Lapidaryforum.net
Rock Art => Tutorials for the Rock Art Area => Topic started by: aksockeye on July 05, 2018, 09:04:53 PM
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Please share your method for shaping hard materials for cabbing. I have 14”slab saw, 8”trim, 4x8” arbor 2 diamond wheels 2 drums. Have seen people stack multiple saw blades on trim saws. Thinking maybe aggressive flat lap? What is your process?
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You can cab on a flat lap, but you can't beat a standard cab machine. Nova wheels work great but diamond belts can do just as well with more flexibility. Start with 80 wheel (unless its soft material) then to 220 to get rid of big scratches and flat spots. Then go 280 600 1200 3000 and whatever else you have to polish. The last 4 and higher grits can be belts all run on one or two expandos (which saves bench space and allows flexibility in grit jumps.
I've never used stack tile blades as a super grinder but I understand the concept. Like cooking, everyone in lapidary has their favorite tools and techniques. Enjoy.
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Cab machines are very nice but over rated.A poly arbor with a expando on one side and the other for switching out wheels worked for me for over 30 years of full time cutting. While flat laps are limited I love them for touching up problem spots and since I am careful while cutting I tend to use them dry or almost dry for that purpose.I use 80 hard then 220 hard then 220 soft nova. For hard stones I sometimes use a Eastwind 60 grit soft wheel after the 80 hard and then go straight nto220 nova. If I can walk ok on a given day that would be my choice for my pendants but the machine with the 60 grit soft is a hundred feet away and can't be moved closer and at times that is too far for me to walk.600 grit next then 1200, 3000, 8000,14,000 nova.I used to do all my coarse sanding on sic then follow with 100 grit nova then 220 nova but bad legs makes that difficult for me now due to the configuration of my shop.
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Maybe I should order a more aggressive wheel for shaping. I now have an easy touch on wheels or discs that took awhile to mature. After I get good shape I’m fine with sic belts adding fine diamond belts for finish. Never really put felt flat pad attachment on Endor arbor. Does anybody use that for final polish?
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I use a worn 100 grit 8" diamond wheel for coarse grinding, a well worn 100 grit 8" diamond wheel for fine shaping and a 8" expando wheel with SiC belts for the rest of the work. On larger pieces I do a lot of the sanding on a dry SiC belt. After the worn 400 belt I go to my carpet covered slow turning polish wheel. This has been my main method for the last 40 years or so.
Bob
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I think people usually use a nova wheel or a slow leather polisher with oxide as the final polish. Eastwind now sells oxide impregnated soft wheels also.
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I stare at the rocks until they give up the will to resist and then take them to the wheels.
Other than that std Slab/trim then 80 grit thru 14k and different oxides depending on the stone to be finished. I also have a 50k but only use that in special cases. I have an inland sintered for my coarse grind but I have yet to mount it.
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Has anyone used a 140g soft wheel to remove scratches after forming, shaping and sanding with hard diamond wheels? A guy who is the honcho at a lap club here in WA says he uses this one before using the 280g soft wheel, etc and he has had great results. Anyone else have an opinion? Thanks
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I never have problems getting out the scratches with the 280 soft wheel. Key is to not use the 120 grit or below over the top of the dome of the cab since this is the area where the least amount of material is removed and makes it the toughest if you put an 80 grit scratch across it. 80 grit and 220 hard 280 first soft then i go 600 1200 14k.
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I have gone to a broken in 220 SC on a rubber wheel after forming cabochons on hard diamond wheels. I do this on most cabochons I make as a rule. Nothing much worse than going to a soft 220 wheel and having little scratches appear that you missed from the 80 or 100 grit hard wheels.
Laugher from the internet: There was a convo about pictures being to detailed and showing to much with high resolution and good focus. A number of replies were to dial down the focus a tad so that the little bitty scratches do not show in the photos. I guess that ranks right up there with the " no fractures or pits" in descriptions. Then you look at the photo. LOL So if the photo is not good do not trust the description.
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I haven’t used a 140 soft but have used a 150 soft wheel and I agree it is somehow better at getting out those deep scratches. I try to always dry well between grits and look under a bright light so I can usually catch these flat scratches and spots. Usually going one direction over the entire stone, then the other direction at 90 degreses ( horizontally, then vertically) will get the scratches. Marking the scratches or even the entire face with magic marker is good as long as there are no fractures and it’s not a soft stone that will absorb it. Blackopaldirect has good videos on YouTube on how to avoid flat spots in the first place by twirling stones lightly and rapidly though I only use that for really small stones.