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Post by tortuga on Mar 10, 2010 20:10:08 GMT -5
I have been tumbling stones in my Lortone for a while now, and as the natural progression probably goes, I've progressed to an interest in slabs beyond little tumbled stones. Slabs, cuts, etc. I was talking to my local lapidary about this, as he noticed I had started buying some rough that tends to have cuts. He took me out to his garage and showed me an old dirty vibratory lapper that he wasn't using, and sold it to me for a great deal. It's a little Covington 392, and came mounted on a little homemade table. It looks like most of the other stuff in his shop... covered in that dried concrete slurry that most of our stuff probably ends up looking like after years of loyal use.
I've never used one of these, obviously, and was wondering how clean the tray needed to be for the process? It has a little piece of carpet in it that will need replaced, and it's caked in gunk. Is it the same rule as the tumblers, that all traces of previous grit must be meticulously cleaned out? Am I putting the media directly onto the waffled metal tray surface and making the slurry in there... or should I be using some sort of disposable surface between the slurry and the metal tray?
If it does need to be very clean, any tips for what I can do to get some of the dried stuff off? Any solvents other than elbow grease and copious amounts of water that will meet me with success?
Thanks, and I'm glad I found this place. Looks like an active and knowledgeable group of people. I'm excited to start reading the guides to expand my learning of this exciting hobby!
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Post by kap on Mar 10, 2010 20:23:23 GMT -5
I have 2 24inch laps and I have trays for each grit so if you only have one pan you will need to clean it between stages.This is what I do. Put the grit and water(not much) on the pan for every step but polish then use the carpet or what ever then. Keep a spray bottle hany to add a little water at times. For the slabs you will need to add a little weight to them by sticking something on top plumbers putty works good and comes off easy. It is a good idea to put something around the stone when using it to keep the edges from hitting and chipping. Cut off pieces of PVC pipe or even cardboard tubes cut of works. The best way I have found to know when you are ready to go to the next stage is take a pencil and put a line across the slab put it back on and run it then check to see if the line is all gone. Hope this helps Keith
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Post by deb193redux on Mar 10, 2010 20:28:09 GMT -5
You want the pan clean enough that there is no grit larger than the course grit you start with, and no residual mud to muck up the grit. After the 1st stage, you want to clean pretty good between stages.
If you are starting with a flat slab, you can like skip the coarse grit and do 120 or 220 1st. Then something fine like 600 or 800. Then replace the pad and use a polish. If the slab was cut with a high quality blade that almost left a satin shine, maybe start with 320.
Most faced rock will be OK on its own. Slabs generally need some weight on them. They sell slab weights, but a rock stuck on top with silicon, or a beanbag full of shot are both good homemade weights.
You want the slurry wet enough but too wet and you get a lot of spatters all around the unit. But with the open top, it tends to dry out. I spritz every few hours when I am in the shop. IF I am working something unattended, I sometimes use mineral oil instead of water. Eventually it gets muddy and you need to change out the grit.
Course is not so important, but in the finer stages you want graded grits. So no 120/220, or 220F(iner) but actual 220. Same for 500 - not 500F. Graded costs a bit more than tumble grit, but it needs to be more uniform for lapping.
Mostly just experiment and ask questions.
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Post by tortuga on Mar 10, 2010 20:35:22 GMT -5
That does help! The pencil line tip is great, seems like an easy way to check the flatness. I do only have one tray, so I guess I'm going to need to get it clean. Any tips for getting the ancient dried slurry cleaned off the metal? I don't want to take a wire brush to it and rough up the surfaces... unless it doesnt matter? Here is a picture of what I'm talking about. In the picture the metal is wet, and what's left is really really stuck on there and I wanted to check if it's OK before I took something abrasive to it. Am I correct in thinking I'm going to be making the slurry directly on the pan surface up until the polish stage in which I will be apparently making it on carpet? I will be able to avoid this kind of buildup again since I'll be keeping it clean between my own uses, but how to get it back to start? Thanks for the fast reply
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Post by Hard Rock Cafe on Mar 10, 2010 22:24:31 GMT -5
If it were up to me, I would just let the rock and first grit do the work.
Yes, you'll be making the slurry directly in the pan and on the pad.
Chuck
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Post by deb193redux on Mar 10, 2010 23:17:58 GMT -5
yeah. put in some gravel and grit and let it scour the pan.
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cornorstone
off to a rocking start
Member since February 2009
Posts: 19
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Post by cornorstone on Mar 12, 2010 16:45:27 GMT -5
a cheap power washer ($80.. Menard's) can help not only keep the pan clean, but is a quick method of getting grit out of the cracks & caves.
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NDK
Cave Dweller
Member since January 2009
Posts: 9,440
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Post by NDK on Mar 12, 2010 23:10:34 GMT -5
I think a 2 dollar scrub brush (like found at the grocery store for doing dishes) and a little elbow grease would work better than a power washer. It would make less of a mess too. But as the others said, run a coarse grit stage and let it clean itself first.
Nate
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