chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Jun 21, 2022 12:05:55 GMT -5
Hello. I`m looking for some more advise about polishing slabs o a 18" flat lap, regular lap, Not vibratory. Bought one used and cheap and reconditioned it with a 3 phase motor and a VFD, which allow for slowing down to any RPM from the motor`s original 1350 RPM. We tried using it with loose grit but it`s too messy and have to wash out each time when changing grit. Anyway, bought a set of 18" diamond disks (80, 220, 325, 600, 1200 and 3000) and set up a drip system. Am used to working with smaller pieces on a 6 wheeled Genie and a 8" flat lap also, using same grits as above. After a 4 hour session of trying to lap several slabs of different materials, it`s been frustrating and results have not been good. Main problems are not getting the scratches out enough between different grits and not getting a shiny finish, even after 3000. Anyway, here are some specific questions:
1.) What RPM do you recommend for this case? Same RPM for all disks of all grits? Same RPM for all stones?
2.) Is it OK on a larger lap like this to try to lap several different stones on the same disk in the same session? (Yesterday, we were lapping 4 to 6 " slabs of crystal quartz, lapis, serafinite, obsidian and even tried to polish the faces of some hard cut in half geodes.) We assumed that this was OK and that we were not contaminating as there was a a good drip on the disks. We cut and polish all kinds of stones everyday on a Genie and never have contamination problems. But maybe on a 18" flat lap it is different.
3.) I was thinking also that maybe we should be more thoroughly washing the slabs and other materials between the different disks, to avoid any possible contaminations.
Any advise would be helpful. I have been excited to put this machine to use after time and $ to set it up. But so far its been quite frustrating. Thanks.
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Post by mohs on Jun 21, 2022 12:19:16 GMT -5
interesting
and I have no real clue
one thing I found is the amount of pressure applied
stone to the flat lap
on the rougher grits
heavier pressure is better
This is just scanty experience for the
grinding of the flats on my rock’n heart joints
and that such a small surface area compared to your tasks
Many of the rocks are have softer minerals embedded
& found the heavy pressure alleviate some of the undercutting
butte this advice is far
from the fabulous experiment
your undertaking
you’ll figure it out !
I have no doubt
Ed
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chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Jun 21, 2022 12:38:14 GMT -5
Thanks Ed and we`ll try that. And I agree that we`ll eventually figure it out. But hoping to shorten the learning curve getting advise from all of you!! Thanks again
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Post by hummingbirdstones on Jun 21, 2022 22:26:05 GMT -5
Tagging HankRocks for you. He may be able to help. |
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Post by hummingbirdstones2 on Jun 21, 2022 22:30:25 GMT -5
I'm assuming you went with some sort of carpet pads for your grits. You can fill us in on the details if you want.
You'd probably want to run your coarse grits at a higher rpm for removing saw marks and heavy scratches.
Just for comparison, the Richardson's buffer we have turns at about 145 rpm. It's a 12" leather final polishing head, used with either cerium oxide or aluminum oxide.
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Post by orrum on Jun 23, 2022 7:26:17 GMT -5
Roy is the man to ask. I have no idea how to tag him.
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RWA3006
Cave Dweller 
Member since March 2009
Posts: 4,633 
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Post by RWA3006 on Jun 23, 2022 9:18:31 GMT -5
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RWA3006
Cave Dweller
Member since March 2009
Posts: 4,633
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Post by RWA3006 on Jun 23, 2022 9:19:00 GMT -5
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Post by woodman on Jun 23, 2022 9:42:25 GMT -5
I have a 36 inch flat lap that I use to remove saw marks. I use wa3ter and 120 grit. Then I go to a bull wheel 100 grit belt then 400 grit and then on to the polish machine.
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Post by hummingbirdstones2 on Jun 23, 2022 9:57:44 GMT -5
Sorry - I skipped over the part where you scrapped the loose grit for diamond.
Sometimes new diamond takes a little while to break in. Are they plated laps?
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chilerock
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Member since June 2018
Posts: 19
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Post by chilerock on Jun 25, 2022 14:54:42 GMT -5
Heelo, thanks for the rply. The diamond disks I have are the cheaper type, made with thin flexible type of base and not the solid plated type, which are quite expensive.
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chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Jun 25, 2022 15:17:18 GMT -5
I have a 36 inch flat lap that I use to remove saw marks. I use wa3ter and 120 grit. Then I go to a bull wheel 100 grit belt then 400 grit and then on to the polish machine. Hello: I saw your reply above and I appreciate it. If possible would be grateful for help with some related questions: 1.) As I am used to the 6 wheeled cabbing machine with the 80, 220, 325, 600, 1200 and 3000 diamond wheels, its hard to understand how it`s possible to go from a flat lap with 120 grit to a bull wheel with 100 and then 400 grits directly to polish. But I have heard of similar techniques, including here inm South America, and so there is definately something working well with this method. But in essnce, what is the dynamic in this case that allows for skipping so many grits before going to polish? 2.) Do you use an original 12" bull wheel with SIC belts. I heard that 12" belts are not available in diamond. 3.) Have heard of people using 8 x 3 inch expandiable drum as sort of a cheaper alternative of the original bull wheel. What are your tought about this option? 4.) As I understand, bull type heels are generally run dry when using SIC belts. But if using diamond belts, I would assume that water must be applied. Thanks again!! |
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Post by woodman on Jun 25, 2022 16:47:33 GMT -5
I have a 36 inch flat lap that I use to remove saw marks. I use wa3ter and 120 grit. Then I go to a bull wheel 100 grit belt then 400 grit and then on to the polish machine. Hello: I saw your reply above and I appreciate it. If possible would be grateful for help with some related questions: 1.) As I am used to the 6 wheeled cabbing machine with the 80, 220, 325, 600, 1200 and 3000 diamond wheels, its hard to understand how it`s possible to go from a flat lap with 120 grit to a bull wheel with 100 and then 400 grits directly to polish. But I have heard of similar techniques, including here inm South America, and so there is definately something working well with this method. But in essnce, what is the dynamic in this case that allows for skipping so many grits before going to polish? 2.) Do you use an original 12" bull wheel with SIC belts. I heard that 12" belts are not available in diamond. 3.) Have heard of people using 8 x 3 inch expandiable drum as sort of a cheaper alternative of the original bull wheel. What are your tought about this option? 4.) As I understand, bull type heels are generally run dry when using SIC belts. But if using diamond belts, I would assume that water must be applied. #2 I use the 12 bull wheel with SIC belts. Run dry with a respirator. I recon I could use some 220 grit after the 120, but I find that 120 works good on the flat lap. The 100 grit belts are used on hard agate before I do petrified wood with them, not so aggressive that way. Sometimes i go directly to the polish machine after the 100 sic belts. depends on material and what it looks like. the used 400 SIC belts are pretty smooth after some use. I use diamond pads at times on large slabs and you do have to do all of the different "grits", if not you will see scratches and will have to ack up and redo it. #3 I used a 8 x 3 expandable drum at first, but it is no comparison to a bull wheel. I found a good used bull wheel. #4 I run SIC belts dry but have never tried diamond belts and they probably would need water. I know a guy who uses water with SIC belts on bull wheel. just a bit messy. Thanks again!! |
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chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Jun 25, 2022 21:45:40 GMT -5
Thanks for the quick reply. I have searched around the internet and not been able to find the original Bull Wheel for sale anywhere. There is a knockoff of sorts from Highland Park but very pricey, $2500 and up. Maybe the Richardson Ranch Highspeed Sander at $495 and their polisher at $395, might do the trick.
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stefan
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Member since January 2005
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Post by stefan on Jun 26, 2022 16:54:00 GMT -5
Just a couple thoughts: Water is important for sure, but too much water can cause a hydroplane effect. Cleaning between each stage is important. New disks, wheels, belts will shed some diamond and that can cause problems. If your backing plate is not flat and robust, you are not going to get a good flat grind. I might be WAY off base here but just thinking as I type.
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Post by roy on Jun 29, 2022 11:25:22 GMT -5
you can get diamond magnetic pads in diffrent grits and you can hold them on with your hands or you can build a fence around the plate and slow it down a bit and use grit  Flat lap by Roy Kessell, on Flickr |
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Post by roy on Jun 29, 2022 15:50:33 GMT -5
you can get diamond magnetic pads in diffrent grits and you can hold them on with your hands or you can build a fence around the plate and slow it down a bit and use grit Flat lap by Roy Kessell, on Flickr i meant hold the slab by hand lol |
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Post by woodman on Jun 29, 2022 16:52:59 GMT -5
you can get diamond magnetic pads in diffrent grits and you can hold them on with your hands or you can build a fence around the plate and slow it down a bit and use grit Flat lap by Roy Kessell, on Flickr i meant hold the slab by hand lol Did you get the big slabs lapped? Talk about hand holding made me remember you had one to do! I still have t4he sweep off of my lap. got a few more big ones to lap one of these days! |
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chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Jul 7, 2022 9:43:36 GMT -5
Not yet. Had to put the slabs on the back burner for now. We mainly make small stone figures, some cabs and related silver jewelry. For instance, we sell and mount rough moldavite in 950 silver settings. But thanks for the advise o the slabs and we'll get back to them soon. (I can`t stand giving up on things like this!) At same time, as we don`t do slabs that often, I am not going to invest in a vibratory lap. As I mentioned to someone else, the Bull Wheel seems like a very good options for slabs, and also for many other of lapidary applications, like maybe more versitile than a flat lap, regular or vibratory. But can`t find it available from original mnfg. and similar products like from Highland Park version are way too pricey. So, thinking about either an 8" expandible wheel that I can mount on a spare motor or maybe the Richardson Ranch vertical grinder - polisher. Any opinions??
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Post by roy on Jul 11, 2022 10:19:57 GMT -5
i meant hold the slab by hand lol Did you get the big slabs lapped? Talk about hand holding made me remember you had one to do! I still have t4he sweep off of my lap. got a few more big ones to lap one of these days! lol i just pulled those out yesterday when cleaning my shop and thought time to get these done no wonder my ears were burnin |
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