his video is for a 8 inch riser so i need to reduce everything by about 40% or so. trying to get an idea of how much fire clay to order. he recons around 92 pounds total weight so if i keep the insulation at 4 inches thick should i assume around 60 pounds or one 25kg bag of fire clay. i have 100 litres of perlite but no fire cement as yet.
would rockwool mixed in with the mix work as well as fibreglass matting? i have both but a lot more rockwool. i know it isnt a precise art but does that sound about right?
its either 25kgs or 50kgs of fire clay.
i got a sheet of aquaboard today similar to hadiebacker board. i am going to try and add a trip wire and the ski slope at the back if i can as well. plus the p channel just to keep right up date. i thought i may try to mould the tripwire into the aquaboard separately cook it in the oven and then fit it on the top of the mould before i finish casting the rest of the mould. not sure if it will work or not.
thomas rubino wrote:Hi Bob; when i built my 8" core using matts plan's, I had 2, 50 # bags of fireclay on hand and I didn't have quite enough! I needed 3 bags ! Even on a 6" I would have no less than 2 bags. I'm sure that rockwool will work fine as a binder. Plywood will work as well as hardy board or aquaboard, what ever you use will burn out quickly. Also matt has plans for a cast riser with the same ingredients , You will need a bag of fireclay for this also . Matt used a piece of stove pipe for his sacrificial inner form , I used a piece of (soni tube) cardboard concrete form as my inner form and it worked great! Good luck Tom
thanks thomas, i have ordered one bag for now to make the riser with so i have some idea of quanities. i am going to use cardboard tube and paint it with cement slip as suggested by someone either here or on donkeys site.
should i make the riser wall 4 inches as well? i have some oil drums 11 inches diameter, but i could easily extend them up to 14 inches if needed. i have plenty of those so easioer to do that than find a 14 inch drum the right height.
With regards to dimensions, I find it easier to think about the size of the openings and passages rather than a percent of what I did for the 8". For a 6" you'll want 5.5" square for those as opposed to the 7 3/8"or whatever it was for the 8". That way you can keep the burn tunnel length and core/feed/riser stub height the same, which I find to work very well.
Tom, I read somewhere about your feed getting banged up, and I wanted to let you know that is totally part of the trade off of this type of core, you did nothing wrong. Light highly insulating properties and hard abrasion resistance are properties that are kinda at odds, so I go with the function I want and deal with the wear. I don't find it too bad, I use care when loading and try to just be patient when the fuel is burning down low so I don't go in there and bang it all around trying to put a new load in too soon. I've tried a lot of stuff to make it more durable and always come back to the softer core mix for the feed since the performance is so good. At this point, I have pretty much settled in to patching my feed a couple times a winter, and I find it totally acceptable.
"How many licks ..." - I think all of this dog's research starts with these words. Tasty tiny ad:
five days of natural building (wofati and cob) and rocket cooktop oct 8-12, 2018https://permies.com/t/92034/permaculture-projects/days-natural-building-wofati-cob