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Old 05-05-2019, 12:09 PM
Fredi Vilina Fredi Vilina is offline
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long annealing cycle help please

My gf is making a cast piece roughly 6"(w)X 4.5"(h)x7.75"(l). According to Bullseye thick slab annealing tips, "... or is anything besides a flat slab of uniform thickness, select an annealing cycle for a piece that is twice the thickness of the thickest area of the piece."

So based on this they recommend app. 1300 hrs! to room temperature with anneal at 900 for about 64 hours then the rest cool down.

We had based it on 1/8" per hour for anneal to get to midpoint of the h. and came up with about 20 hours anneal but then we are at kind of a loss for the rest of the cool down.

any ideas would be appreciated,

fredi
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Old 05-05-2019, 12:29 PM
Shawn Everette Shawn Everette is offline
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Quote:
Originally Posted by Fredi Vilina View Post
select an annealing cycle for a piece that is twice the thickness of the thickest area of the piece."fredi
I don't know that I've ever gone that route. 20 hours may be a bit shy, closer to 24-30, but you're not casting the lens for for the Hubble. As a general rule I go 1.5-2 times longer than my annealing cycle through strain, about 200 less than anneal. I then double that time down to room temp. For example 24hr @900, 60hr to 700, 120hr to 150.

Things like appendages will have me opt for longer cycles, but I've used this method without fail.
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Old 05-05-2019, 01:08 PM
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Pete VanderLaan Pete VanderLaan is offline
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Keep it off the floor.

Try to obtain a copy of "The schedules" by Graham Stone.

Based in my experience, I don't think of Shawn's soak to be long enough. I'd double it. Keep in mind that once you pass the strain point, no further annealing can occur. You're simply trying to prevent thermal shock.
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Old 05-05-2019, 05:21 PM
Shawn Everette Shawn Everette is offline
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That was more to keep an example of how to calculate, I'd probably use that for something in the 5" range. Bullseye is calling for 32hrs for 8", which I might use, but though strain is 370hrs. I've never annealed for 16+ days.
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Old 05-05-2019, 06:04 PM
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Pete VanderLaan Pete VanderLaan is offline
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I'm considering oversized paperweights I've seen on and off and the sucessful soak cycles were really long... really really long. Graham identifies them and lays them out. If you don't have the book, it's one of the mayflies out there.

In a piece of this scale, which isn't all that big. I'd make a clear one first and when done with a long cycle, I'd look in the tell tail tool, the polariscope. Witness pieces are incredibly helpful at simply documenting the event. I know the Simpson planets were in for several months. We never did a clear one though.
Keeping it cooling evenly is important. Keep it off the floor and multiple thermocouples, all over the place are simply smart. Eventually the cost of electricity cooling far out weighs the cost of casting.

I have some castings here that took sixteen years to crack.
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Old 05-06-2019, 09:15 AM
Shawn Everette Shawn Everette is offline
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The 12" paperweight we made at Penland annealed for maybe a week, and we rolled it down the hill. Chipped from our shenanigans, but no real fractures. Glass is s funny thing sometimes.
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Old 05-06-2019, 02:43 PM
Fredi Vilina Fredi Vilina is offline
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thanks

As usual, always helpful and slightly amusing! we have a time crunch of 7 days so we are going to try it with that for the kiln casting. we also have the same one made for ladle casting and we'll anneal that one really long. They will both be clear so I'll let you know what the end results are. the difference though, is the kiln cast is old blenko and the ladle casting will be spruce.
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