Advice on polishing bigger rocks

[bowfin]

I would like to get into polishing rocks baseball size and larger. I've been hand sanding and polishing smaller stones and it takes me about 1.5 to 3 hours depending on the stone. I have a dremel flex-shaft that I should probably be using more to speed things up until I can get a rock tumbler. I tried hand polishing a larger rock about 8 inches x 6 inches x 3 inches and I'm not sure how many hours I put in before I gave up. I got it to an unnaturally smooth and shiny state put there are still a ton of dimples in it.

Mostly just want to polish river rocks that I think have nice patterns. Ones that are rounded and only need to be smoothed and polished

I was thinking of buying an air compressor to power a die grinder or a sander. I saw that you can get sander attachments for die grinders. I was wondering if this is the right route to take. I work stone wet so I was thinking I should use an air compressor to be on the safe side. I've seen polishers for granite counter tops too like this one http://www.amazon.com/gp/product/B001KAM3K4/?tag=treasurenet01-20 Not sure if those are only for the final stages and if they would work well on non flat surfaces.

Any other advice is also appreciated

 

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[DDancer]

You may just want to get a couple of bench grinders and outfit them with polishing pads then set each one up with a different grade of polish compound. Unless you plan on shaping the stones most other types of polishers, besides tumblers, wont work well or will cut the stones. The process is just like the finishing process for cabochon's and you'll have to adapt some tools to hold the stones while working them or make big dop sticks.

 

[hvacker]

That's the first water cooled peanut grinder I've seen. I've had the regular type for years but they aren't cooled. Pricy but cool.

 

[bowfin]

You may just want to get a couple of bench grinders and outfit them with polishing pads then set each one up with a different grade of polish compound. Unless you plan on shaping the stones most other types of polishers, besides tumblers, wont work well or will cut the stones. The process is just like the finishing process for cabochon's and you'll have to adapt some tools to hold the stones while working them or make big dop sticks.

Thanks, am aiming for a really smooth and polished surface like smaller stones you get from a tumbler. I would think they would have to be ground or sanded some.

Put another two hours of hand sanding into the rock I've been polishing and it only seems slightly smoother. Being that it has to have 6+ hours into it, it isn't really worth doing anymore. Determined to beat it, so I'll probably put another 4 hours at most rough sanding before going to the finer stages. I'll just have to consider that the pores give it chartacter. I could remove all the dimples/pores individually with a dremel with diamond bits but not sure if it would cause problems with low spots. Most of little holes are less than a millimeter deep.

Not sure what kind of rock it is. It is black and has a lot of pinkish tan crystals speckled through it which I'm thinking are feldspar. Definitely better off hand polishing Petoskey stones or making small stone pendants the way this is going.

 

[bowfin]

Some pictures of the size of rock I'm trying to sand/polish. First one is of it wet. Also included pics of a pendant and a petoskey stone I hand polished a couple days ago. Petoskey stone isn't as nice as I would've liked but not sure if that is my fault or the quality of the stone

 

[DDancer]

I think your doing a pretty good job

 

[bowfin]

I think your doing a pretty good job

Thanks I'll have to keep working on it

 

[hvacker]

Problem with sanding is many rocks might be harder than the aggregate on the paper. Many papers use flint or garnet. If you can find paper with silicon carbide or diamond paper I think you'll have more luck. Most suppliers of diamond paper sell in bulk so you might have to search.

 

[bowfin]

Problem with sanding is many rocks might be harder than the aggregate on the paper. Many papers use flint or garnet. If you can find paper with silicon carbide or diamond paper I think you'll have more luck. Most suppliers of diamond paper sell in bulk so you might have to search.

Thanks, I'll have to look into that. Hadn't heard of diamond paper before. Will have to check the price but probably won't be that bad considering how fast I go through the wet/dry 3m papers I use. I have diamond files from harbor freight but have only been using them on smaller stones.

Edit: so far have only found diamond pads/paper for power tools. I'll look more, but might have to consider those as an option. Saw some that looked like they were for the oscillating multifunction tools with the triangle shaped heads. Wonder if it would be safe electricity wise if I just keep the rocks moist. I don't really want to have to wear a respirator if I can avoid it by working wet.

 

[gunsil]

It is bad news to grind rocks out in the open. You can get yourself a bad case of "grinder's consumption" a terminal lung disease that grinders in cutlery factories used to get, and they even had water cooled wheels. Best to use a tumbler for the work you're doing. You can use an old cement mixer to tumble large rocks like you wish to do. If you work stone in the open make sure you use a high quality respirator mask, the at least $35.00 kind. This is even if you're hand polishing with sandpaper, the dust is deadly. There is no fooling around here, dremels are particularly bad since their high RPM really spreads the deadly rock dust around. Most professional stone grinding equipment runs at much much lower RPMs than dremels. I am a lapidary, please be careful while you have fun polishing rocks.

 

[galenrog]

Have you looked at the WIDE variety of tools and equipment available at a local rock or lapidary shop? In lapidary publications? Local rock, lapidary, or gem shows? I did a lot of lapidary before the arthritis took over the hands, and I had saws, rotary and vibratory tumblers, grinding and polishing wheels, and countless other tools. Perhaps one of the several lapidary forums could get you more accurate and specialized advice.

Have fun. Enjoy.

 

[bowfin]

It is bad news to grind rocks out in the open. You can get yourself a bad case of "grinder's consumption" a terminal lung disease that grinders in cutlery factories used to get, and they even had water cooled wheels. Best to use a tumbler for the work you're doing. You can use an old cement mixer to tumble large rocks like you wish to do. If you work stone in the open make sure you use a high quality respirator mask, the at least $35.00 kind. This is even if you're hand polishing with sandpaper, the dust is deadly. There is no fooling around here, dremels are particularly bad since their high RPM really spreads the deadly rock dust around. Most professional stone grinding equipment runs at much much lower RPMs than dremels. I am a lapidary, please be careful while you have fun polishing rocks.

When hand sanding I work in a big pan or bowl of water. When I want to change to a finer grit, it gets too cloudy, or I am done I throw the water outside. I then rinse the pan a time or two more and dump that water outside(I've read it isn't good to get that stuff in your sink.) When working with a dremel I either work in a pan of water that can fully submerge the stone or I pour water on as I go. Have tried to make a simple water drip before, but haven't bothered with it lately.

Silicosis does worry me. I'm guessing that is what you were talking about or something similar. So the methods I use would be really that unafe? Only problem I can think of is if I have any splash and don't wipe that up and it drys and becomes dust. I assumed it was safer than the amount of silica dust my girlfriend and I inhale from our cat's litter box

Do appreciate your advice. I'll consider changing my methods if they still seem pretty unsafe. I've considered a rock tumbler, but I'm also interested in small stone carving. I don't currently have a good work area except maybe at my parents house in their back garage.

Have you looked at the WIDE variety of tools and equipment available at a local rock or lapidary shop? In lapidary publications? Local rock, lapidary, or gem shows? I did a lot of lapidary before the arthritis took over the hands, and I had saws, rotary and vibratory tumblers, grinding and polishing wheels, and countless other tools. Perhaps one of the several lapidary forums could get you more accurate and specialized advice. Have fun. Enjoy.

To my knowledge I don't have a good rock shop that is local. Money is tight right now and I like to make small stone carvings. From what 've read a quality lapidary setup with a slab saw, trim saw, and grinder/polisher would cost me 3,000-4,000 dollars. Lapidary grinder's/polishers alone seem to mostly run in the 1,000+ range. I would like to buy all of that someday, but since I'm currently working mostly with small found stones and am not super into making cabochons I don't think it is worth the investment right now. Also since my parents are a drive away I prefer something I can run in a small area of my house. If people consider that to be really bad, even with using water, I'll probably have to stop though. Kind of sucks because I've really wanted to make lasting carvings out of stone and sell some to help with my financial situation. Not sure if there are any dust collection equipment I can use in a house.

Thanks just thought I would give this place a try because I used to visit this site a lot in the past.

 

[Claim Jumper]

Diamond Pacific makes a setup called a "Genie" that is awesome. It's very expensive though. Join a gem and mineral club and you can use their equipment. I'm lucky enough to be able to go to a Marine base with a rock shop.

 

[Claim Jumper]

Also for small items get a Dremel with the wand attachment and buy a bunch of diamond bits and polishing wheels and bits.

 

[gunsil]

As long as you're keeping the stones under water while sanding you should be OK. I have seen folks working rocks with no water and cheap paint masks and they are asking for trouble. You are right about not tossing water with stone dust down your drains. Sounds like you take the proper precautions, have a lot of fun!! Watch ebay and craigslist for used lapidary equipment. I got a 14" Highland Park saw on ebay for 500 bucks shipped, and a Diamond Pacific Titan for 700 bucks on craigslist. Got a Raytech 18" saw at an estate sale for $700. All the older lapidary stuff was built to last a lifetime, and is much more economical to buy than new gear.

 

[bowfin]

As long as you're keeping the stones under water while sanding you should be OK. I have seen folks working rocks with no water and cheap paint masks and they are asking for trouble. You are right about not tossing water with stone dust down your drains. Sounds like you take the proper precautions, have a lot of fun!! Watch ebay and craigslist for used lapidary equipment. I got a 14" Highland Park saw on ebay for 500 bucks shipped, and a Diamond Pacific Titan for 700 bucks on craigslist. Got a Raytech 18" saw at an estate sale for $700. All the older lapidary stuff was built to last a lifetime, and is much more economical to buy than new gear.

Know what you mean. Have seen videos of people drilling stones for jewelry and not using water or advising a respirator. For sanding them I usually keep them part-way in water and keep dipping the sandpaper to keep the rest of the stone wet. Unless I find a really nice rock, probably going to go back to smaller stones. Thanks

 

[meMiner]

Old cement mixer for large rocks. They sometimes come up in auction for next to nothing. But only if you have a place to do it, as it will be noisy.