Hi, I own a Granpa Bear and have noticed a peculiar phenomena, at least in my limited experience.
When we first bought this house the stove was sitting on a bed of mortared flat rocks and was not level. To remedy this I cast 2" diameter concrete pads under three of the legs using rings of PVC as forms. I cast them such that the leg ends did not enter the concrete but just rested so as to make a slight surface impression. Mind you there are no "feet" on this stove. The legs are just plain angle iron that end abruptly.
Fast forward nine years. This morning I noticed the two leg ends on the left side had shifted quite a bit from the center of the pads, the front one outward by 3/8, the back one outward by 1/2. The right side has the one pad in front. That one had obviously NOT shifted. It is impossible to tell whether the leg without a pad shifted.
So over many fires the stove has overall warped a little. All the seams and welds look good. I don't run this stove particularly hot. On my IR thermometer I don't think I've seen a surface temp over 600F. I burn a lot of pine. The wiki article on "creep deformation" seems to fit the bill.
A month ago I took out the factory baffle in favor of a deeper one. The factory baffle was warped in the middle and was welded at both ends, which tells me it was probably in compression. When I took that out it changed the stresses, but enough to do this? I doubt it. But releasing that compression would be consistent with the top of the back leg moving inward and the bottom of the back leg moving outward. To avoid introducing any new stresses I welded my new baffle with an inch long weld only in the middle, with the ends floating on angle iron and about 3/16" clearance.
Well, I guess the only lesson I would take away from this is that if you are going to cast leveling pads like I did make them bigger --say 4" in diameter.
(PS. Thanks for the help with building my new baffle. However I can't provide much scientific feedback on how it worked. I ran out of wood this winter and I'm having to burn a lot of relatively wet wood.)
When we first bought this house the stove was sitting on a bed of mortared flat rocks and was not level. To remedy this I cast 2" diameter concrete pads under three of the legs using rings of PVC as forms. I cast them such that the leg ends did not enter the concrete but just rested so as to make a slight surface impression. Mind you there are no "feet" on this stove. The legs are just plain angle iron that end abruptly.
Fast forward nine years. This morning I noticed the two leg ends on the left side had shifted quite a bit from the center of the pads, the front one outward by 3/8, the back one outward by 1/2. The right side has the one pad in front. That one had obviously NOT shifted. It is impossible to tell whether the leg without a pad shifted.
So over many fires the stove has overall warped a little. All the seams and welds look good. I don't run this stove particularly hot. On my IR thermometer I don't think I've seen a surface temp over 600F. I burn a lot of pine. The wiki article on "creep deformation" seems to fit the bill.
A month ago I took out the factory baffle in favor of a deeper one. The factory baffle was warped in the middle and was welded at both ends, which tells me it was probably in compression. When I took that out it changed the stresses, but enough to do this? I doubt it. But releasing that compression would be consistent with the top of the back leg moving inward and the bottom of the back leg moving outward. To avoid introducing any new stresses I welded my new baffle with an inch long weld only in the middle, with the ends floating on angle iron and about 3/16" clearance.
Well, I guess the only lesson I would take away from this is that if you are going to cast leveling pads like I did make them bigger --say 4" in diameter.
(PS. Thanks for the help with building my new baffle. However I can't provide much scientific feedback on how it worked. I ran out of wood this winter and I'm having to burn a lot of relatively wet wood.)
