So, what to do with this rough stone?
Well, in googling around I found out a few things:
Low end cab equipment costs a few hundred dollars (under $400 if you look around). The all metal models have ok resale values if you find you can't cab very well. The main issue with low end cab equipment is inconvence. If you go with the plain arbor unit you'll have multiple wheels (two in the smaller units) to move to without slowing down, but no trim saw (trim saws save wear and tear on your wheels and can carve up small slabs). Units with a built in trim saw tend to be cramped in front of the wheel and allow only one wheel at a time (meaning you have to take time to switch wheels/sanding pads when you're ready for them).
I decided on the "Rock Rascal" model TM. It comes with a trim saw, 100 grit carbide wheel, 220 grit sand pad, felt polishing pad, mounting head for the pads, and a rubber backer for the pads.
Note on distributers: spend some time in pricing your equipment. You will find very large price differences for the same item at different sites (sometimes by several hundred dollars). I went with the cheapest I could find. That was a mistake. The invoice indicated that they were doing a week long inventory and wouldn't ship. Then it was back ordered. In the end it took about a month to get my grinder. It is near two months now and the last parts of my order have not arrived (a loupe, scribe, and templates). So if you do go with the cheapest distributer, you may just get what you get.
I had ordered some rough moonstone on ebay to go along with what was found at the public mines. Here too, don't go super cheap. Find common rough (like moonstone) that is pretty cheap to begin with and then be willing to pay a bit more. Two examples: #1 I first bought a pound of cheap moonstone for a little over $10. It had little flash or much usable stone. #2 I then bought 500ct of moonstone for the same price. Nearly all of it has nice electric blue flashes and is very usable.
But now that I had my grinder I didn't want my first attempts to be with my bought stone or the public mine stone. Luckly I had a substitute. My daughter has taken to bringing me stones that she finds. NC is pretty neat in that there are all sorts of interesting rocks just lying around. So I had a number of feldspar looking pebbles (translucent creamy colored stones that look stream smoothed).
My first grinding attempt was a learning experiance. Specifically, carbide sanding pads have a *very* short lifespan. I had bought some 400grit and 600grit sanding pads to go along with the base rock rascal. Every pad was spent before I was done with the stone. Around 5 minutes of useful life.
Now considering that the 100 grit wheel is used to get the stone formed roughly into shape and the 220 grit (sandpaper or wheel) is where the real work is done (all other work is smoothing in preparation for polishing), this would have me buying a ton of 220 grit sandpaper. Not to mention that the grinder only came with one 220 grit paper. I simply had no idea how very short a lifespan they had.
So, a 220 grit wheel is an absolute must with a rock rascal type setup.
Something I didn't like about the carbide sandpaper is that when the grit wore out in one area it was still ok in another. This caused some facet like aspects on my first stone. I'm pretty sure that using a 220 grit wheel will help with this, but it still bothers me. There are two other options available: diamond grit on a pad or diamond sandpaper. I'm going to use the carbide sandpaper again when my 220 wheel arrives. If I continue to have issues I'll look into the diamond grit. The diamond sandpaper is awful expensive and I have no idea if it can be recharged.
I had bought several grits of sandpaper the first time around thinking the coarse wheel and sandpaper would leave gouges. This wasn't the case. All grinding left smooth areas. Also, the closer I got to the desired form the faster the grit cut. Sometimes too fast. This left me thinking that I might want to try to get as much of the work done on the wheels as possible and then try just one sanding ~600 grit. If I can get down to one sanding I'd feel better about the costs of using diamond grit. But I just won't have a good idea until my 220 grit wheel arrives.
I used cerium oxide for my first stone and it worked pretty well. This time around I'm planning on prepolishing with tripoli. Tripoli has a grit of somewhere around 1000-1200.
So, if I had it to do over again:
Rock Rascal TM
Trim saw lubricant
220 grit carbide wheel (must have)
400 grit carbide sandpaper (not sure if needed)
600 grit carbide sandpaper (compare with diamond grit if this is the only sanding)
Tripoli with additional felt pad (haven't used at the time of this writing)
Cerium oxide (I suspect any general polish would work)
Carbide wheel dresser (needed with carbide wheels)
Dop wax (didn't use the first time which resulted in limited control)
Dops - various diameters of dowel 3-4" long (pretty much anything can be used)
1" wide paintbrush (for polish... get one per type of polish)
Dop wax preparation (I use old cans on the stove)
Templates (to form stones for commercial settings (not needed at first))
x10 Loupe (not needed at first)
Note on the wheel dresser: I suspect I used too much pressure on my first attempt as some uneveness has developed. This makes it hard to grind well. Remember - light pressure on the wheels.
At present, I've ground four other stones on the 100 grit wheel and am waiting for the 220 grit wheel to arrive. I think I'm catching on to working the coarse wheel as I can get the stone near to sanding ready. The thing that threw me off was how fast the coarse wheel ate into the stone when only ridges were left. I caught myself from cutting away too much, but I did cut more than I wanted on a couple of the new stones.
Well, in googling around I found out a few things:
- As mentioned the other day, public mines are like a lottery and should really be approached as a family fun activity.
- Faceted stones do the best in general (i.e. More setting options and does well unset) but adequate rough is very pricey to just practice on. Synthetic is more reasonable but doesn't sell well.
- Cabochon (aka "cabs") cuts use cheaper rough and is generally thought of as "easy".
- Faceting equipment is very pricey. Generally the price goes along with precision. A skilled faceter can work around imprecise equipment but a rank amateur (i.e. me) can not.
- Cabbing equipment is pricey, but not as bad as faceting equipment. Looking at the lower price range there appears to be some junk mixed in with adequate equipment. The adequate equipment is cheap because it is inconvenient. By that I mean that the work zone in cramped, the wheels are thin, or only one wheel can be mounted on the arbor at one time.
- It is generally thought that, at the very least, a hobbist cutter will be able to pay for their hobby with what they make.
Low end cab equipment costs a few hundred dollars (under $400 if you look around). The all metal models have ok resale values if you find you can't cab very well. The main issue with low end cab equipment is inconvence. If you go with the plain arbor unit you'll have multiple wheels (two in the smaller units) to move to without slowing down, but no trim saw (trim saws save wear and tear on your wheels and can carve up small slabs). Units with a built in trim saw tend to be cramped in front of the wheel and allow only one wheel at a time (meaning you have to take time to switch wheels/sanding pads when you're ready for them).
I decided on the "Rock Rascal" model TM. It comes with a trim saw, 100 grit carbide wheel, 220 grit sand pad, felt polishing pad, mounting head for the pads, and a rubber backer for the pads.
Note on distributers: spend some time in pricing your equipment. You will find very large price differences for the same item at different sites (sometimes by several hundred dollars). I went with the cheapest I could find. That was a mistake. The invoice indicated that they were doing a week long inventory and wouldn't ship. Then it was back ordered. In the end it took about a month to get my grinder. It is near two months now and the last parts of my order have not arrived (a loupe, scribe, and templates). So if you do go with the cheapest distributer, you may just get what you get.
I had ordered some rough moonstone on ebay to go along with what was found at the public mines. Here too, don't go super cheap. Find common rough (like moonstone) that is pretty cheap to begin with and then be willing to pay a bit more. Two examples: #1 I first bought a pound of cheap moonstone for a little over $10. It had little flash or much usable stone. #2 I then bought 500ct of moonstone for the same price. Nearly all of it has nice electric blue flashes and is very usable.
But now that I had my grinder I didn't want my first attempts to be with my bought stone or the public mine stone. Luckly I had a substitute. My daughter has taken to bringing me stones that she finds. NC is pretty neat in that there are all sorts of interesting rocks just lying around. So I had a number of feldspar looking pebbles (translucent creamy colored stones that look stream smoothed).
My first grinding attempt was a learning experiance. Specifically, carbide sanding pads have a *very* short lifespan. I had bought some 400grit and 600grit sanding pads to go along with the base rock rascal. Every pad was spent before I was done with the stone. Around 5 minutes of useful life.
Now considering that the 100 grit wheel is used to get the stone formed roughly into shape and the 220 grit (sandpaper or wheel) is where the real work is done (all other work is smoothing in preparation for polishing), this would have me buying a ton of 220 grit sandpaper. Not to mention that the grinder only came with one 220 grit paper. I simply had no idea how very short a lifespan they had.
So, a 220 grit wheel is an absolute must with a rock rascal type setup.
Something I didn't like about the carbide sandpaper is that when the grit wore out in one area it was still ok in another. This caused some facet like aspects on my first stone. I'm pretty sure that using a 220 grit wheel will help with this, but it still bothers me. There are two other options available: diamond grit on a pad or diamond sandpaper. I'm going to use the carbide sandpaper again when my 220 wheel arrives. If I continue to have issues I'll look into the diamond grit. The diamond sandpaper is awful expensive and I have no idea if it can be recharged.
I had bought several grits of sandpaper the first time around thinking the coarse wheel and sandpaper would leave gouges. This wasn't the case. All grinding left smooth areas. Also, the closer I got to the desired form the faster the grit cut. Sometimes too fast. This left me thinking that I might want to try to get as much of the work done on the wheels as possible and then try just one sanding ~600 grit. If I can get down to one sanding I'd feel better about the costs of using diamond grit. But I just won't have a good idea until my 220 grit wheel arrives.
I used cerium oxide for my first stone and it worked pretty well. This time around I'm planning on prepolishing with tripoli. Tripoli has a grit of somewhere around 1000-1200.
So, if I had it to do over again:
Rock Rascal TM
Trim saw lubricant
220 grit carbide wheel (must have)
400 grit carbide sandpaper (not sure if needed)
600 grit carbide sandpaper (compare with diamond grit if this is the only sanding)
Tripoli with additional felt pad (haven't used at the time of this writing)
Cerium oxide (I suspect any general polish would work)
Carbide wheel dresser (needed with carbide wheels)
Dop wax (didn't use the first time which resulted in limited control)
Dops - various diameters of dowel 3-4" long (pretty much anything can be used)
1" wide paintbrush (for polish... get one per type of polish)
Dop wax preparation (I use old cans on the stove)
Templates (to form stones for commercial settings (not needed at first))
x10 Loupe (not needed at first)
Note on the wheel dresser: I suspect I used too much pressure on my first attempt as some uneveness has developed. This makes it hard to grind well. Remember - light pressure on the wheels.
At present, I've ground four other stones on the 100 grit wheel and am waiting for the 220 grit wheel to arrive. I think I'm catching on to working the coarse wheel as I can get the stone near to sanding ready. The thing that threw me off was how fast the coarse wheel ate into the stone when only ridges were left. I caught myself from cutting away too much, but I did cut more than I wanted on a couple of the new stones.
