Civil Engineering Reference
In-Depth Information
equipment to perform such cuts, and the time wasted performing what should have been
a simple process. Any number of people could tell me how to cut a bale to length but
there didn't appear to be the equipment to cut notches and make holes.
I tried all sorts of equipment including a brush cutter, which did the job but was very
slow and clumsy. On one occasion while my wife Jan was out for the day, I had a brain
wave, and tried out some of Jan's good kitchen knives, much to her disgust. I discovered
that the serrated carving knife with a sharp point did an excellent job. I did make
recompense and replaced her knife with a new one of better quality. The serrations of the
knife cut the straw rather than slide across it, as was the case with a plain knife. I had tried
a hacksaw blade, but found that it grabbed onto the straw rather than cut it. This was not
a serious problem with the serrated carving knife. I tried a knife with a similar serration
that did not have a sharp point, but was unable to drive it into the bale. The same knife is
ideal for cutting holes into existing straw bale walls.
The brand of knife we now use is 'F Dick'. There are two similar knives sold by this
company, one with a straight blade that runs up through the handle and another with a
forged blade. The knife with the forged blade is easily distinguished, as the metal of the
blade, at the handle, bulges out to the width of the handle. I have tried both knives and
have found that the cheaper knife is somewhat lacking in its staying ability. By the end
of that house it is only good for cutting bread. The better knife has a much longer life,
as the steel in it is of higher quality. I have now been supplying these knives to my
owner-builders for some time, and have never had a complaint. At around $130 (2005)
they represent a lot of money for a knife, however when compared to the cost of a good
saw blade at around $200 they are quite reasonable. I am told that you can buy
sharpening stones to suit them, however I am yet to be able to locate one.
Cutting a notch to accommodate a post
To cut a notch out of a bale, which is required when fitting bales around posts, simply
drive the sharp point of the knife into the bale at the desired location and then with up
and down motions, slice the straw at the required location. As the knife will not reach all
the way through the bale, it will be necessary to turn the bale over and repeat the incision
from the opposite side of the bale.
Cutting a hole in an existing wall
To cut a hole in an existing straw bale wall, simply push a single bale needle through the
wall so that you can locate the point at which to cut on both sides of the wall. Insert the
knife into the bales on both the inside and outside of the wall. The knife will reach more
than half the depth of the bales. I recently had cause to insert a piece of 150 mm poly
pipe through an existing straw bale wall for the plumber to feed a sewer line through. We
knew the position of the hole on the inside of the house, so we inserted a single bale
needle through the wall in what represented the centre of the required hole. This gave us
an accurate position for the centre of the hole on the external side of the bale wall. The
render was removed from the surface of the wall to allow the knife uninhibited access to
the straw that needed to be cut. Incisions were made from both sides of the wall in the
position that represented the external perimeter of the required hole.
