Flux resistant forge lining help, bubble alumina

S

stefanj

Joined
Aug 5, 2007
Messages
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I have been having problems burning holes through my forge while using flux.
Maybe I'm using tooo much borax?

I have lined my forge floor with Satanite then ITC-100 and I just recently tried Bubble Alumina and still burned right through.

Maybe I didn't apply the bubble alumina correctly? I need some help since I'm wasting a lot of propane and spending more time repairing the forge vs using it!


Thanks
 
ive heard some people use sacrificial material on the forge floor such as replaceable fire brick and in some cases cat litter, the forge i ordered has a fire brick bottom. hope you figure it out. good luck
 
how hot are you runing your forge
 
Bubble alumina is highly flux resistant.My welding forge is cast from it Don Fogg style, in an old propane tank and the flux doesnt bother it at all.Perhaps your not applying it thick enough?I'd imagine if you applied it thinly the stuff cracks and the flux finds it way through.I think if you went with a minimum of a 1/2 inch thick and allowed it to dry thouroughly for a couple of days before firing you'd be ok.Also take the heats in stages.Heat the forge to say 200 and let cool.Then maybe 500 and let cool.Then up to forging temp.That way theres no water left to crack the refractory.You only need enough flux to coat the steel.When I first started doing cable I was using tons of flux as I didnt know any better and ended up with flux inclusions in the final product.Once I started just applying a light coat of flux I got rid of the inclusions and the steel actually welded better.Just use enough to coat the steel in a thin layer(just wet).Try a shaker,a can with lid and a few holes in it to apply your flux.There shouldnt be rivers of flux running off the steel.Legatos' suggestion of a sacrificial floor is a great idea too.I've read many posts of peaple using cat litter.
 
Thanks!

I do not know how hot I am getting my forge, I do know it is hot enough to melt the end off a W2 blade of a decent thickness in a small amount of time (depending on how much propane is in the tank).

I probably am not getting it thick enough and yes I use a lot of flux (I get worried that I am not getting the coverage good enough also with forge welding cable I worry that I'm not getting it in there (the cables) good to assist welding them together.

I still have a lot of knives I want to work on but work has been keeping me so busy lately that I haven't been able to do much at all!
 
If I keep having problems I will probably either cut out a section of the forge floor or just melt it out and replace with firebrick (cuting firebrick is a challenge).
 
if your melting steel your runing to hot, im guesing your runing above 2500 and could be hiting 3000+ degrees. the hotter you get borax the more carosive it gets.
 
Yep,too hot.Buy a thermacouple,there inexpensive and will allow exact temps to be known further reducing the different variables involved in forging,welding,and other hot work.For cable try dissolving the borax in some water and then put the cleaned cable in there,dry in front of the forge and then put her on in.The water/flux penetrates the cable quite well.Then add flux sparingly as you weld her up.For the easiest cable put several bundles in a can,add powder steel to fill the voids,seal the can,soak for 45-60 min at around 2250-2300 and she'll weld right up.
 
does your forge have a pressure read out thing? those usually help with regulating the temperature. as for cutting the fire brick, a masonry saw blade in the skilsaw works for me. the blades are relatively cheap. theyre like the metal abrasive blades but with a green label. im pretty sure if you dont have a saw, you can put the blade on a bench grinder, i havent done it but ive seen it done with the metal abrasives. good luck
 
A thermocouple would be nice!
The water and borax idea sounds good! How thick should the mix be?

I'm up to try different things.

I'll have to check harbor freight for the blades if I keep having more problems.
Whats a good placeto get a thermocouple on a budget?


Thanks
 
I got my thermacouples from a local clay and pottery supply but I see'm on fleabay too.As to the borax you want it thin enough to penetrate the steel cables,kinda like whitewash fencing.
 
I have been sprinkling it on (left it in powder form) and using the heat to melt it in! I had no idea that I was supposed to use it any other way. The NEWB learning curve is steep:o
 
For most steels you do just sprinkle it on.I think I picked up the borax and water trick for cable from Wayne Goddard.
 
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