Cob: Machine mixing methods.

[SANCO Enterprises, LLC]

Darel, Ryan and others,

When it comes to mixing, most any type of mixing device works well until you
add the straw component--then the challenges begin.  Paddle type mixers
(concrete or plaster) work well to mix cob material when short length straw
is utilized.  When long straw (as most cobbers prefer) is added, the straw
becomes tangled in the paddles and very little mixing is accomplished.  For
these mixers, best practice is to mix the cob soil without straw and then
add the straw as you make cob balls or mix it with your feet.  Still saves a
lot of work

The roto-tiller is great for breaking up the soil, but a lousy mixer when
the material is wet and even worse when you add straw.  It will take two
strong individuals just to pull it from the mud.   Not for the purist, but
mixing with equipment such as a loader or Bobcat in a pit is an alternative
that works well if you want to mix a couple of yards of cob at a time.

Although mechanical, the best bulk mixing method is to use a pug mill on a
very slight incline.  You can initially allow the first stage to mix the
soil and water component then add straw (short or long) in the second or
third stage.  After the mud is mixed, adding the straw is just a matter of
folding it into the mix.  The best part is that it is a continuous mixing
operation.  The amount of water is critical in all mixing methods, even with
a pug.  Less water means a heavy dense mix that is gummy and sticks to
everything.  Too much water and you have a wet sloppy mix that may even
separate the materials.



SANCO Enterprises, LLC
Paul Salas, General Manager
P.O. Box 45741
Rio Rancho, NM  87174
(505)  238-1485
chansey at earthlink.net

----- Original Message -----
From: "Darel Henman" <henman at it.to-be.co.jp>
To: "Shawn Antaya" <antaya_s at hotmail.com>
Cc: <ryan_auge at yahoo.ca>; <coblist at deatech.com>
Sent: Monday, June 10, 2002 8:31 PM
Subject: Re: Cob: Machine mixing methods.


> Ryan,
>
> Another idea for you.
>
> If you made a little cob holding area for mixing.  A hole and possible a
> little levee around it.  You could put in your clay soil, straw, water
> it, and then put on long rubber  boots and employ a roto-tiller, to mix
> up the pit of cob.  I've not done this personally, so I don't know if
> it'll clog up or not, but I  have seen a picture of it.  I should think
> the percentage of water is important.  It would be a very simple
> solution and roto-tillers are usually available at nearby machine rental
> stores.
>
> Darel
>
> Shawn Antaya wrote:
> >
> > Ryan,
> >
> > FYI - I've used a plaster mixer with great success.  The batches have a
> > little extra water but this proves acceptable in the dry Taos, NM
climate.
> > The rubber blades on this mixer scrape the sticky cob off the walls of
the
> > mixer to get a consistent blend of clay, sand, straw and water.  A bread
> > mixer (to my memory) does not scrape the walls.  I've found that cob
sticks
> > to everything while bread dough tends to stick to itself.  A thick cob
> > mixture may not mix properly, a thin mixture may mix well but be too
thin.
> > Good luck.  :-)
> >
> > Sincerely,
> > Shawn Antaya
> >
> > ----Original Message Follows----
> > From: Ryan Auge <ryan_auge at yahoo.ca>
> > Reply-To: Ryan Auge <ryan_auge at yahoo.ca>
> > To: coblist at deatech.com
> > Subject: Cob: Machine mixing methods.
> > Date: Mon, 10 Jun 2002 13:07:09 -0400 (EDT)
> >
> > Hi there,
> >     I've read some of the messages relating to mixing cob with machines,
and
> > was
> > noticing that a lot of the conversation leads towards cement mixers.  I
was
> > wondering if anyone had ever experimented with using a commercial grade
> > dough
> > mixer, like those used in bakeries and restaurant kitchens, to mix cob.
> > Cement
> > mixers tend to basically scrape the contents of the mixer along and up
the
> > outside edges of the container, then let gravity pull the contents back
down
> > into itself.  Dough mixers rely on the motion of the mixing arm to more
> > consistantly kneed the contents of the container into itself.  I would
think
> > this would allow a pretty good cob mix, straw and all, considering the
> > quality
> > of doughs that come out of commercial mixers even when all the
ingredients
> > are
> > just tossed straight into the bowl while the machine is running.  If you
> > have
> > tried, or can try, why not let everyone know.
> >
> > Ryan Auge
> >
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