[Cob] Wood "straw" for making cob

[Henry Raduazo]

Rob:
	Robert already pitched the blades, but they were just rounded over from too much wear. The problem with excelsior is that it is produced by a cutting process that cuts across the grain of the wood and thus weakens the resulting fibers. The stuff Robert's Vermeer was putting out had really incredible tensile strength. His machine was literally tearing the wood fibers apart. The Vermeer people said they could have sharpened the old blades, but he had already pitched them. Robert is an Ashburgers kid so he is a little impulsive.
	I would say just keep using your machine it will get there. Robert used the old blades several times a week for two years before he pitched them. You could also take a grinder and round out the sharp edge.  I just hope it does not wear the bearings too much. With a small chipper you might not have enough horse power to do this. 
	An alternative idea is to use a hammer mill. A hammer mill does not have blades it has a series of free swinging hammers that are pivotally connected to an axil and when the axil is spinning at high speed the hammers swing out perpendicular to the axil. When these hammers encounter something like a branch or piece of wood they just beat on it till it is small enough to pass out through holes in a screen or through the bars of a grate.
	Troy built has an 8 Hp version that has a chipper blade for big pieces of wood and a hammer for leaves and brush. I found that when brush was fed into my hammer mill it came out as fibers. I gave my Troy built to Sam Drogue who is using it to process lumps of clay into earth plaster. To come up with a useable product though you might have to do the shredding in the winter when there are no leaves or separate out the leaves possibly by a flotation process if you have a small body of water to experiment. If you live anywhere near Washington, DC I will be happy to get back the chipper and do some experiments with you.
	I built my wood fiber cob shed with a lot of leaves mixed in but the wood fibers clearly out massed the leaves and the fibers were long and thin while the leaves were small chopped up pieces. I think the leaves aided mixing with a rototiller, did not detract from the wall strength and would add insulation to the finished wall, but that is opinion not scientifically proven fact. 
	Here again the old hammers had rounded corners and you could "sharpen" the hammers by rotating them so that sharp corner became the leading edge. (Each hammer was rectangular plate having four corners and two pivot holes.)
	
	Regarding PS.: Yes I am going to Haiti. No they are not doing cob. I am hopeful that I can persuade someone in the organization and/or someone that I meet in Haiti to do some cob. I am afraid to go to Haiti on my own. If I could find a sponsor who would give me a foundation to work on, straw, clay, sand, water and a safe environment to teach in, I would abandon Habitat in a heartbeat. If you or anyone else knows of such a person or organization please let me know, but that's better discussed off the Coblist.

Ed
http://www.habitat.org/cd/cwp/participant/participant.aspx?pid=93541387

PS. I have pictures of the fibers, the shed and anything else discussed except the Troy built chipper and I think I can get Sam to send you a picture of that. If you live near DC. I can also show you how to do patent searches. I was an Examiner in a former life.


> On Jul 16, 2011, at 10:11 PM, Rob Hayes wrote:


> Hello Henry,
> 
> I wish we could see that Vermeer chipper blade photos.  I wonder if it had a series of notches at the sharp part of the blade.  Maybe the wood was presented to the blade in a way to make longer shreds.  It'd be great if we could find a way to modify the chipper blades or make some corrugations which would produce that "straw-type" wood fiber.  Didn't they used to call this sort of stuff excelsior?  There was something like coarse wood straw used for packaging fragile stuff and for stuffing old furniture too.  Other olde heads surely remember too.
> Henry, I've got a small electric chipper/shredder and I'm thinking of just ordering some new blades so I can modify them for research.  The objective would be to make wood straw and re-learn how.  But, certainly there is something already patented which I should see and imitate first.  If you've come up with any ideas about this please feel free.  Before I subscribe to the patent search.
> There is certainly some advantages to having longer fibers and some airspaces in the cob too, right?  The chips, being shorter length, wouldn't coalesce into a likely stabler structure the way you'd like with the longer wood fibers of the excelsior, right?
> 
> 
> "...The wood wool that is the topic of this article is that which has traditionally been known as excelsior in the United States. Fifteen U.S. patents related to "slivering machines" for producing small wood shreds "known as excelsior" were listed in 1876.
> 
> The 1868 patent "Improved capillary material for filling gas and air carburettors"[39] is on a new use for "fibres torn from the wood by suitable machinery", that "is sold and used as filling for mattresses, its commercial name being 'excelsior'." This is the earliest description of the material by this name cited by the Oxford English Dictionary, though the term "excelsior mattress" had appeared in print as early as 1856.
> 
> In the beginning of the 20th century wood wool was used as raw material for production of wood wool panels in Europe, especially in Austria. By 1930, the wood wool cement boards were being widely produced."...
> 
> 
> 
> 2.
> 
> PS: Is cob being used for the Haiti housing?  I saw the link in your posting and I'm wondering about cob being used to build in Haiti.  The Engineers Without Borders hypar roof design and cob seems maybe perfect for the walls there too.
> 
> 
> 
> Hypar (hyperbolic paraboloid) Roofs
> http://tscglobal.net/?page_id=341
> "...in the most severe earthquake, TSC roofs themselves would likely exhibit little more than lateral cracking."
> "An important advantage to TSC Hypar buildings is the minimal to zero need for lumber."
> 
> see the 14 year old TSC roof being jumped on:
> http://www.youtube.com/watch?v=Jx5kcr-7gCU
> 
> 
> Surely, the Carter Habitat project allow volunteers and fundraisers too for other upcoming dates in Haiti?  The webpage said:
> "Please note: The application process for this year’s Carter Work Project 
> has closed. We hope you will be able to volunteer with us soon!"
> I'd like to consider joining them after the garlic gets planted on the farm here in November.  Do you have a group going Henry?
> 
> Message: 1
> Date: Fri, 15 Jul 2011 17:19:42 -0400
> From: Henry Raduazo <raduazo at cox.net>
> Subject: Re: [Cob] over oiled floor
> To: Coblist List <coblist at deatech.com>
> Message-ID: <8A32C534-2B3A-4374-B9F6-CCC796B1B0E7 at cox.net>
> Content-Type: text/plain;    charset=us-ascii
> 
> 
> I found the answers to questions asked last year and thought some people might be interested. 
>     First: you may remember I built a wood shed using rototiller cob and shredded wood instead of straw. I wondered why Robert's disc style chipper turned willow oak into long straw-like fibers. This year Robert replaced the blades on his chipper and now his 6 inch Vermeer is putting out fine 1/4 to 1/2 inch chips instead of 4 inch straw fibers. Apparently, if you want wood fibers suitable for cob you must use a chipper with a very dull blade.
> 
>     Second: I and many other people have been having trouble with mason bees. Mason bees are beneficial pollinators and non-aggressive, so it was neat when I only had a few of them, but after ten years I was getting hundreds of bees and the population was still growing. I felt this would start threatening the integrity of the wall. 
>     Lime plaster and lime paint seem to prevent the mason bees from attacking new sections of wall, but in places where they are well established, they can and will tunnel through even 1/4 inch layers of lime. 
>     The solution is to hang up a very thin layer of plastic. I used painters tarp so thin a 12 foot by16 foot sheet comes in a plastic envelope and weighs less than 1/2 pound. This blocked the bees access to the wall and they moved to other less critical cob walls on my property or to river banks along the Potomac. 
> 
> Ed
> http://www.habitat.org/cd/cwp/participant/participant.aspx?pid=93541387
> 
> 
>