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More Fun with the Modelo Uno: Forward and Lateral Motion

#161
My package came in today. The faceplates for my pickups came in from the laser cutter.

F3665B70-4D6E-43B4-B708-7C842824E87E-scaled.jpg


The top right is for my bass blade P90 pickup (I call it the JuiceBar), next is a Ceramic 8-powered humbucker (T-1000 Super Duper Ferrite), and 3 of my mini bass humbuckers (no name for these yet). They're laser cut from aluminum. This is officially an experiment; supposedly an aluminum shield will cut some of the highs, but theoretically the shapes of these pickups will help to mitigate the eddy currents attributed to loss of brightness. Will see. If this fails, no biggie - these laser cut aluminum pieces were relatively inexpensive. I can get the same pieces cut out of nickel-silver with a waterjet, but they'll cost roughly twice as much.

For this bass build, I'm leaning toward the JuiceBar. It's fat enough to hold down a rhythm section with a 275-lb. drummer with a 24" kick drum, and bright enough to have that snap everyone just can't seem to get enough of. It's not as smooth as a regular humbucker, but it sounds pretty rocking. I plugged it into the test bass this afternoon and it sounded freakin' amazing.
 
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#162
Last night, I got started on the pickup. I had some flatwork from the laser cutter. From there, I cut a strip of heavy white paper, wrap it around the blade and glue the top and bottom to the paper and the blade. I end up with a structure like this:

9D51C631-26B0-4414-A249-6CE2C303703A-scaled.jpg


I put the magnets underneath to illustrate the structure.

I use white bookbinder's glue. It's basically fancy PVA glue, but it's made for paper products and dries really fast. Then, I fill any seams with CA glue. Overall, it'll hold together until I get it cast in the epoxy.

Here's the pickup being wound on the Funktronic Coil Genie.



On a side note, I am still unlocking the secrets of the pickup winding machine that I designed. What I realized this week is that I could use a finer thread on the feed screw to narrow my spacing. Normally, I use a 1/4 20 screw and by changing the patterns that guide the optical sensor, I can get really tight spacing on both #43 and #44 wire. #42 was kind of left with a not-as-tight-as-I'd-like spacing. So, I threaded a piece of Delrin rod with 1/4 28 thread and decreased the amount of steps on the stepper motor. I now have much better spacing for #42 wire. Here's a picture of the pickup fresh off the winder:

996BB0CF-AC62-47E9-B706-869C2298A31C-scaled.jpg


Next, I did a dry run for the casting setup.

1A865652-EBB5-4B92-B616-0F25F6797B9B-scaled.jpg


Not too many snags. I still don't really know what to do with the ground wire. I think I might consider using a PCB in the future instead of the aluminum plates pictured here. That way I can just solder the ground wire to the PCB and call it a day. I'm working towards using solder-less header pins to join the pickup to the control harness. I'm working with pretty small tolerances, and I worry about the epoxy melting as the wire heats up. Right now that's not going to be an issue with the ground wire, but the header pins are another story. They are a really short length of wire and they get really hot.

There's one more thing: Tomorrow I'm going to dunk this in epoxy. Usually, I color the resin black, but I'm considering using red oxide colored Mixol. It'll be different, and it's pretty close in color to the color of the fretboard. The red color might offset the brushed aluminum and the metallic blue nicely.

2972600D-4033-4E33-A2F1-1CEF9C1A9002-scaled.jpg
 
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#167
Bruce Johnson said:
Maybe you should put some yellow flecks in the red, and make it look like the pickup is encased in Salsa? Or call it the Ketchup Bucker?
Click to expand...

ardgedee said:
You could have a series of Bell, Jalapeño, Habanero, Scorpion, and Joloka pickups, each one hotter than the previous.
Click to expand...

@Bruce Johnson @ardgedee Haha everybody is a joker!

5tring said:
You could make the colour a custom option on your pickups.... for an extra few $ of course
Click to expand...

yeah, it’s doable, as long as I don’t have to get into mixing colors. Once you have to match something like a color, madness seems to quickly rise to the surface. Fortunately, Mixol has a lot of colors and they mix just fine with epoxy.
 
#169
This came out of the mold today. Obviously it will need some cleanup, but once that is done, it will good enough to put into this bass and start rocking. I'm debating with myself about to what degree I should polish the aluminum. Polished aluminum seems to smudge and brushed aluminum seems a little too industrial.

CADEC743-89A9-4E80-B095-6474474C1026-scaled.jpg

63ECF8DA-676E-4382-B344-2EBD5CDE16BD-scaled.jpg


OK , so the last time I reported in, I was casting a reddish brown pickup. Here's what happened: I had a lot of problems with air bubbles. In fact, that epoxy section was two big air bubbles. Normally, that's no big deal - I would just mix up more epoxy and patch it. But, the reddish brown became badly discolored, so I didn't feel really good about it. So, I'm back to black for the time being.

I really like the design structure of this pickup right now. I want to continue pursuing this esthetic. However, I am several castings away from really pulling it off. For one, air bubbles are a real problem. I tried a couple of different methods, but a tiny amount of air just gets trapped in there no matter what. I think that there will be a DIY vacuum chamber in my near future. Colored epoxy is out for now - we'll see how that changes once I build this vacuum chamber. I think I could build one for about $150.

Also, I may consider a PCB baseplate. I have a couple of ground wires to contend with: one that is attached to the face plate and another to the shielding tape that is wrapped around the coil. I have the base plate grounded to the coil tape. But either way, I'd like to have both wires soldered into the PCB with a copper ground plane already built in. That way, leads going to the control harness could be connected to the PCB.

Other than that, assembling these isn't too bad. It's definitely easier than other designs I have made. I think I could streamline the bobbin-making process, but I'm not sure how I want to do that yet.

It's really tight fitting into the body. When I clean up this pickup, I'll sand the sides with a little 600 paper until it fits.
 
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#172
Bruce Johnson said:
That's cool looking! Can you bevel or round off the edges of the aluminum enough to make it comfortable?
Click to expand...

Thanks, Bruce! I’m really happy with how it looks.

Let me think about those beveled edges. It’s a good idea. While I’m at it, I should polish it some more, too. However I don’t want to say that getting it to this point was a struggle, but I’m at a point where I’m feeling like I shouldn’t push my luck.
 
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#173
Freekmagnet said:
Thanks, Bruce! I’m really happy with how it looks.

Let me think about those beveled edges. It’s a good idea. While I’m at it, I should polish it some more, too. However I don’t want to say that getting it to this point was a struggle, but I’m at a point where I’m feeling like I shouldn’t push my luck.
Click to expand...

Yeah, keep the process simple. I'd hand file a simple bevel around the perimeter, sand the top surface with 400 dry, then scrub with Scotchbrite. Leave it at that. Don't bother trying to polish it up.
 
#174
Bruce Johnson said:
Yeah, keep the process simple. I'd hand file a simple bevel around the perimeter, sand the top surface with 400 dry, then scrub with Scotchbrite. Leave it at that. Don't bother trying to polish it up.
Click to expand...

That sound simple enough. I just had a major assembly panic moment when I realized that I didn’t include a way to install the jack in my design. I did some emergency surgery and everything is AOK. I’ll explain in another post after I get the pickguard installed.
 
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#175
I got started wiring the bass up and cutting the pickguard. I kind of had a rough go of it today, but it all turned out alright.

I cut one pickguard wrong, so that was a waste. Then, I had a big panic moment; when I designed the body, I made it 1/8” thinner. I made a 3/8” cap and back with a 3/4” core. The core was hollowed out. What I didn’t do is make enough room to install the jack. I ended up going through the control cavity with a chisel and hacked a chunk of wood out of the inside of the bass right beneath the jack. I got it in OK, and I should be able to remove or without too much trouble. Next time, I’ll make more room with when I lay out the inside.

Here’s the controls:

1FB166B1-2DD4-4C61-9D9F-D91924D62778-scaled.jpg


Then, once I got the pickguard installed, I couldn’t find the black aluminum knobs I bought 6 months ago. I don’t usually lose things, and I tore the whole house apart looking for them. In desperation, I ordered 3 more, and then I found the ones I already had.

Here it is:

C32C54DA-A6F5-4317-81CA-4CCE49E6E326-scaled.jpg


The PG was supposed to be aged pearl, but it doesn’t really match the headstock like I though it would. I would have liked a holly PG, but I couldn’t find a piece of wood that was sized appropriately. I didn’t want to get anything too big, ‘cuz holly is expensive. This PG will be OK until I find something else.

I’m taking a break for the rest of the day. Tomorrow, I gotta figure how I’m going to make the battery cavity work, and if I’m lucky, I’ll cut the nut.
 
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