Propane welder

[Devious Designs]

Originally Posted by GTmike400

Thats something I am going to disagree with. A lot of welding for chopper gas tanks (18gage) is done with o/a. Many metal shapers choose O/A for welding sheet because the HAZ is spread out much more which reduces shrinking unlike the MIG and TIG. Also, o/a is often choosed for sheet because the welds are strong, yet they are very soft (unlike MIG) so they can be planished, wheeled, and shaped. Talk to any metal shaper, most of them will say O/A (a lot will say TIG because its faster).

Even though this might be true for pure fabrication, O/A is NOT for modern cars and bodywork. 1980's + cars use HSS (High Strength Steel) which depending on the alloy used, have a crystalline grain structure that can be destroyed if heated above a certain temperature (700 degrees f ). If the metal is heated to this point or above it will be severely weakened and will cause cracking. So its not practical or logical to use a 6300 degree torch for these jobs, no matter how careful the operator is they will never be able to control the flame to a degree where its safe to use. For this reason auto manufacturers recommend that HSS panels be welded by mig/tig/spotwelds. Not to say that ALL post 1980 cars/trucks use hss, but it would be a good idea to contact your local body shop, or refer to a Haynes manual to find the content of your metal BEFORE using a O/A torch, if not you could quickly do more harm than good.

[mike@af]

Wow, I didnt know that. Most of the o/a work I've seen done is on hot rods and metal fabrication. Thanks for the insight!

[TheSilentChamber]

Thats why the metal started getting alot thinner in the early 80's.

[Cbass]

Originally Posted by GTmike400

Wow, I didnt know that. Most of the o/a work I've seen done is on hot rods and metal fabrication. Thanks for the insight!

Heh, I thought that was to copy the Japanese.

Another advantage of torch welding is that you can preheat and postheat the work piece without having to fire up another torch, saves time when working with the thin stuff.

That being said, I never gas weld.

Best bet is buy a refurbished or new welder off Ebay. You'll save alot of money in the end. Get a Lincoln wire feed welder, 115 volt power so you can run it off of household power easily. You'll still need to change out a breaker so it doesn't keep tripping it. That's against the fire code in most places, unless you have an electrician do it.

http://cgi.ebay.com/ws/eBayISAPI.dll...ory=45032&rd=1

That one is fine for autobody welding, but you'll need a gas cylinder as well. You can get one of those from a gas supply company, buy or rent, your choice.

[mike@af]

Originally Posted by Cbass

...Another advantage of torch welding is that you can preheat and postheat the work piece without having to fire up another torch...

The preheat and post heat is a crock-of-shit. The preheating and post heating cannot be done properly with a torch and in fact does more harm than good. The torch does not slowly and evenly heat the molecules. Plus the temperature is not properly controlled.

A proper pre-heat and post-heat process takes several hours of baking in an industrial oven at certain temperatures depending on the material, hardness, and carbon concentrate.

[PBking82]

Originally Posted by GTmike400

The preheat and post heat is a crock-of-shit. The preheating and post heating cannot be done properly with a torch and in fact does more harm than good. The torch does not slowly and evenly heat the molecules. Plus the temperature is not properly controlled.

A proper pre-heat and post-heat process takes several hours of baking in an industrial oven at certain temperatures depending on the material, hardness, and carbon concentrate.

Damn striaght mike. Proved one of my shop teachers wrong on this. He said that pre/post heating can be done very effectivly with a torch as long as you have "the right touch." I called bullshit on this and challenged him to do it. I used the oven/kiln, he used the torch. Needless to say he ended up with a bent and burnt peice of shit mine was beautifull. Peace-