flexing steel , from heat...

[Three Saps Sugar Shack]

the rails under the pans of my 2.5x8 are flexing inward approx. 1- 1.25 inches when fired... and when they cool down they return to straight... but heres the catch... they have begun bowing outward when cool, a little more after each firing.. to the point that the pans are only sitting on them by .25 inches each side....im affraid my pans will be found in the fire box some morning.. anybody got a cure?

[HanginAround]

We put a tie rod across the middle of the homemade one we made. Never really saw it being a problem on manufactured ones.

[WF MASON]

You've got a problem that going to be hard to stop, the top rail must not be protected by the firebrick or refractory , the rails will unbolt and new angle can be added , you'll have to rebrick the top couple rows.

[maple flats]

What WF said sounds right on. Do you have brick or other insulation up to the underside of the angle that is flexing?

[Fred Henderson]

You've got a problem that going to be hard to stop, the top rail must not be protected by the firebrick or refractory , the rails will unbolt and new angle can be added , you'll have to rebrick the top couple rows.

I think that I am misunderstanding. Are you saying not to bring the fire brick up tight to the top rail/angle?

[WF MASON]

I'm saying the rail MUST be protected , and if the rail is warping it must NOT be protected from the fire. My wife has a hard time understanding what I mean to Fred.Thats OK

[RileySugarbush]

I vote for protected. I fired my homebuilt 2x6 today. I built it with very light angle rails, 1.25 x .125 and insulted right up tight to the bottom of the rails with 1" ceramic blanket. The rails didn't move noticeably in 5 hours of hard boiling. If the horizontal part of the rail is wide, it will have more chance of warping as the inner hot edge expands and the outer cool edge, so maybe the narrow rails help on my arch.

[Three Saps Sugar Shack]

it's a modified 3x8 arch accepting 2.5x8 pans. i have 1.25" of exposed steel inside of the arch and 3" exposed outside the arch half " ceramic blanket and full brick on the inside , tight to the bottom of the rails. Would a few relief cuts in the steel , inside the arch allow the inside to expand , without pulling the outside in....? too many" inside" "outside" referances.. hope i was clear....peter.....

[WF MASON]

I believe the key word is 'modified', use of that word generally leads to problems. Relief cuts would do something, would it make it better or fix it? I don't believe so,BUT it might, steel has an amazing memory , like when you scorch your pan just a little, after that you always have 'that' spot where it wants to scorch and burn again. Or when you bend something and bend it back, it has a weak point.
If you don't want to replace the rails, just put new 1/4" angle over them, and stich weld in place, clamp both rails tight togeather, the hard part is the bolts that are holding the old rail on. The new rail would hit on thoes when you put it on. You could cut out or drill a bigger hole for the bolt heads. But by the time thats done you could have the old rail ripped out and replaced anyway.

[Russell Lampron]

Speaking of warped pans. Is there anyone out there that can straighten them? I have one that is pretty much junk now and I don't want to scrap it.

Russ

[ibby458]

I used a borrowed 2x9 last year that had the same problem. I used 1/2" Stainless threaded rod in 3 places from one side to the other. With nuts on inside & outside of both ends, I put the sides just where I wanted them. I packed refractory cement around the ends on the insides, but the one across the top of the firebox (to hold the broken front together) stretched from the heat. If the owner would have sold it to me, I would have wrapped the rod in ceramic blanket this year.

I got quite a lot of that threaded rod. If you want to try it, PM me.

[Three Saps Sugar Shack]

well... heres what i've done...the 1.25" of exposed steel inside the arch, is now encapsulated with .5'' of 6# ceramic blanket , with half brick protecting it from rough firing... blanket is wrapped up and around the edge of the steel and has also become the pan/firebox gasket, three 3/32" relief cuts have been made in each rail ,to allow for a small amount of growth on the leading edge of the rail, only where the rail previously protruded into the firebox.. and all that is exposed at this point is the ceramic blanket compressed between the pan and rail... any comments?.... all i need now is for the temp to rise so the darn sap will run, so i can see if im in buisiness.......peter.

[Three Saps Sugar Shack]

well....had enough to get a two hour boil... and ..everything held it's shape... worked like a charm....after two hours hard boil.. i could still place my hand on the angles, very little heat at all..that ceramic blanket is an amazing product.