Backroom workshop

I got a 7 x 12 lathe several months ago. Here is a description of my first lathe mod — a carriage chip guard. It is a pretty common and simple modification.

The large black wheel on the carriage drives a rack and pinion system to move the carriage back and forth along the ways. The problem is that the gears are exposed on the back side and easily collect chips. (The picture below is actually the end result with the guard visible…)

The first step is to remove the apron. It is connected with two M10 hex bolts on the top.

Here is the other side:

The goal is to put some kind of shield to cover up the gears.

Here are all the parts:

One little annoyance is that the gears protrude a little above the level of the apron. So I either need to reduce the thickness of each gear or raise the guard up a bit (washers, some kind of O-ring).

I decided to reduce the thickness of the gears (since I have a lathe after all!). The problem is that the apron is not attached and so the carriage might move. I don’t have a carriage stop yet (perhaps an upcoming project) and so I just used a C-clamp (maybe not the best for the ways though).

After facing the gears to reduce the thickness, I found a piece of 3mm acrylic and cut out a rectangle the right size (I suppose polycarbonate or something less brittle would be ideal, but for now I will go with what I have).

I cut a 18mm hole for the pinion with a Forstner bit (for wood).

After that I put the acrylic up to the apron and traced out the shape with a pencil. I used a combination of an acrylic cutter and a Dremel to shape the piece. I put the acrylic over the apron and eyeballed a few places to drill 3mm holes for screws. I countersunk the holes.

Using the acrylic as a pattern, I marked the hole locations and the drilled and tapped for 3mm screws. The post in the center made tapping a little awkward…

I covered the gears with some grease and attached the acrylic guard.

Here is the apron re-attached to the carriage.

Making small lightsabers for action figures is a lot of fun, but it would be even better to make a lightsaber that my kids and I can play with. This project is our experiment in making a big lightsaber.

Perhaps the most important thing is the light source. There are a couple of options, but we opted for the LED approach.  Some internet research turned up some very powerful LEDs made by Philips — LUXEON.

My son and went to Akihabara in Tokyo and found a store selling LUXEON LEDs. We decided to get a few different kinds to see the differences and ended up with a blue and green LUXEON I Star/O which look like this

We also got a blue LUXEON K2:

We also needed a red one, so we got a LUXEON III (which looks very similar to the image above — forgot to take a picture…).

One other important part is the blade. Again, there are a couple of options, but since I’d like the lightsaber to be used by the kids, something less fragile than acrylic would be better. We found 18mm (16mm inner diameter) polycarbonate tubes at Tokyu Hands in Shibuya and got a couple.

Sticking the LED at the end of the polycarbonate doesn’t do much for lighting up the tube. Some sort of diffusing material is need. I found some polypropylene film at the 100-yen store (like a dollar store).

I rolled up several sheets of the film and inserted it into the tube. (This is just a test, for the final version the film was much closer to the end of the tube.)

The LEDs are too strong to look at directly and so an open ended blade is not the best thing. Several lightsaber making websites mention mirrored or half mirrored end caps. This also helps to redirect some of the light back into the tube. I took my shot at making one too. I purchased a 20mm acrylic rod and several small mirrors (probably acrylic with mirror backing).

Using one of my favorite glues…

I attached the mirror to the end of the rod.

I used a lathe to turn the mirror part down to 16mm (the inner diameter of the polycarbonate tube) and the rod part down to 18mm.

I glued the cap to the end of the polycarbonate tube.

Here are a couple test shots with the LUXEON I blue and green and the LUXEON III red.

So far so good!

One note of caution before going on. I got caught up in the construction and didn’t take enough pictures. Also, the first lightsaber is just a prototype and I was aiming for something functional rather than something authentic looking.

Now on to the hilt. I found a 32mm stainless steel tube, a 30mm ABS tube, and a 30mm solid ABS tube (which has already had one end cut off in the image…)

I cut off a bit of the stainless steel tube and attached a piece of paper where I calculated where the screw holes and switch hole need to go. I used a cutoff blade on my Dremel to cut out the hole for the switch.

The final tube looks like this

I used my lathe to turn a couple of pieces to hold the polycarbonate tube within the ABS tube.

Here’s where the construction pictures start to suffer.

For the first lightsaber I decided to use the red LUXEON III LED. The diameter of the LUXEON I LEDs is too much for the tubes I have and the blue K2 would need a bit more work to attach to the base. I thought it might be a good idea to put the LED on a bit of alumium to serve as a heat sink (not sure if this is really necessary in the end, but can’t hurt).

I wanted to put the LED in some kind of “module” — a section of ABS tube.

I should really have taken some pictures of the electronics. Basically I connected 2 AA batteries in series with a .5 ohm resister, a switch, and the LED.

I turned and end cap from the solid ABS tube and screwed it onto the bottom (after putting the batteries in).

Here is the completed hilt with blade. The blade is held simply by friction, but it can be swung around without coming out.

Here is a shot of the lightsaber in the dark. My kids and I are pleased.

My son found Mace Windu in a bargain bin at a toy store the other day. In the movies, Mace has a purple lightsaber, but the action figure came with a blue lightsaber.

We decided to try to make a purple lightsaber for Mace Windu. For this project we decided to make a resin cast. First we need a mold. In the past I have used silicon rubber that takes hours to cure (and is kind of messy to set up). This time we used something called “Blue mix”.

It is a soft binary clay-like material that you just mixed in a 1:1 ratio. It hardens within minutes. Very easy.

After a couple of attempts, I made the following two part mold with a vent to let air escape.

At first I tried to make the mold all in one piece and then just cut it part. This didn’t work out so well. One problem was matching the vent (a thin piece of wire was the pattern) with the end of the lightsaber. For this mold, I put the lightsaber and wire on the sticky side of a piece of tape. I brushed everything (including the remaining sticky part of the tape) with some kind of parting dust which I used before in aluminum casting (probably talc powder). I pushed the blue mix on top of all this to make half of the mold. After it hardened, I removed the tape and carved little holes for registering (matching) the other half of the mold. I then brushed on a bit more separating powder and then mixed and pushed on the other half of the mold. The two halves separate pretty easily (I am not sure how well it would separate without the parting dust).

A helping hand, some clips, and some craft sticks hold the mold together, ready for the resin.

The resin was also pretty easy. I found small eye-dropper like bottles of resin and catalyst. First we just tried the “violet”, but it seemed a little dark. I went back to the store to find a clear one to mix with violet, but they were all sold out. As a substitute I got something called “aquaviolet” which is fairly clear, but glows under black light. Sure, why not?

The shape turned quite well (this is actually the second attempt, the first had a air bubble — the resin should be poured all at once without stopping). Here are two images of the result. To me the actual color is between these two pictures when I look at them on my monitor. The first is a little too translucent and the second a little too opaque.

And the final result — Mace Windu has a proper purple lightsaber!

It took a while, but I finally sanded down the bowls. It took more work than I had hoped (they are only about 23mm in diameter), but I am fairly happy with the way they have turned out.

Next, I’ll investigate painting them or applying some kind of finish.

I still have to admit being a Star Wars fan even after 30+ years. My kids have watched some of the movies recently and now my son is into Star Wars too. He got some action figures with his allowance. He would really like to have Darth Maul, but he can’t find one that he can afford yet. I suggested  that we might be able to make a double bladed lightsaber in the meantime. Needless to say he agreed immediately.

We found some long (90cm) thin (2mm) acrylic rods at Tokyu Hands in Shibuya. They only had fluorescent green, red, and orange (not the blue we hoping for), but no problem. My son was anxious to get started. I had some 6mm aluminum rod already in the workshop. This was all the material we needed.

I turned the aluminum on the lathe thin enough for the action figures to hold and then drilled a small hole in one end big enough for the acrylic rod. I cut the acrylic to length and pushed in into the hole — no glue, just relying on friction to keep it in.

It worked quite well, and now my son has a bunch of lightsabers (Boba Fett, Han, Leia, and Chewbacca have become adept with lightsabers!).

As much fun as it is drive around with the wired controller, my son and I decided to enhance the tracked vehicle by making it wireless.

The first step is electronic control of the motors. We need to be able to reverse the direction of the current through the motors to change their direction of spin. The standard approach for small DC motors like those we have is an H-bridge. After some internet research, I came up with this schematic:

and then built it on perf board:

I found two problems. I really should have tested it more thoroughly before soldering everything together — the value of the base resister on the pnp transistors is too large. They won’t turn on, spoiling the H-bridge. Arg. The second problem is that I need two of these (one for each motor).

More internet research turned up this:

It is an H-bridge on a chip for 210 yen (~2$). This is much easier than my H-bridge.

The next challenge for the tracked vehicle is to make it wireless. I have two basic alternatives: radio frequency (RF) or infra-red (IR). RF has several advantages including farther range, line of sight not required, and larger bandwidth. On the other hand, it is more difficult to build RF transmitters and receivers. Legal regulations for RF transmitters usually make them difficult for the hobbyist. Of course there are packaged RF transmitter and receiver modules that one might use.

For the first run, I’ll use IR instead of RF. It is pretty easy to build a unit that will decode signals from a standard television remote control. There are also a number of relatively cheap remote control toys that use IR.

Eventually I’d like to build my own IR transmitter and receiver, but first I’ll borrow some parts to make things easier. I found this car at Toys-R-Us for 300 yen (~3$).

It is a put-together kit, but I took apart the main body part to expose the circuit board. I unsoldered the motor and the two steering coils. I soldered two long wires to the motor pads. I used a volt meter to find the steering pads that go positive when the left or right button is pressed. Again I soldered long wires to those pads and another wire to ground. A little hot glue helped to keep the new wires from pulling off the pads too easily.

This essentially takes care of the wireless bit.

The IR car runs on 3 volts. I decided to leave the batteries in the car and use the 3V signals. I couldn’t run everthing off the 3V because the motor drivers require at least 4V for part of the control logic. Also I wanted to use 6V for the tracked vehicle motors. I still had the opto-couplers set up for the H-bridge experment earlier, so I just interfaced the IR car and the motor drivers via the optocouplers.

I haphazardly glued a board on top of the tracked vehicle and used double sided tape to attach the IR car guts, the breadboard with motor drivers and opto-coupler interface, and some batteries. It is pretty ugly but it works!

My son and I thought I would be fun to build a remote control vehicle. Since we have a small apartment, my son said that a tracked vehicle would be able to turn easier and climb over stuff.

We found a Tamiya tracked vehicle kit.

This kit is fun, but it has three immediate problems — (1) it uses an onboard manual switch to control the direction, (2) it can only move forward and backward, and (3) it only has one speed.

We decided to attack problem (1) with another Tamiya kit, a remote control box.

This worked pretty well, but not ideal. A wireless controller would be much better.

To address problem (2), we got an extra motor kit of the same kind that the tracked vehicle kit included.

I split the drive axle (with a bandsaw) and mounted the two motors side by side. For now we attached the remote control up to the two motors.

Even though this set up is not quite our final goal, it is a lot of fun to drive around.

I found a great page describing making miniature clay plates (in Japanese). I tried out the method and ended up with some pretty nice plates. I thought it would be good to have some bowls too, but it is a little harder to find a good pattern.

I started out with the same clay that I used for the plates found at Tokyu Hands in Shibuya (525 yen).

The clay seemed pretty tough and fibrous, but got easier to work with after some kneading. After I took it out of the bag it came in, I wrapped it up in plastic wrap and put it into a ziploc bag.

Next is the key part. It is a wood mold that I made on a lathe.

To make a bowl I just take a bit of clay, flatten it out on the table and then squish it in the mold.

Here is a bowl after forming in the mold. I trimmed some of the clay from the edge.

Here is a rough bowl!

I made several. Some of the wood grain is visible on the bowls, but I think some sanding will smooth it out. I still need to trim the edges, file, and sand them, but so far I am pleased with the results.