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I am building paver trays for a new septic system that will have 6 access points under a brick paver patio. The access points need to be opened and inspected twice a year. (underside lot on a lake) I made a 3 section frame that I welded in the tabs last night in the corners that support the actual trays (the corner tabs will actually sit at grade on the dirt) Came out tonight and found the middle of humped up off the table about 3/4. 11ga stainless. Sides are 4. Is there a way with heat or hammer to stretch back out the heat shortened underside?I dont want the top side to shrink and get wavy so I wasnt sure if heat bending like I have used to straighten square tube would give the desired outcomeI also thought about about brute force like supporting the middle and figuring out a way to set something like my truck tires down on the ends
Miller Dynasty 200 DXMillermatic 211Lincoln X-Tractor 1GCHypertherm Powermax 1000
Reply:I would heat around the lower edge (table top side) of that joint around the weld. Then cool it with water use a damp rag. Take your time heat small areas and cool. The cooling / contracting does the bending. You might also support those warps (straighten) with a heavy flat plate and clamps to encourage the direction of bend.Why so much weld?
Reply:
Originally Posted by tapwelder
Why so much weld?
Reply:Stainless expands (and contracts) FAR more than typical steel,, so you are getting more shrinkage than you might expect.I almost got fired from a HUGE company,, because I said stainless had to shrink when welded,,The company flew 6 welding engineers in from other locations,, "to educate me",,It ended up that they all agreed with me,, BOY, I ticked off some high level managers that day!!
All of that because I said we had to redesign in .030" extra length of a part that was to be welded, so that it could shrink,,The part was two stainless tubes about 1" in diameter that was basically butt welded,, with 100% penetration required,,YES, it was gonna shrink,,,I still have one of the parts hanging on my workshop peg board,, it is fun for me to look at,, over 40 years later,,,
Reply:Honestly, just rebuild it. I do a lot of stainless and really you need to learn when to just stop playing with it.Also, welcome to stainless 101. It sucks and it is a very long term lesson. Yes, you welded a lot. You need to really make it out of angle, or something else with a bend in it, as the structure of the metal will resist SOME bowing. The more filler wire you add, the more the stainless will shrink. So tig fusion welds are great for not warping it.You will probably be best off, if using mig, to make the outer frame and the cross supports separately, and then bolt then together. This will eliminate most of the twisting in the outer frame and you can just adjust the bolts for any twist with the cross members. Sent from my SM-G960U using Tapatalk
Reply:I use chains & hydraulic jacks to ease a bow out of things sometimes. In this case, balance a 4x4 block on the top of a jack (drill a hole the size of the ram about 1" deep helps) flip the frame upside down, chain each end to the table top & jack the bow out of it.
Reply:Or set it on some blocks, put it under a truck, and put something on top of it that will support a floor jack. Carefully start "lifting" the truck and watch it bend.I straightened a long gate I built using this "jacking" method. Carefully slid it along under the truck to push on all the right places.I positioned everything so the gate was behind the rear wheels and the jack was lifting on the underside of the trailer hitch.ktech
Reply:AND,, how much do you trust the flatness of those two weld stands,,?AND,,, how flat is the area of the floor the stands are sitting on?You have to measure off a flat surface to determine if your assembly is correct,, or not,,
Reply:I agree, too much weld and probably not the best choice of materials. IF you are getting paid for this and want repeat customers, scrap it and redo. IF you can get it close, it's gonna look like shlt. Sent from my iPhone using Tapatalk
Reply:
Originally Posted by Country Metals
Also, welcome to stainless 101. It sucks and it is a very long term lesson.
Reply:It is lot of work to do job .It best to do job right. Cutting and and backup bar with hammering. Then reweld at right temperature. Dave
Originally Posted by jay gill
I am building paver trays for a new septic system that will have 6 access points under a brick paver patio. The access points need to be opened and inspected twice a year. (underside lot on a lake) I made a 3 section frame that I welded in the tabs last night in the corners that support the actual trays (the corner tabs will actually sit at grade on the dirt) Came out tonight and found the middle of humped up off the table about 3/4. 11ga stainless. Sides are 4. Is there a way with heat or hammer to stretch back out the heat shortened underside?I dont want the top side to shrink and get wavy so I wasnt sure if heat bending like I have used to straighten square tube would give the desired outcomeI also thought about about brute force like supporting the middle and figuring out a way to set something like my truck tires down on the ends
Reply:material expensive. maybe zip wheel some vert slices on your outer bows side at ur crossmember welds , clamp/beat it so close the slices, and reweld. other thing to consider, if all 4"/full heigh isnt nedded, grind tops/bottoms where needed so its flat.Last edited by 123weld; 06-11-2021 at 12:57 AM.
Reply:Easy, just unweld it. Then, when you start welding again don’t put so much heat into it at one time. If you don’t have access to an unwelder or a time machine, then buy a hammer.
Reply:Agree with way too much weld. 1/2" skip welds on the gussets would have sufficed, maybe even less. Also doing short welds and jumping around to limit heat input would have helped. Not sure if it could be straightened without making some cuts in it but I'd treat it like a skid. Used to build lots of heavy skids up to 72'x20' and 20,000lbs.+. Everyone one of them bowed and needed heat straightening. Tops were welded first and then the skid was basically rolled so all the welds could be done flat. To straighten, we turned them upside down with blocks close to the 4 corners under the main beams and heated the long rails where all the main cross members went. Just enough heat to get it to start glowing. The weight straightened the skid on cooling. I don't know if a similar technique would work on your trays? Maybe if you turned it upside down and tried heating opposite the cross members on the outside runner it would straighten? Worth a try since it's already warped. Heating a little more on the bottom so it shrinks more than the top may help.Last edited by Welder Dave; 06-11-2021 at 02:00 PM.
Reply:It just lot of work to fix right.If someone made that mistake it save Monday work rework day.3/4" backup plate and 10 pound selsledgehammer. Just doctor order for a hangover.Dave
Originally Posted by Welder Dave
Agree with way too much weld. 1/2" skip welds on the gussets would have sufficed, maybe even less. Also doing short welds and jumping around to limit heat input would have helped. Not sure if it could be straightened without making some cuts in it but I'd treat it like a skid. Used to build lots of heavy skids up to 72'x20' and 20,000lbs.+. Everyone one of them bowed and needed heat straightening. Tops were welded first and then the skid was basically rolled so all the welds could be done flat. To straighten, we turned them upside down with blocks close to the 4 corners under the main beams and heated the long rails where all the main cross members went. Just enough heat to get it to start glowing. The weight straightened the skid on cooling. I don't know if a similar technique would work on your trays? Maybe if you turned it upside down and tried heating opposite the cross members on the outside runner it would straighten? Worth a try since it's already warped. Heating a little more on the bottom so it shrinks more than the top may help.
Reply:One of those jobs you really have to think about before jumping into with both feet. Stainless steel isn't cheap either.
Reply:
Originally Posted by SweetMK
AND,, how much do you trust the flatness of those two weld stands,,?AND,,, how flat is the area of the floor the stands are sitting on?You have to measure off a flat surface to determine if your assembly is correct,, or not,,
Reply:
Originally Posted by BD1
I agree, too much weld and probably not the best choice of materials. IF you are getting paid for this and want repeat customers, scrap it and redo. IF you can get it close, it's gonna look like shlt. Sent from my iPhone using Tapatalk
Reply:Thanks everyone for the helpMany valuable lessons learned especially with stainless. Using the cut vertical at the cross members and reweld method I got it straight enough (one corner was about ~1/32 low from my 4’ level when finished)
Miller Dynasty 200 DXMillermatic 211Lincoln X-Tractor 1GCHypertherm Powermax 1000
Reply:Nice jobSome lessons are best learned after swearing a lot and then settling down and addressing the issue. It has a very long term effect on how you approach projects for the rest of your life.Sent from my SM-G960U using Tapatalk |
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发表于 2021-9-1 23:17:50