petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 15, 2020 13:48:34 GMT -5
I ordered a 60 grit green silicon carbide grinding wheel of ebay and it does nothing to rocks! Am i doing something wrong? www.ebay.com/itm/8-x-1-x-1-1-4-1-2-CGW-Bench-or-Pedestal-Grinding-Wheel-Green-Silicon-Carbide/123991385491?var=424799156856&hash=item1cde766593:m:mntL9Nh_WmDnkzsU9YGddLQ I had previously been using a couple old silicon carbide wheels someone gave me and they worked good tell they were to small to use. I spent days looking at grinding wheels trying to find the best bargain. Also its really narrow and i had to make shims to mount it on the arbor. Can anyone recommend a place to order the right lapidary wheel? I tried Kingsley North, but the most coarse grit is 100 grit 1'' wide and there is no way i'm paying $75 (w/shipping). I need an 8" wheel 60 or 80 grit probably and it would be nice if it was 1.5" wide! I'm trying to go as cheap as possible. Thank you all very much!
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Post by knave on Jan 15, 2020 13:57:17 GMT -5
Have you tried dressing it? Edit: disregard, see post below...
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Post by captbob on Jan 15, 2020 14:01:32 GMT -5
I wouldn't dress a green wheel.
Never had much use for / luck with green wheels. Wouldn't ever buy another.
Would a 100 grit wheel help ya any or you need the coarser grit for sure.
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petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 15, 2020 14:13:48 GMT -5
Have not tried dressing it, i thought about it though. Will give that a try. 100 grit may work. I'm not sure what grit the old ones i was using were. I have a lot of rocks to work on so i was thinking coarser would be faster.
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Post by captbob on Jan 15, 2020 14:31:03 GMT -5
Coarser IS faster but free be better.
I have some 100 grit wheels and can send ya one or two if you would like.
BUSY w/ stock market. will check back
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petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 15, 2020 14:37:21 GMT -5
Wow Captbob! That would be great!
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Post by captbob on Jan 15, 2020 14:49:16 GMT -5
Happy to help. PM me an address and I'll get to it in the next day or two.
Are you a cabber or tumbler? In case there is extra room in the box ...
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petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 15, 2020 15:51:16 GMT -5
So dressing the wheel did help and it is grinding now! Still not as fast as the old wheels i was using. More inspiration for making a Supergrinder i guess! Thank you captbob! PM sent
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Post by captbob on Jan 15, 2020 16:09:58 GMT -5
Glad the dressing helped! When I tried that the wheel didn't seem any better. knave was right!! PM received, will reply soon.
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whyofquartz
spending too much on rocks
So, Africa is smaller than I expected...
Member since December 2019
Posts: 316
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Post by whyofquartz on Jan 15, 2020 16:48:48 GMT -5
I would guess since it is a grinding wheel for metal the matrix is not durable enough to hold on to the carbide against stone.
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Post by pauls on Jan 15, 2020 18:46:31 GMT -5
I would guess since it is a grinding wheel for metal the matrix is not durable enough to hold on to the carbide against stone. It's actually the other way around, wheels for metal are quite hard and don't shed worn particles, Lapidary wheels are soft so are always presenting new sharp grains of grit. I have used "metal" wheels and they tend to cause a lot of heat at the stone / wheel interface, so often cause nasty chips flying and cracks in your work. That's just my experience, I have long given up on Silicon Carbide and now just use diamond.
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Post by mohs on Jan 16, 2020 9:10:25 GMT -5
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petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 16, 2020 15:07:02 GMT -5
I worked on grinding some agates last night with this wheel and it does grind now, but i was experiencing exactly what pauls is talking about with the nasty chipping. I'm glad i read this because i was thinking it was this particular moss agate. I had not seen a stone chip in this way before and was kind of confused about what was happening. Mohs is also right about Silcon Carbide wheels going out of round fast and how dressing them is important.
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Post by mohs on Jan 16, 2020 15:57:43 GMT -5
yep I just toured a local lapidary shop it was really nice
they had a few 8" by at least 1/1/2" S/C wheels set up on Poly arbors really nice set up
I asked where they purchase those wheels she said Kingsly North
had no idea always bought my S/C wheels from a local distributor
that specialized in grinding accessory for machining
Norton wheels
those wheels set up on that Poly arbor seemed really substantial
I wouldn't imagine keeping them dressed and true would be much of a task
on my Lortone arbor using a 6" wheel always thought I pressed the rock to hard against the wheel that caused it go out of round frequently
always tried to remind myself light touch
anyway-- I was pretty good about using the full width of the wheel altho-- it did have a tendency to dish in the middle
doing hearts-- the S/C wheel was the only way to go on the cleavage 'nmohsopo
grind on
mohs
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Post by pauls on Jan 16, 2020 16:04:15 GMT -5
Running a Silicon Carbide wheel too slow will cause it to get bumpy. Grinding big rocks will do it too, very quickly.
If your wheel is getting bumpy, for safety sake true it up, out of balance wheels can fly apart. When you start your grinder stand to one side while it starts, that's when they tend to disintegrate. Also careful if your water feed is dripping onto the wheel, that can also weigh down one side and make the wheel out of balance. Health and safety rant finished.
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Post by mohs on Jan 16, 2020 19:27:39 GMT -5
yep I always dried to remember to spin it dry working outside in Phoenix dry environment not much of an issue
slower speed probably is the main culprit of the out of round issue
I started the lapidary hobby with a green wheel and variable speed bench grinder
There was this gravel landscaped business that had a ryholite type scape rocks anyway real colorful stuff
I'd hound heart shape little suckers and do touch up profile grind on the green wheel
then I sprayed them with shellac maybe attach a velcro to the back and hand them out to client on my bank route
that how started rocking the hearts
mohstly
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petrifried
starting to spend too much on rocks
Member since August 2015
Posts: 100
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Post by petrifried on Jan 19, 2020 2:13:06 GMT -5
I'll try speeding it up for grinding, think i must be running the sic wheels to slow. I never did the rpm pulley size math, i just found an old 1725 motor and put maybe a 2" pulley on it and hooked to the middle pulley of the arbor. May need to re-think that one (though what ever speed its spinning is working great for polishing sanded flats with the leather wheel on the end). Good to know about standing to the side when starting up, and that out of round wheels are dangerous. The thought of one of those disintegrating sounds pretty scary.
CaptBob went above and beyond and sent me a couple really substantial looking SIC lapidary wheels! Can't wait to try these things out, they make the grinding wheel i got look like a joke!
Lesson Learned, don't get sic wheels for metal to grind rocks!
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