Stainless Access Door for LBC proofer part 2

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Below:To stiffen this door opening and provide an area under the door’s skin for removable, tapped SECURITY screws to fasten the door to the canopy, .125 SS flat stock is plug welded to the underside of the skin. This canopy flexes and stress-relieved itself--after making the rectangular cutout, sagging slightly--so a clamp is fastened across the bottom to straighten it up.******TIP---check flatness, straightness after making cutouts, because alignment will change. Prior to and after the door cutout, straightness was checked along the lengths of the formed panel surfaces with an 8’ straightedge. A clamp shown in red boxes was used to lightly squeeze this slightly sagging, canopy center, bringing the surfaces pretty well back to straight. (This canopy is really flexible.).125 x 2.0 SS flat stock is shown plug welded to the skin. .125 x 1.5 SS flat stock pieces are resting at the right and left sides, ready for fitting and trimming. These side pieces were bent to a template, prior to fitting. Plug welding used .093 holes, TIG welding. In tigging this thin sheet, the arc is pointed straight down in the center of the hole, heating and melting the hole edges, making the hole size grow, then rod is added, once the flat stock has begun wetting and fusion.Clamping close on at least one side of the hole helps prevent the sheet from heat bulging uP. I made up some test pieces of sheet and flat stock to test this plug welding and weld parameters before doing the ‘real’ thing. http://www.weldingweb.com/attachment...1&d=1195883992Below-the right and left side, formed reinforcement flats were trimmed to fit, notched for the hinge mounting bolt, underside nut clearance, then plug welded using .250 slug cut holes. This worked better, for bigger plug welds. Both SS end caps were bonded to the canopy skin by adhesive bonding tape, with several tiny fusion welds on either side--but no welds on the top skin area in the RED OUTLINE-belowI’d noticed this prior to construction and considered doing more tacks--then decided it wouldn’t be needed, since the side reinforcements would be formed, one-piece. Well…..the heat of the plug welds (even with water spray cooling) was enough to loosen that damn tape and allow some pulling distortion of the top skin--down. I clamped down on this red outline area, then added more lettle tack welds to secure it, after the fact. It didn’t appreciably affect the door fit….but was aggravating to see this occur, especially when I’d thought to tack up this end cap seam, then talked myself out of doing just that!             This is how we learn things--sometimes--getting the test-first and the lesson-afterwards.These are plug welds, subsequently finished off-not a work of art tig weld display. The idea is to get fusion to the underlying .125 x 1.5 SS, formed, reinforcement with a high puddle to meet this oh--too---thin skin; as quickly as possible for a minimum of heat distortion of the 20 ga. skin. Water spray cooling with air drying was used on the plug welds to help control distortion. [Spray cooling creates metallurgical problems (carbide precipitation, etc.); this isn’t a highly stressed assembly, and distortion will kill the job. Sometimes, we have to break the rules to do the job.]http://www.weldingweb.com/attachment...1&d=1195884244Below-inside view of reinforced door openinghttp://www.weldingweb.com/attachment...1&d=1195884406Below: outside of door fittinghttp://www.weldingweb.com/attachment...1&d=1195884698Below: inside view of finished reinforcement and cutout.http://www.weldingweb.com/attachment...1&d=1195884814 Attached ImagesLast edited by dave powelson; 11-24-2007 at 01:29 AM.Reason: correct errorBlackbird