rockchipkip14
off to a rocking start
Member since August 2020
Posts: 22
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Post by rockchipkip14 on Aug 20, 2020 21:46:37 GMT -5
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herb
spending too much on rocks
Member since November 2011
Posts: 419
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Post by herb on Aug 22, 2020 15:08:57 GMT -5
Has anybody ever successfully renewed a blade by cutting up a brick or a grinding wheel? This does nothing for my blades, and if you think about it, it doesn't make much sense either. Whether I pay $150 or $50 for a blade for my 12" Lortone, it cuts ok for a while then gets so slow that I hate having to use it. What a pain! I've never understood how cutting a grinding wheel would expose diamonds on the blade. If cutting hard stones like agates dulled the blade to begin with, cutting a hard grinding wheel doesnt seem like the way to sharpen it. I've had much better luck with swaging the blade. Basically bang the edge of a course file along the rim of the blade. Misshapes the softer steel, exposing new diamonds. |
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Post by Bob on Jul 6, 2021 15:29:22 GMT -5
I just found this thread and have read the 2005 document which I enjoyed a lot. Some of it is of interesting to me because I got a used 10" lapidary saw not long ago, and have refurbed it, and have been hand sawing a lot and learned a lot. I have some questions and observations to make about the following things in the document:
1. The Gravity feed system mentioned on page 4. It's the thing about the weight being submerged in oil that puzzles me. Is it trying to explain that if you arrange for the weight to enter the oil just before the cut will end, that that will slow down the acceleration of the weight enough to lessen breakout? Or does it mean that the weight will be in the oil for the entire cut?
2. The ball peen hammer mentioned on page 6 for swadging the edge of the blade. Does this really mean to use the ball peen end of the hammer to do this--which would be very difficult to repeatedly strike centered on the blade edge? Or does it mean just use any hammer that doesn't have a perfectly flat face?
3. Page 7 where it mentions make sure hammer face is concave for tensioning. I just have to think this is an error and should have been convex? Also has anyone done this retensioning procedure which I'm very interested in trying?
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Post by holajonathan on Jul 29, 2021 0:19:56 GMT -5
Has anybody ever successfully renewed a blade by cutting up a brick or a grinding wheel? This does nothing for my blades, and if you think about it, it doesn't make much sense either. Whether I pay $150 or $50 for a blade for my 12" Lortone, it cuts ok for a while then gets so slow that I hate having to use it. What a pain! I've never understood how cutting a grinding wheel would expose diamonds on the blade. If cutting hard stones like agates dulled the blade to begin with, cutting a hard grinding wheel doesnt seem like the way to sharpen it. I've had much better luck with swaging the blade. Basically bang the edge of a course file along the rim of the blade. Misshapes the softer steel, exposing new diamonds. I regularly make cuts into a hard aluminum oxide grinding wheel to sharpen blades on my tile saw or large MK brick saw. It absolutely works to expose fresh diamonds. Never had to do so with my lapidary slab saw since the extremely slow cut rate does not seem to wear diamonds any faster than it wears the metal matrix that holds the diamonds. Agates are hard, but not very hard compared to diamonds. It takes an extremely long time to actually wear down diamonds by cutting agates. Rather than the diamonds actually wearing down, they more often chip or fracture until there is almost no diamond exposed on the cutting face of the blade. When this happens, the blade cut poorly since the steel matrix does not grind through rock very well if at all. This happens most often with manual feed saws (trim saws, tile saws, etc) since pushing the rock into the blade with too much pressure will fracture the exposed diamonds long before they are actually worn down from cutting. Agates are hard but not very abrasive, so they do a poor job of wearing down the steel matrix that holds the diamonds. So trying to cut agates with a "dull" diamond blade will do little to expose more diamonds. Cutting a grinding wheel (AO seems to work better than SiC wheels) exposes diamonds because the grinding wheel is much more abrasive than an agate. A grinding wheel is designed to wear down metal, so a few cuts through a grinding wheel will wear down the steel matrix but will not fracture or wear the diamonds in the blade to any significant extent. So you'll end up with exposed diamonds because you have worn down the matrix. Good slab saw blades seem to have a hard matrix since the slow feed speed will do almost nothing to the exposed diamonds in the blade. I have heard of people using the same slab saw blade for many years with little wear. If you were to put that same blade on a tile saw and manually ram rocks through it, you might have to dress the blade every few cuts. |
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