Post
by larry cottrill » Tue Dec 16, 2008 2:39 pm
Well, Jon, I am an oxyacetylene weldor, tried and true, and I love it. And yes, I have even welded stainless with it, though I'd be hard pressed to recommend it for that (I only mention it because that's what most people want their pulsejets made of, naturally). For the kind of stuff you're talking about doing, I would consider oxyacetylene ideal. Note that EVERY method has its strengths and its drawbacks. But I think, for lightweight welding and cutting of mild or high-strength steels (such as chrome-moly aircraft / bicycle tubing), oxyacetylene has no peer.
You are correct that for a hobbyist, it makes MUCH more sense to own cylinders than the rent them. I think around here, I can get both oxy and fuel cylinder refills for about $120 US, and mine are probably bigger than what you're talking about. Buying the cylinders will cost you more than that, but that's a one-time cost. You will never directly pay for having your cylinders tested (as they must be, every five years). Here's why:
When you have "owner cylinders" and you take them in to be refilled, you don't get them back!!! Instead, you get two identical "owner cylinders" already filled, so you're back in action again right away. The first time you go through this, it's fairly distressing, because you're giving them bright, shiny new cylinders and picking up two that (probably) show signs of normal use (scratched paint, little rust spots, etc.). This is just the way it's done, though if your local weld shop is big enough to actually do their own re-filling, you MIGHT be able to talk them into actually filling your own cylinders when they get around to it and let you pick them up a few days later. But, unless you "know somebody" at the shop, I doubt they'll do this for you. So, just accept it. What you get in return for this weird definition of "ownership" is that, by law they cannot give you cylinders that are due for testing, i.e. you always get "current" cylinders you can be sure are safe. So, accept the "system" and don't worry about what your cylinders look like after the first time you take them in empty.
Even for small work, do not buy the smallest, cheapest outfit (regulators and tips) you can get -- the tiny regulators on these are just too small to maintain pressure accurately as you use them. If you can afford it, get more of a "medium size" outfit with decent brass-body regulators (the "old fashioned" look). The first time you do any cutting, you will appreciate having a good-sized oxy regulator; the small ones are pathetically inadequate. Places like scrap yards that do cutting almost exclusively (and have to do some heavy work) get the hugest oxy regulators you can buy -- they dwarf the acetylene or propane regulators on the fuel cylinder. The worst feature of any welding outfit is the hoses, which are almost always too short for a practical shop environment; many shops will let you "trade up" to longer hoses (you want a MINIMUM of 25 ft, in my opinion) when you buy your outfit from them, for a few dollars more. You should also add a non-return valve where each hose mates with the regulator; these add almost nothing to your cost. Most outfits don't have a small enough tip for REALLY thin welding, so consider buying an extra one for this. You'll get a spark lighter with the outfit, and probably a cylinder/regulator wrench. The goggles provided are usually the usual 1890s version, and you should buy a nice pair of modern soft-shell ones -- you can even fit them internally with closeup lenses, which I always use since I now need reading glasses for anything up close.
It is impossible for me to estimate what size for you to buy. I would say it depends more on the degree of portability you need than your usage. My cylinders are about 4ft tall (acetylene) and 5ft tall (oxy) and are chained into a small hand truck, and this is portable enough for me -- I have lugged them all over the place in our back yard, etc. for different weird jobs. The lack of any need for electrical power for welding/cutting is a huge blessing when you live on an acreage! I need refills about once every four or five YEARS, but then I do almosy no cutting. Keep in mind that, in general, it is unwise to portage the rig with the regulators attached, for safety reasons. This sounds like a hassle, but once you're used to doing it, detaching and re-attaching the regulators just takes a matter of minutes to perform (you can have a lot of fun with the left-hand threads the first couple of times! Ha). You also need to be careful to keep the connections free of dirt, grease, oil, etc. when they're not connected, but this is just a matter of a baggie and a rubber band for each regulator.
Good luck! With guidance and practice, I think you will find oxyacetylene welding to be extremely useful, and an intersting and enjoyable experience. I hope Mike will chime in with some comments on his experience with the Henrob torch.
L Cottrill
. I'm ok with the fact that it will take more work to get the hang of than a MIG or TIG, and my uncle (who let me try his) said he would make sure I was doing things right.