On Tue, 15 Dec 2015 13:24:16 -0600, "Terry Coombs"
wrote:
wrote:
On Mon, 14 Dec 2015 18:43:35 -0600, "Terry Coombs"
wrote:
wrote:
On Sun, 13 Dec 2015 20:03:38 -0600, "Terry Coombs"
wrote:
The day I picked up the stove grates I also picked up a small
"fire pot" that was cracked/broken . The break is across a 2"
horizontal then about 1" vertical - kind of like an angle iron but
not at 90° . I attempted a repair on it yesterday , beginning with
a tack at the corner and one at the horizontal edge . That part
went well ... but when I tried to fill in between the two tacks it
keeps cracking . I have a hammer handy and begin peening before my
helmet clears ... I have not preheated this piece because of the
size and awkwardness, and I think that's what's killing me . The
TIG heat is so localized that the nearby mass of iron is acting as
a chill and sucking the heat out so fast I can't peen fast enough
to stop the cracking . I can't heat the whole part , but I can
heat the repair area . The part is like an oval sleeve , with
nothing to restrict expansion in any direction so I think I can
safely heat just that area . The question is how hot and will this
help keep it from cracking ? I tried some CI strips first , then
the Invar 42 , same results with both fillers ./
Are you anywhere near a pottery supply company? If so, get some
ceramic wool and wrap the piece after heating. As to how hot in my
experience if I heat cast iron to about 700 degrees it won't crack.
I have had the best luck heating to a dull red heat when observed
in low light, wrapping in ceramic wool, and welding. It's a pain
because everything is so hot but on the other hand no peening is
required and no cracking is happening. I have used this method with
brazing rod, aluminum bronze rod, stainless steel rod, and nickel
alloy rods.
Eric
I don't have a pottery supply near , but I do have a large pile of
fiberglass batts . You think they'll work at the temps you use ? The
grates aren't so awkward in shape , I plan to build an enclosure
with firebricks and preheat with my foundry burner . Heat 'em both
up and let one soak while I weld on the other , swap as they cool .
I don't know about the fiberglass batts because I think they use some
sort of glue to hold the fibers together. Tear a small chunk off and
point a torch at it to see if it burns. Not too close because the tiny
glass fibers may burn while in the torch flame. Your enclosure idea
is a good one. Lay the grate on some more fire brick while welding so
that it doesn't lose heat through conduction. You know, I bet the
fiberglass would be fine if it was just used to cover the part while
it was being welded. Try it. It just occurred to me that a fireplace
shop may also have ceramic woll.
Eric
Heh , we don't have one of those too . This is a very small (5,000) very
isolated town - the nearest freeway is a hundred miles away more or less .
Those 'glass batts were salvaged fom a tearout , cost me the labor to load
'em up .
Today I'm working on toy boxes for my 2 youngest grand daughters .
Tomorrow I'll be setting up for the CI job , get it outta the way so I can
go back to laying cement block yecchhh for our new cellar .
Greetings Terry,
The ceramic wool I use is available from Seattle Pottery Supply for
$1.75 per square foot. This link may get you to the right page:
http://www.seattlepotterysupply.com/...gory_Code=CFIP
I live on an island north of Seattle and so I understand what it is
like to have everything you need or want far away. If you are going to
do more than just a few pre heat/post heat type repairs in the next
few years it may be wise to order a few square feet of the ceramic
wool. The stuff is great for wrapping stuff that needs to cool down
slowly. It is pretty light so shipping should be pretty cheap. And I'm
sure there is a supplier closer to you than Seattle.
Cheers,
Eric