Monday, April 7, 2014

Rocks (and not the ones in my head this time!)

One of the questions that comes up from time to time is what I do with the rocks that I bring home. That depends on the rock! Some will live in my collection, some will immediately enter the cue for a project, some will remain in a secured location until I figure out what to do with them.

One thing I DO NOT do is faceting, that would be the cutting of clear stones with lots of flat sides (facets) that bounce light around. It looks like this:

Picture from
This takes several thousand dollars worth of special equipment and a certain kind of obsessive compulsive behavior that I don't do. Faceted stones also don't really fit my jewelry style or the historical stuff I like (with a few exceptions) so I don't do it (there are some stones I intend to get faceted but this is one job I won't be doing myself (wait! I can at least do the heat treating part! I mean it's only several thousand degrees Celsius for up to 12 weeks in specially designed high tech equipment... actually, I see the problem never mind...)) 

Ok, now that I have begged the question (and tried to convince myself to get yet another piece of equipment to set things on fire with!!!) what do I do with the stones??? Answer: cab, carve and tumble (not all on the same stone...

Cabbing or cutting cabochons is where you are cutting smooth domed or flat topped stones usually out of translucent or opaque material (but you can do clear stuff too) and sometimes composite/and or multilayer materials. They look like this:
Thanks to again for the pictures.
These can be cut on flat laps (like a record player but different), on arbors with grinding wheels, on sand paper in various configurations, and leather buffs. These fit my style a lot more than faceted stuff.
Carving, well it's like carving wood (but completely different (unless it's petrified wood!)), or bone, or soap,or <insert material here>.  A lot of times it is done with material that has faults that need to be cut out or other factors that would make it tricky or unsuitable for faceting or cabbing. It is also done with material that you want to preserve something about that would be lost by other cutting methods.
The stone on the left in this picture is orange calcite. It is a great carving stone but a bit too soft for most jewelry purposes so you wouldn't usually cut a cab out of it. The one on the right is sodalite (a blue softer material) on the top end and quartz (good old cut it all day, it's pretty bullet proof to work with quartz) in the rest of the piece. You could cut it in two pieces and make perfectly respectable cabs out of the two materials, but it is really cooler with the two parts attached. The two parts are different hardnesses so it would be a pain  to try to cut a cab out of it and maintain both materials (the sodalite would wear down a lot faster...), but if you're carving you can cope with that issue and make something cool out of the whole piece. (you may be seeing these stones again later as finished pieces, but as of this date/time they are sitting on one of my benches in the official "what should I do with this" section)
Last (we can argue about least later) comes tumbling. Tumbling is the most 'naturalistic' and simple ways of polishing stones. Note that I say 'naturalistic' and simple, not easy (though it pretty much is) or unskilled. There is some knowledge and skill needed to do it well, just not as much as the other methods. 
Tumbling is comparatively cheap tools wise and an easy way in. Tumbled stones also fit with some of my style which has a lot of ancient/primitive/nativistic elements, minimal in actual hands on time per piece and as a bonus is a good way to use up little bits of material that you trim off or are otherwise not useing for other projects (and I like to use as much of my material as possible). Your tumbler can also serve as a metal cleaner/polisher (as many reloaders know). For these reasons combined you will almost always find a tumbler running in my shop (actually I'm looking at buying a second one, but more on that later).
I put 'naturalistic' in quotes, because the action really does mimic natural action but it's hard to call something using electric motors and formulated abrasives natural (it would be closer using wind or water power, but still not quite there...). Basically a tumbler mimics how a river or stream rounds off and polishes a stone (but you can get a better polish because you are using a controlled process with human decision making and planned steps). The best way to understand tumbling is to follow the process, so we will do that in this and an up coming post (two posts because I wanted to start this now, but at 10 days per step (my usual for good old quartz family stones) it won't exactly be finished by dinner time (or even breakfast).
So here we go...
 This charming little engine of destruction is my tumbler, currently loaded with one 3lb and one 1.5lb barrel. the picture below shows the drive rollers without barrels on.
 Mine is a Lortone 3 1.5 meaning it is set up to run with and comes with 3 1.5lb size barrels. It uses essentially the same parts as the Lortone 33b which runs two 3lb barrels  (same motor, same rollers, same belts, as far as I can tell the only difference is the barrels). I also have two 3lb barrels from an old Harbor Freight tumbler that I wore the motor out on (but the barrels are fine!). I use a 3lb barrel for the first (coarse) step and the other for metal polishing. I got the 3 1.5 this time because the coarse step is the most aggressive and results in a fair amount of material loss, moving to the smaller barrel means I don't have to wait through two coarse loads to make a medium load. 
The other reason I went with the 3 1.5 is that I now have a barrel for each step of the polishing process. Cleaning your barrels is important (and even more so if you're using just one barrel) a bit of grit or broken stone from a more coarse environment can ruin a finer level run (and cause you to have to rerun a load at that level or even worse backtrack...). I am ADHD not obsessive compulsive, so running one barrel for each step means I don't have to stress over getting every little bit of grit out (and it's what the professionals do...). 

More to say about tumblers but lets save that for part two. On to the rock!
Here is the load we will be tumbling. It is a mix of chunks, pieces of slabs, and other small bits. You want things of similar hardness (this is good old quarts family (jasper, agate, jasp-agate, crystalline quartz...)) and a mix of sizes.
You want the rock to come 2/3 to 3/4 of the way up the barrel. Now, most of the instructions  you read will say to add the grit (abrasives) then the water. As you can see above I actually do this backwards; the reason being I've found that if I add grit then water more of the grit gets stuck at the bottom of the barrel and doesn't get used. If I add water first I get a better usage of the grit. So, for our load it's fill the water up to just under the top of the stones and then add four tablespoons of course grit.

The first go round is the coarsest grit. I use a 60/90 'split' grit that has pieces between 60 and 90 mesh it's cheaper and a little more aggressive than the 'straight' 80 that some people suggest. You can also use a 40/70 or a straight 30 grit if you want to be really aggressive, but most of the time you don't need it if you choose good rough.

Now it's time to put on your lid (2 parts) screw it down and put the barrel on the machine. At this point there are two mantenancy things to think about: 1) start the rollers before you put the barrel on, this prevents start up shock/strain to the belt and helps you not break them; 2) the 3lb and 1.5lb designations are the total weight of what goes into the barrels, i.e. a 3lb is meant to handle 3lb of stone, and grit, and water, if you are having belt breakage issues you may want to weigh your barrels to make sure they aren't over loaded. While we're at it remember I said fill 2/3 - 3/4 full... the 4 TBS of grit didn't fill the rest and it's not supposed to, we need a little open space for everything to roll around right (and not too much space either). Load it on to the rollers and see you in ten days... but wait, it's best to pick up the barrel and shake it once a day, and if you're doing material you haven't worked with before, even to open the barrel every couple of days to check the action and look for any gas build up (trust me coming back to discover that the end of your barrel has blown out can ruin your day (and your equipment...))

Fortunately for us this post is going up on day 10! So we can see how step one came out and do step two. First a couple of important safety notes... Realize this is messy stuff, don't do this in your kitchen (really if you or your spouse or parent or anyone else who lives with you cares at all about the house don't do it in the kitchen, it would be bad). Realize that the waste material we will be pouring our is a lot like thin cement and will have the same effect on your pipes, so pour it out somewhere other than your plumbing (this is part of why I say don't do this in the kitchen. Your spouse, parent, child, or plumber will murder you). Remember that cleanliness while next to impossible is vital. We will be cleaning out and wiping up everything, bad things happen to you, your rocks, other projects in your work space and the universe in general if you don't (remember you don't have to be completely OCD if you have multiple barrels but still clean them). One tip is to get two or three cafeteria style trays to work on, it contains things and makes clean up easier.

 And we pull the barrel, bring it to our work spot and open it! For the record I'm hearing the full sound track from a video where scenes from House MD are melded with the song "I am a scientist" (this video ) while I do this...

 Er, um, when did we add the chocolate milk? Usually the liquid is grey/silver at this step so something odd happened (note that at the polish step this may be a perfectly acceptable color depending on your polish). So we will drain/strain and examine the stones.
Btw make sure you clean out that barrel! a couple of smaller stones typically try to hide out there. The good news is we got good grit breakdown. 
Remember when I said don't put the water down the sink? I meant it. It is ok to pause at this point and admire the rocks, then pour them out on some paper towels and trouble shoot. we are looking for the brown water culprit, but also other 'trouble stones'
This picture shows two kinds of trouble. First to the back we see two stones that just haven't smoothed out enough  (probably wanted that extra coarse grit...) give them another run in the rough, if they don't clear up we'll deal with it then. The front pile is a completely different problem these are fractured bits from rocks. these will absolutely kill any polish, so we have to find them and the rocks they came from and get them out.
Here we have two broken/ badly fractured stones, the other broken ones seem to have completely become shrapnel (this is why I like to have one or two big ones in the coarse grind, they encourage the breakers to fall apart early). The one in two pieces also shows some areas wearing faster than others (softer stone) this can be hard to spot before hand. Now we decide the fate of these stones, and I'm going to toss them aside into my "pretty fish tank rock" bucket and not try to re tumble.
Then we have this pretty but problematic fellow... he's a softer stone that while cool needs to be with things of it's own hardness (and recognizing the material he's the brown water culprit).

Now that we have filtered all those out, the survivors go into our 1.5lb barrel marked for medium grit.
And surprise surprise they all fit. Most of our material loss was at the first stage and the load will not get too much smaller, but in the next post we will discuss what happens if it gets below our 3/4-2/3 range. Add water and our medium grit (I use a 220 grit). Put the lid on, tighten it down and send it spinning.

The rock has to complete the medium, fine and polish steps so we will pick this thread up again in a month.

We have yet to have any response on names for the starter or shop made tools... those are still open...
Just sayin'
sniff sniff...

No idea what we're going to do next time... the weather is supposed to be highs in the 60's (even up to 70) and the lows above freezing! And with  no rain! Maybe we'll set some stuff on fire... that is where this all started...


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