Flatten bowed smoker lid (plate not round)

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So I'm rehabbing this nearly free smoker (I didn't weld it and let it rust, don't judge me) and I like my smokers to be very well sealed.  Problem is the lid (1/8 plate and angle iron) is concave looking at it from the top, it bows inward.  In the center top, along the angle iron, it's about 3/16 from straight.  If it lightly jump on the underside of the lid, it pops mostly back into place, briefly, then pops back out.  I'm a bit of a lightweight at 160#.I'm considering doing a partial kerf on the underside (the bow faces the underside) and then welding the kerfs while under pressure, hopefully shrinking the plate and pulling it back into place.  However, I have also seen mentions of people welding the top side to straighten it.  I have a Lincoln WeldPak 3200HD with 0.030 flux core wire, which should be adequate for this job.  Does anyone have any suggestions or alternate courses of action?Edit: Aside from 1) buy new smoker, 2) pay someone else to fix or 3) rebuild completely.Thanks!

Last edited by clearchris; 3 Weeks Ago at 02:31 PM.Lincoln HD3200 MIGMiller Synchrowave 180 TIG
Reply:When you mean pops back into place. Is this panel supposed to be flat ?www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:

Originally Posted by TJS

When you mean pops back into place. Is this panel supposed to be flat ?
Reply:Ok. You asked here I go. Don't waste you time. Have a new one made. Find someone with a CNC plasma cutter and make slices near the lip that is bent over where you can bend it over by hand and then weld in the slice. It warped because of the heat. Might need to use thicker material.From design to cut should take about 6 min or less.www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:Yeah, but there's no fun in that.  I like wasting my time.Lincoln HD3200 MIGMiller Synchrowave 180 TIG
Reply:Any thought on welding a angle iron on the underside and pull it flat or add a piece of 1/4" plate on top and plug weld from the bottom.  I've done the later and it worked well.
Reply:Weld nut or thrreaded rod coupling on center to underside of top. Add a cross member with hole to match but location. Use all thread rod with nuts and washers to adjust to flatness. You may consider multiple locations depending. Good Luck Sent from my iPhone using Tapatalk
Reply:

Originally Posted by Bob-O

Any thought on welding a angle iron on the underside and pull it flat
Reply:I think welding a kerf will work. Clamp it flat before welding to help the process.
Reply:

Originally Posted by clearchris

Yeah, that's another option.  I was thinking against it because it already has angle along all the edges and the angle is being pulled out too.  So it would have to be something pretty heavy.That's an interesting option.  Would make for a heavy-duty lid for sure.  Glad I was planning on adding a counterweight anyway...Hmm, and adjustable too.  Interesting.
Reply:By the time you go through all this honky suggested Bullcrap,You’d be better off to go down to the scrapyard and get a small piece of quarter inch steel and make a new one. It would take you what? 20 minutes to fabricate the whole thing… Oh I forgot,you like to waste your time…Carry-on.Miller 211Hypertherm PM 451961 Lincoln Idealarc 250HTP 221  True Wisdom only comes from Pain.
Reply:

Originally Posted by John T

By the time you go through all this honky suggested Bullcrap,You’d be better off to go down to the scrapyard and get a small piece of quarter inch steel and make a new one. It would take you what? 20 minutes to fabricate the whole thing… Oh I forgot,you like to waste your time…Carry-on.
Reply:Maybe use 3/16”x 1” or similar flat bar.   Clamp and weld the pieces on edge where you have the  (X) red lines in your first post. Sent from my iPad using Tapatalk:
Reply:

Originally Posted by John T

You’d be better off to go down to the scrapyard and get a small piece of quarter inch steel and make a new one. It would take you what? 20 minutes to fabricate the whole thing
Reply:I hope so.  And yeah, I could really use more more arc time.  So I don't consider it time wasted.When I said " wasted time " I was referring to the time you'd be wasting your get materials. Sent from my iPhone using Tapatalk
Reply:I made a heater out of 24" pipe. For the door I made 2 cam lock type deals to hold it closed tight. Just used a piece of 1" flat bar, put about a 15 deg. bend on it so it will hook under the edge of the pipe and tighten up when it's turned 90 deg's. Used some 1/2" round bar bent at 90 deg's. for the handles. You may want to put some thicker pieces on where the cam locks hold it closed.
Reply:Just get a wood stove gasket kit for like $10 and glue it around the edges.  Done.Century buzzbox that I learned on 40+ years ago (was Dad's)Crappy Century 110volt mig 70 amp pigeon pooper.Lincoln Idealarc TIG-300
Reply:Just put an inch or so of weld in the middle of the concave portion, but weld on the convex side. While it is still hot put it on a welding table, convex side up, and give it a whack or two with a good size hammer. Once cool it should be close to flat, then just hammer to suit.
Reply:Just run a bead on the concave side and you'll turn that frown upside-down. Be advised that a 1/8" panel of steel without some curvature is gonna be wibble-wobble spaghetti-weak, which is why most car makers have the sense not to make sh_tboxes that look like this:

Last edited by Kelvin; 3 Weeks Ago at 10:18 PM.
Reply:

Originally Posted by BD1

When I said " wasted time " I was referring to the time you'd be wasting your get materials.
Reply:

Originally Posted by Kelvin

Just run a bead on the concave side and you'll turn that frown upside-down.
Reply:

Originally Posted by John T

By the time you go through all this honky suggested Bullcrap,You’d be better off to go down to the scrapyard and get a small piece of quarter inch steel and make a new one. It would take you what? 20 minutes to fabricate the whole thing… Oh I forgot,you like to waste your time…Carry-on.
Reply:

Originally Posted by TJS

After reading thru all the suggestions, it seems like a lot of time wasting is going on here anyway.
Reply:

Originally Posted by BD1

No wasting time here. IF one member learns something from the responses posted here it’s worth it. Sent from my iPhone using Tapatalk
Reply:

Originally Posted by Lis2323

Agreed. I picked up a few good ideas here, but it’s debatable whether or not I will remember any of them when needed.

Sent from my iPad using TapatalkWithout any sort of support to stiffen it , the lid will probably warp from the heat again. I would guess it didn't warp as much in the long dimension because of the metal the handle is welded to prevented some of that.


You could use 16ga x 1/2" cold rolled, or what ever is handy at the time, the 1" x1/8" might add a little weight but will be easier to weld. The key is being able Press/Clamp it flat , and then tacking it together.  Resist the urge to weld every joint possible. Just my 2 cents Are there any latches to lock the cover down, or a hinge. I didn't notice in the pictures(maybe I missed it)Good luck, let us know how you did.Last edited by albrightree; 3 Weeks Ago at 11:36 AM.Airco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:

Originally Posted by clearchris

BTW, does Lincoln publish the amps at A, B, C, D settings in some hidden place?  I have looked, but found nothing.  Kind of hard to use calculators without any idea of what the settings actually are...
Reply:Look on the inside of the door you open to get to your wire for the settings chart.
Reply:The Manual :   https://www.lincolnelectric.com/asse...LN3/IMT786.pdfThe door chart from manual :

Hope this HelpsRegardsLast edited by albrightree; 3 Weeks Ago at 12:29 PM.Airco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:

Originally Posted by albrightree

The Manual :   https://www.lincolnelectric.com/asse...LN3/IMT786.pdfThe door chart from manual :

Hope this HelpsRegards
Reply:In a case like this - thin material needs to be flattened, seems to have even bowing - I just heat to red/weld a small bead in the same general shape of the panel in the center of the panel.  .15 mins average including pulling out and then putting away equipment, and grinding if needed.  Fast and easy and generally works great.  Which side you weld/heat doesn't make much of a difference with thin material.example on heat/weld shapes: a rectangle, it's usually a centered line. For a circular panel it's either a dot in the center, or small circle.  If the panel is a triangle then i will heat/weld a small triangle/arrowhead shape in the center.  etc.
Reply:

Originally Posted by walker

Look on the inside of the door you open to get to your wire for the settings chart.
Reply:Start with a small bead (low setting), even if it doesn't penetrate the heat will do it's thing.Better to go in small steps, than mess up and try to fix.Good luck and watch out for the tinglies!Fine clean up/grind with fiber resin disk or flap disc.It may bow up again depending on the heat, if it does a cross member will be in order, or learn to love it as is.Was it bowed from the start or did the heat from use bow it?Last edited by SlowBlues; 3 Weeks Ago at 04:57 PM.
Reply:The only thing that could be an issue on your 3200 is that the drive roll is designed for .035 Fluxcore. The .030 might slip and cause feeding issues.but you can grab a small roll of .035 if it does become an issue.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Look at the "Red X" on the first picture,,That red X is how they "Cross Break" ductwork so that the sheetmetal does not flap around when the fan comes on, and the air is blowing through the ductwork.(You know, like the ductwork Bruce Willis is crawling through in the movie "Die Hard")Adding a cross break does the same thing as making the part out of thicker metal,, the part is stronger due to the cross break.You could fake making a cross break in the lid with a wide chisel, and a hammer.Set the lid in some sand, and create the crease that duplicates the red X.The lid will stay bowed out, and the "X" in the lid will look stylish.If you have a friend with the right tool, you could get the lid done.http://sheetmetal.me/tooling-terminology/cross-break/
Reply:Great idea about the cross break.A not razor sharp chisel or chisel like object will do, and a few layers of jeans/leather/heavy cotton fabric over wood/concrete/hard dirt will also do.Metal is pretty simple, it always listens to the hammer.
Reply:"Approximate / Suggested Settings"

Most likely going  to be "D" voltage, and then adjust wire speed, but then it could run better on "C" with a much higher wire speed. You can use some scrap to tune your settings, the charts a just guides, should get you close. There are only so many settings on a machine like this, a little tuning is all it should take.How hot does this lid get ? Bending heating or welding back flat may not last long if you heat it up to 500 deg often.BTW-  what do you cook in this the most ?RegardsAirco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:Just an impractical suggestion -- If you use an optisometer, you could measure lengths along curved surfaces and find the differences between what they are and what they would be if they were flat.. In theory then, you could cut custom slices to remove material to press and return the surface to flatness.
Reply:

Originally Posted by SlowBlues

Start with a small bead (low setting), even if it doesn't penetrate the heat will do it's thing.Better to go in small steps, than mess up and try to fix.
Reply:Hmmmmm,, another answer,, similar to the Cross Break,,We had a manager that INSISTED the way to get rid if burrs in 10 gauge sheetmetal (about 0.105" thick hot rolled steel) was to sand blast the burr side.This was sheetmetal that had been run through a very large punching machine, to make doors for electrical panels.Well, to show the results that would occur, we took a panel out to a sand blast shop, and had it blasted.The blasting added so much stress to the surface, it literally expanded tie blasted side,,The sheet ended up looking like the bottom of an old fashioned oil can.. It was amazing how much the steel curved For this application,, IIRC,, you would blast the outside surface, and the new stress would cause the surface to bow out.My neighbor has a sand blaster that you hook to a pressure washer,, (The attachment only cost about $25)He was restoring a garden tractor, and sand blasted the hood of the tractor, so that he could repaint it.The hood bent like crazy from that sand blasting.
Reply:

Originally Posted by SweetMK

about 0.105" thick hot rolled steelThe sheet ended up looking like the bottom of an old fashioned oil can.. It was amazing how much the steel curved
Reply:

Originally Posted by clearchris

That's really thick metal to get distorted by blasting.  I almost can't believe it.  Thanks, I was considering getting a cabinet, and you likely saved me from some large mistakes.Edit:  So are blasting cabinets only good for cast parts?  Or was that a bad choice of blasting media?
Reply:Looking at it, the first thing that popped into my mind was to make a reinforcing bar like you use on metal brakes.If you don't reinforce the sheet, I think it'll just bow under the heat again, so you really need something in there.  The bridges used on finger brakes give you adjustability, plus it could be used as a handle.  It's not the best idea, sure, but I'm looking for something that'd be just plain neat to build, giving you some time on the welder, and solve the problem.

You could do something like this, but with a bolt that goes through the door.  As you tighten the nut, it draws the bolt head up into the arc of the bridge portion and pulls the bow out of your flat door.  It'd make a nice handle, too, so you could get rid of the current handle.No matter how the door might bow in the future, you can always give the nut a bit of a turn just align things again.  Not the most ideal way of reinforcing the door, imo, but it'd be a fun project, something you don't see every day, and would really set your cooker apart from the herd!  Scott's channel is always worth watching because you never know what kind of design ideas he's going to come up with.
Reply:

Originally Posted by SweetMK

Sandblasting literally "peens" the surface, but, it does nothing to the other side,,so, what happens is that the sandblasted side gets larger, the piece of metal curves.If it is thick, like a truck frame, the steel holds it shape, as the metal gets thinner, more deformation occurs.I do not think I would blast anything under 3/16" thick, if I were worried about the part holding its shape.Media choice may have some effect, but, if the blast is enough to remove rust, or paint, media selection would not matter.