Selecting a Welder....

[Phil]

Yeah a thread about a welder on an RV message board... Really.

Actually while I was at OSH, I took a crash course on TIG welding with the Lincoln Electric folks. It was time well spent. I also took a class on gas welding, but it seemed a little primitive for some of the applications I could see myself using.

Thanks to a pair of misplaced #30 holes, I now have an opportunity to close them up with a weld and reposition them to the correct spot. I just got off the phone with ken@vans and he said the heat is no big deal on this specific part.

So I think I might be in the market for adding a TIG welder to the arsenal. I've got a ton of uses for it beyond airplane specific things.

So the question is which one do I want to buy? I'd like the opportunity to build a tube and fabric airplane at some point in the future (if it presents itself). How large of a welder would I need to get full penetration of a tube airframe?

Also, if anyone has any suggestions/experience on a specific model, please let me know.

Thanks,
Phil

[Auburntsts]

Phil,
If you don't get good answers here, you might want to ask these same questions over on OSH365, if you haven't already. I know there have been some welding 101 type threads that might already cover the answers to your questions.

[scard]

I've been having great fun with a Miller Dynasty 200 with a water cooled torch (http://www.millerwelds.com/products/...ty_200_series/) for the past year. It does just about everything I could imagine wanting to do right now.

[tomcostanza]

The EAA did a webinar on welding with a guy from Lincoln. Of course he recommended one of their units. The cost of entry was in the $1500 range. It would do AC and DC with infinitely variable duty cycle. I don't remember the model, but I think you can view a recorded version of the webinar on the EAA web site. Anyway, there's no way I can justify that expense.

Let us know what you decide.

Clear skies,

[rocketbob]

Personally I don't care for the little TIG boxes because they don't have the duty cycle and amperage to do serious work, and they don't have the plumbing for water-cooled torches. I picked up a Syncrowave 350 on eBay for $750 with the chiller and everything, so if you are patient about looking there are bargains to be had.

[CMW]

I second the suggestion for the Miller Dynasty. I have a Miller Syncrowave 250 and it's a great welder but probably weighs 500 lbs or at least feels like it does. The Dynasty will do everything and more the Syncrowave will do and only weighs 45 lbs. Another advantage of the Dynasty is that you can plug it into anything from 115 single phase - 460 three phase.

[wjnmd]

I bought the above unit several years ago and it provides everything I need. Most likely for what you will use it for that is plenty adequate. They discontinued it several years ago but brought it back because it seemed to be pretty popular. I believe the info packet you got at the seminar from Lincoln Electric has a rebate on that unit or others, also. Now that I have finished my RV-7A, I am learning to weld to work on the steel tube fuselage.

If I could give one word of unsolicited advice, practice for many hours prior to taking on your project. What you do in the controlled environment at the Lincoln Electric booth is far different than what happens in your home environment. The worst thing to do is to make a big hole out of a little one. I have ordered several boxes of scrap tubing from Aircraft Spruce and my welds while not looking good are at least less awful. That being said, welding is a blast!!!!

I also bought the commemerative(sp) EAA helmet and I love it.

Bill Near

[Sam Buchanan]

Originally Posted by Phil

So the question is which one do I want to buy? I'd like the opportunity to build a tube and fabric airplane at some point in the future (if it presents itself). How large of a welder would I need to get full penetration of a tube airframe?

Just recently finished welding my first tube fuselage. Gas welding is still a preferred welding method for thin wall 4130 as is used in our airframes. It seems most fuses are made of 0.035" wall tubing which is pretty thin. The oxy-acet torch is a versatile device which can be used for welding a wide range of tubing thicknesses and has the built-in capacity of normalizing the carbon steel for max strength.

There is, however, much more art involved in making pretty welds than I have currently attained......... ......... but welding the fuse was an enjoyable project.

[akschu]

A few quick comments:

1. I prefer the Lincoln and have a Precision TIG 225. It's as big as you can go and get a air cooled torch.

2. You can get a big transformer based tig or a small compact inverter based tig. The difference is almost double the cost, but the inverter only weighs 40lbs and can weld on 115 or 230v without conversion.

3. Liquid cooled allows you to run a smaller torch and/or more amps which is nice.

4. You cannot weld 2024, so forget about filling holes in most aircraft sheet metal.

5. For building a fuse, I think gas welding is better. Tig looks nice, but requires much tighter gaps, doesn't fully heat a cluster, and can make the area around a joint brittle. So even if you tig, you should use a torch to normalize the metal after the weld.

6. You can gas well aluminum, and in many ways it's nicer than tig because you don't have to weld the backside. If you butt weld 5052 with a torch and flux, you can immediately take it over to the air hammer or wheel and roll the weld flat which allows you to polish the part.

I have a stick, tig, mig, and gas setup, and I find myself doing more and more gas welding when it comes to airplane stuff. If I weld on a tab or need something really small and precision, then I'll tig, but for everything else I'm moving over to gas.

If you want a great little gas rig, or just want more info, look no further than Tinman Technologies:

http://tinmantech.com/

Here is the meco torch I use:
http://tinmantech.com/html/meco_midget_torch.php

schu

[wjnmd]

What are you building Sam? I'm building a Marquart Charger.

Oxyacetylene welding is traditionally preferred for steel tube fuselage but TIG is rapidly taking over. I've done both and I prefer TIG

Bill Near