Madmike, The more practice the better. I'm just a home shop guy with some extended education classes for local community colleges but I find the more I do the better the finished product looks. When I started my truck rebuild with full pen welds they looked terrible (good welds, just not pretty) but by the time i finished the rebuilds the welds were looking like they came out of welding shop.

My first post didn't answer one of the questions I meant to. [/QUOTE]Anyone know about a propalene setup as opposed to acetylene? I've heard you can get a real hot flame with it, a guy demo'ed it to a friend of mine and he said it cut thru 1" steel ina single pass, clean asa whistle[QUOTE]

Propane burns at a maximum flame temperature of 3800 degrees in a controlled settings but in practicle useage the average temperature achieved with air may be closer to 2500 degrees. Using bottled oxygen with propane will bring the temp closer to the 3800 degrees. Mild steel melts about 2700 degrees which is the temp necessarry to do a fusion weld. It is possible to weld with propane and oxygen but it works a lot better for brazing.

In contrast the concentrated flame of an oxy/acetylene torch has a temperature of about 6300 degrees. This works a lot better and is a lot more efficient than propane to bring the base metal to welding temperature. As for cutting with propane, check with your local metal fab shops. If propane was a good deal more of them would be using it. It is my understanding propane will melt the metal away which is a whole lot different process than using an acetylene cutting torch.

 

Thanks for the info, maybe I misunderstood what he was talking abt then....I'll stick with my oxy-acet.

 

As for doin sheet metal witha MIG, I was always told to turn ur wire feed way down andcrank the amps, and just do a bunch of tack welds. As soon as it arcs, let off.

Actually, your wire speed and amperage go hand-in-hand. It does depend (to an extent) on what gauge sheet metal you're fabricating on. If your speed isn't relative to the amperage, you'll get a lot of splatter and hardly any penetration. When I used to weld (before I got a new carrer) I would always set my wire speed about 1/4 lower than the amperage, after that you just have to fine tune it to get the best results. You are correct on using the " tack welds and let off", but that mainly applies to 16ga. or less. Btw, I don't use anything but a Miller 250 mig. Tried others, but they failed the minimum stress tests that I had to meet.

 

If you are thinking about mig i have ran miller, hobart,GE,Esab and lincoln welders. From experience i have learned that a 200 amp lincoln will outweld a 300 amp Ge and a 250 amp esab. there are less feed problems, they are easier to adjust for current, and they will weld anything up to 3/4 inch plate steel. I have also found lincoln stick and mig welders to have better arc characteristics than any other brand i have run.

 

if you are going to do a lot of brazing or cutting go with the oxy propane system it will cut smoother than acetylene and will be much easier to braze with. I have an an oxy propane system and use 2-3 oxygen bottles per propane refill with oxy aceteylene you will use about 2 acetylene bottles per oxygen bottle and acetylene is expensive when compared to propane. If you are going to weld go with acetylene because propane will not weld at all. but brazes will stick with propane when they will not with acetylene. In fact oxypropane systems were developed for brazing car bodies together by the automakers in the early 1900s

 

[/QUOTE]but brazes will stick with propane when they will not with acetylene.[QUOTE]

The lower temperatures of the propane setup may make it more forgiving for use in the brazing process but anything that can be brazed can be brazed using acetylene. It's all a matter of controlling the temperatures. The metals being heated don't know what method is being used to heat them up. Brazing with acetylene is mostly a matter of using the proper tip size, using the correct gas pressures for the tip size, and controlling the distance the flame is held from the metal being heated.

 

Just for fun...

When I first started auto DIY I used a MAPP gas and OXYGEN set-up. Ever see those little suckers in Lowes? For like $50.00? It has a yellow cannister and a red one and a cheap little torch? The same guys that sell the blue propane bottles Benzomatic (or somthing like that).

I used that little guy to braze and cut all sorts of things (including exhaust work). It was very handy for heating stuck bolts too. Portable to say the least. The down side was that the oxygen tanks lasted barely 10 minutes when cutting (melting really, although you could cut using oxidation) so the expense in the long run may have been higher (10 bucks a pop).

I now have a set of torches and a 110V Hobart (good little unit) but back in the day you'd be shocked at what I got out of that $50.00 unit. I brazed a fitting for my EGR valve aspirator tube into my exhaust manifold ages ago and she still holds!! Ah, memories...

 

I'm not sure the name was Benzomatic but those blue bottles were the back bone of the gas bottle line-up in my shop for quite a few years. A person couldn't cut or weld but they worked for soldering, silver brazing, bending small metal parts, and loosening frozen nuts. I'm not saying they were fast or efficient, but they worked. Ah the memories.....lol

 

Great for heating and soldering indeed.

Madmike33