Homestead mailing list

[Tvoivozhd <tvoivozd AT infionline.net>]

You have to visit the Onebone website or the Paul Sarnstrom archives for 
photos of the Onebone mixer, but here is something I found in my files.

Thank you for a crystal clear description of your mixer.  The description of
the bucket brake on the 28th was equally crystal clear.  I am wondering if
you have equally elegant and simple methods of handling the materials you
put into the mixer.  Working out of cement bags is inconvenient and probably
unhealthy due to the cement dust.  And they are damn heavy and they seem to
get heavier with every passing day.  I suspect you use something other than
brute force to handle them?

Richard in Kansas


----- Original Message -----
From: <onebone AT iwon.com>
To: "Ferro Cement Mailing List" <ferro-users AT ferrocement.net>
Sent: Wednesday, March 03, 2004 8:58 AM
Subject: Re: [Ferro Cement] onebone mixer



> >  --- On Wed 03/03,  < FountainB AT switch.aust.com > wrote:
> > I was going to ask onebone for a set of his fine blades, but<br>then it
>  
occurred to me that either the thread or the rod diameter<br>are likely to
be incompatible with the metric stock we have<br>here. Are there photos
posted somewhere that describe the<br>onebone mixer
construction?<br><br>Bruce Fountain<br>Senior Software Engineer<br>Union
Switch & Signal<br>Perth, Western Australia<br><br>

> > Right you are, Bruce.  I'm afraid I don't do metric, and haven't yet made
>  
any photos for the list, but, at the risk of pissing the Yanks off with
monotonous repetition, I'll run thru it again.

> > The Onebone mixer is as simple as can be.  There are two blades, mounted
>  
at right angles to each other on a driveshaft.  The vertical distance
between the blades is usually not important, and mine, at the moment are
about 2 inches (50 kilometers) apart.  I told you I don't do metric, so stop
snickering!

> > The mounting holes in each blade are threaded with a coarse thread, 1/2
>  
inch in diameter, with 13 threads per inch.

> > The driveshaft is allthread, (do you have allthread in Australia?) and,
>  
obviously, also, 1/2" X 13 thread.  It would not have to be allthread--I
simply used that because it's convenient to do so, as there's a lot of it
lying around my shop.

> > The driveshaft can be any length you fancy, but I'd recommend about 32
>  
inches. (800 milliliters?)

> > The only "magic" about the mixer lies in the dimensioning of the blades:
>  
Pay attention here! This is paydirt! The blades are only 1/4 inch thick
(about 6 meters) and you DON'T want them to be much thicker than that! They
are not twisted or enhanced in any way.  They are 1 inch wide (25
centimeters) but this dimension is not supercritical.

> > Here comes another critical dimension: Are you still with me?  The blades
>  
need to be just a wee bit shorter than the inner diameter of the buckets
you're going to use--say 1/8 inch, or even less. In the case of most of the
5 gallon buckets we use hereabouts, that dimension is around ten inches, but
measure the I.D. of the flipping bucket before you cut the blade!

> > The corners at the ends of the blades need to be rounded by grinding or
>  
filing, so that they don't cut the bucket.

> > You're probably curious, so for your information, the first bucket that
>  
failed cracked on the bottom near the sidewall after mixing about 800
batches of rather rocky mix.

> > The lower blade is located (threaded) onto the shaft with its bottom
>  
surface precisely even with the bottom of the shaft. A regular old 1/2 inch
by 13 nut is located above it on the shaft (no washers anywhere) and the nut
is run tightly down against the blade.  This is what we call a jam nut, and
it locks the blade into position on the shaft.  The upper blade is locked in
the same manner, with a nut above it on the shaft, and, as I said above, the
blades are rotated so that they are at 90 degrees to each other.  This is
another important piece of magic. The upper blade thus keeps the lower blade
centered in the bucket, and this is VERY important.

> > If you don't get the jam nut tight enough, the blade may start walking up
>  
the shaft, but if this happens, you just screw it back to the bottom and
make the nut a bit tighter.

> > Due to the length of the blade, it takes quite a lot of torque to turn it,
>  
and I drive mine with a right-angle drill called a Hole Hawg, which pulls, I
think, about 12 Amperes, and I run it at its lowest speed, 300 RPM.

> > It is necessary to prevent the buckets from spinning as you mix. I have a
>  
fixture made from a scrap of plywood with two boards, 2x4 inch, nailed to
the top surface, spaced so the two buckets fit close between them, Then I
take small wedges of wood and attach them to the buckets with duct tape, so
that, as the buckets start to spin, the wedge contacts the 2x4s and
restrains the spinning.

> > That's about it. If you have any questions, feel free to come back to me.
> >
> > Regards,
> > Onebone

On Wed 03/03, Richard Miller < mtndir AT earthlink.net > wrote:

Onebone -<br><br>Thank you for a crystal clear description of your mixer.  The description of<br>the bucket brake on 
the 28th was equally crystal clear.  I am wondering if<br>you have equally elegant and simple methods of handling the materials 
you<br>put into the mixer.  Working out of cement bags is inconvenient and probably<br>unhealthy due to the cement dust.  And 
they are damn heavy and they seem to<br>get heavier with every passing day.  I suspect you use something other than<br>brute 
force to handle them?<br><br>Richard in Kansas




Ahh, Hell, Richard. You caught me. I was going to keep this one up my sleeve 
until I got some photos posted, somehow.

I use a lot of HD rocky road ready mix in 60 pound bags (HDRRRM) which is 
about as heavy as I want to handle.

I cobbled up a table out of a scrap of 3/4 plywood. I made fences for both 
sides out of scrap 2x6s, standing on edge, drywall screws from underneath. 
Then I made a V-shaped splitter, also from scrap 2x6 on edge, on the far side 
of the table.  I plop a bag of HDRRRM onto the near side of the table, slit 
it crosswise with trowel or boxknife, and roll it gently forward to minimize 
dust, and lift the bag away and put it into a plastic trash bag which is 
nearby in a dedicated bagholder.

At this point, the mix is starting past the V splitter, and I've tried to 
dump it so that half of it goes on each side.

Since I find that HDRRRM is too rocky to suit me, most of the time, I now add either one-half or one shovel of Portland and either one or two shovels of sand on each side of the splitter. 

The mixing buckets are already charged with ten seconds' worth of hosewater, 
and are in their bucket-brake frame on the far side of the table.

I now pick up the near side of the table and tip it so that the mix slides 
into the waiting mixing buckets.  (The table is supported on stacked concrete 
blocks.)

Then I walk around to the other side of the table, grab the famous Onebone 
mixer, and, without moving the buckets, go Brrrrrrt, Brrrrrrt, with the 
mixer, about ten seconds in each bucket.

Then I put the mixer down, grab the buckets by the bails, and lug them, or 
wheel them on a hand truck, to where they need to be.

After dumping, both buckets go back to the bucket brake frame, get another 
ten seconds of hose water, and the process starts all over again.

Having a couple of helpers speeds the process enormously.

The mixer does its job so quickly, that if I were to do nothing but stand 
there and run the mixer, I could probably keep ten  or more men busy with the 
other tasks of loading and dumping the buckets. I could set up two, or even 
four tables, with the mixer in the middle, and really fly, because, as I've 
tried to explain many times, the mixer is NOT the bottleneck. It probably has 
the potential to mix mud faster, maybe MUCH faster than two or more drum 
mixers.

Maybe I will make a serious effort to get up to Nolans this summer and knock 
everybody's sox off. We'll see.

Regards,
Onebone


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