A microtome is a device for slicing very thin cross-sections of stuff, in order to view them under a microscope.  Commercial ones are available, but they cost upwards of $50.  There is a classic DIY solution, but it involves a piece of old technology — a wooden spool for thread.  Outside of antique stores, those aren’t common.  Plastic ones tend to be hollow, meaning there’s no guide surface for the razor blade; and the razor is likely to shave the plastic instead of slide across it.  Gluing a washer to the plastic spool would address both of those problems.  But there is very little gluing surface on the end of a hollow plastic spool.



Lacking a wooden spool, I cut a cube off the end of some scrap 2×2 and bored a slightly-oversize hole through it.  Using Gorilla Glue, I attached a flanged nut and a flat washer to opposite ends of the hole.  Before the glue set, I used the bolt to center and clamp them over the hole.  Gorilla Glue expands 30% as it sets.  To avoid permanently gluing the bolt into the body, I carefully removed it after a few minutes.  You can see glue in the threads adjacent to the bolt, in the image at right.  A few minutes with a wire brush cleaned the bolt threads.






Lastly, I flattened and polished the washer on a lapping plate.  The edge of the washer-hole was rough, and glue had expanded out of the hole and onto the surface.

The nut & bolt are 1/4 x 20.  One complete turn is 1/20″.  So a quarter-turn should be 0.0125″ thin.  That, and a fresh razor blade, should make slices thin-enough for a microscope.

Magic Mirror Theater Prop

My sister is a Theater Manager at the Patel Conservatory in Tampa, FL.  About two weeks ago she texted me and asked if I could make her a prop she needed for an upcoming production.  “How keen would you be on making me a mirror for “Beauty and The Beast,” she said.  “They want a mirror that lights up and sparkles like the one from the movie.” Even with limited experience just tinkering around, I knew I could do something fairly easily, so I agreed and got to work.

I combined two different circuits (a 555 timer to flash and a RC circuit to fade) and built a wooden frame with acrylic plates for the front and back.  The wood and plastic were CNC-milled, then sanded and painted before the electronics were installed and glued into place.

The result was a fairly decent-looking, shiny, light-up hand mirror with a small thumb button on the right side that flashes 16 bright green LEDs when pressed.  It all runs off a single 9-volt battery and the back can be unscrewed to replace it should it ever die.

Total build time from start to finish was probably close to 15 hours over the course of one week.  The play was Thursday, July 19th and from what I’ve heard, it was a great success.  I’ll add pictures from the performance if I get some.

Android Blue or iOS Purple? Update on the OOMA project

The Object Of My Affection Lamp   I thought I would jump in and blog on my current progress at the Makerspace with a lamp called OOMA, or The Object Of My Affection. It’s a lamp that is shaped like a GPS Navigation pin that rotates to always points toward the one you love… as long as they allow you access to their Google Latitude account :). I am finalizing hardware designs and now moving into writing the software and how it talks to the Internet.

Initially I would have waived it off as using WiFi, or Ethernet, but work on another project (Marco) has illuminated several obstacles over multiple use cases (configuring Wi-Fi, closed networks, IP addresses); instead I think the approach will be to opt over USB (via Arduino Leonardo). I figure, if people will load up a coffee cup heater or foam missile launcher to USB, than there is no issue with port scarcity.

It’s not a lamp without light, and at some point OOMA will light up in either Android Blue, or iPhone Purple. Lighting the lamp will, however, have to relegated to a v.2 build, due to some complexity in the diffusion of light in such a cramped space. Additionally, I’d like to investigate EL panels to light it up.

Finally, I am coming up on the decision to be a DIY offering, or to design it to be marketable - do I build as a one off and just offer the blueprints to others or build an end-to-end consumer solution complete with potentially an NFC tag to tap and pair a user and their lamp.

MegaMax 3D Printer

MegaMax 3D Printer

MegaMax 3D printer based on MendelMax but bigger and minus plastic parts.

This is my on-going project at the Milwaukee Makerspace.  It is a 3D extruded plastic printer with about 1 cuft build envelope.  I want to print life-size human skulls (among other things) from CT scan data.  The printer is made mostly from salvaged parts and materials so the cost has been very low.  When it’s finished it will have a heated 12″x12″ bed (13″x13″ if I can find an aluminum plate that big) and dual extruder so it can print in two colors.

I have learned a lot on this project- some things that work and others that don’t work so well, and how to use a milling machine to drill holes precisely and square the ends of the 8020 extrusion pieces used to build up the frame of the machine.

I could not have done any of this without access to the people, materials, and tools at Milwaukee Makerspace.  Every time I go there to do some work on this project someone says something that gives me new ideas for improvements to the design.   I frequently find materials and parts left for me on the machine’s cart by other members who know what I’m trying to do.  If you have a project idea find your local Makerspace and get busy- there is nothing that will get your creative juices flowing like being around a bunch of people with similar interests and different skills and experience!

MMS Eclipse watching party

Although poorly attended (only one full and one future member) everyone had a great time observing the 98% solar Eclipse.

Using the official MMS pinhole card:





Too bad the eclipse image is so poor, what a minute – whats that on the building next door?


Openings between the leaves of trees are acting as pin hole cameras and giving hundreds of images of the eclipse, we felt a little silly looking at the tiny ones the card was making for the first half hour :-)

You can also see some on the leaf in the foreground (I’m writing this on an old netbook so I can’t tell how the pictures are coming out, so I didn’t clip or tweak them)

And just so you don’t think its some other effect, here’s a shot at the max we witnessed, notice the arc is at the top instead of the side:

I’m still not sure why we had such a poor turnout, after all its only a 36 hour drive to San Francisco!



Makers, assemble!

Yeah.  Having access to a laser cutter is pretty boss.  I’m planning to wear this to the premiere of a certain movie this weekend.  Four layers of acrylic; two diffuse, two opaque.  11 LEDs, 11 100 Ohm resistors, some phone cord, some solder, and a 9V battery.  There’s no lack of great pages on Instructables about how to make your own.

Toddler Swing from a 5-Gallon Bucket!

So how exactly DO you make an 18-month-old girl happy? Well, it doesn’t take any money or a trip to Wal-Mart. In fact, some rope and an old 5-gallon bucket are more than enough for a fun springtime afternoon!

Last weekend, my wife, young daughter and I went over to my parent’s house. My Dad had recently been over to the store to get chicken wire for the next chicken coop he’s working on, and looked at some playground equipment while there. (They have EVERYTHING at the farm store!) He mentioned how the toddler swing-set they had seemed “too-safe”. That is that it was all blow-molded plastic, had straps and safety belts in all directions, and looked like it would take longer to get the child in and out of the swing then she would actually spend playing in it!

It seemed like it would be simpler just to build something ourselves. We had a 5-gallon bucket and some rope, along with a drill and a jig-saw. Thus, the 5-GALLON BUCKET SWING was born!

Construction was pretty simple. We just pulled off the bucket handle, and then cut two “mouse-holes” for the legs in the front of the bucket. Matching cut-outs were made in the BOTTOM of the bucket, because toddlers legs are so short. We cut down the total height of the bucket, and made it swoop very low in front, high on the two sides, low again, and then high for a back-rest. Four holes were drilled (3/4″) to pass the rope through. Rope goes down from the top, loops through the holes, then back up and out the other side. That way, we only needed one piece of rope, instead of two, and it makes it a little easier to adjust for height.

We didn’t even have a good tree to hang the swing on, but there were two great pines (which provide shade.) We ran a length of sturdy steel pipe between the trees as a cross-member to hang the swing from. Once tied in place, the swing was ready to go.

She swung on it for nearly an hour and a half – this from a little girl who usually spends no more than ten minutes on the swing at the public park. Unfortunately, I didn’t have my camera with me, nor could I really document building the swing, as we were making it up as we went. However, my brother had his cell-phone camera with and grabbed a pair of photos of the first use of the swing.

Being made from plastic, the bucket swing is weather resistant and should last a long time. It wasn’t made in China. It didn’t have any packaging, and it was plenty of fun to make and use. Not bad for a weekend afternoon.

But what’s that? YOU want to make your own 5-gallon bucket swing? Sounds great! Go for it. Here’s some general directions for you.

First, get a bucket. You probably already have one around, but if not, you can buy one at the home improvement store. Better yet, just ask for one at your favorite local restaurant. Pickles and all sorts of industrial-sized food goods often come in 5-gallon buckets.

Next, remove the handle.

You don’t HAVE to take it off, but it will just get in your way otherwise while you are working on the project. Look where the handle connects to the bucket and you will be able to see which way you have to bend the handle to be able to just pull it out by hand.

Next step is to cut a pair of “mouse-holes” for the child’s legs. In these photos, I’m using a black marker to show where I’ll being cutting. When you do this, either cut around the OUTSIDE of your black markings, so there’s no marks done on your finished swing, or just eye-ball it. The leg holes are cut in both the front AND the bottom of the bucket, so the child’s thighs sit on the bottom of the bucket, but from the knee on down hangs straight downward through the bucket.

You can cut the bucket with almost anything, a handsaw, a Dremel tool, a jigsaw, or reciprocating saw. I think a jigsaw is the easiest and most straight-forward for this.

Try to make all the cuts on the project nice swooping curves. Once all the cuts are made, you can sand the edges as well.

Next thing to do is mark the lines for the main cut. Essentially, you are cutting really low across the front, above the leg holes, and then high on either side, near where the bucket handle originally connect, swoop low again for where the kid’s armpits are going to be, and high on the back for a back-rest. That may sound complicated, but a couple pictures are worth a few thousand words.

You’ll also need to drill four holes. Two are the main “hanging holes” which will be located directly below the original bailing handle connection points. The other two are roughly below where the child’s armpits will be, and allow for the rope to go through to the back of the swing, around the outside of the bucket. That way, the rope acts as part of the back-rest, and prevents backward tipping, but is not between the child and the back-rest. You probably want to drill the holes BEFORE cutting the bucket in half, as it will have more strength and is easier to handle in its original bucket form.

Once those holes are drilled, cut that swooping line to make the bucket into two halves.

Frankly, I’m not sure what to do with the top half of the bucket that got cut off. If you have a good idea of how to make use of this “waste”, please let me know!

By now, the bottom half of the bucket should be starting to look like something you might see at the park.

Next, get yourself some rope that’s at least twice as long from your favorite tree-branch to the ground. Thread one end of the rope DOWN through the outside of one of the ears, out through the next hole, around the outside of the back-rest, back IN the next hole, the up and out the other ear. Again, it makes more sense if you look at the photos.

Also, please note that on this particular bucket swing, the back-rest is a little low. It should really come up nearly as tall as the side ears. When we worked on the first one at my Dad’s the little girl was right there. She cooperated well in that she was happy to sit in the bucket while we marked the positions and distances of the various parts of the swing. (The little girl was not around while I was working on this particular bucket. I highly suggest using your toddler as a template for your project!)

Next, you just have to hang it. Tie one end of the rope to the tree branch. Make sure the swing is facing the direction you would like it to face. Slide the swing on the rope until it is at the height you would like it to be at. That’s usually between the height of an adult’s waist and knee – a good pushing height once the swing is drawn back.

Most likely, you will want to use an outdoor-rated, UV-resistant, artificial fiber rope. Otherwise, you could also chain or cable, but rope is simple, easy to work with, and doesn’t pinch little fingers.

The proof is in the pudding. After checking that the swing is tied securely, at the right height and level, put your little darling in there and give him or her a push!

If all has gone well, you have a smiling child swinging away on your aren’t-you-proud-you-made-it-yourself swing-set!

Once the tot is in there, you might want to confirm that the leg holes are the right size, and that there’s no chafing or rubbing. In the photo above, it looks like the left leg hole (her right leg) could be a little bigger.

If you, like me, enjoy irony, you might want to design your bucket so that it keeps the “THIS IS NOT A TOY” warning on the side.

Here’s a couple of views of the back. In these photos her shirt is covering part of the back-rest, but it’s still a little low. In the next bucket swing, I am going to make sure the back-rest is higher, nearly as tall as the side ears. Make sure that there are still the downward swoops for the armpit area. This allows the child to have comfortable arm position, NOT rubbing on the bucket, and still easily reaching up to grab the rope.

That’s about it! It’s a simple project, inexpensive, fun to make, and fun for the kids to use!

Here’s a video quickly showing all the steps as well!

Do you have any ideas for improving this design? Have you made one? Let me know! Leave a comment or post a photo!

One last treat for you – I created a one-page PDF file for you that has step-by-step directions for how to build the swing. Click the link , then print out the file and take it to your workshop with you!

Lastly, HAVE FUN!

DIY Slide Scanner

DIY Slide Scanner

I have a confession to make: I’m about 80% done with my own device to photograph slides and convert them to digital form. I’m pretty sure I will abandon all of my efforts and attempt to replicate this DIY Slide Scanner I saw from the Metrix Create:Space folks.

And yeah, I’ve already got a working slide projector. It may be the same model you see in the photo above. (I picked it up at a WCTC auction for $5.00 years ago.) I’ve already got code to trigger my Nikon via an IR LED, so the main thing I need to do is wire up the remote to advanced the slides, and fit it all together. I’ll probably just build a wooden platform to hold it all.

And then it’ll be time to… DIGITIZE ALL THE SLIDES!

Unexpected Detour

When I arrived at the space Sunday, I had planned to work on a circuit board design in DipTrace.  After I left, I had spent six hours rewiring a golf cart.  Allow me to explain…

It all started when I went to take the trash out.  I used the golf cart with the flatbed to ferry the cans out to the dumpster.  After emptying the cans, I rode back and decided to charge the cart’s batteries.  Tom and Rich had just returned from lunch and Tom suggested we swap out batteries instead.  While swapping them out, we decided to also rewire them.  While rewiring them, part of the cart broke.  There’s a small white plate under the driver’s seat.  It’s about 4″ x 6″, likely made of asbestos, and holds a series of copper contacts that a lever attached to the gas pedal slides over to select the speed of the cart.  And it broke in two when we tried to tighten fix a wire on it.

We had a few options: try to mend the old, brittle plate, replace it with something new, rewire the whole thing, or scrap everything out for a solid state motor controller.  Not wanting to adopt a new project or sacrifice a motor controller that could be better used elsewhere, I volunteered to try and fabricate a replacement for the broken part.

First I documented everything just the way it was.  I labeled wires, took photos, scribbled down notes, etc.  Next I went about removing the broken plate.  There was probably more rust than metal on those bolts.  Then I took a pair of digital calipers and a ruler and measured the locations and sizes of holes for each component.  I considered using the CNC router or drilling a plate by hand, but the laser cutter seemed to be a much faster and precise approach.  I drew up my replacement plate in CorelDraw and found a scrap of 1/4″ acrylic that matched the size and thickness of the old plate.  After some tinkering with the printer driver and a dozen passes with the laser, I had a copy of the original in plastic form.

The next few hours were spent migrating the old parts over to the new one and wiring it back in.  Right around 7:00 PM, I tied some batteries together and the thing leaped forward.  A few more tests and it should be as good as new.  Someone suggested that maybe the plate was asbestos to avoid heating issues so we’ll keep an eye on that too.