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Post by Deleted on Oct 10, 2014 12:41:55 GMT -5
Greetings [deb193redux] Another list that can not count, note 14,000 = 1 micron, but 0.5 micron = 50,000!? It is amazing how many companies copied that list with it's glaring error! Please check out my Sticky's below. -- Please click images to open larger images in a new Tab, same with everything that is Underlined! I currently have a 3lb Beach (UK), Lortone QT 12/66 (USA) rotaries & 2x Viking Vibrasonic (Diamond Pacific) (USA) virbrating tumblers, with Silicon Carbide grit F80, F220, F600, F1200, with Tin Oxide (1.0 micron) & Aluminum Oxide (1.0 micron & 0.3 micron) polishes. I hail from (The Barony of Seabegs) Bonnybridge, Stirlingshire, U.K, where aliens (15mb) sometimes come for a visit & about 4 miles west from that monstrosity & 7 miles west of this new monstrosity! Sticky's: their contents are resource information 1#: Vendors worldwide (2mb), 2#: How to use the forum, 3#: How to identify rocks & minerals, 4#: Save money on expensive grits & polishes, 5#: Aussie Lapidary Forum: Rock Tumbling Guide!
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Post by rockpickerforever on Oct 10, 2014 13:20:50 GMT -5
I was thinking the brain in the jar was that of a 9 year old girl, a specimen he keeps in a jar. Could be, we don't really know this guy ! Who knows what other kinds of things Ted I mean Tony might have lying around...
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Post by deb193redux on Oct 10, 2014 13:25:32 GMT -5
Greetings [deb193redux] Another list that can not count, note 14,000 = 1 micron, but 0.5 micron = 50,000!? It is amazing how many companies copied that list with it's glaring error! I am not sure I follow you. You seem to assume a linear relationship. I always assumed that the relationship was nonlinear, or even arbitrary. Upon investigation, I find that it is an exponential decay function. So, if you only looked at larger grits it would appear to be a steep linear line, and if you only looked at smaller grits, it would appear to be a flattish linear line. see straightrazorplace.com/srpwiki/index.php/Formulae_For_Converting_Between_Grit_and_Microns
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Post by mohs on Oct 10, 2014 13:26:20 GMT -5
so then, the grit starts to cut the stone and cleaves before making a long scratch? Each cut made by the grit is more like a nip? I am still looking for the sand blaster that put such deep divots in that piece of glass. They don't seem deep to you ? That photo represents 1 inch left to right. So about 4X magnification. those are some deep holes !!?? Hi James the 30 grit was the original grinding process…Right? I’m not sure I understand why you think it shouldn’t have deep divots at that grit level Ed
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jamesp
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Post by jamesp on Oct 10, 2014 13:34:09 GMT -5
I am still looking for the sand blaster that put such deep divots in that piece of glass. They don't seem deep to you ? That photo represents 1 inch left to right. So about 4X magnification. those are some deep holes !!?? Hi James the 30 grit was the original grinding process…Right? I’m not sure I understand why you think it shouldn’t have deep divots at that grit level Ed They look deep for a slow rolling tumbler. That is what puzzles me. Seems more force would be required to gouge out so much material. And the lack of scratches still bugs me. Maybe I need a more diabolical reason
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Post by deb193redux on Oct 10, 2014 13:41:46 GMT -5
I think the issue is deep scratches vs deep divots. Scratches are consistent with abrasion/scrape, divots invoke scoop or gouge.
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Post by parfive on Oct 10, 2014 13:43:53 GMT -5
I’ll take half a micron for 28,000, Alex.
Note: For comparison only. All manufacturers’ abrasives differ slightly. Grit sizes, microns and inches may be approximate in some instances.
The end user of micro grits must not assume that materials having the same size designation from different manufacturers will be equivalent to each other or that they will produce the same finish.
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Post by Deleted on Oct 10, 2014 13:50:43 GMT -5
Greetings [deb193redux] Another list that can not count, note 14,000 = 1 micron, but 0.5 micron = 50,000!? It is amazing how many companies copied that list with it's glaring error! The "mesh" size is not a direct linear mathematical conversion to micron such as you seem to describe. This is not a math error so much as it is a peculiarity of two vary different measuring systems. I found this link www.rimworld.com/nassarocketry/pdfs/005-PARTICLE%20SIZES.pdfThat says (amongst other good knowledge) I hope this is useful.
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Post by deb193redux on Oct 10, 2014 13:50:49 GMT -5
The end user of micro grits must not assume that materials having the same size designation from different manufacturers will be equivalent to each other or that they will produce the same finish. I think the variability (lack equivalence) is mostly manufacturing and grading standards.
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Post by deb193redux on Oct 10, 2014 13:54:37 GMT -5
Greetings [deb193redux] Another list that can not count, note 14,000 = 1 micron, but 0.5 micron = 50,000!? It is amazing how many companies copied that list with it's glaring error! The "mesh" size is not a direct linear mathematical conversion to micron such as you seem to describe. This is not a math error so much as it is a peculiarity of two vary different measuring systems. I don't think is was the mesh-micron conversion that was at issue, but rather the grit-micron conversion. Mesh is complicated by wire-thickness. I am not sure why grit sizes follow an exponential decay. I would speculate that there was some exponential aspect of the process used to sort out graded grits.
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Post by mohs on Oct 10, 2014 14:14:01 GMT -5
Hi James the 30 grit was the original grinding process…Right? I’m not sure I understand why you think it shouldn’t have deep divots at that grit level Ed They look deep for a slow rolling tumbler. That is what puzzles me. Seems more force would be required to gouge out so much material. And the lack of scratches still bugs me. Maybe I need a more diabolical reason I like diabolical grinding you mad hack lapidarian! are the deep pits created from the sharp edge points of the 30grit or is it natural abrasion and the divots that are not smoothed out by a finer grits? in example-- the divots are the natural unevenness of the surface material…
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jamesp
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Post by jamesp on Oct 10, 2014 14:20:23 GMT -5
I think the issue is deep scratches vs deep divots. Scratches are consistent with abrasion/scrape, divots invoke scoop or gouge. Well my tumbler must have some divot power. The issue may be influenced by glass. It does weird things. I will say that agate does not have such deep divots in 30 grit. No where near. And that makes sense. Never had trouble tumbling agate in the rotary. But glass and obsidian is just plain weird. Scratches weaken glass a lot. In fact, unscratched glass is one of the strongest substances on earth to resist bending. Put a long tiny scratch across it and everything changes.  For perfect glass fibers, strength is 500,000 psi (3500 MPa). For polished glass windows, in air, strength is 7000psi (50MPa) For scratched glass, 100 micron deep scratch, it is 2500 psi (20 MPa) For scratched glass in high humidity for several years it is 1000 psi ( 7 Mpa) And a glass cutter does some real nasty stuff to glass besides putting a single scratch across it. It sends multiple fractures in many directions. Yes it will break on the deepest gouge it digs out, but it can wonder down other fractures. But this is off subject. It does relate to obsidian and how it grinds and polishes though. And that was the limit of my experience.
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jamesp
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Post by jamesp on Oct 10, 2014 14:24:52 GMT -5
They look deep for a slow rolling tumbler. That is what puzzles me. Seems more force would be required to gouge out so much material. And the lack of scratches still bugs me. Maybe I need a more diabolical reason I like diabolical grinding you mad hack lapidarian! are the deep pits created from the sharp edge points of the 30grit or is it natural abrasion and the divots that are not smoothed out by a finer grits? in example-- the divots are the natural unevenness of the surface material… The divots in that material were on the flat polished face of the glass shard Ed. diabolical
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quartz
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Post by quartz on Oct 10, 2014 14:25:02 GMT -5
Regarding the divots vs. scratches discussion; I would think a comparatively large piece of rock or glass helped by momentum and who knows how much weight pushing it, dropping onto a little bitty [again comparatively] very hard and sharp piece of grit would tend to dig a divot rather than slide and make a scratch. In a way, like sandblasting in reverse, throwing the object at the sand instead of squirting the sand at the object. Laps, on the other hand, everything is sliding, mass scratches. My .02. Great discussion, thanks to all. Larry
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jamesp
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Post by jamesp on Oct 10, 2014 14:40:26 GMT -5
I’ll take half a micron for 28,000, Alex.
Note: For comparison only. All manufacturers’ abrasives differ slightly. Grit sizes, microns and inches may be approximate in some instances.
The end user of micro grits must not assume that materials having the same size designation from different manufacturers will be equivalent to each other or that they will produce the same finish. 14,000-1 micron 28,000-.5 micron 50,000-.3 micron grit and micron linear Manufacturers certainly do vary. Most are plenty close enough for lapidary work.
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jamesp
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Post by jamesp on Oct 10, 2014 14:54:19 GMT -5
Regarding the divots vs. scratches discussion; I would think a comparatively large piece of rock or glass helped by momentum and who knows how much weight pushing it, dropping onto a little bitty [again comparatively] very hard and sharp piece of grit would tend to dig a divot rather than slide and make a scratch. Laps, on the other hand, everything is sliding, mass scratches. My .02. Great discussion, thanks to all. Larry I agree. The problem I have is the 12 RPM/7/8 full barrel/heavy sugar syrup thing. I can not imagine an impact that dug that deep under those conditions. But what you are saying sure makes me think the action you describe is responsible for the frosted/divoted finish and not a scratched finish. I was just surprised at those divots in 30 grit. The load I was tumbling were pre-ground close to round. None of the almost round rocks that I sampled had scratches. However, one of the few flat rocks in the load had these:
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Post by mohs on Oct 10, 2014 15:02:12 GMT -5
a sand blaster at this fine of tumbled smoothing is probably a good analogy Still puzzled by the deep divots that the 30 grit caused in the photo above Ed. I don't think the 30 grit caused the divots I think the 30 grits smoothed the surface and divots are what naturally remain until you use smoother grits further polish the surface but divots will probably always remain albeit very much more diminished mostly
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Post by mohs on Oct 10, 2014 15:06:48 GMT -5
its like the moon with craters if you drag rough grit across it the surface will smooth but the craters will naturally remain until smoother processes are employed
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jamesp
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Post by jamesp on Oct 10, 2014 15:11:45 GMT -5
Still puzzled by the deep divots that the 30 grit caused in the photo above Ed. I don't think the 30 grit caused the divots I think the 30 grits smoothed the surface and divots are what naturally remain until you use smoother grits further polish the surface but divots will probably always remain albeit very much more diminished mostly The divots were worn off by the 220. No problem. But I had to run it a while. And the 220 does remove the divots fast. But the rocks sure got smaller to remove them. I like the fast grind of the 30 grit. Don't get me wrong, I could have used 90 grit. And slowed the rounding process. I was just curious why they were so deep on a surface that was polished.
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Post by mohs on Oct 10, 2014 15:54:03 GMT -5
I understand James and I don't have a specific answer to your precise analysis & wonderment
but I will throw this out and let you all interpret as you might
at the quantum level there will always be fuzziness
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