Heat shrinking suggestions

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Working on this 5/8 ss shell that is nearly an inch too big on the diameter and I'm looking for advice on heat shrinking it. You can see where I've already done some heating but the amount of movement I'm getting is minimal.Sent from my SCH-I545 using Tapatalk
Reply:I would use a #2 cutting tip in your torch. Start in the center and heat a cherry red line. Soon as you move to the next line, have someone spray water on the heated line you just did. Start in the bottom of the pipe, and work your way up the walls. Do not start the second set of lines until the pipe is dead cold. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Here is another example of how heat can roll plate.  Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I'm not seeing any movement at all not even a measly sixtheenthSent from my SCH-I545 using Tapatalk
Reply:Go with a bigger tip, and heat a solid line. And use a straight edge. Do you happen to have a tractor torch?Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPGo with a bigger tip, and heat a solid line. And use a straight edge. Do you happen to have a tractor torch?
Reply:Do you need to maintain at true semi-circle radius?  Or are you just trying, now, to bend it like a taco and get the legs of the semi-circle 1" narrower? Heating the metal is Voo-Doo for internet welders. Simple to type, very hard to do, especially evenly across a part that is easy to see and measure and fight fitting the misalignment. I don't see any way except adding more of what got it to its current state. add more cowbell.
Reply:I'm looking at all those little dots in there and all you are doing is pissing it off.  When CEP says heat, he means heat!5/8 plate is kinda thin for heat shrinking without using strongbacks ime, although I have no experience with SS.  Your dinky pony bar clamps don't count as a strongback.  I'd make a couple of solid clamps, with a section thickness at least 1/4 of the plate I was trying to bend, since the strongbacks will be in tension only.  You could also put a strong backer along each edge, and weld straps across the backers.
Reply:When doing something like this, I really like to use a tractor torch. The tractor torch will give you even heat. With controlled travel speed. You may need to add more come-a-longs to force the issue!Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by Jimmy_popDo you need to maintain at true semi-circle radius?  Or are you just trying, now, to bend it like a taco and get the legs of the semi-circle 1" narrower? Heating the metal is Voo-Doo for internet welders. Simple to type, very hard to do, especially evenly across a part that is easy to see and measure and fight fitting the misalignment. I don't see any way except adding more of what got it to its current state. add more cowbell.
Reply:Originally Posted by bentI'm looking at all those little dots in there and all you are doing is pissing it off.  When CEP says heat, he means heat!5/8 plate is kinda thin for heat shrinking without using strongbacks ime, although I have no experience with SS.  Your dinky pony bar clamps don't count as a strongback.  I'd make a couple of solid clamps, with a section thickness at least 1/4 of the plate I was trying to bend, since the strongbacks will be in tension only.  You could also put a strong backer along each edge, and weld straps across the backers.
Reply:looks pretty, not reality. Its called plate rollers or press brakes
Reply:Originally Posted by Jimmy_poplooks pretty, not reality. Its called plate rollers or press brakes
Reply:Originally Posted by aarolarBasically yes, the concentricity is not super crucial and I can pull the ends in as they get welded to a end plate but I just don't want the middle to be bowed out.It's a clamshell and the bottom looks like this the top is basically the same.Sent from my SCH-I545 using Tapatalk
Reply:If it isn't a problem you could weld beads down the inside to pull it in.Last edited by Bls repair; 05-11-2016 at 03:14 PM.
Reply:Originally Posted by Bls repairIf it isn't a problem you weld could beads down the inside to pull it in.
Reply:Depending on the alloy and application, each one of those heated spots may now be a corrosion issue. Used to work with 304 and 308ss for some nasty Urea piping and if you goofed on backpurge or overheated the weld... it was gone in one season.
Reply:CEP, why suggest a cutting torch versus rose bud?  I know a cutting torch is used to pre heat but the rose bud uses less gases. Im guessing its an iron worker thing. An iron worker i know insists on a cutting torch for heat but I have to pay for the gas.aarolar, I have no useful advice but good luck.
Reply:Originally Posted by InsanerideCEP, why suggest a cutting torch versus rose bud?  I know a cutting torch is used to pre heat but the rose bud uses less gases. Im guessing its an iron worker thing. An iron worker i know insists on a cutting torch for heat but I have to pay for the gas.aarolar, I have no useful advice but good luck.
Reply:Oh I’m all for a rose bud. Sometimes a cutting tip has more direct heat, for a small heat line. I’ve straightened 36” x 300-pound W-shapes. A cutting tip won’t touch that kind of iron. Even a #12 rose bud takes forever to heat them! Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPOh I’m all for a rose bud. Sometimes a cutting tip has more direct heat, for a small heat line. I’ve straightened 36” x 300-pound W-shapes. A cutting tip won’t touch that kind of iron. Even a #12 rose bud takes forever to heat them!
Reply:I know one member here thinks this is all voodoo. But it does work! The guy who taught me how to heat shrink was on this project bending these beams at Todd ship yard on Harbor Island. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I would buy several sticks of 1" all thread, make some brackets and atach the brackets so you can insert an end of the all thread through them and attack about every foot or so.  Tighten the nuts and the sides will pull in, but be sure you attach securely enough to stand the pressure, possibly less likely of getting hurt.  For holding the center cut a U shape to go around the outside of your desired dimensions.  BE CAREFUL there is a lot of pressure this is why so many bolts to share the pressure.  Good luck, my two bits
Reply:Anyone who has this book. This picture is in it. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPAnyone who has this book. This picture is in it.Where I got to at lunch today I think I'm going to drop some braces in to replace the come a longs and hold it there while I weld it out.Sent from my SCH-I545 using Tapatalk