True! The right cutting angle and a sharp blade and counterblade, minimal gap between them give you efficient chopping. Length of chip is invertedly proportional to energy per unit of weight, and since we want chunky pieces to provide adequate interstices between them, we want a chopper and not a chipper. More: if we leave the lower side cover of the disc housing open, we discharge at floor level in along arch which nicely separates the fines from the chunks... Rolf
Enviado desde Samsung [email protected] escribió:[Default] On Thu, 2 Jan 2014 20:31:27 -0500,"Crispin Pemberton-Pigott" <[email protected]> wrote: >There is some merit in the slicer when looking to cut woody things. The >guillotine is much more difficult to operate, in my experience. If it bends >the material away before slicing, things get even better. You can try it >with a pen knife: cutting directly at 90 degrees or slicing into wood at 45. Sorry for the delay in replying Crispin This comment is pertinent: if you have cleft material for things like wattle fencing you will have learnt to steer the split by putting tension on the side of the piece you want the split to go toward. This must be because wood is short fibres glued together with widely differing properties in shear, bending and tension. So in cleaving we are mostly shearing the glue between fibres and this does not require much force. We need to separate the force to comminute the wood from the energy necessary. With efficient gearing force is not a problem, though the device becomes more costly. For a man powered device we need to minimise the energy required to produce a particle of the desired size. Rolf has commented on a hacker that minimises the number of cuts and cuts at an angle, Richard mentions the need for the cutter to maintain an optimum angle. Has anyone measured the forces in these differing scenarios. Energy is force moved through distance and even though the force may be lesser on the angled cut as it is cutting a larger face the distance is increased. One of the principles of the teardrop chunker was that the cut pieces dropped under gravity and the cutting did not impart any kinetic energy to the particles, this differs considerably from commercial chippers which blow particle a long way (principally to load a truck), this pneumatic delivery is energy costly. Another thing about commercial chippers to be avoided is making unnecessary cuts or producing small particles because each of these particles has needed energy to produce. I noticed early on that the chippers that cut at an angle would not feed at all well if slightly blunt, all out modern chippers cut at right angles and will continue loading the truck even if the blades are dull, albeit the chips then become stringy with a lot of fines ( i.e. a lot more energy has been expended making them). AJH _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://stoves.bioenergylists.org/
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