Off-topic: new toy=TIG welder!

davesisk · Jan 20, 2003

Hey Charlie:

Another thought...Miller has some training materials (video's and CD-ROM). I've bought both videos. They're expensive for what you get, but the "Intro to TIG" video was quite informative. The "TIG setup" video was pretty useless, IMHO. I haven't bought the TIG CD-ROM, but I have heard that it's quite a bit more info than the video, and it's cheaper. See <A target="_blank" HREF=http://www.millerwelds.com>http://www.millerwelds.com</A>...

Of course, I think the best training you can get is the equivalent of "seat-time"...fire it up and weld some scrap, you'll learn an amazing amount by trying some different type joints. If you can get the metal to puddle, then you've got enough juice going. If you're welding without filler (one of the nice things you can do with TIG), then you just push the puddle around with the force of the arc, and back off the amptrol to let it solidify (and repeat as necessary). One really nice thing is that you can see what's happening so well, since there's no spatter and sparks flying! The being able to see part is why TIG can product x-ray quality welds.

Can you tell I really like the TIG process? /w3tcompact/icons/smile.gif

HTH,
Dave

davesisk · Jan 20, 2003

One of the most common automotive uses for TIG is chrome and stainless steel exhausts. What do you think, guys? Should I build some big honkin' chrome hot-rod exhaust for the PT-1418? /w3tcompact/icons/love.gif Can you see it?

Dave

Spencer · Jan 21, 2003

davesisk, Thanks for the extra information and the link. I checked it out on their website and that looks like a great machine. You got a lot more machine than what I got for 2 grand, but I needed something portable that would work off of 120 or 240 volt.

Spencer · Jan 21, 2003

Charlie,
Here is a table from my "Modern Welding" text book. It shows the variables for welding up to 1/4" mild steel when using DCEN GTAW.

Good Luck!

duane · Jan 21, 2003

Dave,

I agree TIG is a sweet process. I have never tried it on sheet metal, but I suppose it would work well, especially since you can melt the base metal without adding filler material.

Our welding engineer used to scold me for 'walking the cup', hey, my free hand is not as steady as it used to be (come to think of it, maybe it was never that steady) Sharp tungsten works good as a toothpick, but a little rough on the teeth/w3tcompact/icons/smile.gif

Duane

davesisk · Jan 21, 2003

New TIG project: gas log heat exchanger

OK, I think I have a first good TIG project lined up: a re-vamped gas log heat exchanger. I've already helped a neighbor make a new grill grate out of some tubing and expanded metal, but this one will require a little more precision I believe.

We have a wood burning fireplace right now. It's a masonary fireplace with glass doors, screen, blower, and wood grate/heat exchanger. I was surprised to recently discover that it's all one piece! Anyway, after our recent power outage from freezing rain, we decided to go ahead and get the gas logs we've been talking about for a year installed (I got tired of slonkin' out into the yard at 4am with tree limbs and ice falling around me to get more wood!) I've bought the gas logs and just have to get a plumber to come install them.

The issue is that I'd also like to keep the blower and heat exchanger deal. With a wood fire, that blower was VERY effective. However, it won't work well (if at all) with the gas logs. The gas logs would have to sit on top of the grate/heat exchanger, which would not only look kinda stupid, but the air circulating through the grate wouldn't get hot (gas log heat goes up!). I've looked at a couple of blowers/heat exchangers designed to work with gas logs, and they are kinda dinky and expensive. One ($250) sucks air from the top of the firebox and blows it out the front, which I'm not sure that I like. We'll be burning ventless gas logs, but we still plan to open the flue at least one click. (The instructions with the gas logs say that, even though they are ventless, open a window about an inch if they will be burning for a long period of time.) With all this in mind, I'd really rather not mix the gas log exhaust with the air in the room to such a high degree (a little is OK). I like the idea of sucking air out of the room, circulating it through a heat exchanger, then blowing it back into the room (which is what the current wood blower/grate/heat exchanger does). There was another model that sucks air from the bottom, circulates it to the top, then blows it out the top, but this one would require the gas logs to sit on top of it and I dont' think I'd like how that looks, plus this unit is $500. Ouch! Seems like a ridiculous price for such a simple thing...

So, what I intend to do is to cut the grate/heat exchanger off of the current door/blower/heat exchanger assembly (the grate/heat exchanger tubes are merely square tubing), weld up a new heat exchanger out of square tubing that will be positioned above the gas log fire (top back of the fireplace), then re-attach it to the blower. Sounds like a good TIG project, don't ya think?

I may get started on it this weekend. Should be a fun project, and instead of costing $100+ to replace the glass doors/screens + $250-500 for a blower, it'll cost about $50 worth of tubing (if that much) plus part of a weekend.

I think the current grate/heat exchanger tubing is 1" or so square and 1/16" thick, so I'll probably use the same thing. It doesn't need to be perfectly air-tight, just pretty good. I'm thinking simple butt-welds (some straight, mostly right-angle) throughout will be the best answer...

I know this is all hard to visualize, but the current heat exchanger is the grate that the wood sits on. I need it to be above the fire now rather than below it...I believe this will be quite a fun and useful project!

Thx,
Dave

Charlie_Iliff · Jan 21, 2003

Great table. Thanks.

EdDekker · Jan 25, 2003

<blockquote><font size=1>In reply to:</font><hr>

3) You need about 1 amp for every 1/100th of an inch,

<hr></blockquote>

Dave a good post but you dropped a zero. Corrected this reeds: You need about 1 amp for every 1/1000th (thousandth) of an inch for steel or aluminum.

In general:
Start with 1 amp for each thousandth of an Inch of thickness (0.001").
For inside fillet welds, increase amperage by 30%
For outside fillet welds, decrease amperage by 30%

For steel and aluminum use this amperage.
For stainless steel, decrease amperage by 30%.
For copper, increase amperage by 100%.
For bronze, decrease amperage by 50%.

davesisk · Jan 25, 2003

Good post...you are correct. For 0.250", you need 250 amps (+/- 30-50% depending on the joint, metal mass, type of welder, type of filler, etc.) These really are just guidelines, though. I've lap-welded 1/4" thick flat stock to the 1" x 1.5" curl arm on the tractor with a 115V 85amp stick welder (6013 rods), so mileage really does vary...

Thx!
Dave