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View Full Version : Aluminum welding project presents a big dilemma



winchman
08-05-2011, 01:14 AM
We've got this big aluminum railing project going on at the school. It consists of three sections. One is straight and 27 feet long. The other two are about 18 feet each with a short ell on one end. The top rail is 2 1/2" schedule 40 pipe, and the uprights and intermediate rail are 1 1/2" pipe. The rails will be installed on top of a brick retaining wall between a new classroom building and the existing administration building. The contractor wanted $11,000 for the job, but they decided to have the welding class undertake the project to save money.

The instructor assigned one of the older students to help me cut the pieces and tack them together. He's a great helper, but he doesn't have any experience welding aluminum. We got the 27-foot-long section tacked together today, and I'm really pleased at how well it went. All the joints are square, the uprights are parallel to within a small fraction of an inch, and the intermediate rail is evenly spaced from the top all along it's length. It's as close to perfect as one could want.

BUT, there's a LOT of welding left to do, and it's going to be in all sorts of positions because of the pipe-to-pipe bird-mouthed joints. Of course, that's complicated by the sheer size of the weldment. And we haven't even started on the other two sections yet.

There's only one student in the class with any aluminum welding experience at all, and most of that has been in a booth with thinner material. The instructor and I have been coaching him for the past two weeks on the pipe joints, but he's struggling, to say the least.

I LOVE to weld aluminum, but it's hot as blazes here, and I'm 65. I can wring the sweat out of my shirt most of the day when I'm working. We can't use fans because they blow the shielding gas away. It would really be nice to turn the project over to the youngster for the rest of the welding, but we put a lot of effort into getting it started well, and I'd just hate to see it ruined.

I know it's a school, and the "real" student should be working on this project, but I want it to look good. I'm having a really hard time letting go of this project.

EddyCurr
08-05-2011, 01:47 AM
Cut small segments and fit them together for the student(s) to practice
on. Afix your coaching cap to your head and show your stuff by helping
to bring out the best in the pupil(s).

Once the results of practice joins are reasonable, are there railing segments
in less visible areas that can be tackled first?

It seems that the difference between the contractor's quote and the cost
to keep the work in house leaves a little latitude for replacement of material
that maybe doesn't pass first inspection (assuming that the unsatisfactory
work can not be salvaged.)

For yourself, if time permits, consider rigging up or purchasing a Cool Shirt (http://www.coolshirt.net/)
to help beat the heat. Some hardware store vinyl tubing, a t-shirt,
a pond/fountain/aquarium pump and an ice chest make a good foundation.

.

doctor demo
08-05-2011, 01:49 AM
Would mig welding the intermediate rail be an option ?
It would speed things up a great deal and it is farther away from the eye.
Sounds like a lot of work, I did a bunch in stainless once and swore I'd never do that again. Heck 1-1/4" sch40 black is getting to be too much trouble, I guess I've just reached the limit on hand rail.
Steve

jnissen
08-05-2011, 01:53 AM
Are you tigging this together? The MIG based spool guns work fairly well. Recently was involved in a large aluminum frame for some awnings. The MIG based gun worked surprisingly well. While not a real fine bead it worked great for larger pieces. I would think it would also work in this situation.

EddyCurr
08-05-2011, 01:57 AM
"The instructor and I have been coaching him for the past two weeks on the
pipe joints, but he's struggling, to say the least."EddyCurr fails reading comprehension.

What about recruiting other members of the class to the practice sessions,
even though they have no prior experience welding Al? There is a certain
amount of craft to this kind of welding and some people bring an innate ability
that others simply do not possess.

.

macona
08-05-2011, 02:54 AM
Unless you have a high end pulsed mig the welds will not be aesthetically pleasing.

This job may be beyond your scope. It time to bring in someone.

winchman
08-05-2011, 09:05 AM
We're doing TIG welds with a Miller Synchrowave 250. We have an old spool gun, but we've never been able to get consistently good results with it.

I've cut several dozen sample pieces of pipe with bird's mouths for the student to practice on. It's not easy having to deal with the uneven heat absorption of the through piece compared to the cut piece while working from vertical to flat around a curve while keeping the bead width even.

I learned to weld aluminum pipe repairing soccer goals and building new ones. I'm really proud that none of the ones I built or fixed has come back for more work.

Wow!! That Cool Shirt would be...er...really cool.

vpt
08-05-2011, 11:20 AM
I run the fan when I am tig welding in the shop. I just use a blocker of some sort in front of the weld I am doing. Most of the time it is a cardboard box.

Scottike
08-05-2011, 11:38 AM
Perhaps, you can make a class lesson out it by bringing in someone with more experence (certified?) for a day to help trouble shoot what he's doing wrong or give him some tips on how to do it right. But, often times it just boils down to practice, practice practice.

BigMike782
08-05-2011, 12:25 PM
If time is not a major factor there has to be some cream in the class that will rise to the top.Given enough natural talent,some expirienced over sight and some time I cannot believe this is beyond the learning ability of the class.

danlb
08-05-2011, 12:58 PM
The savings from the $11,000 contractor bill will pay for a real nice spool gun that you can then use to teach the kids for many years. :)

I thought that with non-professional projects it was perfectly OK to use flap-sanding disks in the angle grinder to make welds look better. That and Bondo and a coat of paint. :)

Seriously, look closely at similar railings at the mall, city hall, industrial parks, etc. They are often pretty crude. Well built is more important than aesthetics sometimes.

Dan

Fireman11
08-05-2011, 01:12 PM
Hey make a teaching system for it:
Make 5 or ten sets of practice joints. Have the class watch you weld one, then have them each weld their joint. Discuss it with the class. Repeat. Have the class weld the railing at the end of the exercise and put a plack on it at the end...

Also even if you have to rent a couple of welding machines you are still comming out ahead.

By the by I have been welding coke cans together by their bottoms (or trying). Then I went to do some stainless tube, it was like running up a hill and carrying someone on your back: When you drop them off its like you are floating. After futzing with the cans my Tig ing was noticably better...

wierdscience
08-05-2011, 09:40 PM
Build yourself a glove box.

It's what I've done when Tig welding outside.Just a simple box with a pair of bead blast cabinet gloves in the side notched out to fit down over the pipe and a flame blanket to drape underneath for a bottom.
The top can have filter plates in several places so there is no need to wear a helmet.Just hang a towel over your head to block the Sunlight.Purge the box with Argon.Run you torch right in through the bottom.

With this method you can have a patio umbrella for shade and as much shop fan as you want and not affect the process.

vpt
08-06-2011, 10:38 AM
By the by I have been welding coke cans together by their bottoms (or trying). Then I went to do some stainless tube, it was like running up a hill and carrying someone on your back: When you drop them off its like you are floating. After futzing with the cans my Tig ing was noticably better...


Start welding razor blades together too.

EddyCurr
08-14-2011, 12:47 PM
Any follow-up news ?

.

Forrest Addy
08-14-2011, 03:17 PM
Sorry for the hijack but speaking of welding and coke cans:

It's probably an apocyphal story but back in the 80's it was alleged that a weld school made a free standing Christmas tree of welded coke cans complete with a trunk and many branches. This coincided with the advent of the first digital variable pulse width welders. Another elaboration I heard was a Jewish student welded up a Menorah from soft drink cans favored by his community as a bid for equal representation.

I never saw the tree of coke cans or tracked down the school that made it. Those who heard the story always opined it was built by another school half a state away.

Now that the story is out again we'll probablly see all sorts of cultural icons of welded beverage cans crowding for attention in a weld school lobbies and weld equipment sales showrooms demonstrating the quality of their equipment and the prowess of their practitioners..

winchman
08-14-2011, 06:22 PM
I welded together some aluminum lawn chair tubing a while back. I haven't tried anything thinner.


Well, the youngster did a pretty good job on the rest of the long section of railing that I had tacked together. That's all he had time to work on before the quarter ended.

The instructor wanted to get the project completed so the maintenance people could get it installed over the break. I got a friend to assist me in framing up the other two sections, and we got them done in two days. I did all the welding. I'll get some pictures when they're installed.

EddyCurr
08-15-2011, 12:40 AM
Well, the youngster did a pretty good job on the rest of the long section of
railing that I had tacked together. That's all he had time to work on before
the quarter ended.That's great news.

This is a positive experience he will carry with him through out the rest of his
life. I think back to such events in my past and can imagine the sensation
he might feel whenever he walks by that railing.

Well done.

.

metalmagpie
08-15-2011, 01:43 AM
I think you guys got lucky. Anyone who has welded a bunch of pipe railing knows how bad warping can bite you. Typical scenario: long straight run with one vertical leg. Fit the leg up under it, weld all around then stand around and swear when you realize the bottom of the leg is an inch off the ground from the top bar warping on you. The only solution is to prewarp the top bar, literally bending it upwards on either side of the joint, then weld and let it back down.

I do this with a portapower and a piece of 2x2x1/4" square tube and a couple of 3' double strength slings. Use the square tube as a strongback spreader and push up on the center of the square tube with the slings out at the end of the tube, around your long pipe. Jack up the portapower until you've got a positive upbend maybe 3/8" on either side out about a foot from your joint. Then make your weld and let it back down.

On some railings it's mandatory. Stainless moves the most. I really don't know how much aluminum moves, it's just something to keep in mind.

And yes, this is definitely a job for a spoolgun.

metalmagpie

winchman
08-15-2011, 04:24 AM
I was surprised at how little warpage we had. In fact, I'd say it was negligible. I came up with a pretty effective way of clamping the loose pieces in place for tacking and some of the welding. We kept the parts hanging off the table supported with adjustable stands.

Having that large flat table really paid off on this project, and I'm sure it'll keep right on making things easier.

We've got some aluminum pipe in both sizes (2 1/2" and 1 1/2") left over, so I'm trying to think of something to build with it. We bought a notcher (goes in the ironworker) for 90 degree joints on the small pipe joints, and I can cope the ends to fit the large pipe with our 3" face mill.