Furnaces

[andu]

I bought a furnace from vevor from which i pushed the burner too hard and messed with the wool, this meant my furnace auto ignited after aluminium just started to melt, okay, lets just say that furnace is gone, I bought a new second furnace, different this time, it had a stopper so you dont push the burner too far, no matter how deep it was fit it started autoigniting again smashing all my hopes. There is a chance one simply needs refractary concrete, but this is not mentioned anywhere and they becoming most useless.
If you cool them down with water, youll eventually have a drop inside and it will explode and do much damage, including killing you..... im devastated by having my furnaces fail me each time, maybe devil-forge is really worth it and any other brand is garbage, worth mention DF does tend to provide some cement, altho expensive can be found otherway.

 

[Shark]

Reline the container or start with a new one. Use hard fire brick for the bottom, and a replaceable center core is helpful for foam overs or spills. Line the sides and top with soft fire brick, and coat with a high heat cement. Better yet, use one of the heat reflective coatings. Add burner in the same manner as your old furnace.

Hard fire brick will withstand flux spills better than soft firebrick, but absorbs heat unlike soft firebrick, which reflects heat but will dissolve on contact with most melted flux’s.

 

[4metals]

You can use a cardboard concrete form made for pouring pillars as a form. Get one in a big enough diameter and one smaller diameter for the inside diameter. Fill them with a cast able refractory cement. Make sure you add a cardboard tissue roll center to make the pass thru for the burner. The bottom is just a solid disc made of the same refractory cast able cement. If you choose your OD and ID to be close to the unit you purchased you can see the height above the bottom for the burner to enter.

I always liked to make the burner higher up on the wall to allow you to place a crucible rest on the bottom so the flame hits the bottom of the crucible. The flame should hit at an angle so the flame path will circle around the crucible but be parallel to the bottom so the flame spirals more before passing out the top. You make the crucible rests so they are smaller by a few cm than the ID and as tall as you need it. You also make them from cast able refractory cement.

 

[4metals]

check out this thread for more details