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.

First attemps at TIG welding stainless steel

I've spent most of my TIG welding practice time on aluminum, but have recently started to experiment with stainless steel (all 304 for now). It's difficult! Most welders say that aluminum is the most difficult because it liquefies quickly and has oxide layer problems, but in my opinion, stainless is more difficult because of the shield gas requirements.
Here's my setup:
.040" tungsten -- my local welding shop convinced me to try this instead of 1/16" tungsten. They somehow thought I could weld with less heat while using .040". I didn't understand it when they explained it so me, and I still don't -- especially since it makes no difference that I can tell.

no. 8 cup with gas lens

less than 1/4" stickout




Here's a 1/16" thick 304 sheet. The upper bead was done with 10CFH argon, the lower bead was 20 CFH. The picture shows the front and back of a simple bead with 1/16" filler. I was using as absolutely little heat as possible, sometimes solidifying the weld pool as I moved, making for an irregular bead. These beads both have major problems. They are pretty gray except on the left side where I finshed the weld and the post-flow cooled off the bead. The rest of the weld cooled outside of the gas shield, turning it gray, which is bad because the structure of the stainless steel has been altered. This will likely lead to corrosion or stress cracks.

I prepped the left side of the top surface to see if it would be any different than the un-prepped right side. The metal has a smooth almost plastic-like feel, so I was unsure if this was normal. It didn't seem to make any difference.

The backside shows major problems too. The upper bead looks better because there was more sheet metal all around the weld to soak up excess heat. The lower bead is "sugared" because it got very hot in an oxygen atmosphere. The weld is close to the edge of the sheet metal, so the heat built up more quickly.

To attempt to fix the topside problems, I've ordered a "large gas lens" setup with some huge gas cups from an online welding store. I tried to order these parts at my local welding shop, but they didn't have them, and were somewhat hesitant to even order them for me. I have no idea if the large gas lens will work, but the parts are relatively cheap.

To attempt to fix the backside problems, I've ordered some Solar Flux B, which was originally made for gas welding stainless steel. The alternative to flux is to build an argon purge for the backside of welds. This purge could be a box, a nozzle, or some other device to make sure the backside is flooded with argon. The problem is that every weld situation (tubes, sheet metal, angle, etc, etc) requires a custom purge setup, and argon isn't exactly cheap either. I'll definitely be posting more information about the flux in the coming weeks.


Here's a weld made on thicker (about 1/8") stainless. The grade of stainless is unknown. Don't mind the soot. I was just too lazy to regrind my tungsten after I hit it with the filler rod. Notice the bead is NOT gray. The thick metal is able to pull heat out quickly enough to prevent problems. Unfortunately, most of my stainless welding will be on tanks and tubes that will never be 1/8" thick. I need to find a solution that will work down to .049" at least.

DIY aquarium chiller

See update here:
http://benkrasnow.blogspot.com/2010/04/titanium-heat-exchanger-for-diy.html

My nano reef aquarium is usually 2-3*F hotter than the ambient room temperature (after the heater setpoint has been reached). This is a problem, since the temperature in my living room is often higher than 82*F in the summer. This puts the tank water at an uncomfortably high temperature (84+), and I think that the corals suffer from the temperature swings as well as the overall high values.

So, how to lower the tank temperature? For a 5 gallon tank like mine, a peltier heat pump like the Coolworks Ice Probe would seemingly be a good choice. I tried building just such a device a few years ago, and it was a big failure. I learned that peltier heat pumps cannot be controlled by raw pulse width modulation (PWM) signals, and they don't do well in thermostatic (on/off) systems either. One reason is that the semiconductors inside the Peltier device do not like the thermal shock of the constant on/off switching. Also, Peltier heat pumps are already horribly inefficient, and using PWM or on/off control makes things even worse. During the "off" cycle of either the PWM pulse or the on/off cycle, the heat will flow backward though the device -- the same heat that the device just pumped during the "on" part of the cycle. Think of bailing out a sinking boat with a bucket that has a huge hole in the bottom. The best way to control the peltier modules is to generate high-frequency PWM, then smooth it out with an inductor/capacitor filter. There is still the problem of the peltier junction's inefficiency, and the hot-side heatsink must be massive with a massive fan to make the system viable. Anyway, I haven't heard anything great about the Ice Probe, nor any other Peltier cooling systems designed for any application that requires a good amount of cooling. I have a thermoelectric refrigerator that is just marginally good enough for its purpose.

So, today's design for a new aquarium chiller will NOT use Peltier junctions, as much as I love the idea. I bought a $99 water cooler that uses a conventional compressor and r-134a refrigerant.
I filled the cooler with tap water, and mounted a Rio pump with an outgoing hose and return line.


The two hoses connect to a stainless steel coil. I've had this thing laying around my shop for a long time. It came out of junked, expensive lab equipment. It is non-magnetic, which indicates 3-series stainless steel. I'm guessing it's 316, which is highly corrosion resistant. Of course, the aquarium purists would insist on titanium, but I don't have any, nor do I think it's really necessary. I'd love to hear from anyone who saw a stainless steel chiller coil corrode, or definitively caused tank poisoning.

I melted a couple slots in my hang-on cheapo protein skimmer (it's not a Skilter, but very similar). I would have used a dremel, but I didn't feel like taking the filter off the tank, and I also wanted to avoid getting plastic shavings in the water. The stainless coil sits down into the slots and is just held by gravity.

The cooler is plugged in all the time. It keeps its insulated water chamber around 47*F. The Rio pump in the cooler is turned on and off by the PID temperature controller that I mentioned in a previous blog post. The controller can be configured to use a longer cycle time (eg 30 seconds) since it is controlling a pump, and it would not make sense to turn a pump on and off once per second as it would be for a heater.

The cooler is rated 86 watts. If this is what the compressor draws while normally running (I didn't check it). I would estimate the cooler can pump about 170 watts of heat (about 580 btu/hr). The coefficient of performance is around 2 for small compressor systems. For comparison, a large peltier device can move around 70W under ideal conditions, at a very specific current/voltage. The coefficient of performance for Peltier devices usually tops out around 1, and is often about 0.5 for realistic situations. So, a peltier pump drawing 86 watts, would only pump about 43 to 86 watts of heat.

I just installed this chiller today, so I'll monitor it on hot days and make another post about its performance.