zentz
starting to shine!
Member since August 2005
Posts: 31
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Post by zentz on Aug 19, 2005 12:04:19 GMT -5
Good morning...it's my turn for a silly question (is there such a thing  ... I was wondering if it is possible to use a regular bench grinder as a rock grinder/polisher? I notice that the pads on the lapidary one's are around 3 inches wide, would it be possible to modify a bench grinder to hold these? and would the guard come down to far to be able to work a stone?...just my inquisitive mind working over time ;D Andrea |
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Duckbean
fully equipped rock polisher
Looking for rocks in all the wrong places
Member since February 2005
Posts: 1,072
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Post by Duckbean on Aug 19, 2005 12:26:24 GMT -5
I'm using two bench grinders to shape stones now. You have to take the wheel covers off and on some you need shaft extensions that you can buy and then you need to rig up a water feed for most lapidary wheels. I use a regular silicon carbite wheel and a 4 inch diamond grout remover wheel on one so there is no water involved. on the other I use a expanding 1 1/2 drum and a flat on the other end, which need water. Their are others on the board that have made much nicer units and I'm sure they will give you their feedback! I'm still new at this but in short yes bench grinders can be used.
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Post by Tweetiepy on Aug 19, 2005 13:08:19 GMT -5
I have a regular bench grinder and all I've done is replace one of the wheels with a carbide wheel. I didn't want to mess with expandable wheels as the shaft would not accommodate the extra witdth, now would the guard on the edge (now would my budget at this time). I don't suggest wetting the carbide wheel as it seems to wear down incredibly fast when it is wet, I just wet the stone in a dish of water as I'm working wearing both a dust mask as well as protective glasses (I previously sprayed the wheel with a spray bottle & wet the stone, but it wore down very fast (like 1/2" within an hour)). I only have a fine grit wheel which seems to do a very quick job of grinding it down. The wheels that came with the grinder are for metal grinding and they do squat to the stones, it takes forever for them to wear down even a little bit! For someone who can't afford the "real" machines that could do very well. If you can find the other grits for this type of carbide wheel you could take it all the way down to polish. Unfortunately, I can only find this grit here, so I'm only using it for rough shaping.
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stefan
Cave Dweller 
Member since January 2005
Posts: 14,113
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Post by stefan on Aug 22, 2005 10:30:40 GMT -5
Yes you can! Pay attention to keeping both the stone and wheel cool- and the various grit stages (most grinding follows a 100, 220, 400, 600, 1200, polish cycle- but in my own cabbing I have been following this cycle 100, 120, 220, 320, 400, 600, 1200, 3000 (for very special cases) and polish- Remeber a few key points- Water and electricity don't work well together, Ideal RPMs for cabbing is in the 1750 RPM neighborhood, Some stone is harder than metal, Rock dust can cause health problems.
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Post by Tweetiepy on Aug 22, 2005 11:08:36 GMT -5
Stefan, I've gone from 220 to 400 to 600 to polish on my leopardskin jasper - on the mex lace I had to do the shaping on a 100 as it was pretty hard then on to 220 etc. but are all those belts really necessary? Maybe I just skipped steps - although the mex lace is very nice even up close with a magnifying glass
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stefan
Cave Dweller
Member since January 2005
Posts: 14,113
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Post by stefan on Aug 22, 2005 12:55:08 GMT -5
No tweet all them belts are not necessary- unless you are like me- I can't tell a 100 scratch from a 600 scratch! I have hit dead ends in my cabbing- so I've decided to use as many steps as possible- Sands clued me into running a 600 belt dry to see what you have- Well I did this and MAN I'm missing a lot of scratches- so I run as many steps as I can, dry the cab between steps and try to get to polish with out any scratches sneaking onto the cab!
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Post by Tweetiepy on Aug 22, 2005 13:22:01 GMT -5
Stefan I have to plead ignorance, you can't be missing scratches, cuz I wasn't even looking for scratches when I moved on from one belt to another. But I do have to say, get some dop wax. I can rough out the general shape with my hands (where I once again ground my nails (manicures are wasted on me)) I get it as close as I can to the final shape (the oval dome is very easy to accomplish) and then dopped the stones, (not knowing if these things were gonna fly off again like last time - dopping seems to not work for me on the shaping part as there's too much vibration) and press like the dickens on the belt working in a circular motion - which may be why you still have scratches if you can't press hard enough on the belt to grind them out - as I only ground on the finer belts a total of 5 minutes for 220, 400 and 600 belts - 10 minutes tops for all 3 remaining belts! And 2 minutes on the polish disc. I guess if you can't push hard enough on the belt evenly, the scratches remain.
Anyone can correct me if this is incorrect information - this is only what I learned in my 2 impromptu sessions
Oh I forgot, someone had mentioned this before, make sure the stones are dry when you look at them to see if they look okay
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stefan
Cave Dweller
Member since January 2005
Posts: 14,113
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Post by stefan on Aug 22, 2005 14:26:56 GMT -5
Yea I look at em dry (actually installed an incandescent light to dry em under) I press hard enough to squeal the belt that is not the problem- I think I'm actually pressing Too Hard- I'm not sure how long I work any one rock cause I sit down and work at least a half dozen at a time- I think it is a mental thing with me- I thought it would be easier so I'm doomed to scratches as payment to the rock gods- should have the bill just about paid in full! Oh I tried doping- I think it made things worse- as I started on the wrong side (you finish the back first)
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zentz
starting to shine!
Member since August 2005
Posts: 31
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Post by zentz on Aug 22, 2005 14:50:59 GMT -5
Wow! Thanks for all the information from everybody...:-)
Andrea
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stefan
Cave Dweller
Member since January 2005
Posts: 14,113
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Post by stefan on Aug 22, 2005 19:20:30 GMT -5
Ooops sorry didn't mean to steal your thread! Yes you can use a bench grinder
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... I was wondering if it is possible to use a regular bench grinder as a rock grinder/polisher? I notice that the pads on the lapidary one's are around 3 inches wide, would it be possible to modify a bench grinder to hold these? and would the guard come down to far to be able to work a stone?...just my inquisitive mind working over time ;D
