jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 28, 2016 9:45:49 GMT -5
Not adding SiC 30 every 12 hours is a mistake.(for my particular arrangement). Removing grinder scratches, first pre-grind: 0 hours 12 hours(added fresh grit) 24 hours, scratches gone This time the rock ran 24 hours with no grit add at 12 hours. 2nd pre-grind 0 hours 24 hours, no grit added, scratches not gone
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 28, 2016 10:39:07 GMT -5
Seems like bumpingthe grind a secon time is way worthwhile. We do the same process in sphere making. Bump the hi spots on the super grinder. Rock and roll...
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 28, 2016 11:04:01 GMT -5
Seems like bumpingthe grind a secon time is way worthwhile. We do the same process in sphere making. Bump the hi spots on the super grinder. Rock and roll... I see why. the tumbler does give you a good idea of the high spot simply by wearing them down and smoothing them. Check out the fringe benefit of grinding these big rocks since Sept. 11. Never had coral shape so fast. Sept 11 Today, Sept 28. Never had coral shape this fast. Not close. Look at how many rocks I had to add just to keep barrel 3/4 full Sept 11- Sept 28. Insane.
|
|
|
Post by orrum on Sept 28, 2016 17:57:46 GMT -5
Hey that's making a lot of nice smaller tumbles for real!!!
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 28, 2016 18:25:15 GMT -5
I have been pondering this.
The heavy stone puts far more pressure on the grit and onto the smalls under it. Makes the cut deeper. Deeper cut removes more material. That equals faster tumble!!
Makes perfect sense.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 28, 2016 19:52:49 GMT -5
I have been pondering this. The heavy stone puts far more pressure on the grit and onto the smalls under it. Makes the cut deeper. Deeper cut removes more material. That equals faster tumble!! Makes perfect sense. Stretch it the other way. Try 1/4 inch tumbles !! All 1/4 inch tumbles takes forever. Even soft 1/4 inch glass takes forever, even in a 10 inch PVC barrel it did not break down coarse SiC in a month. No pressure. That is why I never finished those small almandine garnets. They will grind with a big rock in with them. Less smalls makes more pressure on the target 1-2 inch tumbles too. So the reason for the new 6-7 pound 6" PVC barrels. More pressure on all rocks because the big rock pressure is focused on less target tumbles. If the barrel was 10 feet long the big rock would only be applying it's pressure to a small segment of the 1-2 inch tumbles. The barrel I have been running these large rocks is 18 inches long. Trashing it, will start tumbling in the new short 8 inch long barrels. They should have super grind rates with big rock added. Big rock method not suggested for obsidian. Best with quartz gems.
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 28, 2016 20:00:52 GMT -5
jamespI love your technique "stretch it the other way". I share your enthusiasm for this. I try to explain difficult visuals by using the extremes. Shoot a rifle at a target 45 degress uphill. Will it hit high or low based on point of aim. Same example downhill. High or low? Both will hit high. Gravity effect is lessened. Now visualize this nearlt straight up or down. Easy to visualize. I love your experiments. Thank you.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 28, 2016 20:12:57 GMT -5
jamespI love your technique "stretch it the other way". I share your enthusiasm for this. I try to explain difficult visuals by using the extremes. Shoot a rifle at a target 45 degress uphill. Will it hit high or low based on point of aim. Same example downhill. High or low? Both will hit high. Gravity effect is lessened. Now visualize this nearlt straight up or down. Easy to visualize. I love your experiments. Thank you. Extremes were taught to us in engineering school. As speed approaches infinity heat approaches X As diameter approaches infinity centrifugal force approaches Y It is the basis of integral calculus. Example, the numbers 1 and 2 are the 'limits'. The measurements for instance to be plugged into the mathematical formula to the right. Describes diminishing returns and exponential behavior. Any process
|
|
|
Post by captbob on Sept 28, 2016 21:47:33 GMT -5
Shoot a rifle at a target 45 degress uphill. Will it hit high or low based on point of aim. Same example downhill. High or low? Both will hit high. Gravity effect is lessened. Wouldn't that depend primarily on the distance to the target? Not like the trajectory of a bullet is a straight line...
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 28, 2016 23:09:39 GMT -5
Shoot a rifle at a target 45 degress uphill. Will it hit high or low based on point of aim. Same example downhill. High or low? Both will hit high. Gravity effect is lessened. Wouldn't that depend primarily on the distance to the target? Not like the trajectory of a bullet is a straight line... Nope. Its because your second statement is true. At any angle other than horizontal, the curvature of trajectory is flatter than true horizontal.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 29, 2016 4:22:04 GMT -5
Ah. An engineering problem I had stuck up my #$%^ a hundred times. Again, take it to the extremes. If your target is directly overhead in line with gravity, gravity would not effect left/right/windage. Just prevent the bullet from going as far. " " " " down " " " " " " " " " . Just help bullet go further. Or in mathematical terms: "As target approaches 90 degrees from horizontal deviation from target due to gravity approaches zero." To describe mathematically you would replace the '1' with 0 degrees and the '2' with 90 degrees in the below integral. Then replace the equation f(x)dx with a complicated trajectory equation and solve for 'x'. Which I for one has long forgotten how to do as it is torturesome.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 29, 2016 4:50:47 GMT -5
So, if 30 grit breaks down to about nothing in 12 hours due to efficient heavy rock grinding in thick mud slurry is that 12 hours equal to waiting a week to do coarse grit change ? Sure looks that way.(my answer is absolutely). So tumbling with the big rock for 12 hours equals one week of conventional tumbling doing clean out and grit addition every week. I say yes. Looking at the coral media I would guess it has 12 weeks of conventional tumbling method. In reality it has had closer to 12 days with the big rock tumbling method. Some may cry about using a cup of SiC 30 every 12 hours. Cry away, they can use a cup every week for 12 weeks. Guess what, your power bill is going to out cost your grit bill. As the weight of the rocks approaches infinity the grind time approaches zero. Ha, only in math. This was a 30 pound load I did long ago in an old 30 pound barrel. No smalls. Depended on thick slurry for protection. Must have used 20 pounds of sugar in AO 500 and AO 14,000 steps in the rotary to thicken slurry to protect the big rocks from banging. Thankfully the vibe replaced that process. It was a fast tumble. These are some of of the larger tumbles and the photos does not do the polish justice. Nor do the photos show the slight bruising that occurred on some of the sharpest edges of the softer materials from so many 10 to 12 ounce rocks.
|
|
|
Post by MrMike on Sept 29, 2016 5:33:47 GMT -5
Not an engineer but would a larger diameter barrel make for a more aggressive tumble?
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 29, 2016 7:21:54 GMT -5
Not an engineer but would a larger diameter barrel make for a more aggressive tumble? Yes. I have tried 6-8-10 inch diameters. 6 inch can run 55 rpm with thickish slurry without damaging rocks 8 inch 45 RPM 10 inch 30 RPM All those are a bit fast. Too fast for obsidian. Fine for hard stones. I prefer 6 inch(Inside diameter) at 55 RPM for Mohs 7 stones. Maybe the edge speed is the same for all those sizes but the higher 55 RPM cycle rate really gets it done. Edge speed and rotation rate is two different things. 4 inch tumblers too small.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 29, 2016 7:51:38 GMT -5
A little Rio fortification to pre-grind and throw in with the bloodstone today.
|
|
|
Post by MrMike on Sept 29, 2016 17:53:45 GMT -5
Not an engineer but would a larger diameter barrel make for a more aggressive tumble? Yes. I have tried 6-8-10 inch diameters. 6 inch can run 55 rpm with thickish slurry without damaging rocks 8 inch 45 RPM 10 inch 30 RPM All those are a bit fast. Too fast for obsidian. Fine for hard stones. I prefer 6 inch(Inside diameter) at 55 RPM for Mohs 7 stones. Maybe the edge speed is the same for all those sizes but the higher 55 RPM cycle rate really gets it done. Edge speed and rotation rate is two different things. 4 inch tumblers too small. Gotcha, Should have guessed you've tried them all 🛠⚙
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
|
Post by jamesp on Sept 29, 2016 17:55:45 GMT -5
I have done a few MrMike. Like the such 40 6" PVC best. Fittings affordable and smooth high speeds.
|
|
|
Post by orrum on Sept 29, 2016 19:18:04 GMT -5
Jim you mentioned the 30 grit being crushed by the big rocks.... 12 hours ain't long to break it down to nothing. I am no engineer but I am a decent hillbilly country boy can get by. So perhaps the effect is actually a hammer and anvil action. The grit is actually pulverized by the effect instead of sliding and grinding? Of course it's still getting great grinding and shaping very fast. Wonder if you could somehow moderate the action somehow to make the grit last longer and still be grinding with the effect of bigger scratches getting smaller and smaller for the last go round of 30 grit?
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 29, 2016 20:53:58 GMT -5
My theory is the grit will cut a certain volume of stone. Do it slow or do it in 12 hours, cutting action is finite.
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Sept 29, 2016 21:00:11 GMT -5
A little Rio fortification to pre-grind and throw in with the bloodstone today. Fortification or waterline?
|
|