From: muratlanne@gmail.com   
      
   "Richard Smith"  wrote in message news:m1a5d7bsh1.fsf@void.com...   
      
   I have contributed - this has started to happen.  I used "the bubble"   
   (spirit-level) on some fabrications, and found that what it cost in time   
   to set things off parallel at the first stage was more than made-up for   
   by the "ideal" time it took to fit-up and weld the rest.   
   Show the approach and the corrections, the owner and designer where on   
   the press-brake with dial-gauges, etc., and made adjustments.   
   ie. there is something positive going on. ...   
   -------------------------   
   Could you expand on that?   
      
   I found out the hard way how much welds can distort a precise alignment,   
   especially a weld across an inside corner. I had to jack the sawmill ladder   
   frame parallel (enough) and mill the shrunken gap in a bending brake hinge   
   assembled from surface-ground plates. The surface welds along the sides of   
   the plate stack didn't destroy the 0.005" fork/tongue clearance, but welding   
   inside the fork did.   
      
   Do diagonal or fish mouth/tail ends (vs square) improve stress distribution   
   and/or reduce distortion in butt joint splice plate welds? One end of the   
   splice plate would be bolted, the other welded after aligning the beams.   
      
   When I was building custom machinery the press brake operator and welder   
   compensated for distortion, the all-welded machine frames were square to   
   1/32". They were mostly multiple 19" relay racks that we had to fit the   
   equipment panels into, so we would see any error. I knew they marked the   
   prints with allowances for bending and welding but they didn't share, and   
   the front surface welds had been ground and filled as invisible as auto body   
   repairs.   
   tia, jsw   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)