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lcs
 #1 
Hello, I haven't posted in a long while. This past week I finally got down to West NC to do some rock hunting. We had a great time and found way more than expected. We did a few 'gem mines' and went out on our own. We came back with corundum (light pink and darker), kyanite, emerald, tigers eye, many different quartz (some with nice inclusions) and lots of small pieces of garnet.

My question is what to do with all of this material. I have wanted to polish/cut some of these stones. I have looked into lapidary equipment, but it looks rather expensive. I was wondering if using regular bench grinders with different wheels would be good for a beginner? Should I just buy a tumbler? I know this wouldn't get the best results from many of these pieces, and some of these pieces are already small. Any help on this would be great. I haven't been able to find much else out on the web.

Thanks

Luke
lcs
 #2 
I forgot to mention that I do have some shop equipment that I may be able to use. I have a dremel and a 1950's shop smith. I'm not sure if I could rig up a grinder to the shop smith or not.

Thanks
Eva
 #3 
From what I have seen so far, you can put diamond grit wheels on any proper sized arbor (make sure the bore hole is the right size or get cheap plastic spacers for inside the wheel to make them fit) and they will work fine to grind stone as long as you can get a decent amount of water onto the wheels, either via drizzling from the top or squirting up from the bottom. In a pinch, I will squirt the wheel with a squirt gun in one hand while holding the rock against the wheel with the other hand, but this is a difficult way to cab!

And of course you need a motor system to turn the arbor. I think about 1/4 to 1/3 horsepower will do it, but would have to check what we are using to make sure. The bigger 8 inch wheels are on the higher end for needed horspower. Most people are happy with 6 inch wheels which cost less. If you have big hands/fat fingers, then you may want to make a lot of space between wheels, but it's not essential. Use spacers between the wheels to add space, or just have more than one machine with just a few wheels on each. Make sure the motor type is that slower turning and higher torque kind, I think that's 1750RPM if I remember correctly which is what they use for grinding and cutting where a lot of pressure/drag goes onto the wheel. Also you will need some kind of splatter guard, which I have at times jury rigged by cutting up stiff but thin pieces of plastic and holding them in place via strong magnets. Magnets worked because the anchor spots were metal.

The main prob is that you need a number of wheels to get a decent grind and polish, each wheel with a finer grit. I don't know how few you can get away with and still get a decent shine. Typically, we at our shop use 6 wheels and sometimes need a separate buffing at the end for that last high polish, but could be you could get away with fewer wheels and use some diamond grit buff pads. Maybe others here can make suggestions on minimum wheels needed.
-Eva
http://www.rockchaser.com

Harry Polly
 #4 
Unfortunately, most of the material from the gem mine slucies are tumble grade at best. Sometimes, you will run across a piece that is cabbing grade, and maybe even facet grade. It all depends on the price of the bucket you paid for. Remmber, these places make their money by salting their buckets. Their real brad and butter money comes from you leaving your finds with them and letting them cut it for you. Their typical price ranges from $40 - $65 per stone. Do you get the stone you left? Sometimes.

Your best tool for grading is a strong flashlight. If the stone is thumb size or larger, check to see how clearm it is. If it has a lot of cracks and fractures, toss it aside for tumbling. Now that you have eliminated most of your pick, what is left? You have a couple of options. Contact a local gem club, inquire about classes to learn to cut your own, or have a member cut them for you. Purchase or build your own cabbing machine and learn to cab yourself. Contact members of this group and ask them to cab and or facet the stones for you for a fee. Generally speaking, you will pay anywhere from $15 on up for any given stone. Is the stone going to be worth that much when it is finished? I have cut a lot of stones for people that have found their stones at these gem mines. I have just finished a piece of green dyed quartz that a lady wanted me to cab. She has a $10 stone now. I am charging her $15 to cut it. I have just finished an emerald for another lady also. Again, my fee is $15, but her stone will be worth $30-$50. If you have good clear amethyst, topaz, emerald, citrine, smoky and good clean corundum, the stones might be worth cutting. Most of the garnets are not worth tumbling. Most are so weathered, they just crumble when you try to do anyting with them, even tumbling.

Hope this helps. I am not rying to discourage you in any way, but to offer you advice and insight. If you cannot find anyone locally to cut your stones, contact me off list and I will see what I can do for you.
Tom K.
 #5 
Hi Luke,
Although Eva gave you some great help I'd like to add my 2 cents worth here,,,,,,,,,,

Trying to do lapidary work with what's normally found in a "Handyman's" work show is like trying to take a tire off of a rim with a screw driver!

You can do it but you WILL have to work VERY hard to get the end product!

It sounds to me like most of the rocks you have were found at the roadside Gem Mines and as you say,most are pretty small already.

It would be fruitless for you to try to grind/polish any of the rocks you have using a bench grinder.
(before i forget),,,,,DO NOT use ANY water with ANY electrical equipment that is not designed to be used with water!!!!!!

If you try to grind/polish your rocks on your bench grinder you will create a LOT of heat and will probably wear down the grinding wheels faster then the rocks even if you keep dipping the rocks in water to cool them.

Getting into this hobby can be quite expensive if you try to jump right in but if you take it slow and maybe start out with tumbling it will teach you the process of how rocks are polished.

Rocks are polished by simply removing the scratches made by the previous grit used.
Think of it like sanding down a nice piece of wood with progressive sand paper starting with the roughest down to a very fine sand paper.It's really that simple but doing it with rocks takes a little more time and effort using the proper supplies and equipment.

If you wanted to get into grinding/polishing Cabochons I thin about the cheapest way would be to use Silicon Carbide wheels specifically designed for lapidary work but they will need an arbor to be mounted on.
Here are few wheels just to give you an idea of the cost,,,,
(you would need a wheel that's at least 1" wide)

(scroll down to bottom of page)

Click Here

This is only the tip of the iceberg and I hope I haven't discouraged you but to try to do ANYTHING without the proper tool and equipment can be much more discouraging.

If I can help more,,,,,,just ask!

Tom K.

Eva
 #6 
OH yeah! Good point. All the machines I have converted were either designed to be used with water, or had the motor far away from the main unit and moved the arbor via a pulley. A lot of them, I had to put the motor on myself, mounting the whole thing onto an old piece of plywood, etc, just like how a lot of the lapidary units are already set up.

One of the units I had donated had some kind of weird huge wheels covered in wet dry sandpaper. This also came with water tight troughs that went under the wheels, but splatter protection was minimal. What I did was yank off the funky sand paper wheels and replaced with regular diamond pacific genie wheels. Then I added a bunch of plastic splatter guards to keep the water away from the motor, which was separate and behind. And I used lapidary spitters under the wheels to keep them wet. This unit actually grinds better than a genie because it has a strong motor and only two wheels on it, instead of 6, so the torque or 'bite' on the stone is better. We put course grit wheels on it for fast grinding down of tough and hard stones.

We also had all of the outlets in the shop set up for machines that use water, just like are in most bathrooms these days.
-Eva
http://www.rockchaser.com
George Finley
 #7 
Hi Eva. The information from others is great. I just have another way that may help you. Go to http://www.freewebs.com/sgams and go down to number 14. At the bottom of number 14 is a another way to work your stones. Hope this helps. George
Docia
 #8 
pick up a copy of this month's Rock and Gem magazine - it has some links to sites with info on building cabbing machines and such!
lcs
 #9 
Thanks to everyone for the information. You have me pointed in the right direction now. These machines look to be quite expensive! I may invest in a tumbler for now.

I wanted to mention that we made one stop at a roadside "gem mine", I was warned from a few others on these, and the material found here wasnt too good. While they all may not be bad, I decided to stay away from them for the rest of the trip. We visited Mason mine in Franklin and had a go at their dig pile. We also visited a few creeks (streams) and road cuts we stumbled upon. Most of our good material came from these random sites.

I have finished sorting out our finds, and I do have some low grade stuff that may not tumble up well. But I do have a handful of pretty clear (clear and no cracks/fissures) and a few really nice pieces that could be cut.

Found your advise on the garnet was correct, most of it is full of cracks and not too clear but it has great color. I may just tumble these.

Most of the quartz could be cabbed in my opinion, I have some fist size chunks of really clear material. There are a few good pieces of emerald (about 1/2" in size) with clarity and nice color, the rest is maybe tumbler grade (very dark or with cracks)

The kyanite, tigers eye, moonstone and other are 3" or so pieces we found in the creek. These may polish up nice in a tumbler as well.

I am not too sure on the corundum as how to judge it. You can see the 'shine' on many of the pieces, and some are transparent when held to a bright light. You can see really good color on a few pieces. I have one large stone, I had a friend measure, and he estimates it to be around 900ct. I am not sure how this is measured, I doubt the whole stone is one crystal, made a bunch of small ones?

Last night I broke out the dremel and a diamond wheel. With some patients and a bowl of water to dip the stone in, I was able to shape a garnet pretty easily. The stone is now a pea size teardrop shape with flat back. With the finest grit tool I have, I was able to get the stone smooth, but not polished. I will need to figure out a way to polish these. If I were to shape some stones and them throw them into a vibrating tumbler, would I get good results? I have read that vibrating tumblers keep the stones shape better, and just get a nice polish.

Sorry for such a long post, and thanks again for the help
Harry Polly
 #10 
"shape the stones and throw them in a vibrating tumbler, would I get good results?"

Yes, that is the way mass produced caqbs are finished. The stones are preformed and then tumbled. Do they look as good as a hand cabbed stone? No, but they are after lots of cabs at cheap prices. That is why you can purchase a cab for $5 and under.

If you really want that self cabbed look, try this method. Get an assortment of wet/dry silicon carbide paper, available at your local automotive paint store. Get 400, 600, 800, 1000,1200, 1500, and 2000 grit sheets. If you can buy individual sheets, one of ech is enough, If not, 3M sell jobber packs of 5 sheets for about $7 each. Cut the sheets into fourths, which will be about hand size. Soak the paper in water for about fifteen minutes. Lay the paper plat in your hand, and work the stone in a circular motion with your other hand. Keep the paper wet by dipping it in the water as necessary. Go through each of the steps of paper. Remember, you are removing the scratches from the previous grit. You can skip steps, i.e. leave off 600 and go 800, leave off 1000 and go 1200, then 2000, BUT it will take much longer to remove 400 grit scratches with a 800 than it will with 600 and then 800. The finer the grit, the longer it takes to remove rough scratches.

When you have finished with the 2000 grit, you can usually hand polish with a fiece of felt or leather and some cerium oxide or tim oxide in the same manner but with less water. In this case, you only want enough water to make a slurry and to work the stone until it is dry. A muslim wheel on a buffer works great.

If you decide at a later date that you want to do this more, you can look at puchasing a cabbing machine. If you are interested, I have an old B&I refurbished machine with 10 inch saw blade and all attachments, including faceting head and motor that I would be willing to let go of. Contact me off list it you are interested.
lcs
 #11 
Thanks for the advice Harry, I will try this out and see how it goes.

I'm still looking to pick up a vibrating tumbler, but will need to wait until payday to make this happen. I think doing some by hand will hold me over until then.

We are making plans to return to the Franklin area over Memorial Day weekend, hopefully we can find some more good rocks!
Eva
 #12 
I totally forgot about flat laps! Sometimes you can get a totally cheap old faceting machine or flat lap, that no one wants to use for actual faceting as those old ones are hard to use and inexact compared to the new ones. But all it really needs to do is turn a lap decently enough and if you are cabbing then a bit of bounce or lack of perfection is not a big deal.

You can buy diamond grit laps rather cheap at richontools.com. YOu can also put buff pads on the lap for final polish. I have heard some people who started out learning cabs on a flat lap got so accustomed to it that they never did bother to learn to do it with genie style grinding wheels. I know a while back, our club got several old flat laps donated and we sold em for about $50.00 each or less. The motors worked great and they would have been fine for cabs. YOu would just need to buy some laps to go on top.

The laps for faceting cost a TON because they need to be all perfect, but the laps for just quickie grinding like at richontools are fairly cheap, but you would need to fabricate some kind of backing for them. We had some old heavy plastic lap backings at the shop already so what I did was buy laps from richontools and used some kinda sticky spray on glue to glue the laps to the backing. I think you could probably (maybe) even get away with using wood for the backing.
-Eva
http://www.rockchaser.com
Tom K.
 #13 
Harry,,,
Through the years I've tried many times to finish cabs in my vibe tumbler but as you say.they just didn't come out as if they were done by hand.
However,I recently got hold of Tom who manufactures the Lot-O-Tumbler at Belt Corp and had a very nice chat with him on the phone about this subject.

He suggested using a type of ceramic media that he found which is fired to make it quite hard and has a heavier specific gravity then the ceramic media that is commonly used today.
To back up a little here,,,,,

The main problem with doing small slabs and or cabs in a vibe is that they tend to get their flat surfaces stuck together which defeats the entire process.
The "norm" for using a "filler/cushion" in a rotary tumbler is to use plastic pellets but these pellets do not work in a vibe so a ceramic media is used instead.

OK,,,,We're back on track again,,,,,
I bought the ceramic media from Tom and tried them with some cabs and they work great!
I got the shine of all shines on some cabs that I have never got doing them by hand!

I was able to do about 7-8 cabs and a few small (2"x2") slabs with the ceramic media from Tom and none of the cabs or slabs got stuck together!

Live and learn!

Tom K.




Tom K.
 #14 
Ics,,,
Something to consider when buying a vibe tumbler is the size of it.
If you buy a 10lb unit you MUST fill it every time with a full load or it won't work properly.

There are several good vibe manufacturers so do a little research before you buy one!

Tom K.
Geoff
 #15 
Before everyone rolls on the floor laughing, an orbital sander in the vice with some P1200 paper gives you some idea of the stone. Can cut stone with an angle grinder with a stone disc. This is rough and slow but cheap for someone that just wants to see inside that rock without spending any money yet.
Beware! You will become addicted.
Harry Polly
 #16 
Geoff, you are correct in saying this,, but it can b very dangerous and DEADLY!!!. Cutting, grinding, or polishing without the use of water can cause silicosis. This is the main reason All lapidary machines are equipped with some type of water or oil system. The other reason is to keep the blade or wheel cool. BTW, P1200 sandpaper is not the same as 1200 paper. It is more in the range of 1000 grit. The "P" range of papers come from Europe and are not as fine a grit as a regular grade.
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