unclesoska
freely admits to licking rocks
All those jade boulders tossed in search of gold!
Member since February 2011
Posts: 934
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Post by unclesoska on Apr 23, 2014 20:24:11 GMT -5
Howdy All- I hope I'm posting this in the right place- A project I'm working on requires the polishing of many slabs and I'm ruling out doing them all individually on my drum sander. Some slabs are 3/4" thick and about 3-4" in diameter. The other slabs are 3/16" and 2-4" in diameter. Most of the material to be polished will be translucent agate varieties. I'd like to batch process the like sizes and will be looking on Ebay & Craiglist for something used but not abused. I realize there's been a good few varying designs over the years and want to get an idea of what to avoid and what the treasures are. Any help here is greatly appreciated. Blessings All!
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Post by 150FromFundy on Apr 23, 2014 21:04:12 GMT -5
I've heard nothing good about them. New ones are really expensive. Thousands of dollars, not hundreds of dollars, so used is the way to go.
They are really noisy. They spatter everywhere. They require constant attention to kept the slurry moist. They are a pain to clean and avoid cross contamination. You have to weight down thin (light) slabs.
Hopefully someone with more experience will say something positive about them. The only positive thing I can say about them is they produce amazing results when in the right hands.
Darryl.
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Post by jakesrocks on Apr 23, 2014 21:13:31 GMT -5
I'd suggest looking for a good Highland Park Vibro Lap. I have a 20", but it's already promised to someone.
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unclesoska
freely admits to licking rocks
All those jade boulders tossed in search of gold!
Member since February 2011
Posts: 934
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Post by unclesoska on Apr 23, 2014 21:43:50 GMT -5
Jake- What would one expect to pay for such a machine? Are parts still available? How long for each grind step? I'm a total newb when it comes to this type equipment.
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Post by jakesrocks on Apr 23, 2014 22:06:25 GMT -5
Jake- What would one expect to pay for such a machine? Are parts still available? How long for each grind step? I'm a total newb when it comes to this type equipment. If you check the 20" vibrating tumbler in the Diamond Pacific catalog, they got the patterns for the old HP lap. The only change I can see that they've made is to add a perforated metal guard around the base. All of the parts should interchange.
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jerrys
spending too much on rocks
Member since February 2014
Posts: 263
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Post by jerrys on Apr 24, 2014 11:59:42 GMT -5
I use three vibrating flat laps to sand and polish. I would recommend staying away from aluminum pans as they wear and can dish. Especially with heavy rock such as bookends. I use a thick plastic sheet to cover the lap and hold it in place with clothes pins. This eliminates any splash. The plastic also minimizes evaporation so the pan doesn't run dry. I run them 24/7 and check them 3 or 4 times a day. Ask around and look for estate sales for the best deals.
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Apr 24, 2014 13:29:40 GMT -5
Vibrating laps can give a great polish. But it takes practice and experience to get good results from them. Do not expect to buy one and to immediately start producing a great polish. They are fussy beasts. It is a multi day process to get a polish. The length of time mostly depends on how long it takes to get a totally flat surface.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Apr 24, 2014 14:34:58 GMT -5
I can only speak to the Lortones. I bought one and within a few months polishing big flats and coconuts halves, the bearings wore out. Had them replaced and they wore out again even faster. Threw the piece of junk out and my wife used the trays for plant dishes. Pretty much a waste of money. I think a good wet flat lap , a reciprocating lap ( Rockciprolap?) or, high speed polisher like Richardson's sells are the best bet. I had one of those in the past and they work dry so you have to use precautions but they work real fast and do a good job.....Mel
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Post by rockpickerforever on Apr 24, 2014 19:33:57 GMT -5
Picked up this 20" Rose Rociprolap at a local club's silent auction last year: forum.rocktumblinghobby.com/post/666675/thread
I haven't used it yet, but it's a keeper. It is very well made (cast iron!) and in great shape. I already have slabs picked out to be polished, just haven't got around to doing it yet...
Craigslist, club sales, estate sales, garage sales - those are all good bets. I wish you success in your search. Jean
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Apr 24, 2014 21:50:11 GMT -5
I've been using an old 20" Lortone for almost 3 years now. I've found that it produces a great polish and perfectly flat slabs/nodules. I, recently, modified it to have a circular/reciprocal action using an offset shaft and 2" shock mounts to reduce/eliminate the up/down hopping that the old "steel flag on a shaft" design had that caused orange peel texture on some rock species. I get a lot less problems with rocks banging into each other and chipping with this setup as it's not as chaotic. It does seem to take longer than the old design but that may be because I'm only jiggling at 1075rpm instead of 1550rpm. Gonna try a different pulley combo for that. There are ways to eliminate the problems of splashing and drying up. You can make a simple drip system and suspend it over the pan. As far as splashing, if it is splashing out, you have too much water in the pan. Sometimes it's unavoidable without a drip system. What I've done is I got a 14 or 16 inch bike inner tube and sliced it open, length-wise. I then stretched the inner tube around the pan so that it overhangs the lip by 1/2" to 1". This channels the great majority of the slurry back into the pan. I, usually, don't need it here in Florida since it's almost always so dang humid, but it works great in Winter. Get some 1-3lb lead ingots off of Ebay to weight the slabs down. Be sure to cusion the bottoms of any weights you use so that they don't dent the rock - takes a lot of grinding to get those dings out as even lead will ding a rock if it rattles against it 1000 time per minute all night and is heavy. Wrap the edges of your slabs with duct tape to cushion any collisions. On the bigger slabs, make little "fences" around the edges to keep a lot of your grit from being deposited on top of the slabs. You can end up with half your grit out of the pan bottom and not working for you if you don't. Wrap thunder eggs completely with duct tape because their rinds are always so crumbly and you don't want pieces getting into the bottom of the pan and making deep squiggly scratches on the rocks' surfaces. Run your grinds longer than the book says, especially the 60/90 and 600. You want the 60/90 grit to have time to break down to as near the 220 as possible. On the 600, the longer you grind, the smoother the slab gets. You want it to break down to at least 2400. Consider adding a 4th step using 1000-1500grit silicon carbide if you don't want to run the 600 so long. Anyhow, I'm thinking of doing a sticky on "jiggle pans" if I figure it out and/or they let me. Here's some pix of some rocks in my pan: The giant slab only has one lead weight on it in the one pic because it had a big nub/high spot that needed to be evened out before I could proceed in getting the slice flat. It, also, has some plastic tubing taped to wooden slats taped to the top of the slab because it had a sharp edge and was super heavy with 4 weights atop it and would have made a mess of broken pieces in the pan if allowed to crunch up to the other ones. Also, note the 1/8" sheet rubber taped to the bottoms of all of the weights. C-ya, Rick
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Apr 25, 2014 13:11:42 GMT -5
Really nice Rick. I'll be stealing your tricks. Steve
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unclesoska
freely admits to licking rocks
All those jade boulders tossed in search of gold!
Member since February 2011
Posts: 934
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Post by unclesoska on Apr 25, 2014 14:33:25 GMT -5
Thanks Steve for sharing your process- it's been a real eye-opener.
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Apr 28, 2014 3:06:10 GMT -5
Always glad to help. Jiggle pans are a great way to work up lots of slabs at one time while doing other things. I know the tape bit seems sort of tedious but, like anything else, you get really fast at it with repetition. I can dress up 20 slabs in 10 minutes. C-ya, Rick
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1nickthegreek
spending too much on rocks
Member since February 2014
Posts: 383
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Post by 1nickthegreek on Apr 28, 2014 8:03:12 GMT -5
Just traded for an old Lortone 20" vibe setup, thanks for all the tips and tricks, do I need to use different grit in the flat lap, or can I just use the regular tumbler grits that I already have? Thanks in advance!!!!
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Apr 28, 2014 10:34:43 GMT -5
It's important that you use graded grits (like 220) with laps. Do not use the split grits (like 110/220) that often are used for tumbling. Otherwise the answer is yes.
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Apr 28, 2014 20:32:20 GMT -5
My grit sequence is 60/90 - 220 - 600 - Tin Oxide polish. I add an optional 1000 or 1500 grit phase after the 600, sometimes. Usually for Montana Agates and Obsidian. I think just doing 2 consecutive 600 grinds works as well. I just did that last week and hard to polish rocks like amethyst slabs turned out awesome. Make sure you have a separate pan with a felt pad to do your polishing and store it wet in a sealed garbage bag after you're done. Tin Oxide and Cerium Oxide hardly wear down at all, so saving the polish in the pan saves a good chunk of change. You do have to add a tablespoon here and there as some polish slurry gets lost on the rocks and some collects and hardens on the lip of the pan.
Whenever you start a new batch/grind, make sure to stay and watch the movement in the pan for 5-10 minutes before you go off to make cabs or whatever. Sometimes there will be a rock or two that doesn't play well with others and you can end up with gridlock in the pan. Other than the first little while on the coarser grits where the rocks/slabs will jitter around chaotically, once the grit wears some, the rocks should rotate together around the pan slowly - or sometimes faster than slow. It's usually long, rectangular slabs that cause the most problems because they are always trying to spin on a long axis and can end up wedging rocks on the other side of the pan firmly against the side and stop the rotation. That's why you want to keep an eye on them for a while and play "traffic cop" if any combo of positions of the rocks stops the rotation. Sometimes you just have to move a rock or two to a different spot in the pan. I try to keep round/squarish ones in the center and have the long ones at the edge, travelling around the pan parallel to the edge of the pan. Moving length-wise, in other words. It's pretty easy to move rocks around as you watch and set them so that the long, narrow ones always stay pinned at the edge. Fill the pan completely and then remove one or two rocks. You have to have enough rocks in the pan to make sure they all stay rotating and in their place where you want them. Too much empty space and they just loiter in the same spot or the long ones spin and get sideways an create a logjam.
Sometimes, since the slabs all have heavy weights on them, a lighter rock might even get shoved over the top of the traffic jam and start whacking against the top of some other slab at over 1000 times per second and make some pretty deep dings that require you to take that one all the way back for multiple grinds at 60/90 to re-flatten the slab. That sux! Doesn't happen very ofter and, if it does, it's usually in the polish phase where the rocks/slabs have some drag from the felt pad rather than skate over the top of grit bits. If the rocks stay in one place for too long, you end up with a grid of circles in the finish. Remember, Tin Oxide is very hard stuff. I was going to add a picture of my prize, 8" slab of Rolling/Waving Hills Dolomite to show the effects of gridlock in the polish phase, but I didn't get a pic that showed it well. Now, dolomite is kinda soft - polishes well, but it *is* soft. On one side of the slab, the rocks got stuck sometime overnight. It resulted in one side of the slab having a thousand round dings and a texture like a waffle. It was shiny, but sitting in the same place so long made the polish dig little round dents all over the slab. They are fairly deep, too - like a millimeter or more. I'll have to totally redo that side. The harder rocks didn't get dented, per se, but you can definitely see a grid of little circles in the polished faces if you look.
I find that 95% of all gridlocks happen in the polish phase. Usually caused by a "slow" rock that doesn't have it's edges all beveled at 45-ish degrees or, occasionally, a rock whose tape is too low on the edge and drags against the pad. You want to make sure to bevel all edges of every rock/slab a fair bit at the very start of the grinds. This helps the grit get under the rock. Not beveling causes the center of the rock to not get ground/polished. Also, sharp edged rocks drastically decrease the life of your polishing pad. The sharp edges - with a couple pounds of lead weight behind them - will mow the fibers off the pad like a lawnmower cutting grass. Most times, a worn pad means half a pound or more of lost polish. I've started trying to save the polish slurry and let it settle out in a jug to see if I can't save $$ by adding it to the pan with a new pad. I'll find out in a few days if it works to do that.
Use "outdoor" graded duct tape during the polish phase. You don't want the tape to come off the slab and the weight to fall off the slab and go merrily around the pan polishing itself. Tape coming loose is rarely a problem in the grind phases. But it's a real pita when polishing. That's because 1)the polish is so much finer than any of the grits and can get under the tape somewhat but mostly because... 2)The the felt pad offers way more drag/resistance than grit does. This means the weights will wiggle more on the tops of the slabs and eventually work the tape loose, aided by the water/polish slurry. The outdoor tape sticks a ton better than the regular or "advanced" duct tape. Anyhow - this is freaken long... C-ya, Rick
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Apr 28, 2014 20:55:52 GMT -5
1nickthegreek - Here's a link showing how I modified my 20" Lortone to be like a Reciprolap. Got rid of the orange peel texture on some rock species, though it seems to work slower. That may be due to the motor running at around 1050rpm or so rather than the 1550rpm of the stock motor. Might also be because I need to anchor the rig down better to stop the base from jiggling so that only the pan jiggles. forum.rocktumblinghobby.com/thread/62688/presenting-reciprotoneC-ya, Rick
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1nickthegreek
spending too much on rocks
Member since February 2014
Posts: 383
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Post by 1nickthegreek on Apr 29, 2014 2:24:38 GMT -5
1nickthegreek - Here's a link showing how I modified my 20" Lortone to be like a Reciprolap. Got rid of the orange peel texture on some rock species, though it seems to work slower. That may be due to the motor running at around 1050rpm or so rather than the 1550rpm of the stock motor. Might also be because I need to anchor the rig down better to stop the base from jiggling so that only the pan jiggles. forum.rocktumblinghobby.com/thread/62688/presenting-reciprotoneC-ya, Rick Thank you so much for this link Rick, was going to ask you for help with doing this LOL
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Apr 29, 2014 23:42:08 GMT -5
No prob, man. The only thing not pictured is the 4-bolt 3/4" pillow block bearing I installed to the bottom of the pan holder pan. I had to drill 4 holes and mounted it dead center.... ish. You don't need the set screw in the bearing because you want the offset shaft to be able to spin freely in it. Good thing, too, because I have no idea how the heck I would have gone about tightening it! C-ya, Rick
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on May 1, 2014 19:50:15 GMT -5
I have two 27" Highland Park, and a 20" Beacon Star. Everything 150 said about laps is true. Plus, if you don't get them set up right, they will destroy themselves and everything in your shop. Set up right, and they will crank out nice stuff. Here is what I recommend from a lot of trial and error.
First, you need to set these things up so they will not move. Take a couple of 2x4s, drill half through at the foot spacing dimension, place the machine on the boards where you want it, and ramset it to the floor. Level the platter. Don't level off the ring.
NEVER let these things run dry. On the HP models, get rid of the silly rubber-coated ring and replace it with a piece of 3/8" tubing. Silicone it down to the outside edge of the plate. Build a wood cross that separates the platter into four sections. Use slices of 4" or 6" pvc drain tube to separate rocks within each section if necessary. Once the machine is secured in place and level, tighten all the bolts. Believe it or not, when set up properly these machines are pretty quiet. Took me a while to get to that point. My first lap marched all around my shop. Thought it was possessed.
I have tried everything known to man to attach the lead weights to the slabs. Here's what works best for me. Place a small drop of Gorilla Glue on the back of the slab, set the lead on it, and let it set overnight. This systems is not without its problems, but I process a lot of material and I can't spend the time taping, etc. I can glue up thirty slabs in 2-3 minutes. Done. Problems: you have to get the hang of how much glue to use- too little, and the weight comes off during operation. This won't hurt anything, you just have to start over. Problem: use too much glue on a thin slab and you will break it taking it off. I pop the weight off with a chisel, and scrape the remaining glue off the back with a razor blade scraper. I have had to use a fine dovetail saw to slice between the weight and slab on occasion. Problem: sometimes the glue will stain the back of the slab. Oh well. Here's why I like this system. I have a 27" dedicated to rough grind- I never clean it,just replenish the 220 grit. I also have a 27 dedicated to final polish- I never clean it either. Between these steps I use a bull wheel, and the cool thing about my setup with the weights is they make great handles to control the sanding steps on the bull wheel. If you've used a bull wheel you know how difficult it can be to control a small slab wearing gloves. My system eliminates that problem. The weights stay on through the entire process. To be honest, if I had to clean the lap between steps I would not use them. For what it's worth, the bull wheel was the best $ I have ever spent on a piece of lapidary equipment.
The 20 and 27" HP are the same as the Diamond Pacific units. Advice: the four-bolt bearings are about the only thing that really wears out on these things. DP charges about $60, or you can get them all day on ebay for less than $10. It's an easy swap.
A used 27 will run you about $500. I have a 20" for sale at $375.
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