keeping brackets square during welding

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What is the best way to keep angle iron shelf brackets square when welding? I want to make some shelf brackets out of 1x1x1/8" angle. Can I make a fixture out of 2x2x1/4 angle welded together to form a L , making sure it is square, then clamp my angle pieces to it and weld? Leave them clamped until that are cool? The joints will be cut on 45the degree angles. Is there another method to insure they will be square after welding? Thanks for the help
Reply:Tack it together in a fixture, measure for 90 degrees after tacking. Adjust and then weld.  If the thing always cools and closes up 2 degrees, then tack the next one at 92 degrees before you weld.  Fixtures won't preclude internal stresses in the part that come from high heat.Or add a third leg and make a triangle?   What are you making?--zip
Reply:You need to think and plan about what you want to do and where and when you weld. Simply clamping the pieces and welding away with abandon simply will not work.Metal pulls as it cools. Keep this in mind and plan accordingly. If you weld one side of a piece, it will pull that way as it cools. You can compensate by tipping the piece away from the direction it will want to pull a bit, and then it will pull straight. How much is a bit of trial and error mixed with experience. Thickness of material, length of weld and so on will change how much "tilt" you need to use to have it pull straight. I like to use a bit of a gap when doing tube and such. I can tack one side, then pull it back to square and tack the 2nd side and usually it will stay square. If not buzz off the tacks and try again, possibly with a bit of extra tilt in the direction oppsosite it pulled. It also helps to weld on the sides away from the critical angle 1st. IE if you have a square tube to weld all 4 sides and side A/B are in the direction thats critical, weld C and D 1st and chances ar the A/B side will stay square even if the C/D side moved slightly.The better braced the piece is in the final product the better it can withstand the cooling forces. as well. 2 pieces welded at 90 deg will pull pretty easy. Add a diagonal brace and tack it all up, and it will move less.There's been so many "how to keep corners square" threads here I don't even want  to think about it.Last edited by DSW; 11-15-2011 at 11:01 AM..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks for the tips guys
Reply:Remember as well to use the lowest setting you can for the least heat input.
Reply:1x1x1/8 is fairly bendable. If they come out crooked you could clamp one leg in the vise, slip a pipe over the other end and adjust as necessary.Ian TannerKawasaki KX450 and many other fine tools
Reply:Don't forget the universal fine adjustment tool (8lb sledge) - for some fixtures this can straighten angles very quickly and easily between tacking and final welds - even after final welds depending on weldment size I will tack stuff to my welding table if the angles are critical.Wooden jigs that fit tight and provide good clamping surface can be a big help for odd angles especially.  A chunk of 4x4 or 2x8 cut to fit your preferred angle is cheap, easy and works well.Hobart LX235Victor 250 Oxy-Acetylene Rig (welding and cutting)Bobcat 773F-350, 1999, 4x4, 16' 10K# trailerOutdoor Wood Burner - 10 cords/year