best way to hinge 3" angle iron?

admin

i need to put a hinge on 3"x3"x1/4" angle. i want to make a sheet metal brake. i need to fashion the 2 peices int a capital case "T". i've drawn the s**t out of my idea but am stuck on the hinge. i want as little of a gap between the 2 pieces and try to keep the top flat without the hinge pin protruding.Ideas? piano hinges, pins and collars, door type hinges?Lincoln Idealarc TIG 250 AC/DC, Lincoln 175 HD and one fine grinder.
Reply:Pin and collar is the more likely way to go. You should look at a few brakes and see how they are built; the stresses involved in bending even thin sheet metal will make anything using angle iron not hold a true edge. My small brake is still heavy, and it flexes enough that 4' wide sheet material doesn't want to bend a true 90 all the way across easily. Has to be tuned still, I have been without enough shop space to work with it enough to sweat it.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:1/2" solid rod inside 1/2" schedule 80 pipe makes a good hinge.
Reply:there are several shop built brakes on here and on the hobart board.  Each one approaches the hinge in a slightly different way.  You may want to look at them to get some ideas.
Reply:Thought this may help.Hand made 16ga x 25" long capacity bending brake.Weak areas are the bending in the middle which is why the angle iron/beams have much reinforcement (2 angles welded inside to form a box) The top hold down on my machine needs a verticle tee welded to the top to keep it from bending up in the middle (for wide stuff) and a bevel in front to go beyond 90 degrees. (Someday I'll finist it....)The hinges once made were welded on the ends only after the 2 angle iron pcs were clamped together to insure no gap at the bend line.Never had a problem with the hinge, just not removeable without blowing out the welds.Hinge design credit goes to one of the welding project forums, can't remember which one so my guess is the Miller one.For the thicker stuff I just add 1"dia rod handle extensions inside the existing ones and go after the base is clamped down in the front. Attached ImagesLast edited by Qwert66; 03-19-2010 at 10:22 AM.