and strong, but I may consider adding a carbon fiber stiffener on my next build.

I was having doubts after my struggle with the truss rod install, but with this new carve I think I might be getting to be a better luthier.

Next up, I just have to install the bridge plate. After that, I think I can get back to designing the pickup.
 
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A note about your neck shaping:

You showed how you are now shaping the neck so that it changes radius/contour down its length. That's an important feature that you will see (well, feel) on hand-shaped Boutique instruments, but not on mass-produced instruments. The feel of the neck is a big reason for spending the money for an expensive bass.

In a factory, they want to shape the back of the neck with a radiused router or shaper bit. That's the fastest way to do it. The classic Leo method; all Fenders are done that way. But it means that the radius has to stay constant down the length, even as the neck gets wider. You can't vary the radius down the length, using that manufacturing method.

A standard 3-axis CNC machine can cut a variable-radius neck, but it's very time-consuming. You have to use a ball-end cutter, and make a whole lot of narrow passes, close together. Then you have secondary finishing operations to clean up the ridges between the narrow passes. Most factory operations with CNC machines don't bother doing this, because it takes too long. Every second of CNC machine time is money. So, they use a radiused cutter, like the Leo method, but driving it around with the CNC. Doing that, they can't get the cool variable radius. But, it's a tradeoff to keep the cost down.

You can cut compound radius necks more efficiently in a CNC machine if you add a 4th Roll axis. That is, the neck can be rotated about its own center axis. But I haven't seen any instrument factories doing that, so far.

But, hand shaping necks like we do, it's easy to do compound complex radiuses. We can make necks that feel much better than factory necks. I shape my necks about the same way as Jeremy does above, with the facets. I've evolved my standard Scroll Bass neck shape over time, to what feels the best to me. It's a varying radius going around the neck, and it also varies going down the length of the neck. When I cut my facets, they change in width and twist, going down the neck. That's the beauty of hand shaping. I can make shapes like that.
 
Wow! Cool explanation there, Bruce!

But, hand shaping necks like we do, it's easy to do compound complex radiuses. We can make necks that feel much better than factory necks.

Yeah, that’s true - shaping the compound radius wasn’t any more difficult for me that shaping any other neck. I guess what it boils down to is 1) knowing how changes to the radius will feel to the player an 2) being able to make a repeatable shape. Since I’ve only done one compound radius neck, I don’t know if these points are applicable yet.

What’s interesting is that the neck feels both good and strange - as my hand goes up to the wider part of the neck, the neck feels smaller even though it’s not. I guess that will take getting used to - I’m used to just a regular old Fender neck shape. But when I think about it, it makes sense to have the wider part seem smaller because it’s easier for my hand to reach around the fingerboard.

I’m trying to make a neck I can play all night. We do 3-4 hour sets and my hands get tired by the end. I used to think I liked big thick necks because I liked the firm, solid feel. But, as the gigs keep getting longer, my hands have been happier playing a thinner neck.
 
Now that I’ve pretty much got the body and neck built out, I’m back to pickup making.

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My first wind was OK, but it was a little mid-heavy and the bass was really murky and dark. I was also getting what I believe were microphonic vibrations that I couldn’t pinpoint.

I took this new wind count down about 20% and while I was at it, I made the bobbins about 1/32” narrower. I also omitted the steel slugs I had placed in the bobbin cores. I figured that the slugs were overkill and if anything, they were likely to be the source of my microphonics.

The new wind sounds really good. I really like it. The bass, middle and treble are nicely balanced. It’s bright, but not too bright. The upper highs are nicely extended without sounding clangy.

I still don’t think it’s realistic to have bridge pickup serve as both a bridge and a rhythm pickup without the assistance of a preamp. There’s just not enough low-end happening down there. I do think that this one comes pretty close - it has plenty of output and almost enough lows, but not quite.

I’m going to sit on this one for a few days and maybe see if I can knock out a quick 2-band pre and see what happens.

The next step is two-fold. I have to make an attachment that allows my winder to wind these small coils more accurately. I also have to figure out how I’m going to build this monster.

The hard part is going to be wire joints. Maybe I’ll make half of the bobbin a cast piece with the wire terminals poking out. The other half will be thin cardboard. The wire terminals could then be joined to a little circuit board. Something like that. Then just dunk the whole thing in epoxy. I’ll have to think about it.
 
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I stopped by Bruce’s place on an unrelated errand last week. We got to talking about bobbins and threw some ideas around. As it so happened, we had some similar bobbin brainstorms. In the end, it's all boils down to execution.

Basically, the idea was to use one cast polyurethane side of the bobbin to house the wire terminals. The other half would be made of paper. Eventually, I’ll seal the wire side with another piece of paper before assembly. So with this concept, I made my first bobbin prototype:

img_6613.jpg


This piece is really small. It measures about .6875" tall and a little less than .875" wide. It's smaller than a nickel. It's .25" thick. The polyurethane base that holds the wires is .09" thick. I cut the grooves in the base with a small file.

Making the master was really easy. For the flatwork, I cut a shape out of .09" aluminum and drilled a 5/16" hole in the middle of it. For the central core, I stuck a 5/16" wide aluminum spacer I bought at the local hardware store. Since the bobbins are offset, I need a pair of mirror image bobbins. To make the second mold, I flipped the flatwork over and re-inserted the spacer. Here's a picture of one of my first attempts.

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This bobbin is a crucial step on a long and complicated road. Space is tight. There's a lot of parts to make and wire joints that could fail at any time during assembly of the pickup.

I'm really excited about this pickup design. I still have my last prototype installed in the test bass. I also built a little preamp based on the 3-band StingRay pre. I basically removed the middle band and changed the treble control to cut off at about 1000Hz - basically the treble cuts and boosts both the mids and the highs. Overall it sounds great. The pickup sounds as thick as a brick, but the narrow sidewinder coils really extend in to the upper range. I tweaked the input cap on the preamp to allow more of those highs in. I'm boosting the bass a little bit - if the center of the pot is zero, I have it at dialed in at about 1.5. The treble knob hovers at around .5 to 1. If this pickup were in the P-bass position, it probably wouldn't need a preamp at all. I think the only thing that matches my excitement is my desire to get it up and running.

I still haven't modified the winder. I'm waiting for some parts in the mail.
 
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I don't have too much to report this week. Basically, pickup making is all about making lots of small parts. So, I've been making lots of small parts.

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Clockwise from top left: A pile of cast polyurethane bobbin halves for the Funktronic Exotica pickup; six epoxy-encapsulated coils for the Funktronic Bass Sidewinder pickups; a pile of ears for the Funktronic Bass Sidewinder pickups; some 430 stainless steel blade poles for the Funktronic Bass Sidewinder pickups.

I set out earlier in the week to make parts for the new Exotic pickup and make 3 Bass Sidewinders that I'm hoping to unload. After starting by making molds for the Exotica bobbin halves, I cast a whole bunch of them over the last couple of days with the Smooth-On bright white polyurethane casting resin. I like the Smooth-On stuff - at least I like it more than I like the black ModelMaster stuff I've been using. I just get better castings out of it. In any case, the shelf life once it's opened is really short, so I'm trying to use up as much as I can. Bruce suggested using the aluminum base plate he made for me a while back as a master. Hopefully, I can get to making a mold from it later in the week and use even more of the Smooth-On before it starts going bad. I'll have to remove the pickup from the test bass, dis-assemble the pickup and cast the part. With any luck, the coils and wiring will be intact enough to re-assemble and re-install it into the bass.

Speaking of the Exotica, I've been playing it quite a bit in the test bass. The jury is still out as to weather or not it could work on it's own as a passive bridge pickup; I think it puts out a respectable amount of lows and mids for its size - it just doesn't quite have the volume to drive the amp. I'm pretty sure it would be great as a middle (P-bass) pickup, but for now, I'm going to keep this one in the bridge position and boost it a little bit with the on-board preamp.

I should have the Bass Sidewinders finished by next week. It's hard to say - I'm working on two different projects simultaneously during my off hours. I have the materials to make a 6-7 pickups, and I figure I should just build them up. Sanding the blades by hand is a PITA. I should probably sit down one of these days and figure out what kind of bench-top machinery I could use to polish them up more quickly.

I'm still waiting for some pickup winder parts to come in the mail. They should have been here a week ago. In the meantime, I'll keep casting parts.
 
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I got a little sidetracked with a few other projects over the last couple of weeks. I managed to assemble on of the new pickups using some of the newly designed parts.

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It looks a little more like something that will work. Despite its looks, assembly was not a complete success. The parts worked and putting the pieces together was definitely easier. I first had to add a 1/32” strip of aluminum to the cast polyurethane base to keep it from flexing. More shielding, I guess. Plus, my original plan was to solder the wire terminals to a circuit board. However, I miscalculated the width of the bobbin and the opposing terminals were basically touching. Just to get this prototype working, I insulated the wires with electrical tape. That worked, but there was still no way to solder them to a circuit board. On the next iteration, I’ll have to stagger the terminals somehow.

The next big fail came when I realized that I’d wired one of the coils backwards. Since they were glued together there was no easy way for me to determine which one was bad. I figure since I have to redo these anyway, I’ll just chalk this set off as a loss.

Just to see if some of the other changes worked, I replaced the new coils with my previous set. The pickup sounded good, and in fact I think it sounded a little better. I think having that solid aluminum baseplate directly in contact with the wood may have been contributing to the overall noise from handling the instrument. The polyurethane may be dampening it a little bit.

I also realized that the strength of the magnets were pulling on the low E string when I played further up the neck. I’m probably going to have to use smaller magnets. This may be a good thing, but I’m a little worried because I really liked the amount of nicely rounded lows I was getting out of the pickup. I’ll order some smaller ones and see what happens. In the meantime, I should think about designing a shell for the finished pickup.
 
I’m just doing my weekly update. I got some work done this week. I wound a new set of coils, tinkered around with the pole height, experimented with shielding my coils and built a rough little PCB. Here it is in the bass:

img_6693.jpg


I knocked out that PCB in about 40 minutes. I used a Sharpie as a mask - I’ve never done that before, and it seemed to work. This stage I’d consider “extreme” prototyping ‘cuz sometimes you just gotta go in there and get it done by any means necessary. In a perfect world, I’d be knocking the PCB out with a small consumer-grade benchtop CNC router. I really hate dealing with etchant solution.

I lowered the poles on the E and the G string. The “wolf tone” I was getting seems to have been mostly abated. But I’m not sure - I keep thinking I hear it a little bit. Part of it might be the really old strings or my imagination.

I might have shortened the poles too much. The A and D strings are noticeably louder. The G is too quiet. That’s an easy fix. I’ll make new E and G poles and pop them in there over the weekend.

Overall, I’m feeling really good about this pickup. It sounds great. I just have a few adjustments to make, and I’m done. With this particular pickup, I think I’m hearing the “neodymium sound” and it’s interesting. It’s got this largeness and an immediacy without being overly aggressive. I think I like it.

On a side note, we’ve been having some really hot, dry weather in SoCal. There’s been a lot of fires. Anyway I looked at my unfinished holly-bound bass body and noticed this:

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Another easy fix, boy am I glad this happened before I finished the bass!
 
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That is just the coolest looking little funktron... :thumbsup:

Yes, and one of the rules of pickup development is that if it looks amazing and cool, and sounds okay, then by definition it sounds amazing and cool.

Thanks, guys! I’m thinking about casting it in white polyurethane. That’ll be an interesting challenge. Then I think I’ll put a nickel silver cap over the face. Part of me wants to cover the sides as well - the poles are mild steel and they’ll rust if they’re exposed. But then, the face is curved, so making a curved joint where the side shield and the cap meet might be more work than really I want to do. The other thing is I’ve had those thin pieces of sheet metal pull right off of some of the epoxy parts I’ve made before.
 
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Weekly update:

I’ve been plugging along with my “completed” prototype. I built up a whole pickup, cast it in white resin and glued a nickel-silver cap on to the face of it. Here’s the rough:


9E853750-88E5-49B2-A4C7-421853CB305A-1024x1024.jpg


The encapsulation itself went OK - everything seems to have survived. The white resin was problematic at best. I had a lot of pitting which sucked. Also, you could pretty much see the poles and the magnets through the resin. I’m probably going to have to paint it, which I’m not too excited about.

The next thing is the nickel-silver cap - I glued it on there with CA glue and it definitely did not hold. I’ve used epoxy before, and that didn’t hold either. I’m going to try Gorilla Glue tomorrow and see how that goes.

So, once I get the cap glued on and sanded down, I’ll fill the pits with CA glue and finish the resin parts with WB Polyurethane mixed with white. Hopefully that’ll hold up with regular playing.

I don’t think I’ll be doing a white encapsulation again. If I want to do a white pickup I’m going to have to use another approach.
 
Weekly update:

I’ve been plugging along with my “completed” prototype. I built up a whole pickup, cast it in white resin and glued a nickel-silver cap on to the face of it. Here’s the rough:


9E853750-88E5-49B2-A4C7-421853CB305A-1024x1024.jpg


The encapsulation itself went OK - everything seems to have survived. The white resin was problematic at best. I had a lot of pitting which sucked. Also, you could pretty much see the poles and the magnets through the resin. I’m probably going to have to paint it, which I’m not too excited about.

The next thing is the nickel-silver cap - I glued it on there with CA glue and it definitely did not hold. I’ve used epoxy before, and that didn’t hold either. I’m going to try Gorilla Glue tomorrow and see how that goes.

So, once I get the cap glued on and sanded down, I’ll fill the pits with CA glue and finish the resin parts with WB Polyurethane mixed with white. Hopefully that’ll hold up with regular playing.

I don’t think I’ll be doing a white encapsulation again. If I want to do a white pickup I’m going to have to use another approach.
 

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