oil canning in bottom of syrup pan?

[Justin Turco]

http://www.youtube.com/watch?v=F6rPdaZQ7_c

Maybe this is the answer to this particular problem.

Don't melt your solder!

[Mark]

That is what happens when you burn the pan, some areas have shrunk causing the waves in the bottom. To straighten the pan you have to stretch the areas that have been shrunk with a planishing hammer.

[Haynes Forest Products]

Mark I might be mistaken but a planishing hammer is for smoothing out metal but not shrinking it. Pounding on dented or warped metal will not remove the dents but will expand the area.

[Justin Turco]

At some point, I'm going to try it. I've got a couple of small "oil can" spots where niter popped off while boiling and then the spot got shock cooled by the syrup. I usually try to NOT let my pan niter up like that. But I have been known to keep pushing the pan toward the end of a long day when it really needs to be cleaned.


Justin

[Brent]

I think this technique may work but maybe not for the reason noted above.

Background: a few years back we sold a Japanese made engine lathe and the customer had a crash with it that resulted in a bent shaft in the headstock. Just so happened that when he did it we had some factory reps visiting us. No problem the rep said, bring me the shaft. We took it out and brought it to our shop where he put it between centers on our own lathe, put an indicator behind it so he could find the high spot of the bend and see how much pressure he was putting on it when he wound the toolpost forcefully in to push the bend straight and then somewhat past straight. Then he took a hammer and whacked it about 20 times and left it while he took us to lunch. Came back from lunch, released the pressure and the shaft was darned near perfect. He said he just applied pressure and whacked it to let the shaft "remember" and jar the molecular structure back to its straight state.

I think heating the bubble in the sheet metal, then whacking it, did more or less the same thing. I think it would have been even better if he could have applied some constant pressure, like the Japanese mechanic did, to press the bubble down to flush and keep it there while he did the hammering and let it cool under the pressure too.

Hope I never have to test the idea though.

[Mark]

If you want to learn how to straighten metal get a video from this guy. I have been to several of his classes. The key is to know where the pan has shrunk and stretch it wit a planishing hammer in the flat areas and I have also used a hardwood wedge in the corners.

http://www.tinmantech.com/

[Haynes Forest Products]

SS has greater thermal expansion and lower thermal conductivity than carbon steel. so things can act differantly than car bodies. Thermal stress relieving is the controlled heating of the warped area to an elevated temp followed by controlled cooling:rolleyes:

Keep in mind that heating cooling and wacking on a warped area isnt going to remove the warps if your doing it in the wrong area. It takes a keen eye to know where to do the heating and cooling. DONT ask me how and were to do it I only watches and expert do it and tried to understand his ART.

I have two pans that are all wrinkeled up and distorted into the sides and I cant tell you that beating them flat with a rubber hammer on the barn floor out of desperation to get back to boiling only had a limited effect.

[Mark]

A rubber hammer won't do anything, you need a steel hammer with a steel backing behind the pan. He does not use any heat to straighten the pan just a hammer. The best way to learn is to bring a pan to this guy and have him show you what to do. I have been lucky because he has a class at a locale airshow every year.

[Haynes Forest Products]

Mark Im well aware what a rubber hammer on a warped pan will do on a flat cement barn floor........................you did read the part about desperation. When all tanks are full and the sap is running and you are making nice light syrup and its Friday and you stand to either make or loose in production you dont start driving around the country looking for Paul Rever;)

[Jeff E]

Your hilarious Haynes!:lol:

[red maples]

WOW!!!!haynes:lol:

Ok maybe I am wrong here... but if you are heating up stainless til its cherry red isn't that going to change some of the molecular structure reducing the "stainless" effects and allow it to oxidize (rust) just like a bad welding job will rust? And if that happens isn't that area going to have a bigger niter build up and create a hot spot that could possibly burn easier? Its not like a car door or fender that is carbon steel that is sanded, primed and painted and is not continuously subject to the high temps of the inside of an evaporator.

I am no chemist or metal worker but it makes sence to me.

[Mark]

A good way to keep you from experiencing that desperation is to have extra equipment. I have an extra 5x10 flue pane still in the crate and 6 extra new syrup pans that have never been used. I would hate to miss a few thousand gallons of syrup just because of a little slip up and a burnt pan.

[Haynes Forest Products]

I agree that extra equipment is the key to being ready for that day that we all experiance BUT dang a whole set of pans with extra syrup pans. I did just order up a extra syrup pan.

Red Maples Yes I believe that you can burn the pans to the point that alot of carbon is introduced and you ruin the SS properties. My burnt pans are a gun metal grey but havent rusted even in the corners.

I will get a photo of the pans and post them they look like a peice of tin foil that you ball up and then try and flatten on the carpet:cry:

[Brent]

I think most of the corrosion you see on weld repairs if from contamination or using incorrect stock. Heating to less than melt down will not cause loss of the chromium, which does form the oxodized protective layer on stainless.

[red maples]

oh yes true brent.

[Haynes Forest Products]

I keep hearing about a protective layer on SS:confused: SS is SS thru out so why do you need a protective layer?