More Fun with the Modelo Uno: Forward and Lateral Motion

Discussion in 'Tele Home Depot' started by Freekmagnet, Jul 9, 2019.

  1. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    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]

    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 miniature 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:

    [​IMG]

    Another easy fix, boy am I glad this happened before I finished the bass!
     
    Last edited: Oct 26, 2019
  2. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    I'm going to be gearing up this week for a "completed" prototype...

    [​IMG]
     
  3. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    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:


    [​IMG]

    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.
     
  4. Jim_in_PA

    Jim_in_PA Tele-Holic Silver Supporter

    Posts:
    778
    Joined:
    May 31, 2019
    Location:
    SE PA near New Hope PA
    Make sure that the back/bottom side metal is thoroughly (and chemically) clean and has some "tooth" to it for the adhesive to grab onto.
     
    Freekmagnet likes this.
  5. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA

    I wiped the metal down with acetone and sanded it with 80 grit paper first. I’m really not sure why it’s not sticking.
     
  6. matmosphere

    matmosphere Tele-Holic

    Posts:
    666
    Joined:
    May 27, 2015
    Location:
    earth
    The adhesion might not be working with the resin. Problematic at best is not reassuring. I’m sure you’ll work it out though.
     
  7. Jim_in_PA

    Jim_in_PA Tele-Holic Silver Supporter

    Posts:
    778
    Joined:
    May 31, 2019
    Location:
    SE PA near New Hope PA
    That's a good point...the particular type of resin might have something in it that's not happy with adhesives, perhaps something that helps it release from a mold or something...
     
  8. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Maybe, but the glue remained on the resin piece, not the metal.

    I’ll figure it out. My retired aerospace engineer friend suggested spray painting the coil assembly white before casting it. I had to laugh because that is a pretty obvious fix.
     
    Arch Stanton likes this.
  9. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Just for the heck of it, I dropped that pickup I made into the test bass.

    [​IMG]

    The good news is that it works and sounds great. I now know that I can build, assemble and encapsulate this pickup and I don’t have to worry too much about it.

    The bad news is that I decided that while I could make this shell design work, I’m going to do another one. So, I gotta go back to the drawing board. Last night, I stayed up late carving a new shape.

    [​IMG]

    [​IMG]

    The old shape is on the top/background and the new shape is on the bottom/foreground. The idea is that I can more easily put a cap on top or shielding on the sides and then just grind it smooth on the ROSS. I made the little ends flare up to give some extra thumb planting space. We’ll see how it goes - I liked the retro dog-ear style of the old shape, but when my casting went south, I realized that because of the square edge, there wasn’t too much I could do about it.

    The new shape is growing on me. I think it’ll work with the “vintage modern” vibe I’m striving for with this new bass.
     
    Last edited: Nov 17, 2019
    Arch Stanton and Zepfan like this.
  10. guitarbuilder

    guitarbuilder Telefied Ad Free Member

    Posts:
    20,934
    Joined:
    Mar 30, 2003
    Location:
    Ontario County

    Very cool. One issue that epoxy potted pickups have that I've noticed is that the thin hookup wire can break off outside the pickup. I have noticed this on some Gibson ones I've owned. Just something to consider in your development. Trying to dig wire out to resolde to is a pain and difficult in a few cases.
     
    crazydave911 and Freekmagnet like this.
  11. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Thanks for the heads up.

    I usually make little terminals out of 22awg solid copper wire that stick out of the bottom of the pickup. I solder the stranded control wires to the terminals.

    I suppose the terminals themselves could break off, but they’re li’l stubs that stick out. I figure once I have the pickup in the guitar, they’ll be safe - until they’re not...
     
  12. guitarbuilder

    guitarbuilder Telefied Ad Free Member

    Posts:
    20,934
    Joined:
    Mar 30, 2003
    Location:
    Ontario County
  13. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Gotcha - I don’t do it like that. That’s asking for trouble right there. I do it like this - here’s an image of another pickup, but I use the same principle.

    [​IMG]

    Once I solder the output wires, I trim the terminals down leaving a short nub of wire going into the pickup.

    In the example you showed, the stress point will be where the wire enters the epoxy. Those long wires are going to twist and bend and eventually break. With the method I’m using, the idea is that the stress point - the point where the weaker, stranded output wire is soldered to the terminal - is outside of the epoxy. It is still entirely possible for them break, but it seems like it would take a little more effort.
     
  14. guitarbuilder

    guitarbuilder Telefied Ad Free Member

    Posts:
    20,934
    Joined:
    Mar 30, 2003
    Location:
    Ontario County
    That looks like it is made for crimp on terminals.....
     
    crazydave911 and Freekmagnet like this.
  15. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    They are! They’re header pins, although I solder the wire to them. I used them ‘cuz they’re cheap and I don’t have to make the part myself.

    I’m striving to eventually use solderless connectors, but I haven’t come up with a good solution yet. Maybe once I get past the initial prototyping stage, I’ll take some time to make a PCB base plate and have the right angle terminals coming out of the bottom. For now, I’m just trying to get this boat on the water.

    I’m looking at some of those small consumer-grade bench-top CNC machines. Among other things, I’d like to make circuit boards and small parts with it. It depends on how deep I end up going with this pickup-making obsession. Even a small CNC machine is expensive tool that would require an additional commitment of space and time. One thing for sure is, I would not miss dealing with those etching chemicals.
     
    Last edited: Nov 17, 2019
    matmosphere and guitarbuilder like this.
  16. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    The was not my original plan...

    [​IMG]
    [​IMG]

    I wanted to just cast the coil assembly in a block of white polyurethane and glue a nice, nickel silver cap on it and call it a day. But no, that didn’t happen.

    I initially tried the method that @dwizum suggested, and that helped with the pitting somewhat. I got better results this time, but I think the resin cured too fast, and whatever bubbles were in there formed and just weren’t going to float up to the top because the resin was already beginning to harden.

    The next obstacle was that whatever tooling had to be done, would leave its mark in the white plastic. In conclusion, I’m not sure if casting the whole pickup in white is the best approach. Perhaps it would be better to use a 3D printed white shell and pour the resin into that.

    So, I bound and capped it in nickel silver. I had better luck with the softer adhesives like E6000 or Gorilla Glue. For some reason, CA or epoxy wouldn’t hold the metal down. I’ve never had that problem - usually epoxy will do it.

    After gluing, I soldered the cap to the binding with my soldering iron. In another life, I used to solder little structures like this all day long. Back then, I used a propane or oxy-acetylene torch. This was the first time I’ve done it with a soldering iron. It wasn’t too bad. The nickel-silver is really forgiving; I had a sand-through that I patched with a blob of solder (it’s really thin metal). Once you sand it, the patch is barely perceptible. At the very least, my cap and binding job will provide some shielding.

    The wood skirt is cosmetic. The white polyurethane was stained and it just looked terrible. I know that part won’t be visible but it would of driven me crazy looking at the picture.

    For now, I’m going to leave it sanded to 600. I may change my mind later.

    Ultimately, I will not be taking this approach with this pickup again. I just did this because I was out of magnets, and I had these materials on hand. I want to get this pickup into a bass and start testing it in the field. I’m going to have to come up with another way to attack this. I’m not ruling out the possibility that I will have to come up with a way to make the poles adjustable. I’m not sure how I’ll do that because much of the assembly process up until this point has been an effort to keep the pickup itself from imploding. (It actually does implode.)

    I really do want to make a white pickup.
     
    Last edited: Nov 23, 2019
  17. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Well, I decided to polish it.

    [​IMG]

    I have a few scratches I gotta go back and hit with 220, but there ain’t nuthin’ like the look of polished nickel. I’ll prolly do it before I install it in the bass - it’ll get scratched just laying around my shop.
     
  18. guitarbuilder

    guitarbuilder Telefied Ad Free Member

    Posts:
    20,934
    Joined:
    Mar 30, 2003
    Location:
    Ontario County

    You are KILLING me with this cover!!!!
     
    crazydave911 and Freekmagnet like this.
  19. Engraver-60

    Engraver-60 Friend of Leo's

    Age:
    67
    Posts:
    3,689
    Joined:
    Jan 6, 2008
    Location:
    Brentwood, TN
    This is awesome looking. I hope it sounds good too.
     
    crazydave911 and Freekmagnet like this.
  20. Freekmagnet

    Freekmagnet Tele-Meister

    Posts:
    393
    Joined:
    Dec 7, 2015
    Location:
    Ventura County, CA
    Thanks, guys! My initial experiments have been promising. I'm really anxious to get it into a bass and start really testing it.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.