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Post by 1dave on Jan 17, 2021 9:30:23 GMT -7
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Post by 1dave on Jan 17, 2021 9:36:37 GMT -7
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Post by 1dave on Jan 19, 2021 10:56:23 GMT -7
@jasoninsd @fuzzyb SiC 30 break down experiment for a fast step 1. It would be nice to have constant SiC 30 injection. SiC after 9 hours at 30 rpm with clay slurry. After 24 hours at 30 rpm the SiC was gone.Gravity and many clean water purges were used to separate the SiC from the rocks and slurry since SiC is dense. Separation steps - www.flickr.com/photos/67205364@N06/sets/72157677229423944This experiment surprised me much. A 6 inch I.D. barrel was used. SiC 30 break down: 30 rpm/6" barrel/fresh clay slurry/virgin SiC 30/3/4" to 2" agate  The captured SiC 30 was put in a jar and placed on a vibe to separate particle size:  The loss of volume of SiC 30 after 9 hours:  |
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Post by 1dave on Jan 19, 2021 10:59:33 GMT -7
Constant SiC 50 injection using 'time release' crushed fused SiC 50 grinding wheels. I found about 200 pounds of these lead center bearing vintage 6 inch SiC grinding wheels in an industrial junk yard. Purchased them for $100.(most modern grinding wheels are AO because it is much cheaper than SiC). AO wheels useless for shaping. This relates to 'fixed sandpaper' rock tumbling @fuzzyb. It takes about 2 to 3 weeks for these chunks to break down. However these chunks will flat eat up a rotary barrel. And your rocks.  After 2 weeks SiC 50 chunks are rounding and so are rocks. First charge. Note this is rhyolite and is softer than agate at about Mohs 6. Agate will not shape this fast.  SiC 50 grinding wheel chunks are rounding off after 2 weeks running at 30 rpm. Note purple/red particles ?  Chunks generated a constant supply of SiC 50 to SiC 500 and smaller particles for 3 weeks for a 'time release' situation.  |
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Post by 1dave on Jan 22, 2021 9:26:01 GMT -7
jamessp, I had posted this recently in another thread, and wondering what you think? "This is sort of a tangent but also related. I converted tablespoons to cups years ago, and throw 1/2 cup of grit or polish in the 6lb barrel, 1 cup in the 12lb barrel, 2 in the 20lb, and 4 in the 40lb. It seems close enough and works well. What would happen if we went overboard or underboard? Has anyone ever tried it to see what happens? I'm going to take a guess, but this is only a guess. If batches usually are just right after a week (a timing which I kind of like also) wouldn't using too little grit merely mean the batch would get done sooner because the grit would be worn out sooner? Or would the grit still "last" a week just a lot less grinding would happened?" Is the reverse true? What if I threw in 2 cups (twice normal) of coarse grind grit in a 12lb barrel? Would it grind twice as much rock off in a week so would not be a waste of money? Or would the grit last longer than a week? For finishing steps in a vibe I have reduced the doses to 1/5 of the manufacturer's suggested dose and seem to get faster polish times. As if it takes longer to break down larger doses - makes sense. Use only what is needed to get to polish. The Lot-O came out more recently and it uses smaller doses than the older vintage vibe recommendations. Rotary may not work the same way... As far as step 1, it is a totally different animal. More more more. The more abrasives the better IMO Bob. As long as the batch is not hindered in movement. With a good slurry, abrasive(SiC) particle distribution can be one particle per square mm, one particle per each square 1/4 inch, one particle per each square 1/2 inch, etc etc. It would not be too difficult to calculate the approximate surface area of 12 pounds of rock and the amount of say SiC particles in a cup of SiC 46. One could easily calculate the surface are of 12 pounds of one inch marbles, easy enough and should give a good surface area approximation for rocks. Looking for the quantity - particles/sq. cm. for instance. Why not have 10-15 particles per square centimeter ? Old tumbling instructions rarel suggest adding a slurry additive, they always start you with water which likely limits the amount of coarse SiC. Slurry can carry and distribute much more coarse abrasive. Those are my thoughts. |
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Post by 1dave on Jan 22, 2021 9:30:26 GMT -7
I've got a calibrated mic (UMIK-1) feeding into RoomEQ Wizard. I position the mic just by the guide on the idler shaft of my A-R1. Here's my current run with 500 Al 2O 3.
Very cool to see the sound profile of that run. I could see how that could be a good indicator for when the grit is exhausted in stage 1. Given the time over which the run occurs, it would probably be difficult to identify a 1 dB drop, or when you may have an inflection point in your curve that signals a change between grit-on-rock grinding to rock-on-rock grinding. Like @wooferhound pointed out, it would be interesting to see the frequency response over time as well.  |
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Post by 1dave on Jan 23, 2021 7:11:52 GMT -7
Now you got my attention. I provide Sound Systems all over the North Alabama area. Interesting concept but not very useful in my opinion. Might work to some extent in stage 1 but almost useless in later stages. When I tumble I like for the Slurry to get very thick at the end of a run and can even completely stick together leaving only motor noise. This assures that as much grinding is being done as possible in the week that it runs. Would be interesting to get frequency analysis too and see how the High and low frequencies change.
I have never written anything down in my few years of tumbling with 3 barrels rolling. I only got confused about the contents once but everything came out fine. For a while I thought that a Post-It note for each barrel would be fine but I never actually did it.
This was my finding woofer. A good slurry quiets the rotary to a low pitch grinding sound as opposed to a water slurry making a higher pitch rattling sound. Run glass in straight water for an hour at high rpm and it will be bruise damaged. So it is mandatory to add slurry thickener and maintain it's viscosity thru out the entire run. To maintain a consistent slurry viscosity I pour off some slurry and add water about every 2 to 3 days. The sound of the barrels will let you know if the viscosity is correct. But it is safer to check the viscosity every 2 days. With glass at only Mohs 5, SiC lasts about twice as long when running glass as SiC lasts with Mohs 7 rocks of equal size. A large rock in the batch reduces the life if SiC a large amount which equates to a faster grind. Some tumbled glass using protective clay slurry. Upper right tumble has small bubbles causing the spots.  From same batch. Example of bruises from watery slurry in top 3 tumbles visible in glare. Lower 3 were re-run starting at 220 grit to shave of bruises.  SiC 16 SiC 60 in rotary for 10 days total, AO 220 AO 500 AO 14,000 in vibe for 7 days total. 5 steps. clay in rotary, sugar in vibe.  Wear resistant 8 inch HPDE barrels to handle super coarse SiC. The 6 inch PVC barrels last a long time with finer abrasives. Front shafts are high speed for coarse grind and rear shafts are slow speed for finishing/polishing.  |
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