Primitive Technology
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Woodash Insulated Furnace
🕑 Added 2023-08-03 21:35:10 +0000 UTCI made a furnace insulated with wood ash for smelting iron. I'd previously seen rocket stoves that used wood ash as an insulation and remember reading that dry wood ash performed as well as the mineral wool insulations they use in modern furnaces. It worked well but the blower broke during the smelt. It was the third most successful smelt I've done in the wild and when I repair the blower I'll test it again. Much appreciated.
Comments
Primitive Technology
I considered that too. It's got potential.
Kenneth Crips
I was looking at a pole spring lathe. This lathe in one form or another have been used for 1000's of years. I was looking at the drive, a springy tree branch. You could very easily adapt this drive to move a blower. instead of using your hand to power your blower you would have a simple foot pedal.
Primitive Technology
The larger diameter negating the need for gears perhaps.
Primitive Technology
Yeah I think I've seen the video you mention, it's British people recreating Edwardian period iron smelting to make a weather vane. I did play around with the idea of making a clay disc with wooden dowl pegs as teeth but I didn't get it going past that. I'll think about it some more, it would be good to get rid of the string drive for something more durable. Also, maybe a larger fan diameter with a 1:1 ratio hand crank.
Kenneth Crips
Have you experimented with wooden peg/pin gears. I was looking at a primitive smelter and they were using a cranked set of peg gears to power the blower. Being able to just turn a crank would be a lot easier and move more air then your string drive. It would also be within your technical limitations.
Primitive Technology
I made this video on fire sticks way back https://youtu.be/z9n9rqb-lvY . I don't know the name of this wood for sure but was told by a local here it was Abroma mollis (now reclassified as Abroma molle). The stick and base board are the same timber with the base board being slightly thicker. Other wood I've used include Fiddle wood, African tulip and lantana. There were others too but I don't know their names. Basically use a soft wood from a fast growing tree. The low density wood seems important for the hand drill. Thanks.
Primitive Technology
The preheat with wood only took an hour, then the proper smelt with charcoal took 1 hour 30 minutes. All up 2 hours 30 minutes, but it would have taken less had the blower housing not broke.
Hizuna
Very interesting. How long did the whole heating process take? My main question may be a bit out-of-line, but I couldn't find a specific hand drill video here: what type of plant do you use for drill and fireboard/-stick in order to make fire? Are both things of the same species? Is it softwood on softwood? (I can only use bowdrill so far, but then it would be softwood on softwood for me.)
Primitive Technology
I have slag, that might make a good substitute. Only enough for small quantities though.
Primitive Technology
I tried making a piston bellows from clay at home after our last conversation Kenneth. It was 50 cm diameter and 50 cm tall so it would roughly expel the 300 l needed per minute in about 4 strokes. It was vertical rather than horizontal. But the piston which was also clay attached to a wooden rod broke. Prior to that, it was working slightly with cardboard flap valves working somewhat. Getting the seal was also difficult as I used cloth to form a gasket. I now see that feathers were used generally. I might make one with a smaller diameter and see if that works.
Kenneth Crips
You have already made Quicklime from there with Slaked Lime it is easy to make Roman cement. You just need a source something like volcanic ash.
Kenneth Crips
I was looking up Iron age iron smelting blowers. It was very interesting to see Google images mostly of you and your string cranked blower. There are other Iron age blowers. of course but they all use animal skin bellows, something I cannot see you doing The push-pull Chinese box blower is just a little beyond the tech level you have to make one.
Primitive Technology
I'll have to investigate it. If it's as simple as mixing clay with ash and calcining it then it will be an option. Thanks.
Primitive Technology
Maybe it would make a good insulator. I heard that dry wood ash is on par with kaowool. Thanks.
Primitive Technology
We'll see. Thanks.
Morten Bjerkvig Jølnæs
Also still super interested to see if you can make proper cement clinker. Even low quality Portland cement would allow you to cast so many things.
Morten Bjerkvig Jølnæs
Very nice work with the upgraded furnace. I wonder if a better insulator could be made with expanded clay balls? I believe the secret to them is coal or other combustible pieces intermixed with the clay when rolling the balls balls. In industrial scale it happens automatically in a in a rotary furnace but could probably be done relative quickly by hand in limited quantity?
Laudern
Can we get an hour long version of that blower gowing. It's like rain sounds. Perfect to fall asleep... 😅
Primitive Technology
Can't hurt.
Amy Tobol
An extra twirl for luck.
Primitive Technology
Just to be sure I thought to my self. Thanks.
Amy Tobol
2:09 when our man gets caught up in the hypnotic rhythm of drilling and starts another round of drilling after an ember has already formed but catches himself
