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A Homemade Progressive/Universal RF Coil Winder

Posted on by by Posted in DIY, Electronics, Odd, Strange, & Curious, Theremins, Tools & Machinery, Vintage

The mostly-completed progressive/universal coil winder. The universal portion is my adaptation of Morris Coilmaster design with some added features. The progressive feature is new. All parts were designed in Fusion360 with the exception of the very nice 3-jaw chucks posted by user “mdkendall” on Thingiverse.com (link in text below).

A few years ago I became fascinated (obsessed) with theremins to the point that I’ve ignored maintenance of this website and I’m pretty sure I can’t even play guitar anymore.  The theremin is a miserably difficult instrument to play, but in the early morning hours when no one else can hear me I find a deep satisfaction in playing a musical instrument that almost seems to be connected directly to my brain.  If you can think of a melody you can play it (how well you can play it is another matter).

It’s strange that I resisted the theremin for so long in my younger years.  It is a natural fit in that it is an electronic instrument that uses radio frequencies and oscillators and filters, all stuff that I’ve been into since my pre-teen years.  The theremin story is for another time, though.  This project, a coil winder that allows one to make high-frequency coils with winding patterns that are impossible to do by hand, is actually a side task for a theremin construction project that I’ve managed to stretch out for over a year now. … Read the rest


A Milling Machine Spindle Camera

Posted on by by Posted in DIY, Electronics, Tools & Machinery, Video Equipment, Videography

Modified Webcam Provides Tool’s-Eye View of Work

 

Camera Mounts in a 1/2" Collet In Milling Machine Spindle

Camera Mounts in a 1/2″ Collet In Milling Machine Spindle

It’s been a busy home-project summer (as in home-maintenance) but there have been a few shop projects that I have not had time to write about. One of these projects was the fabrication of a video camera that could be swapped for the milling cutter and used to precisely place a target under the cutter visually rather than by the numbers.

Sometime last spring I got the urge to buy and perform a CNC conversion on a small Grizzly G0704 milling machine.  Before beginning this project I knew there would be a need to machine stepper-motor adapters and other hardware components to a higher degree of precision and accuracy than I routinely care about.  And since many of the parts would have to mate with the machine castings, I needed a way to measure dimensions and hole spacings more accurately than by simply using a dial caliper.

Many other DIYers have built spindle cameras (I’m calling this one a mill-cam from here on), and a web search turned up several different approaches.  I incorporated many of their ideas into this design and added a few of my own, including the ability to adjust the tilt the vertical axis of the camera.… Read the rest


Review: AmScope 3.5x-45x Boom Stereo Microscope

Posted on by by Posted in Tools & Machinery

Circuit Board Model with Trinocular Camera Port and 144 LED Ring Light

AmScope Model SM-4TX-144A Circuit Board Boom Stereo Microscope

AmScope Model SM-4TX-144A Circuit Board Boom Stereo Microscope

One of the perks that you lose when abandoning the corporate engineering environment is the access to high-end test equipment to use or borrow for your own projects, and one of the things that I missed the most was having a good quality stereo microscope within reach. Working with microwave ICs and picosecond-range pulse circuits required spending a good portion of the work day staring through microscopes while assembling die-level circuitry and performing wirebonding. Microscopes were so common in the workplace that I never really understood how pricey they were until I had to purchase a Leica scope & wirebonder and the ocular-less Mantis for general assembly work in my development lab.

I have always had some of my own basic gear at home – oscilloscopes, a logic analyzer, and other basic equipment – but no network or spectrum analyzers, and no microscope. Surplus name-brand scopes in decent condition can still command high prices, and I was recently looking for a nice used Nikon or Leica when this AmScope stereo boom microscope happened to arrive courtesy of Santa Claus. A few years earlier I had come very close to purchasing a different AmScope model based on a high percentage of favorable reviews.… Read the rest

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DIY Resistance Soldering Outfit

Posted on by by Posted in DIY, Electronics, Tools & Machinery

Put Soldering Heat Where You Need it – Now!

This Home Resistance Soldering Rig Can Deliver Over 350 Watts of Pinpoint Power

This Homemade Resistance Soldering Rig Can Deliver Over 320 Watts of Pinpoint Soldering Power

Resistance Soldering

Resistance soldering is a process by which objects to be soldered together are heated by passing a current through them rather than by applying heat from an external source. Localized heating is caused by relatively high current passing through the resistance of the junction. As long as the heating rate of the junction exceeds the thermal dissipation rate, the temperature will rise high enough for solder to melt and flow.

There can be several advantages to using resistance soldering for certain applications, but two big ones stand out:

  • Speed – a resistance soldering unit can generate heat in a localized spot much more quickly than application of a 700 to 800 degree soldering iron which relies on conduction for heat transfer. A resistance soldering unit can also exceed soldering temperatures, heating a junction to bright orange, actually welding small parts together.
  • Steep temperature gradient – because of the rapid heating of the joint being soldered, it is possible to obtain a very high temperature gradient over a short physical distance, making it easier to prevent nearby solder joints from melting and falling apart.
… Read the rest
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A $20 Transistor – L/R/C ESR Tester

Posted on by by Posted in Electronics, Tools & Machinery

Displays Device Parameters and Lead Configuration

IMG_7811_LR

Displays Battery Voltage While Testing (or Looking For the Nonexistent DUT)

I don’t know how long these have been available, but they are pretty cool. These testers are all over eBay in various forms for around this price, give or take. After ordering this I found a different one for about $23 with a built-in ZIF socket, which would have been handy instead of the pin socket shown here. But that didn’t have the ultracool white-on-blue backlit display.

Display Unplugs From Processor Board

Display Unplugs From Processor Board. The Trimpot Adjusts the Display Contrast.

I am really surprised how well it works. It runs on a 9v battery. There are three available connection points (pins 1-2 are connected, as are pins 4-5 on the socket) marked T1, T2 and T3. For 2-terminal devices use any two connections, and for transistors use all three. You do not need to know diode or transistor lead configurations for the test – it finds them for you. SMD pads are available on the main board itself for testing surface mount components.

When a device is connected and the test button pressed, the display initially shows the battery voltage. After a short time the display will show a symbol of the component and the assignment of the pin numbers in accordance with the way you have the part connected.… Read the rest

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Pressure/Vacuum Casting Chamber with Camera

Posted on by by Posted in Sculpture, Molds, & Casting, Tools & Machinery

Allows Visual Monitoring of Degassing and Casting Operations

See What's Going On Inside Under Pressure or Vacuum

See What’s Going On Inside Under Pressure or Vacuum

Right or wrong, and subject to controversy, these are the general steps that can help produce bubble-free parts or molds using resin or silicone rubber:

  1. Measure out the two parts of the casting/molding material
  2. Mix any pigments or additives with one part of the resin or rubber, usually recommended by the manufacturer
  3. Optionally degas the components now – before combining – to minimize entrapped air or moisture. Do not over-pump below material’s vapor pressure, or you will create a nearly endless supply of new bubbles..
  4. Prepare to work quickly once the materials are mixed in the next step. The clock will be ticking…
  5. Thoroughly mix the two parts together, stirring and scraping the side walls. Transfer the mix to a new container if desired to minimize unmixed pockets of material.
  6. Fast-cure resins or mold rubbers may not give you time for this step, but degassing the mixture in a vacuum for a short time will help remove air entrapped in the stirring process.
  7. Remove the degassed mixture and carefully pour around part or into mold.
  8. Again, and only if time permits, quickly degas the the resin/mold or the mold-material/pattern to boil off bubbles introduced during the pour
  9. Apply 45 – 60 psi pressure to the casting chamber for the duration of the material’s cure time.
… Read the rest
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The Taig Lathe

Posted on by by Posted in Tools & Machinery

Treadmill Motor Drive and Custom Power Feed

Taig Micro Lathe II With Modifications

Taig Micro Lathe II With Modifications

This whole tangent – acquisition of a small lathe – started when I had a need to make a tiny 1/8″ diameter internally-threaded sleeve for tensioning a thin aircraft cable. The aircraft cable would have a small brass collar crimped and silver soldered on the end, and the sleeve would rotate freely on the cable as it threaded onto a 4-40 rod, thereby tensioning the cable. The problem wasn’t that I couldn’t chuck the small parts on my Logan/Wards 10″ lathe, but that the lathe couldn’t really achieve the spindle speeds needed to do a good job on the small-diameter parts.

For several months I had been looking for a smaller lathe – something of the Sherline variety – that would be more comfortable to work with at higher spindle speeds. I knew a little about the Taig lathe, but for some fickle reason I didn’t seriously consider it until later in the process. Early on I had also started watching for vintage Unimat lathes on eBay. A Unimat would not be the most practical choice, but I had been fascinated by them since the ’60s when their ads could be seen everywhere in hobbyist magazines and catalogs.… Read the rest

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Review: SJK-1 Digital Wax Carving Pencil

Posted on by by Posted in Sculpture, Molds, & Casting, Tools & Machinery

Inexpensive Dual-Handle Unit With Independent Temperature Controls

This is Just One of Several Types of Inexpensive Wax Carvers Available on eBay

This is Just One of Several Types of Inexpensive Wax Carvers Available on eBay

After experimenting around with a few different sculpting mediums, wax seems to be a material that I might be able to do something with. Subtractive sculpting in wood requires too much vision, training, or talent – none of which I have. Clays allow addition of material to fill in mistakes, but I haven’t had much luck obtaining a finish suitable for producing a final mold from which I can cast multiple pieces.

But wax is different. Some of the harder varieties of sculpting wax can be carved and polished to a very high finish and are durable enough to easily make it through the process of mold-making. The ability to build up or repair wax fairly quickly makes it attractive for experienced sculptors as well as those of us that have to repeatedly add or subtract material until whatever we are making looks right.

It took about five minutes of using an alcohol lamp to heat tools and melt wax to realize that an electric wax pencil would be a necessity. And since I didn’t know much about what I needed or whether I would stick with carving, I looked for something that didn’t cost several hundred dollars.… Read the rest

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