My DIY Tig Cooler & DialArc HF Overhaul

[CharleyL]

This is my first attempt at posting pictures. I'll try again if I fail.
Some other pictures will follow (but not tonight)

Here are some photos of a Miller Dialarc HF welder that we've restored (father-son project), plus a DIY cooler that I recently built for it. (I know that the Miller Logo isn't technically correct on the welder, but a friend made it for me, so I've got to use it).

I wasn't happy with the idea of putting the cooler on top of the welder, so we built a frame/stand to put underneath the welder to hold it. The welder had to be re-painted because a leaking cooler had been placed there and the whole top half of the welder was rust when we got it. The stand under the welder easily holds the cooler, with space remaining to store the foot pedal and TIG supplies. It all looks top heavy, but is surprisingly stable. It won't be seeing the outdoors much anyway. Thankyou duaneb55 for the filler rod storage idea. It seems to be working perfectly, although there isn't very much in them yet. The only uncompleted plans that I have remaining in this restoration are to add some cable hangers to the right side and then to paint the stand, probably black. GTAW is new to us, so this project is the low budget classroom for both of us to get started.

The Cooler -

I did a lot of research before trying to build my own cooler. The thread on this site by the late Sundown (George Bright) provided a wealth of info about doing it, and reinforced my desire to make my own version. My cooler was built from a used Cornelius soda fountain carbonator that I bought for $125 from a restaurant that had replaced their entire soda fountain system. Ebay is supposed to have these always available, but when I was looking they were nearly non-existant. Fortunately, this one turned up on Craigslist and was only 1/2 hour away. It has a 1/3 hp motor, a brass rotary vane pump, and a 2+ gallon stainless tank. I decided to use original tank as the reservoir. This has worked out very well, but with one exception. The top port is only a 3/8 flare fitting, a bit small for filling the tank, but it will do for now. When I figure out how to get acceptable TIG welds I'm going to cut a bigger hole in the top and weld in a larger stainless bung so that filling will be easier.

I removed all of the original plumbing and then re-connected it with 3/8 reinforced plastic tubing to make it into a TIG cooler. I also removed the electronic motor control/liquid level detector PC board from the metal box on the top of the motor. This box is now just a junction point for all of the wiring. For a radiator I added a transmission oil cooler (Imperial Econokool #242009 from Advance Auto - $20). This unit is very small (5" X 12 1/2"), fitting well into my plan, and it already has 3/8 hose connections on it. They have 5 larger sizes available, if you feel that you need a larger one. I ran my welder and cooler for one whole afternoon doing a bunch of practice welds without any radiator. When I shut down for the day the water temperature in the tank was only about 20 deg above ambient, so I decided that the smallest radiator would be more than enough for me.

Using a flat piece of 26 ga galv. sheet metal from Lowes (HVAC area), I made a 5 sided box around the coil with about a 1" space inside between the back of the box and the coil to act as an air manifold. I notched the sides of the box so that the body of the coil would fit flush with the sides and the U bends of the coil's tubing would extend out past the ends of the box. I cut two 3" holes in the back side of this box plus mounting holes around them to mount two 3" muffin fans. I could have used one 4" fan, but I already had these 3" fans - they are Dayton Fans (Grainger 3LE75) The radiator coil just fits into the open side of this box, forcing all of the air from these fans to move through the coil. I then fabricated two welded 5"X5" L brackets from a piece of 1/2X1/2 square tubing and mounted the coil-box-fan assembly to the end of the base of the carbonator using these L brackets and some #10 bolts, lockwashers, and nuts.

Since the vane pump is capable of moving much more water than the torch can handle, I decided to add a bypass valve to the pressure side of the pump to divert most of this excess pumping capacity back to the tank. The pump has a pressure regulator in it that controls the pump's output pressure by bypassing excess capacity and pressure, but it dumps this excess immediately back into the intake side of the pump in a very short path within the pump housing. This technique recirculates the majority of the liquid many times before it ever leaves the pump housing, and this pumping action in itself causes a thermal rise in the liquid (more heat to get rid of). By using a bypass circuit that is external to the pump I can minimize this heating effect. I can also run this bypassed liquid through the radiator before returning it to the tank, thus giving me a constant recirculation of the majority of the liquid coolant from the tank through the pump, through the bypass valve, through the radiator, and back to the tank, which gives me the ability to cool the reservoir of liquid many times before it is used to cool the torch again. Most coolers have the radiator connected in the return line from the torch, allowing the coolant to only receive one pass through the radiator before reaching the tank. My bypass connection constantly recirulates the reservoir coolant back through the radiator, cooling it on each pass down to whatever the ambient temperature is. The return line from the torch dumps directly into the tank where it mixes with recirculating coolant.

For external liquid connections beyond the cooler a 3/8" coolant line runs from one side of the pump output T to the torch connection coupling at the front of the welder. The other side of this T is connected to the external bypass valve. Another 3/8" line runs from the power block at the front of the welder back to the cooler's tank. All of the liquid lines are 3/8" reinforced plastic tubing with 3/8 hose barb and small radiator style clamps to hold them together.

The electrical connections are very simple. I didn't want any chance of accidentally shutting off the cooler, so I decided NOT to put any power switch on it. Instead I plugged it directly into the 120 VAC receptacle on the front of the welder. Whenever the welder is ON the cooler is also ON. This also makes the wiring very easy. I ran the wires from the fans into the box on top of the motor. The original power cord already ran into this box, as well as the motor power cord. Wiring it is as simple as connecting all of the white wires together with a wire nut and then all of the black wires together with another wire nut. The green ground wire in the power cord and the one in the motor cord get re-connected to the existing ground bolt in the corner of the box. If you have green wires from your fans, connect them to this ground screw as well. All the wires of the same color get connected together.

I put a pressure gauge on the output of the pump and I highly recommend doing this. It makes it very easy to check the operating pressure (50-60 lbs) and to set the bypass valve (Carbonators are set for 100-120 lbs). Once you have checked all of your connections and filled the tank with coolant (distilled water) set the bypass valve closed. Start the pump and adjust the pump pressure down to about 60 psi by turning the screw on the side of the pump that's under the brass cap nut. Once this pressure is set, begin opening the bypass valve slowly, while watching the pressure gauge. When the gauge pressure begins to fall, stop opening the bypass valve, then close it back up just a few degrees to restore the pump's set operating pressure. Now remove the handle from this valve to prevent it from being turned accidently. Put the cap nut back on the pump presssure adjustment screw and you are finished with the setup and calibration.

I live in the Southeast and my cooler will never be exposed to below freezing temperatures, so I doubt that I will be using any type of anti-freeze coolant, just plain distilled water. You Northerners should run distilled water until you are sure that you don't have any leaks, and then put that expensive anti-freeze in your cooler. Avoid automobile anti-freeze because it will clog your torch. Get one of the anti-freeze solutions that are recommended for TIG Coolers and use it full strength or in whatever blend that is recommended by the manufacturer. RV drinking water system anti-freeze is a possible cheaper alternative.

The Latest -

Yesterday I added a Radio Shack indoor/outdoor thermometer to the cooler. The outdoor temperature sensor is a small encapsulated bulb on the end of a 2 conductor wire and it fits through one of the top fittings of the cooler's tank and down into the coolant water. A piece of velcro holds the indoor/outdoor thermometer display onto the front of the welder. I can now read both the coolant temperature (outdoor) and the ambient temperature (indoor)just by looking at this display on the front of the welder. This is an un-tried experiment and I have no temperature data available from it yet.

Total Costs

Carbonator $125 Used - Craigslist
Fittings & Gauge 64 Lowes
Hose 12 Lowes
Sheet metal 7.60 (I think) Lowes
Radiator 19.95 Advance Auto
In/Out Thermometer 21.54 Radio Shack
Distilled water 2 gal 1.98 Grocery Store
---------------
$252.07
Labor = about 12 hours

Would I do it again? Yes, certainly


Charley

[ponch37300]

looks great. It is a good feeling when you can build something that you can buy!

[DesertRider33]

Looks great! Nice job on the cooler!

I'd be nervous to have that much weight up so high on top of the cart. These Dialarcs probly weigh over 600 lbs.

[CharleyL]

DesertRider33,

I too was a bit nervous when we first built the frame and then put the DialArc on it. The design didn't seem quite as high on paper, but after it was assembled I tried rocking it from side to side and found that it was much more stable than it appeared. It isn't intended for outdoor use. It will remain inside the shop on a flat concrete floor and I feel that it's quite stable for this environment. It's only outside trip so far has been for these pictures.

Charley

[CharleyL]

I gave the DIY cooler a pretty good workout this afternoon. I had to weld about 60 feet of 1/8 aluminum with my Dialarc. With an ambient temperature of 76.4 degrees and cooler's water temperature at 75 degrees when I started, the water temperature climbed to 94.7 degrees about an hour after I started welding, and then never went any higher. I'm sure that I'll have to push it harder someday, but this convinced me that it will easily handle my needs. I wouldn't have been surprised if it had gone to 120 degrees or above, but it stayed well below that.

Charley

[rode2rouen]

Wouldn't it be cooler to divert your bypass from the pump directly to the reservoir and the return from the torch through the cooler?
To my mind, there is a greater heat gain from the torch.


Rex

[CharleyL]

Rex said: Wouldn't it be cooler to divert your bypass from the pump directly to the reservoir and the return from the torch through the cooler?
To my mind, there is a greater heat gain from the torch.



Rex,

I thought about that, and decided that your way would only pass the heated coolant through the radiator once, where my way would continuously pass all of the coolant through the radiator many times giving it a better chance to cool down. The return coolant from the torch is surprisingly cool. I measured it once when I was initially setting up the cooler and my son was laying a heavy bead. It was only 121 deg. so I decided that with such a low thermal rise that I would be better off with a continuous recirculation of the coolant through the radiator to cool it a little bit multiple times over the single pass method. It's very difficult to cool something when the thermal difference in the air / coolant mediums is so low. Either a very large radiator with a large single pass flow or lots of recirculation through a small radiator with a smaller air flow is required. So far my choice seems to be working very well.

I had initially considered getting the largest trans cooler coil and attaching it behind the fan on the DialArc, as the fan is continuous running. After measuring the torch coolant return temp. I decided that this idea was excessive and I opted for the smaller coil and muffin fans with multi pass cooling.

Thanks for bringing this question up. A lot of thought and trade-offs went into this design. I had planned to add all of this information in my first write-up, but somehow forgot to add it.

Charley

[PilotDan]

Looks Awesome!! Nice job! Post some more pics after you make the larger opening on the cooler tank. I would love to do a project like that some day...