Is JB Weld a hole filler or a real metal replacement?

[sofasurferlinux]

I hear people talking about using JB Weld to fill holes before retapping. Or bonding metals together. What is JB Weld really good for? Is it a hole filler, similar to wood putty on wood? Or is it truely a substance that bonds to metal and is as tough as metal? I used to use furnace cement to fix the burned out fire pots on old pot belly stoves. Is it similar to furnace cement?
What have you used it for?

 

[Humsuckler]

jb weld is not as strong as metal when used to bond to pieces of metal togeather, you can snap it with your hands, i tried it.

i remember back a couple years ago in high school tho when i took the pins out of a buddies locker hinges and jb welded them back into place with a good load in his lock. didnt get it opened up for over a week and when he finally did he bent the door all to **** haha

its good for fixin up threads thats right, and i have hered it used a couple times to repair chain smacked crankcases in dirtbikes. im not too sure if its as good as furnace cement tho, i have never hered of that.

jb weld makes wicked bombproof locktite too if you need something to never move again

 

[sofasurferlinux]

Well, if anyones interested, furnace cement is unbelievably hard stuff. Don't know about its bonding limits but like I said it is good enough to seal up a completely burned out fire pot (where the hot coals are) in a furnace. Thus, the name "furnace cement". And when shaping it, a high speed grinder is barely a match for it. Takes forever to grind it. Probably comparable to the hardness of the rear sproket when I had to enlarge to hole.
Anyone ever used it?

 

[Saddletramp1200]

Sounds like fun. Where can I get furnace cement?

 

[sofasurferlinux]

I used to buy it at the hardware store. Also called "retort cement" I think.

 

[2door]

I know a lot of the guys swear by JB but I'm not a fan. If I want a true metalized epoxy based adhesive/filler I use Devcon. They make several different products specially formulated for repairs on steel, aluminum and other metals. They have some high temp stuff called 'Liquid Titanium' that I saw used successfully to reattach a broken cast iron flange on a steam boiler. I've used both,the 'Liquid Steel' and 'Liquid Aluminum' with good results. You'll pay a lot more than the hardware store JB but like they say; "You get what you pay for".
Tom

 

[tyrslider]

I can echo what others have stated and add a bit. i like devcon better but jb is good stuff. They are as hard as metal but not as tough i.e brittle. Their effectiveness has everything to do w/ surface preparation as well as application.

I've repaired gas tanks, crankcases, made molds/ fixtures for machining, tapped and machined them. They can be very useful!