My jewelry's site
My experiments And other metal melting techniques: And chemistry:
Site index

Home built barrel furnace 2018


Building the barrel furnace June 2018

play Some steps of the building process of the barrel furnace.

Second fire the barrel furnace June 2018

play The first warming up resulted in a fail due to the Kaowool was not as heat resistant as expected, but here an attempt with the old Mizzou furnace inside it with Kaowool insulation.

I built a new 'roaring furnace'. My old one made from Mizzou concrete takes up too much heat which prevents heating it up much.

So I ordered a 60 liter barrel (56cm/22" height and 36cm/14" diameter) and made a furnace of it. I use only Kaowool instead of 'traditional' refractory. The floor is lined with YTONG cell concrete of 5cm /2" thick and a plinth of 10cm/4" diameter and 7.5cm/3" high in the center of the same material. This is all covered with a single 1" layer of Kaowool and a graphite pad on top of it to prevent sticking the crucible to the plinth.

The inner walls are a single layer of Rockwool and the outer layer and two 1" layers of Kaowool. Finally, the inner diameter is 23-25cm (9-10") which fits even a 1 liter crucible (I have one of it, rest are 0.5 liter ones). The inner height is 30cm/12", with plinth under it, the top of the crucible is a few cm below the top of the furnace.
The lid has two layers of Kaowool which are kept inside by bending the cut off top and the center hole inward. When cutting off the top of the barrel (about 13cm/5") which is the lid, I cut perpendicular vertical cuts of about 5cm/2" to allow them bending inward which holds the kaowool inside. Moreover, I'll bend it in the furnace body only 45-60 degrees and in the lid 135-120 degrees, so it appears a bit conical which helps preventing sideways venting.
The top hole I'll use a similar approach: cut 4-5 10cm/4" long cuts in the center which have a star-like appearance initially with the angle grinder and then bend them inward for holding the kaowool in the center and leaving the exhaust hole in the center. I'll leave the original hole at the rim of the lid barely covered with kaowool to allow an extra peephole for e.g. pyrometer access. Furthermore I'll use two handles made of rebar with M10 bolts welded to it and mounted on the lid with corresponding nuts + washers.

The burner hole is about 10cm/4" above the (gross) bottom which is about 3cm above the inside bottom. I cut this out the same way as the exhaust hole and bending it inward, but then elliptically because of the tangential anticlockwise burner entry. I use a propane burner with forced air which I already have (see photo).

First fire failure

Unfortunately, the lining melted like plastic at the first fire, it was not 1500°C rated as expected. So I used the old Mizzou furnace built in 1992, which is 1650ºC resistant, but not well insulating. I put it inside the insulation wrapped within the Kaowool which then will not be heated above 1200°C. The first (second) fire succeeded and melted some brass.

animate copper melting
Melting copper viewed through the exhaust hole.


Photos of building of the furnace June 2018

thumb./barrelfurnace/-tn-IMG_2852.JPG
The plain barrel just received
thumb./barrelfurnace/-tn-IMG_2853.JPG
This is how the burner will enter the barrel
thumb./barrelfurnace/-tn-IMG_2854.jpg
thumb./barrelfurnace/-tn-IMG_2858.JPG
thumb./barrelfurnace/-tn-IMG_2860.JPG
The grooves cut for folding down later
thumb./barrelfurnace/-tn-IMG_2863.JPG
Grooves for the exhaust hole
thumb./barrelfurnace/-tn-IMG_2864.JPG
thumb./barrelfurnace/-tn-IMG_2865.JPG
The grooves cut for folding down later
thumb./barrelfurnace/-tn-IMG_2867.JPG
The barrel cut open
thumb./barrelfurnace/-tn-IMG_2868.JPG
Handles ready for installation
thumb./barrelfurnace/-tn-IMG_2869.JPG
Drilling holes for handles
thumb./barrelfurnace/-tn-IMG_2870.JPG
The lid prepared
thumb./barrelfurnace/-tn-IMG_2871.JPG
The lid lined
thumb./barrelfurnace/-tn-IMG_2872.JPG
... and edges folded around it
thumb./barrelfurnace/-tn-IMG_2949.JPG
Lining of the furnace with Kaowool
thumb./barrelfurnace/-tn-IMG_2950.JPG
thumb./barrelfurnace/-tn-IMG_2951.JPG
Furnace and lid, unfinished yet
thumb./barrelfurnace/-tn-IMG_2965.JPG
After first fire, the Kaowool appeared to have a too low temperature rating....
thumb./barrelfurnace/-tn-IMG_2968.JPG
The Kaowool removed from the barrel
thumb./barrelfurnace/-tn-IMG_2969.JPG
Empty barrel again with old furnace inside it
thumb./barrelfurnace/-tn-IMG_2972.JPG
Step 1 for new setup of old furnace insulated by the Kaowool
thumb./barrelfurnace/-tn-IMG_2973.JPG
Step 2, bottom lining
thumb./barrelfurnace/-tn-IMG_2974.JPG
Step 3, old Mizzot furnace inside it
thumb./barrelfurnace/-tn-IMG_2975.JPG
Step 4, kaowool above it
thumb./barrelfurnace/-tn-IMG_2976.JPG
Step 5, kaowool above it, finshed
thumb./barrelfurnace/-tn-IMG_2977.JPG
Lid closed
thumb./barrelfurnace/-tn-IMG_2978.JPG
... and burner in it
thumb./barrelfurnace/-tn-IMG_2980.JPG
Crucible in it
thumb./barrelfurnace/-tn-IMG_2981.JPG
... and lid closed gain, ready for use
thumb./barrelfurnace/-tn-IMG_2994.JPG
Prepared for copper melt
thumb./barrelfurnace/-tn-IMG_2996.JPG
Copper melting
thumb./barrelfurnace/-tn-IMG_2998.JPG
Copper molten
thumb./barrelfurnace/-tn-IMG_3000.JPG
Castings (blanks for sheet rolling) remainder

IYC 2011 logo

Powered, developed under Linux linux and Mac macOS and hosted under Linux.
This site is best viewed with Firefox, Safari, Chrome and Opera. Using landscape mode on a smartphone gives a better view.