<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body><div>True!</div><div>The right cutting angle and a sharp blade and counterblade, minimal gap between them give you efficient chopping.</div><div>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.</div><div>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...</div><div>Rolf</div><div><br></div><div><br></div><div><br></div><div><br></div><div><div style="font-size:100%">Enviado desde Samsung tablet</div></div> <br>ajheggie@gmail.com escribió:<br>[Default] On Thu, 2 Jan 2014 20:31:27 -0500,"Crispin Pemberton-Pigott"<br><crispinpigott@gmail.com> wrote:<br><br>>There is some merit in the slicer when looking to cut woody things. The<br>>guillotine is much more difficult to operate, in my experience. If it bends<br>>the material away before slicing, things get even better. You can try it<br>>with a pen knife: cutting directly at 90 degrees or slicing into wood at 45.<br><br>Sorry for the delay in replying Crispin<br><br>This comment is pertinent: if you have cleft material for things like<br>wattle fencing you will have learnt to steer the split by putting<br>tension on the side of the piece you want the split to go toward. This<br>must be because wood is short fibres glued together with widely<br>differing properties in shear, bending and tension. So in cleaving we<br>are mostly shearing the glue between fibres and this does not require<br>much force.<br><br>We need to separate the force to comminute the wood from the energy<br>necessary. With efficient gearing force is not a problem, though the<br>device becomes more costly. For a man powered device we need to<br>minimise the energy required to produce a particle of the desired<br>size.<br><br>Rolf has commented on a hacker that minimises the number of cuts and<br>cuts at an angle, Richard mentions the need for the cutter to maintain<br>an optimum angle. Has anyone measured the forces in these differing<br>scenarios. Energy is force moved through distance and even though the<br>force may be lesser on the angled cut as it is cutting a larger face<br>the distance is increased.<br><br>One of the principles of the teardrop chunker was that the cut pieces<br>dropped under gravity and the cutting did not impart any kinetic<br>energy to the particles, this differs considerably from commercial<br>chippers which blow particle a long way (principally to load a truck),<br>this pneumatic delivery is energy costly.<br><br>Another thing about commercial chippers to be avoided is making<br>unnecessary cuts or producing small particles because each of these<br>particles has needed energy to produce. I noticed early on that the<br>chippers that cut at an angle would not feed at all well if slightly<br>blunt, all out modern chippers cut at right angles and will continue<br>loading the truck even if the blades are dull, albeit the chips then<br>become stringy with a lot of fines ( i.e. a lot more energy has been<br>expended making them).<br><br>AJH<br><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br>stoves@lists.bioenergylists.org<br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br>http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br>http://stoves.bioenergylists.org/<br><br></body>