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A good day: yardwork, heat treat oven progress. - Doug Ayen's Blacksmithing Blog [entries|archive|friends|userinfo]
Doug Ayen

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A good day: yardwork, heat treat oven progress. [Oct. 20th, 2012|04:53 pm]
Doug Ayen
I woke up this morning feeling like actually doing something, and managed pretty spectacularly.



First, I cleaned out a bunch of brush and small trees from the side of the house, then tackled a lilac bush that had grown out of control, cutting it down to some short trunks and saplings. The last time I did this, the next year saw a lot of new growth, only this time I'm going to try to keep it trimmed down to reasonable size and shape.

After a break for some shopping, I hit the shop and tried to get the outer shell off of the old heat-treat oven I've been hoping to convert from and inaccurate and hard to manage gas setup to a computer controlled electrical model. Months of soaking in Kroil finally worked, and all but two soft iron screws came out of the cast iron frame without issue. Those two's heads sheared off, and inspection showed that they had welded themselves to the frame, and probably wouldn't have come out no matter what. I'll drill and tap new holes, and replace them with stainless.

With the screws removed, the shell lifted right off, and I was able to take off the back plate, allowing access to remove the refractory. The top piece was in sorry shape -- powdery, crumbling, and already broken into 7 pieces, just barely holding together through friction. Considering it's condition, I'd say it was just a matter of time, and not much of it, until it had failed completely anyway. The back refractory was in similar shape, crumbling to the touch and altogether in bad shape.

The good news is that I can fairly trivially replace the top with kaowool, and the back looks like it pretty close to the standard firebrick shape. Furthermore, the sides are in pretty good shape, a few cracks but fairly solid, and certainly not crumbling like some other pieces of refractory. I think I should be able to get them out in one piece, route in a channel for the heating element, and get them back in without too much problem. Run the heating element loop around the bottom, up to the channel, then back and it should be a pretty good setup.

The top piece might be salvageable through use of furnace cement, but I think I'll try the kaowool first. In a worse case scenario, I can use the shell as a mold and cast a new piece, but that shouldn't be necessary. Similarly, the refractory on the door has fallen apart and glued back together so many times I think it's time to just replace it with kaowool as well.

All in all, a good day. Right now, though, my body is reminding me that I've been pretty sedentary lately, and is complaining about all the activity.
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Comments:
[User Picture]From: josephrjustice
2012-10-21 01:07 am (UTC)
When you put it back together, perhaps you can use some sort of heat-resistant anti-seize lubricant (assuming one exists which can stand up to the temperatures you expect the heat-treat oven to typically generate) on the screws to make it easier to disassemble the oven in the future?
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[User Picture]From: blackanvil
2012-10-21 02:29 am (UTC)
You bet. I have NUCLEAR GRADE nickle-based anti-sieze in the shop for just such a situation.
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