exnailpounder wrote:One of the great things about AL is that it doesn't distort and move when you weld/tack it.
The only AL I have ever seen warp or distort is flat plate, round and square tube and angle usually dont . It will distort when it gets really hot but nothing like other metals that's why everything needs to be restrained. For those little welds the OP has to do...a simple jig or clamp set up will be fine and I highly doubt his box tubing is going to warp uncontollably from those small welds. I wish I has taken pics of the AL diamond plate square tubes I just finished. Fully OS corner welded and not so much as a wrinkle...and not restrained or clamped whatsoever.cj737 wrote:exnailpounder wrote:One of the great things about AL is that it doesn't distort and move when you weld/tack it.
Not sure what AL you weld, but AL surely DOES warp/shrink/twist due to heat. And it does move A LOT.
It is my opinion that you will want to fully restrain the rails while tacking and position and tack the tubes within the rails. Once each tube is tacked 2x on one end (I'd use a 180* opposite tack) swap to the other side and lay down tacks. Ultimately 4 tacks per tube.
Then I would set the bars up so the tubes are vertical, welding the rail/tube connection for one side completely, flip over, then weld the other side. But, I would have the rail I'm welding against fully clamped during the welding process. Let cool, then complete it.
Sidebar:
I do not wish to offend you, but, if you are uncertain about how to weld this, then I would suggest to you that AL is NOT the correct material to use. AL is prone to cracking at the weld if done improperly, and not the best material to choose for such an apparatus, especially when live loads (human weight) is involved. At the very minimum, you should confirm that the section strength of the tubes/rails exceeds the strength requirements. AL will fail without notice under load stress and you certainly want no responsibility for injury to a small person.
-Just meant as a safety concern-
...weird huh?
Admittedly I don't do alot of AL plate or even alot of AL at all but my last AL job was 1/8" diamond plate cut into 4"x5' strips and full corner welded into square tubes to slip over some bollards at my friends bar. No distortion or problems at all...just put a few tacks on them, made sure they were square and started welding. I had to let my torch cool off a bunch of times so I didn't really heat soak them but they were nice to work with. Plate is a problem...especially thin plate. Thin ANYTHING will warp when you heat it but to suggest that all AL severely distorts or warps is plain wrong. Other than AL having it's own characteristics to deal with, aluminum is a pleasure to work with. Now stainless steel will do some amazing things when you get it hot and thin mild square tube will teach you a lesson but AL is nice to work with.WoodpeckerWelder wrote:I've had serious problems welding AL plate (like it looks more like a bowl than a plate when I finish), but I can weld 4x4 1/8th inch square tube on a mitered 90 degree corner top and bottom, inside and outside corners with zero distortion.
That is beautiful! Three weeks??? WOW! If you drill your bars into the box tube so that you're not relying on welds then you'll be fine. Most in-the-know welders won't make treestands or ladders out of AL because of the liability. Even ladder manufacturers use mechanical fasteners on their rungs or they bore and crimp them to eliminate the weak link, which is a weld. Unless you have 400 lb. kids I wouldn't worryBramR wrote:Thanks for the replies guys!
I'll take mky time tacking and welding. As i read your posts i'm not that afraid that i'll get a helicoil.
I'll start in a week or two, and i will keep you informed. Till then i'll keep practicing. I started Tig welding three weeks ago. I got some box and round to practice the bulk of the welds.
Here a sample of my lastest test weld. I'm not at all disapointed. Hope i can get most of the welds like this. I'll keep you informed of the progress.
You obviously have welding and mechanical knowledge so I say weld on...and let us see the final product.
)Opps...we've all run out of gas.BramR wrote:I sliced a box section in halve to check the weld. As you look close there is a line in the bead. Is this the residue of the oxide that floated on the penetration?
This is the inside of the tube.
This is the same weld from the outside. I think I started to cold, that is were there is lack of penetration.
(The black blob on the right tube is were I ran out of gas
Sure does and crack kills, so be careful with that. Before hanging anybody or anything on any item I build, I tend to put it to the ultimate retard test to make sure its all good.exnailpounder wrote:That sure does look like a crack on the bottom of that weld. Even though it looks like you got great penetration, that bulging metal is your base metal that is sagging down and never fused together. Make a small gap between your pieces so when you weld, you will melt in on both sides and that will make a little keyhole that you will dip into. What you did was the same as welding over the top of a crack. Your welds sure look nice though.
That's blistering on the back of the weld, from too much heat. It should look like the start of the weld where it was colder and you just see the original joint between the two pieces of material. Excess heat is also what causes the longitudinal cracking along the weld. I'd try moving a bit faster and/or reducing the current.BramR wrote:As you look close there is a line in the bead. Is this the residue of the oxide that floated on the penetration?
