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Post by jasoninsd on Nov 20, 2021 20:47:42 GMT -5
I can rough grind a dome just as fast (and maybe faster) with a new 60 or 80 grit lap disc. But the lap disc will only grind really fast for about 15-20 hard (agate) cabs, before it starts slowing down. After 30 or 40 cabs, it might take me 30-45 minutes to grind a dome on my Ameritool 8" flap lap. Performance seems to plateau around there for a while, and after a few hundred cabs (or the equivalent amount of grinding specimen / tumbles) it will start getting slower and slower. That is when I consider it worn out and replace it. These times and numbers will obviously vary based on the quality of the disc, the lap speed, how much pressure you apply, the type of stone, etc... But they are estimates based on my personal experience. Same goes for a new 60 or 80 grit cabbing wheel. They grinder super fast for a while, level off for a long plateau, and the good ones (DP Galaxy, for example) never stop grinding, they just get very, very slow after years or use. I am talking about plated wheels, not sintered. What is special about your saw blade is that it still grinds fast after having been used so much. I achieve similar results with a sintered cabbing wheel by dressing it frequently to expose new diamonds. The sintered wheels costs many times more than a trim saw size blade, making the blade grinding method an economical option. Finally, if it takes 2 hours to dome anything on your slab cabber, you need a new lap disc.  Or try lightly running a dressing stick over the face to wear off a tiny bit of the metal plating. You aren't really supposed to dress plated wheels / discs, but it's worth a shot if it's otherwise going into retirement. So, today was a day of discovery. My 80 grit disk is absolutely shot...gone...done for...needs replacement! I knew my 180 was seeming a bit aggressive lately, so I decided to try shaping some cabs with the 180 rather than the 80. I hadn't bothered trying this as I started out with the 180 originally...and thought it cut slow, which is why I ended up getting the 80. I've been using the 180 on slow speed just to get rid of the 80 scratches. Anyway, I went full throttle today and shaped a bunch of cabs...and it was cutting like a hot knife through butter compared to how my 80 has been grinding. I did take a dressing stick to the 80 grit to see if I could get it working any better. And I did see a slight...and mean VERY slight improvement. So, I know without a doubt I need to get a new coarse disk. I'll go back through our messages and see if you said where you got those disks from... MsAli - I forgot to mention...I've seen miket 's neck in person...it's as red as they get!  Hopefully that's a compliment... 😄 Of course it is! My neck is as red as yours brother! I can rough grind a dome just as fast (and maybe faster) with a new 60 or 80 grit lap disc. But the lap disc will only grind really fast for about 15-20 hard (agate) cabs, before it starts slowing down. After 30 or 40 cabs, it might take me 30-45 minutes to grind a dome on my Ameritool 8" flap lap. Performance seems to plateau around there for a while, and after a few hundred cabs (or the equivalent amount of grinding specimen / tumbles) it will start getting slower and slower. That is when I consider it worn out and replace it. These times and numbers will obviously vary based on the quality of the disc, the lap speed, how much pressure you apply, the type of stone, etc... But they are estimates based on my personal experience. Same goes for a new 60 or 80 grit cabbing wheel. They grinder super fast for a while, level off for a long plateau, and the good ones (DP Galaxy, for example) never stop grinding, they just get very, very slow after years or use. I am talking about plated wheels, not sintered. What is special about your saw blade is that it still grinds fast after having been used so much. I achieve similar results with a sintered cabbing wheel by dressing it frequently to expose new diamonds. The sintered wheels costs many times more than a trim saw size blade, making the blade grinding method an economical option. Finally, if it takes 2 hours to dome anything on your slab cabber, you need a new lap disc. Or try lightly running a dressing stick over the face to wear off a tiny bit of the metal plating. You aren't really supposed to dress plated wheels / discs, but it's worth a shot if it's otherwise going into retirement. Something else that may help to keep it cutting well is to scrub your metal lap with a toothbrush or small scrub brush after you're done using it. Run the water drip pretty fast and scrub to get all the swarf out from between the diamonds. Otherwise the swarf dries in between the diamonds like cement and really inhibits the cutting action. I do think I need to start doing a better job at cleaning the disks like this after each use. I have noticed buildup...but I didn't think it was effecting things. Thanks for posting this Robin! And I do think getting a new 80 or 60 grit disk is a better solution to using the saw...just sayin'... |
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Post by holajonathan on Nov 21, 2021 0:54:35 GMT -5
I've tried a few different brands of lap discs. My favorite (for the price) is a brand called THK. I bought a 10 disc set and I have been very impressed with them. The 60, 80, and 100 grit discs all grind fast, and the finer grits perform like they should. The discs are well balanced and the hole is centered -- not the case with the very cheapest brands I have tried. The bad thing about the THK is that they ship directly from Hong Kong, so it takes something like 10-14 days to get here. I don't remember exactly how long it took, but orders have actualy arrived faster than I expected. These discs also require a backup plate. My favorite (can't remember where I got it) is a plexiglass one. I know I only paid a few dollars for it. The THK discs are pretty rigid on their own, so they don't need a metal backup plate in my experience. I have an aluminum backup plate as well, but I prefer the plexiglass one. You can get the THK discs here (Ebay). $20 for an 80 or $22 for a 60 -- free shipping. I have also ordered directly from their website without a problem. The prices on the website are only 50 cents cheaper than Ebay, unless you get 4 items, in which case there is a shipping discount and the discs will come out to $1.50 less than Ebay. You could get (4) 80 grit discs for $74 shipped. That probably isn't that much more than a A single 1/4" thick steel 8" lap disc is $71 from Kingsley North. I'm sure it's better than the THK thin discs + backup plate, but I'd take 4 of the THK discs instead.  |
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Post by holajonathan on Nov 21, 2021 1:06:24 GMT -5
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Post by jasoninsd on Nov 21, 2021 3:56:39 GMT -5
I've tried a few different brands of lap discs. My favorite (for the price) is a brand called THK. I bought a 10 disc set and I have been very impressed with them. The 60, 80, and 100 grit discs all grind fast, and the finer grits perform like they should. The discs are well balanced and the hole is centered -- not the case with the very cheapest brands I have tried. The bad thing about the THK is that they ship directly from Hong Kong, so it takes something like 10-14 days to get here. I don't remember exactly how long it took, but orders have actualy arrived faster than I expected. These discs also require a backup plate. My favorite (can't remember where I got it) is a plexiglass one. I know I only paid a few dollars for it. The THK discs are pretty rigid on their own, so they don't need a metal backup plate in my experience. I have an aluminum backup plate as well, but I prefer the plexiglass one. You can get the THK discs here (Ebay). $20 for an 80 or $22 for a 60 -- free shipping. I have also ordered directly from their website without a problem. The prices on the website are only 50 cents cheaper than Ebay, unless you get 4 items, in which case there is a shipping discount and the discs will come out to $1.50 less than Ebay. You could get (4) 80 grit discs for $74 shipped. That probably isn't that much more than a A single 1/4" thick steel 8" lap disc is $71 from Kingsley North. I'm sure it's better than the THK thin discs + backup plate, but I'd take 4 of the THK discs instead. Thanks a bunch for posting this Jonathan! I just went to eBay and they say THK is a seller I've purchased from before...but I'll be danged if I can remember what I got from them! Now that I think about it, it might have been diamond paste. I'd prefer to order through eBay, just for the "protection" in case there's an issue in shipping. I believe I'm going to order two 60 grit disks. I'm just going to use my existing 80 grit disk and remove the disk itself from the backing plate (or put it on the underside of the plate and leave the 80 grit there...which is probably closer to 220 now! LOL). If I use a heat gun on it, I'm thinking it should release the disk from the plate. ETA: I was pretty excited to realize my 180 would grind like a champ, so I spent the day (off and on) shaping all 24 cabs I had dopped! LOL - I'm not kidding when I say it was cutting like a hot knife through butter compared to that worn out 80 disk! LOL |
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Or try lightly running a dressing stick over the face to wear off a tiny bit of the metal plating. You aren't really supposed to dress plated wheels / discs, but it's worth a shot if it's otherwise going into retirement. 
