Generating Plasma at OMG

During one of our Tuesday evening meetings we experimented with creating plasma.
How do you make plasma? Well, usually air insulates electric charges, so it requires high voltage to break apart the molecules. In a partial vacuum, however, this breakdown potential may decrease enough that two uninsulated surfaces with different potentials might induce the electrical breakdown of the surrounding gas. For example, the exposed tips of two big screws, such as we have in our experiment.


When there are molecules and free electrons floating around inside a chamber like ours, there is the chance of collision between an electron and a molecule, which could ionize the molecule. Electric fields need either very high temperature or very low pressure to break down a gas so we used an old pump to suck as much air as we could from a sealed PVC tube. Of course it wasn’t completely sealed – it’s impossible to create plasma in a pure vacuum because plasma is defined as ionized gas. As you’ll see in the video, we control the amount of gas in the chamber by fidgeting with the release valve. After a few trials we discovered the amount of air pressure required to ignite the plasma then we decreased pressure to maintain the pretty purple lights.


Once upon a time in Tübingen a gentleman named Friedrich Paschen wrote a physics paper about the potential difference for sparking air at various pressures. The formula he magicked from the ether became known as “Paschen’s Law” and it’s an equation that gives the voltage necessary to start a discharge between two electrodes in a gas as a function of pressure and gap length.
If you are curious, follow this link to a web site where you can calculate the breakdown of your own gas!
https://www.fxsolver.com/browse/formulas/Paschen%27s+Law

A Complete Story of Hammer Making

This video details the process we completed in order to cast a hammer from aluminum, from making the kiln through making our own foundry tools, testing, and finally pouring in our handmade cast. The product would be a hammer that would not produce sparks if dropped on concrete, but the goal of the project was to learn how to cast metal. We worked on evenings and weekends during the month of October with help from several makery members and in the end we made a pretty good hammer. If you would like to see the beautiful shiny hammer live in person and grip it by the finely-detailed handle, just come on by Omaha Maker Group whenever you see the “open” sign indicated here on the web site. We also have meetings on Tuesday nights.

Casting Aluminum

OMG has had a kiln made of high quality refractory brick for a while now but recently Kevin led an effort to rekindle it. After a couple weeks of preparation we spent Saturday morning making last minute adjustments and then fired it up. In all, it only took a half hour or so to turn a bucket of scrap aluminum into ingots of metal, ready for casting. Several members stopped by to watch and help out. The weather was perfect and the procedure went smoothly – hopefully this is the first of many times the kiln will be used, now that we have streamlined the process and assembled all the necessary tools.
Here’s a link to a quick edit of video footage from a camera stationed on the dock behind OMG. A more complete video of the process is forthcoming.

What’s inside an integrated chip?

I damaged a CD4093BE and instead of throwing it away I decided to satisfy my curiosity regarding its guts. I used Omaha Maker Group’s belt sander to grind away the top layer of material and it revealed a tiny chip embedded within. The slightly orangey color on the right side is where I sanded away a little too much of the tin protecting the copper legs. In the closeup view, you can just make out where filamentous wires must connect the legs to the chip.

Preparing to apply the IC to a belt sander

4093 integrated circuit beneath the covers

How to make an “Omaha Maker Group” patch!

Our embroidery machine can embroider text and borders very easily thanks to our wonderful donor.

If you are unclear at any step, please consult the babylock manual for the machine. It’s in the drawer labelled “Embroidery Machine Manual”.

You will need at least the medium hoop for our standard patch.

 

Cut a piece of fabric about 3/4″ larger than the hoop. Cut a piece of embroidery stabilizer that same size. Place the stabilizer over the inner portion of the hoop. Place the fabric over both of these. Then place the outer portion of the hoop over all of that, ensuring the post holes are opening towards the floor and the right-side of your fabric is on top. Flip this over and gently tug the fabric and stabilizer taut. Cinch down the hoop and tug fabric and stabilizer even more taut.

On the machine, ensure the embroidery foot, embroidery needle and embroidery arm are attached. Turn on the machine (do not attach the hoop to the machine yet). When prompted, click/press the “Check” button. The machine will do a calibration.

Hit the white “Embroidery” menu button on the screen.

Click on the on-screen button with a bunch of shapes. This will allow you to create the border. Select the rectangular option and then the solid bold line. On the next screen click the “layout” button. On the layout screen, click the size button, and resize the rectangle to 4.5 cm x 6.3 cm. When you’re finished, click the “End Size Changr” button. Then orient it however you’d please. You’ll need to match this orientation for your words.

If you have not done so, thread the machine with a bobbin matching your fabric (or your top thread) and the top thread in the color of your preference. OMG’s official patch has a dark purple border with a white fabric background.

Now, attach the hoop to the machine.

Lower the presser foot and click the green back-lit “Start/Stop” button. If this is not green, stop, something’s wrong. Consult the manual or Sarah if she’s available.

In about 3 minutes, you’ll have a border.

Clean up the extra few stitches the machine puts in the middle with a seam ripper.

Click the white “Embroidery” button on the screen. Click the letters with the serifs. Assuming your border is the OMG dark purple, click on the “L M S” button until “S” is highlights, and then type in “Group” (lower-case letters are in the visual tab below the upper-case letters). Now click “Layout”. Orient the words with your border. Next, position the needle near the bottom middle of the interior of the border. If you’re doing math, it’s 0.2 cm from the bottom.

Again, lower the presser foot (if needed) and click the green back-lit “Start/Stop” button. If this is not green, stop, something’s wrong. Consult the manual or Sarah if she’s available.

In about 3 minutes, you’ll have the word “Group”.

Switch the top thread out to light purple. Click the white “Embroidery” button on the screen. Click the letters with the serifs. Click on the “L M S” button until “S” is highlights, and then type in “Maker” (lower-case letters are in the visual tab below the upper-case letters). Now click “Layout”. Orient the words with your border. Next, position the needle near the bottom middle of the interior of the border. If you’re doing math, it’s 1.5 cm from the bottom.

Again, lower the presser foot (if needed) and click the green back-lit “Start/Stop” button. If this is not green, stop, something’s wrong. Consult the manual or Sarah if she’s available.

In about 3 minutes, you’ll have the word “Maker”.

Switch the top thread out to bright blue. Click the white “Embroidery” button on the screen. Click the letters with the serifs. Click on the “L M S” button until “S” is highlights, and then type in “Omaha” (lower-case letters are in the visual tab below the upper-case letters). Now click “Layout”. Orient the words with your border. Next, position the needle near the bottom middle of the interior of the border. If you’re doing math, it’s 2.25 cm from the bottom.

Again, lower the presser foot (if needed) and click the green back-lit “Start/Stop” button. If this is not green, stop, something’s wrong. Consult the manual or Sarah if she’s available.

In about 3 minutes, you’ll have the word “Omaha”.

Lift the presser foot and pull up the hoop. You now have a completed embroidered pattern! Remove the fabric from the hoop. Removing as much of the backing as you can. Cut a piece of iron-on adhesive to fit the size of your patch. Attach this with an iron per the adhesive’s instructions. Peel off the paper backing from the adhesive. Carefully cut out your patch!

Now, clean up the extra stitches the machine added between each letter and you’re done! Iron-on that patch wherever you please!

Toner Transfer Testing


My wife ask about me lasercutting a sign for some friends, but at the time she ask, our laser was still down for repairs. I remembered Ben doing a toner transfer project several years ago, so I googled it up, and it turned out to be easier than I remembered.

This isn’t intended to be a tutorial, but the general steps are as follows:

  • Print Design on a laser printer (mirrored)
  • Sand wooden surface (I bought a prefab plaque at Michaels 40% off)
  • Tape paper to surface so it doesn’t move around
  • Apply acetone (a little goes a long way)
  • Remove paper before toner bleeds everywhere.
  • Apply clear finish

This was my first try at toner transfer ever, and the photo below wasn’t my final product. The toner doesn’t soak in very deep, so it’s easily sanded off for another attempt.  I ended up resanding and transferring 3 times, due to incomplete transfer or smudging (as below).

Lighter weight paper seemed to work better (the paper at OMG was quite a bit lighter than what I had at home, and worked great) as it didn’t want to soak up so much acetone, and transferred more completely as a result.

Once I was satisfied with the transfer results, a quick coat of spray lacquer finished the project.  Setup, drying and cleanup took the majority of the time and effort here. Total hands-on time was about 15 minutes.

Gingerbread Teaser

While we’re waiting on the “good photos” from Garrick, enjoy these two less good photos I snapped of some our members’ handiwork.  As always, we had quite the turnout for this event, with several members bringing friends and family to play along.

A special thanks to Sarah and Jeff for helping make it go off without a hitch, particularly in the processing and emergency procurement of our frosting supply.

New Ryobi Tool Center

It’s been a few months now, but I’m finally getting to documenting the tool storage wall we built. I found a plan online to build some PVC drill/driver hangers, and adapted it to carry the grinder, glue gun and angle drill by their battery holders.

All the tools in one place!

The slanted pipes below the drills are some spare PVC cemented to a piece of Sintra (which is also PVC, so I used pipe solvent). These tubes, which have since been labeled, hold cylindrical tools, such as our rotary and oscillating multitools and apparently a caulk gun.

If you’re in the market for some drill hangers for yourself, we have a fancy jig built (for 3″ pipe, but 4″ works too), so c’mon down and build some for yourself!