tgotch
off to a rocking start
Member since October 2011
Posts: 6
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Post by tgotch on Oct 27, 2011 19:26:26 GMT -5
Hi, I am new to lapidary, and looking to get in on the cheap I have access to a Craftsman 8" variable speed (1725-3450 RPM) grinder. Can this be converted to a Cabbing machine? I was looking to put some 8" expanded disks with diamond belts on the unit. From what I can tell I will need the following: Gravity feed drip system Drip pan Wheel cover My biggest question is, how can/do I mount the wheel to the shaft? Any suggestions is appreciated.
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Post by jakesrocks on Oct 27, 2011 19:50:15 GMT -5
The answer to your first question is yes, as long as you can isolate the motor from your water source. Keep the grinder cranked down to its lowest speed if you're going to use expando drums.
The drums will mount the same way regular grinding wheels mount. If you buy new expando drums, they'll come with shaft adapters to fit to the size shafts on your grinder motor.
DO NOT run lapidary wheels of any type at more than 1725 RPM's. These wheels are designed to run at or lower than this speed. Crank them up too high and you run the chance of them coming apart.
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ol3m3
noticing nice landscape pebbles
Member since September 2006
Posts: 85
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Post by ol3m3 on Oct 27, 2011 20:24:13 GMT -5
At what speed can expando drums run?
OM
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Post by jakesrocks on Oct 27, 2011 20:57:32 GMT -5
1725 or under.
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Post by johnjsgems on Oct 27, 2011 21:09:52 GMT -5
I think 8" drums (Raytech) say maximum speed 1800 rpm, 6" 2200 rpm.
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tgotch
off to a rocking start
Member since October 2011
Posts: 6
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Post by tgotch on Oct 28, 2011 8:35:32 GMT -5
Thanks for the info.
Couple more questions:
I am planning on grinding/sanding/polishing saw cut glass bottle rims. Would expando drums be the best solution for this?
I was thinking of doing initial rim grinding on a flat lap (maybe 220 or 400 grit). Then sanding edges with homemade grinder as mentioned in OM. Then polishing with a leather wheel. (Does this sound like a decent process?)
Also, I see expando belt grits as high as 50000 (dont think I need to go this high). What grit sequence would you recommend for the rims with the benchtop grinder?
Finally, do you know a good source for expando drums (if this is the best solution), or if used drums are a viable option.
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Post by johnjsgems on Oct 28, 2011 9:12:47 GMT -5
Do you already have a flat lap? If so I would just buy more laps. 220, 360, 600, 1200, 3000 (optional) and a polish lap. If you don't have the flat lap I would use the grinder with a 220 diamond wheel and one expando with same sequence. Will the bottle rims be rings? If so you will only be able to sand/polish the outer surfaces with either set up. A vibe lap or rotary tool could be used on inner surfaces.
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tgotch
off to a rocking start
Member since October 2011
Posts: 6
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Post by tgotch on Oct 28, 2011 9:49:39 GMT -5
John, I am actually building the flat lap first. I think I will need this anyway to keep the rims level/true. I don't think this can be as easily accomplished with a circular grinder....at least with my skills at this point The bottle rims will be mostly rings, but some will be square, oval, rectangle, etc. Can you clarify how a vibe lap would accomplish the inner ring sanding?
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Post by jakesrocks on Oct 28, 2011 10:07:37 GMT -5
I think John is talking about using a vibratory tumbler to accomplish inner ring sanding. With ceramic tumbling media as a filler and cushion, it would remove any sharp internal edges.
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Post by johnjsgems on Oct 28, 2011 10:17:08 GMT -5
Sorry, I'm on decaff now. I meant vibe tumbler. You could do all your shaping on a lap and sand/finish in a vibe tumbler. I don't think anyone can sand flats on wheels.
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Post by jakesrocks on Oct 28, 2011 11:23:27 GMT -5
Tried that decaff once. Started having withdrawal. Wasn't very pretty around here, until my wife got some caffinated coffee for me.
Something I've been tossing around in my mind for a couple months, that sort of fits in with what tgotch is trying to build. I have a vertical arbor for a flat lap. I've been thinking of putting a radius wheel on it to run horizontal. Want to do freeforms, and think it might be easier to grind inside curves with the wheel laying flat. I'd use a sponge to wet the whole side of the wheel. Ideas ?? Think it would work ?
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Post by johnjsgems on Oct 28, 2011 11:32:08 GMT -5
I would probably use a drip water system. I don't know why horizontal would be better than vertical.
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Post by jakesrocks on Oct 28, 2011 11:37:20 GMT -5
Seems to me that it would be easier to see what you're doing. Anyway, just a thought. I don't have the radius wheels yet. I'm thinking sponge because I'm afraid the water would be slung off the crown of the wheel, leaving the bottom dry.
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Post by johnjsgems on Oct 28, 2011 16:35:37 GMT -5
Don, if you decide on Diamond Pacific's radius wheels (they call them Galaxy Carvers) I get the same discount as their other Galaxy/Nova wheels. I have no idea how 30% off DP compares to Chinese wheels but bet the DP wheels are better.
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Post by jakesrocks on Oct 28, 2011 16:57:54 GMT -5
Still in the thinking and planning stages, but I'll keep that in mind.
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