Background:

When hackaday announced the circuit sculpture challenge in august I was very excited. I was already impressed by Mohit Bhoite's sculptures on hackaday and his interview on embedded.fm (ep 314) really encouraged me to give it a try. So what better excuses than a hackaday contest.

Never having made a sculpture before I thought it be wise to do a basic tutorial for one first (the link in the embedded.fm shownotes was very helpful). Trying things for the first time not being challenging enough I thought it would be fun to try this as a date.

On this date we learned the following:

Cutting mats are not heat resistant
You will need up to 4 hands to complete some connections
Double sided tape is not ideal.
SMD LEDs like to stick to soldering iron tips
Soldering is a fun date activity

Most circuit sculpture tutorials recommend holding parts in place with double sided tape. However the heat of the soldering iron will reduce the stickiness of the tape (to not sticky at all anymore). So the need for a solder-able hold in place method was born.

I like to hobby a lot with soft robotics projects which (for me) are made of silicone. Because silicone is quite heat resistant the idea of using as a jig cam e to mind. When pouring silicone you will almost always have a little left over which pools at the bottom of your mixing cup. When this eventually sets it forms a nice round complementary soldering pad. Trying to make another one of Jiří Praus' LED jewelries, but this time on my own, worked quite well even with just a flat silicone pad.

Since its possible to shape silicone in many ways when you actually pour it into a mold (instead of leaving it in the cup); the idea of making a pattern to hold the brass rods in place started to form. Later the realization came that the air pumps I was using for my soft robotics project could be used to create suction to keep SMD components in place.

Leading to the project page we are on now. I had a complicated idea for a circuit sculpture in mind for the contest, however working on the jig itself became quite interesting and challenging. I also hope that by making this project page I can receive some input from other circuit sculpture builders. Mainly about what parts are often used and difficult to work with without a jig, also for which orientations solder support is appreciated. Plus feedback on the OpenSCAD is also appreciated. I am really curious what people think about the variable naming scheme, since I'm personally really fond of it.

OpenSCAD file

Naming scheme for variables is based on parts of a city. Code is now on Github, though it still needs development in order to produce a useful jig.

Variable names above ground	Variable names underground

Keep in mind that the current physical build is far from perfect. The 3D model code is also quite inefficient since it takes both a long time to render as well as to preview. The concept of this jig is great, however there is a lot to improve before it's ready help anyone. But I believe the soft soldering jig can help with circuit sculptures.

Model versions

V0

This was the prototype version, to see if the concept even works. Area is deliberately very small for rapid printing and less silicone use. The airflow works and keeps 1206 LEDs in place. This jigs is surprisingly useful already. Even for non circuit sculpture stuff like soldering wires to each other.

Mold consist of 2 parts. The cylinder containing the city topology and a plug to be inserted to claim the space later occupied by the air tube. Plug can be held in place by elastic band.

V0 jig model	V0 mold and result.
	Left: Silicone jig right: mold

V1

First full scale design. with lots of manholes for air intake. Unfortunately it could not create any suction since there where to many manholes. The bigger surface is great to keep longer rods in place.

Made with both shore 8 and shore 15 silicone. Both having a nice firmness. Though people seem...

The big recap post
Inne • 04/16/2023 at 21:37 • 3 comments

Note

This project log is for everyone that wants to know what happened with the soft soldering jig since the last update. If you are mostly interested in the newest files please hold out for a bit; in the coming week I will be publishing the files for version 3 (v3) of the jig.

Renewed interest

It is good to be back. After being featured on the Hackaday blog and podcast (ep213) last week, my motivation has very much returned. Since I last submitted something, in 2020, I have been working on and off on this project doing bits and pieces. This post is to catch up with what has happened since then, what works, what needs improvement and what my goals are for this project. Sprinkled with a bunch of pictures to keep it entertaining.

Festivals and talking to people.

In 2020 this project won a prize in the special category (best jig) of the circuit sculpture contest. It was a really validating experience, and really felt like something I made was appreciated and celebrated.

In the years after, I kept taking the jig to Makerfestivals and Hackercamps. Both to solder on and to show as part of my portfolio. They came in handy many times, though not as often yet to make actual circuit sculptures.

One of the coolest things was when someone asked me if this could be used to mix fluid droplets for microscope. We tested it on the spot, and it worked pretty well. It was really interesting to hear the feedback, whenever I showed the soft soldering jig.

All and all, I am very happy I wrote up this project page. Consistent writing and documenting doesn’t come natural to me. However, having all the files and photos in one place, somewhere that you can point someone to, has been great. I am glad I did it, and can recommend to everyone making a project to give it a try and see where it goes.

Picture 1: Giving a lightning talk during Hackaday Berlin 2023, that kicked of the renewed interest.

A look at the technical side

Time to look back on the Hardware. As of posting, there are 3 versions of the jig, v0, v1 and v2 with v3 coming shortly. V0 is cute, small and has working vacuum. V1 is the main design, has top and bottom layer and doubles as fidget toy. For v2, the mold has brass rods inserted, instead of 3D printed ones, they make me less sad when they inevitably break in transport, as opposed to v1. The following are the lessons learned along the way.

The vacuum suction system

As it stands, the vacuum system is a major failure. The core principle doesn't work, it was supposed to hold SMD components in place so they wouldn’t stick to the soldering iron. There are however too many (man)holes to create proper suction. You would need to cover all of them. Even with the v2 model with fewer holes, you would still need to plug them all, which is too much work.

Initially, I was hoping the air pumps would be strong enough, and the (man)holes tiny enough, that the suction was sufficient. However, even once you plug all the holes, the silicone is too flexible to withstand the vacuum and will cave in.

Therefore, the SMD hold-in-place system needs a redesign. This can be either vacuum or something completely different. Since there are other, more pressing, design challenges; I decided to remove the complete underside from the jig (for v3). Even though, suction does work for v0. Removing the underground saves a lot time on production and makes everything easier to work with. See Picture 2 to get an idea of what assembling them involves. It shows connecting the top (above ground) and bottom (underground) parts for jig v1.

Picture 2: Assembling jig v1. a) Both halves of the silicone for jig v1. b) Make shift tool to center halves on top of each other, a cardboard tube happened to same diameter as the jig. c) Example of pouring the (other) parts of the mold, left over silicone goes in v0 molds. d)...
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Soft soldering jig in action
Inne • 11/10/2020 at 02:19 • 0 comments

TLDR: Made an audio amp just look at the pictures.
Realizing that I haven't really posted anything about this jig in action, I took the opportunity to make this post. Not making an actual sculpture for the circuit sculpture contest left me a bit without pretty pictures. Though I actually use this jig quite often for soldering wires and components (i.e. non circuit sculpture activities). Thankfully the Remoticon gave me a nice opportunity to take some pictures of an audio amp I build.

During the remoticon I joined the "finding sound and making microphones" workshop. Part of the workshop involved making your own mic using a piezo element. On the required materials list was an audio amplifier which I managed to source before the workshop. However it turned out to be very much broken when I retrieved it from its packaging.

This being at noon while the workshop was in the evening it left me some time to build up anxiety about failing to meet the requirements. But also time to remember that I bought some LM358P OpAmp ICs once. At the time they were to complicated but turned out to be super welcome right now.

I googled a diagram for an audio amplifier and tried to match the value of the passive components as best I could. Which turned out to be only a capacitor that was 4.7 uF instead of 10. Starting with one of the LM358 pins I followed the traces in the diagram, adding parts as I encountered them. Sometimes having to take a minute to think how the pins/traces will interact, but overall its a quite relaxing experience. Even if you don't see the appeal in making pleasing art, I would definitely recommend you give this kind of "sculpture" a try. If only to experience this method of "getting things done".
In the evening the workshop came around. I will not pretend that this method saved my bacon, because at the time I was too scared to plug it into my computer. Luckily the piezos provided audible sounds even without amplification. after the workshop I spend some time finishing the mic and while staring at my brass rod structure masquerading as an amp I couldn't resist the urge to finish it and plug it in. To my complete amazement It turned out to be actually functional. The amp even boosted the mic in such a way to allow me to sit at an comfortable distance away from it.
Moral of the story. I guess that it is useful to have a general purpose soldering tool/jig. It feels amazing to promptly finish something with parts you have lying around. And please take a look at the pictures.