Even more detail for aquarium DIY top-off system

In this post, I'll describe the machines and methods that I used to make the optical sensor head for the aquarium top-off system.

Step 1: Cut off 2" of 1/2" diameter black Delrin rod. Delrin is a brand name for a specific type of acetal copolymer plastic. You can get it at www.mcmaster.com


Step 2: Square-off the end of the rod on the lathe.


Step 3: Drill two holes at 30* to the rod's major axis so that they intersect a few mm in front of the rod's face. You may need to use a punch or dremel to prevent the drill bit from wandering on the sloped face of rod. I like to use the vise-within-a-vise method for drilling angled holes on the drill press.

Step 4: Taper the end of the rod with a coarse file.

Step 5: Use a smooth file to tidy everything up.

I found that the optic fibers should be cut square, and then recessed into the sensor head so that nothing sticks out. This allows air bubbles to form harmlessly in each of the spaces created by recessed fiber ends. If the fibers stick out too much, an air bubble might become trapped between them, and the system will have a "false positive".

More detail for the DIY auto top-off system for aquariums

I've had a few requests for plans of the auto top-off system for aquariums. This project is fairly straight-forward, and I would imagine the most difficult part is machining the sensor head that holds the two optical fibers. This will require a drill bit that is sized just right, and the angles need to be pretty accurate. The wiring and electrical side of this project is very easy, and only requires minimal soldering. Here's some rough instructions and part list that I emailed to an interested DIYer:

This project involves wiring a household electrical outlet. As you know, saltwater is a great conductor and the wiring must be protected from drips, etc. Always disconnect the power when working on the circuit, and use good wiring practices.

I'd start by getting a Keyence fiberoptic sensor FS-V11 (or similar) ebay like this:

http://cgi.ebay.com/Keyence-FS-V11-FSV11-Fiber-Optic-Sensor_W0QQitemZ390020341450QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item390020341450&_trksid=p3286.m20.l1116

Next, you need a wall-wart power supply (AC adapter) to provide low voltage to the Keyence. You'll need 12V DC at almost any current rating (mA rating). Be sure the AC adapter is a linear voltage supply, not a "switching" supply -- it should be relatively heavy.

You'll need some 1mm jacketed plastic (PMMA) fibertoptics. I didn't find any at a great price on eBay. You'll have to hunt around a little. Edmund Optics sells it per foot, so you might be able to just order a small amount.

Get the Aqualifter AW20 pump ($10 or $15)

Get a solid state relay eg Kyotto KB20C02A (Jameco #175214) $6.55

You can wire it all together in a standard electrical box with an electrical outlet from a home improvement store.

The basic idea is that the Keyence device gets power from the 12V DC supply, then controls the solid state relay with its output. The solid state relay controls power to the electrical outlet, which is where the AW20 pump is connected.

I don't know if I would recommend this project to someone who has never done any electrical/electronics projects before. It involves wiring a household electrical outlet, and this really has the potential to cause a lethal shock -- especially around saltwater aquariums.

Another problem is that a malfunction might flood your house! I noted problems about air bubbles. If the fiberoptic sensor head traps a large air bubble, the top-off pump will continue running even after the aquarium overflows. For the first week or two, I used the top-off system as just an indicator -- not risking any floods. You should do the same if you attempt this project. I modified the sensor head, so that I doubt air bubbles will cause any more problems, but you never know.

Feel free to give me more feedback in the comments...

Lathe-turned wood vase

Here is another project that I completed a couple years ago. It was a wedding present for a good friend.

I started by laminating pieces of rosewood, padauk, maple and walnut in a symmetric pattern. After the glue dried, I sawed off the corners, and mounted it in my wood lathe.
This was the largest chunk of wood that I had ever turned. The lathe took almost 5 seconds to get up to speed, and I was more than a little concerned about the wood coming loose.


I only have one proper wood lathe tool. It's a rough gouge, and I use only that tool to get very close to the final shape on most of my projects.

I use chisels, files, rasps, and finally sandpaper to finish the piece. I usually sand to 220 grit while the piece is still on the lathe. For the final pass, I stop the lathe and sand by hand in the direction of the grain.

I built a crazy-long extension for a Forstner bit.


I made an acrylic tube that sits down into the vase, allowing it to hold water without damage to the wood. The top section of the vase is painted with black semi-gloss. The wood finish is either wipe-on polyurethane or a Tung oil finish (I can't remember).

Bent TIG electrode = trailing shield?

Do you think this looks messed up?

Check out the welds that I can make with the messed up electrode. This is 1/16" 304:
I purposefully bent the electrode in the direction that I was moving the TIG torch. That way, there was a lot more gas coverage behind the arc than in front. It worked wonderfully! Even near the edge, the heat buildup was much less of a problem. I think the next step will be to make a trailing shield for the torch. Trailing shields are available, but only for amazingly high amounts of money. One alternative might be the "Monster nozzle". It could be large enough to act as a trailing shield.

Improved stainless welds with large gas lens

My new TIG parts just arrived today, and I had to do a quick test. In short, the large gas lens makes a huge difference. Take a look at this beast: #12 cup with "large gas lens" and 1/16 tungsten


I am using the same exact 1/16" thick SS304 sheet metal that I have been practicing with all along:

Compare that weld bead to the pair of beads in my previous post. All settings are exactly the same except for the gas lens. Well, I guess I was using .040" tungsten in the previous post, but that should have helped if anything.


Here's a few more. I've heard that "salmon color" is the best thing a stainless welder can hope for. I changed the flow rate from 10 to 20 CFH going from top to bottom -- not much difference. The bottom bead had a longer post-flow, so the tail of the bead has less purple/blue.

The backsides of these welds are pretty messed up. I'll report about the Solar flux later.