[Cob] roto-cob

[Henry Raduazo]

	I hope that everyone understands the difference between front tine and rear tine tillers. The more expensive rear tine tillers do not work as well as the cheap 5 hp front tine tillers. This is because the rear tine tillers have power driven wheels that prevent you from hovering in one place while your turn clay rich soil into compacted concrete like mud which is totally unsuitable for gardening. Also the rear tine tillers have a rear mounted pivoting plate which prevents your feet from being chopped up by the rear tines and also prevents you from dragging the tiller back across the clay against the motion of the tines. 
	With the front tine tiller you can let the tiller walk forward and then drag it back across the pile of clay as many times as you want to mix and compact the soil. When mixing on a concrete slab I start with 5 wheelbarrows of clay and 5 wheelbarrows of sand or rock dust (2000 pounds of material and the mix changes depending on how much clay is in your clay rich soil). I mix the first two ingredients together then shovel the mass into a pile, make a well in the middle and fill the well with water. I then mix clay sand and water together while an assistant throws dry mix into the wet spots and adds water till we have a uniform but slightly soft batch of mud.
	Next or prior to the mixing I lay out straw on the ground and run a sharpened lawnmower over the straw, rake it up and do it again until all of the straw is chopped into 3-6 inch pieces. We have been trained to use long straw but when you uses as much straw as I do the length does not matter. The main point is to chop the straw enough so that it does not wrap its self around the tines of the tiller. I then add as much of the chopped straw to the mix as it will hold and till it until all of the straw is well mixed and coated with mud.
	When working off a slab you can pick up the cob with a sand shovel or a dirt fork. When you mix the cob in a trench you will want to pick the cob up and put it in wheelbarrows using a dirt fork. If you are doing trench mixing you might want to read "Water Harvesting For Dry Lands and Beyond" and locate your trench so that it can be filled with wood chips or brush to harvest water runoff and become part of your garden. 
	I have an article about using a tiller to build a wood shed with pictures and descriptions if any wants a copy.

Ed
raduazo at cox.net


On Jan 29, 2014, at 4:07 PM, Robert Alcock wrote:

> Hi Pavel
> 
> That's a rotavator (rototiller), and yes, this is a very effective way of mixing cob. About 20-50 times faster than the tarps method. It'll chuck the rocks out of the soil, too. You have to take care not to get the straw mixed around the tines -- mix wet, spray the tines with a hose and add the straw last of all.
> 
> good luck!
> 
> Robert
> www.abrazohouse.org
> 
>> 
>> Message: 2
>> Date: Wed, 29 Jan 2014 16:37:38 +0200
>> From: Pavel Velikodvorsky <willyns59 at gmail.com>
>> Cc: coblist at deatech.com
>> Subject: Re: [Cob] interview about cob self-build
>> Message-ID:
>> 	<CAB4rQxKgynn3=cL5nOA5U7-yHzvV9oLpkk1yxjEjWpJ=DhhiDg at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>> 
>> Hello to all!
>> Thanks Robert for the link to the interview. Hope i'm doing right by
>> answering to this email to keep converstaion.
>> I got interested in the picture with the caprion Another way of mixing cob
>> in this article. There is the guy mixing the cob using this moto-thing (i
>> don't know how it called right)
>> Does anyone know how effective is this? There is a huge amount of cob to
>> make in front of me this summer and I didn't come to any conclusion how to
>> do it fast and effective - in meaning of good quality of cob.
>> So far I used the cement mixer for my little cob shed, but for the main
>> house even this won't be that fast as needed. Can anyone share their
>> expirience in mixing huge amounts of cob?
>> I tried to mix it in the pit with the tracktor, but we have such a rocky
>> soil here, so all rocks were in the cob and it wasn't that good.
>> 
>> Regards,
>> Pavel
>> 
>> 
>> On Wed, Jan 29, 2014 at 4:10 PM, Robert Alcock <ralcock at euskalnet.net>wrote:
>> 
>>  
>>> Hi all
>>> You might like to check out, just posted today, an interview about the
>>> house project with Rob Hopkins of Transition Towns.
>>> https://www.transitionnetwork.org/blogs/rob-hopkins/2014-01/
>>> can-earth-building-scale-mainstream-3-robert-alcock-power-keeping-it-small
>>> cheers
>>> Robert
>>> http://www.abrazohouse.org
>>> 
>>> _______________________________________________
>>> Coblist mailing list
>>> Coblist at deatech.com
>>> http://www.deatech.com/mailman/listinfo/coblist
>>> 
>>>    
>> 
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>> End of Coblist Digest, Vol 12, Issue 8
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