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Strong backing

Posted: Fri Mar 15, 2013 10:23 pm
by TamJeff
your work. Do any of you aluminum fab'rs do this? Aluminum moves a lot. Many of us don't get to use much in the way of jigs or fixtures, especially once projects start going towards 3D. I used to notice a lot of other fabrications with that bamboo effect between joints etc and it used to irk me. Then when you're done, tweaking something that is all caged in a 1/4 or 1/2 inch requires some substantial leverage. This is what I do. It helps keep things straight and factory looking. Many people who don't weld aluminum a lot tend to treat it like steel, meaning, they will assemble and tack all of the parts together and then weld it out all at once. For those who don't know, this little trick can save you a lot of work and make your stuff just look neater overall.

Image

R6 and R11 framing clamps have to be one of the best inventions of modern times. I save all my oddball drops of angle and such for things like this. The above picture is a piece of 2" x 2" x 1/4" aluminum angle. You can tell by the masking tape (for use with anodized) on it's showing face that it has been used a lot. On heavier material, I will double these up and even employ shims to add pre-stress to help combat warpage. At most a good bump with a rubber mallet will fine tune any remaining distortion between welds.

Re: Strong backing

Posted: Fri Mar 15, 2013 11:05 pm
by delraydella
I've noticed it when I've done large truss like structures out of aluminum tube...there is movement.When i first started doing them, there were many times that i had to cut out internal supports because the whole thing had warped in some weird way. I was used to doing steel and was just starting aluminum. Now I will usually use many horizontal and vertical support spacers that are clamped to the structure itself, but I really like the strongback idea as well.

And you're right about those clamps, they are a great invention. I don't think anyone can have ever enough of them.

Re: Strong backing

Posted: Fri Mar 15, 2013 11:43 pm
by TamJeff
Yes, and put all the braces in place as spreaders etc. I built a hinging base CB antenna once and that was a project that made me really pay attention from then on to be a lot more strategic with my approaches. When we have had people working at our shop, none really thought about it without thinking much beyond the actual welding or that it even moves. Turns out they were just used to working at places with substantial and repetitive fixturing. Free building, not so much.

Re: Strong backing

Posted: Sat Mar 16, 2013 1:50 am
by weldin mike 27
Hey,

Thanks Jeff, another tip to add to my repertoire. When my work used to heavy, (Read HUGE) steel fab, the guys really had to think and some of the old photos showed lots of strong backs and special bracing. Although its not Al, it was how you said, stop it moving because once it does, the hulk and superman wont move it back. lol

Mick

Re: Strong backing

Posted: Sat Mar 16, 2013 4:23 am
by TamJeff
Especially now in the day of DIY and home ops where you don't even have a substantial fab table to use for fixturing, or even straightening after the fact. We had a guy at our shop build a small part and it was racked, so he clamps it down to the table and goes to pushing down on it's extremity and the clamps slipped off and he hit himself in the mouth with the frame and knocked himself silly. His teeth marks were actually in the aluminum. How it didn't knock them out is beyond me.

Re: Strong backing

Posted: Sat Mar 16, 2013 4:50 am
by weldin mike 27
Hey,

Yup, You really have to watch things under tension and stuff like that. Its like "yep this is going well.... bang.... ooowww that hurt." or 911.

Mick