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[Rei]

Hi all! I've been collecting minerals for a while (everything from as soft as massive calcite to as hard as chalcedony) and just finally got a big vibrating lap for smoothing and then polishing slabs :) But.... I've never used one before!

* I purchased a variety of grits but they haven't arrived yet and won't for a few months. I do have various sandblasting media on hand - soda, glass and sand. Is it okay to use these (for coarse grinding, of course) or should I wait until the grits I got for lapidary work arrive?

* Two pans have a "carpet" in them, the others don't. If I remember right, the carpet is for fine grits, right?

* I'm supposed to add water and keep it moist in the pans, right?

* Light samples get weighted down, right?

* Would there be any problem if I made a dust tent / soundproofing around it, so long as the motor was provided airflow to stay cool?

Thanks all!

(Oh wait, one thing unrelated... I know that there are liquids used to fill cracks in specimens or add a surface gloss as if the specimen was always "wet" - can you recommend anything for that purpose too?)

[Steve]

Welcome from central New Mexico...............

[Jhon P]

I had one but sold it. I decided it was too much trouble and went to dry sanding.
If you look on the internet (put in "lapidary vibrating lap instruction") there are some very good instructions. There is too much to try and give you here.
Use the proper grit, keep it wet (slurry) if it drys out it can glue to the pan like concrete. it takes time hours and hours per grit. It can splatter mud all over the place. You have to clean the pan and rocks between grits. One grain of grit will scratch the stones and you will have to go back. The pans with the carpet should be for pre polish and polish don't use for anything else. It takes days and days to finish stones but will do a very good polish. You need patience ( I don't have) You have to check it every hour or it may dry out. I can dry sand a geode or slab in 15 minutes without the mess. Have fun I have known people that love the vibrating laps

[jakesrocks]

First of all, welcome aboard.

* Wait for your lapidary grits. Soda is too soft for lapping & will dissolve in water. Glass is too soft for anything harder than the glass itself. Sand, while it could be used for anything softer than the quartz minerals is in ungraded sizes & may give bad results.

*The pans with carpet are for final polish only. Unless you know what type of polish was used with each, I'd remove the old carpet & replace it with fresh. Store these in plastic bags to prevent cross contamination.

*There must always be enough water in the pans to create a slurry. Never let them run dry.

*Yes, light samples need additional weight. I purchased small lead ingots off of Ebay to weight mine.

*There should be no dust created as long as your grit is kept wet. Sound deadening certainly helps, as long as the motor can breath. I wouldn't recommend enclosing your flat lap if you live in a very hot area, unless you can set up a fan to blow cooling air across the motor. You might also want to set up some sort of water drip into the pan. Remember, if it's out of site, you still have to keep it wet enough at all times.

Now a few other things.

First, if there is a little nub left on your cut pieces from saw breakout, grind it off as flush with the cut surface as you can get it

 how smooth is the saw cut on your specimens ? If very smooth you can skip coarse grit & start the lapping process with something like 180 or 220 grit. if there are deeper saw grooves in your specimens, start with 60/90 grit.

You'll need to run several pieces at the same time to balance out the load in your pan. Use some sort of bumper strip around each piece to keep them from banging into each other & chipping the edges. Short rings of PVC pipe works good for this.

Flat lapping is a learning process. You'll make mistakes along the way. We all do. Keep a note pad handy & keep notes of what you're doing & trying. Learn from your mistakes.

Good luck, and post lots of pics of your triumphs & mistakes. We're all constantly learning. Maybe we can learn a new trick from you.

Don

[Rei]

Thanks Jake!

Re waiting: as mentioned, some of my specimens are soft (massive calcite, zeolites).  Would it be wrong to do a coarse grind on them with sandblasting media?  Obviously chalcedony won't work with something that's no harder than it itself is  ;)

I made a soundproofing box today out of thick rockwool panels.  I put in two holes for ventillation and a fan blowing air into it, to avoid overheating (re: whether it's hot "here" - here is Iceland, so no, not naturally - although we keep our indoor spaces just as hot as you do!  ;)  )  I'm thinking about lining the rockwool with plastic tomorrow before I do a test.

My cuts are unfortunately very rough.  :Þ  I use a tile saw to do the cuts, and since the blade is short** I frequently have to cut from multiple angles, which pretty much guarantees a rough cut.  And I'm a chicken, so rather than holding specimens with my fingers, I always try (awkwardly) to hold them with a clamp.  Also, cutting chalcedony is always awkward (it likes to fracture), so whereever there's one side that's naturally broken "flat" I'd rather just smooth away any imperfections than try to cut it better.  The main appeal to me of getting a flat lap was that I could just put my ugly-cut pieces in there with a coarse grit and leave them alone for ages, just topping up the water as needed.

((** Actually, the blade itself isn't that short, but the table that you're supposed to slide tiles across gets in the way.  I've many times pondered just cutting off the table with an angle grinder to get full access to the blade  ;)  ))

Running several pieces at a time won't be a problem - it'll be constantly full for months on end!  I've got big piles of boxes of neat mineral specimens I've collected over the years.  My ultimate goal is to get most of them to roughly the same thickness and well polished on one side so that I can use them to make custom countertops for the house I'm building.  :)  Maybe even mosaics.  A lot of the specimens were collected on my own land (it has a lot of mineral veins), so it'd add a very personal connection with the land itself.  My favorites are the poppy jasper and the zeolite-veined basalt.

[Rei]

I decided to do a trial run.  I emptied out part of the the contents of my sandblaster (apparently I was using glass last) since I need to empty it anyway, and put in some of the softer pieces I want to polish (calcite, zeolites... also some things with basalt, which while it contains hard grains also contains soft grains and thus can often be worn down).  Full tray.  I put it it in my soundproofing box, and made a pouch out of plastic sheeting over the tray to prevent splatters and help trap moisture.  With the soundproofing box closed, and a couple blankets over it (being careful not to block the fan's air intake or exhaust) it's surprisingly quiet here in my living room (it's in the plant room).  I can barely hear it with the TV on.  It's sort of like someone's driving a motorcycle 3 blocks away.  Come winter, when I can actually close the door to the plant room (it'll get too hot there in the summer with the lights for the plants), it'll be even quieter.  :)  So I'll call the soundproofing at least a success so far.

How often do you think I should check the water levels, and how often should I check the stones? 

[jakesrocks]

Check the water often. Let the rocks run a couple days before checking. You'll need to add a tablespoon full of grit every couple of days.

[Jhon P]

Post some pictures! I want to see the progress.

[Rei]

So, I did a general check this evening (I'd been periodically adding water, as per the instructions).  I'm amazed by how quickly a thick layer of "mud" has built up in the pan.  I'm sure it's technically a clay, but it was ultra-smooth and silky, like a mud facial.  I'm guessing that my glass had basically disintegrated?  I removed a lot of the mud (how much grit/water mix should be in the pan, anyway?)

I've been getting varying degrees of wear.  A couple small pieces of softer material are done with a coarse grind (I may just finish them with sandpaper).  A few larger pieces are "nearly done".  Most pieces aren't though (not surprised!). 

I'm giving it a rest for the night. Do you think it'd be okay to continue the test tomorrow using sand rather than glass, and see how that goes?

Re: pictures.  Here's the box:



Here's the air intake and the exhaust pipe.  Note the 90 degree bends to enhance sound deadening.  I really could use a proper duct fan, desk fans aren't designed for the resistance of blowing air through a tube... but whatever  :)




Here's the bagged tray atop the lap inside:



As I feared, while the bag is being a great asset, it's not wearing that well - it's gotten a couple small holes already.  For now I'll just tape them up as they form.   But eventually I might try to make a more durable "lid" for everything.



Here's the couple little pieces that I took out this evening.  The lighting doesn't show it well, but they have sides that are about as flat as I'd expect a coarse grit to get them.  I have pieces in there right now that are ten times bigger (and one that's at least 50 times bigger, but I don't expect that to finish any time soon!  ;)  )



Obviously I only need one side flat, as they're going to be used to make countertops; the undersides can be rough.  I'm going for a variety of looks and textures via mineral selection so that I can try to make a mosaic with them.

[Rei]

Just an update.  :) 

So, I'm still eagerly awaiting my proper grits next month and am still running on sandblasting glass.  The results have been expected: quick progress on calcite, slow progress on zeolites, no progress on quartz-based specimens, basalt more "grinds" down than "polishes" down (becomes flat but not smooth).  All expected.  The nice upshot is that I know that glass should be putting no wear on my pans.

I'm loving the results.  Especially on the massive calcite.  Raw massive calcite is kind of ugly, but polished, *wow*, it sure pops, with all of those crystals intergrown together.  I don't think I have the heart to use some of these pieces in countertops, I'm thinking I'm just going to facet them on all sides and use them as decoration or give some to some of my hippie-ish friends who are into crystals for metaphysical reasons  ;).  The polished zeolites sure look nice too, also with intergrowth - but again, they're progressing slowly.  Might be tempting to make jewelry out of some of them, but I don't know where to start with that.

My bagging system is holding up - it seems to last better now that I've taken the giant piece of jasper out of the pan (as well as all other quartz-based minerals).  Having somewhat of an even mix of sizes seems to work better than having some orders of magnitude bigger than others  ;)   With the bags I find that I can run 24/7, just filling up in the morning before work with water and extra grit, and again in the evenings.  I'm settling in on a "take everything out and check" every two days cycle.  The rock wool soundproofing box is working like a charm, I couldn't be happier with it.

Things that have surprised me include:
 * How silky / frothy the "mud" can get
 * How smooth specimens start "sticking" to the bottom of the pans.  Because you have two smooth objects up against each other with water between them, it's like doing the same with pieces of glass  :)
 * How tightly the "mud" embeds itself into cracks in the specimens.

The latter case is rather unfortunate.  The specimens don't seem to clean as easily as they did when I first found them.  I'm starting to wonder if  (for any specimens that won't be fully polished on all sides) using a flat lap is going to necessitate having to buy an ultrasonic cleaner  :(

[Sandsave]

I had one and sold it. I used a weight to keep them down, I also put a piece of thick plastic block weighted down to keep the rock (s) I was trying top polish moving around.
I got lead wheel weights from a local tire store and melted them down into different sizes. I helped for the various types of rocks I was working.

[Rei]

I had one and sold it. I used a weight to keep them down, I also put a piece of thick plastic block weighted down to keep the rock (s) I was trying top polish moving around.
I got lead wheel weights from a local tire store and melted them down into different sizes. I helped for the various types of rocks I was working.

How would you keep lead weights in a particular location?  I'd think they'd just move around too on top of the rocks.

So far I couldn't imagine selling mine.  It's so great how it's working without involving any labour from me except the occasional top-up and random checks to see if things are done  :)

[jakesrocks]

I used a little bit of dop wax to hold my lead weights in place. Others probably use other methods.

[womanwithatorch]

I had high hopes when I bought a vibrating flat lap about a year ago.  After several failed attempts, its now gathering dust.  Noise and messy splatters were bigger factors than I'd anticipated. Rei, it seems you have creatively resolved the issues of noise and splatters, with a bonus of reducing the frequency of adding water. You say you made a plastic "pouch". I can't tell much about the pouch from your photos. Are you saying the specimens, grit, and water are all inside the pouch? I am having trouble imagining any plastic bag would hold up for long. Or does the plastic pouch just sit on top of the rocks in the pan? like a lid?

[Steve Ramsdell]

I have one of those beasts too.  I used a box around the outside edge but had no cover.  I used to run mine only while I was in the shop (about 9 hrs a day).  The problem with what you are doing is that the grits may enter the cracks in the specimens and be very hard to get out.
What I used for rough or step one grit was waste material from grinding wheels.  You may know someone that has this to get rid of.  Machinists use it too.