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I've looked for the same thing, all i've found is rather expensive
I figured on finding a larger engine-driven chipper with a bad
motor, and substitute a PTO hookup for the engine. that gets you most
of the way there if your PTO speed approximates the engine speed.
Rod Richeson wrote:
I have previously found a site showing a home made chipper, but it was not
that big. From memory it was a larger version off a small domestic chipper,
running of a single cylinder petrol engine (between 5 and 8 hp possibly).
There are several different forms of chippers. The type you would probably
be most interested in, would be the most common version off
industrial/arboriculture chippers. These consist off a flywheel, with 1 or
more blades mounted on them. The flywheel is normally constructed from 2
discs off steel, joined by strips of steel welded radially from the centre
out, so as to create a centrifugal fan. The blades are then mounted in cut
outs on the face off one off the discs. On basic chippers, the blade is
simply mounted onto the face off the disc, whereas a reasonable chipper, the
blade will be mounted onto an adjustable block, as the distance off the
blade edge from the disc face, is the main factor in chip size. Around the
outside off the flywheel will be fingers, which can either be an extension
off the radial strips holding the two discs together, or seperate blocks
welded on. These fingers pass through other fingers mounted on the inside
off the chipper body, and serve to break up the chips (explained further
The chipper body, consists of some form off feed chute (can be either self
feeding or powered). At the end off the feed chute (where the cutting blades
pass), will be mounted a solid steel plate (the anvil), which supports the
wood as the blades cut the end off. There is also the exit spout, which
normally comes up vertically from the body, and has fingers (essentially
strips off metal mounted so as to follow the circumference off the flywheel)
which prevents long pieces off wood from exiting the chipper.
A brief explanation of how it works.
Wood enters the chipper from the feed chute, where it will hit the face off
the flywheel. As the blade comes round, it will force the wood down onto the
anvil (if it's not sitting on it already) and slice a section off the end.
This section will then be forced to the outside edge off the flywheel, where
it will be caught by the fingers on the flywheel. The section off wood will
then be fragmented between the fingers on the flywheel, and the fingers
mounted on the side off the chipper body, as they pass through each other.
At this point, the wood chips should be small enough to be blown up and out
off the chipper, however, if they aren't, they will be picked up by the next
set off fingers on the flywheel. The set off fingers mounted on the bottom
off the spout, prevent any large sections off wood from exiting the chipper,
causing them to be knocked back down into the flywheel fingers.
I could supply pictures off this type off chipper if needed. The main
problem with this chipper, would be getting the right size off flywheel. Too
light, and the cutting shocks/stresses will be transmitted through to the
tractor, which could quite easily damage the tractor. Too heavy, and you may
have problems getting it started, although once running very few shocks
would be transmitted through to the tractor. Also too small a diameter, and
you won't create enough draft to expell the chips (which could be
counteracted by increaseing speed off the flywheel), and too big, there
might not be enough power for the blades to slice through the incoming wood.
Then there is the problem off balancing the flywheel.
There are other types off chippers. There are ones (small domestic type)
that consist off small teeth mounted on counter rotating drums. Wood is
simply passed onto the top off the drums, and as the centre off the drums
turn into each other, wood is gradually chipped off, and discharged below.
The problem with this design is on a larger scale, you would have a major
problems with wood chips being thrown back out the feed chute due to the
forces, and also the drums and mounting would have to be off a suitable
construction to prevent them being forced apart when larger pieces off wood
enter. Also, should any solid material enter this, it is far more likely to
be blown apart. Although there are newer versions off this design which use
diamond blades, so as to be less effected should metal enter.
There are also ones which use disc cutting blades, although I've never seen
one up close to tell you how it works.
On Fri, 4 Feb 2005 21:07:04 -0000, "Moray Cuthill"
......and in reply I say!:
remove ns from my header address to reply via email
You left out the hammermill style. These are simply flails, on a
spinning frame, that thrash the wood to pieces. They are incredibly
noisy, but are very tolerant of dry wood and stones etc. Get a piece
of gravel in a disc or drum cutter and you have a major sharpening job
on the blades.
They work much like a sort of multi-layer, multi tine lawnmower.
Some of the largest mulchers have gone to this style, as have many
garden ones. The main advantage is sheer toughness. I have dropped a
3/8" hardened steel chain into a tractor-driven one, and it broke a
belt, rounded the flails a bit, filled my undies, and completely
destroyed the chain. The machine still works, although not as well.
Also, all blade style chippers need to be kept very sharp, and are
best given only green wood. I have a drum style one, and when it's
working we spend nearly as much time sharpening as chipping, to keep
the thing easy to use and efficient. We used to sharpen every couple
of truck loads.
All chippers are extremely dangerous. Hydraulic feeds seem to help,
but in many cases have actually dragged people in anyway, in spite of
stop bars etc. Hydraulic feeds certainly lower operator fatigue
(DAMHIKT) but are costly and complex.
Anyway, all of this says that there is more to making a chipper than
meets the eye. They need to be well-balanced, very strong and with
very hard yet tough cutting surfaces of whatever sort.
Actually, talking of lawnmowers, a nice mulching tractor mounted mower
may do the job.
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