jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 23, 2014 8:08:23 GMT -5
Been using a slow speed(3600 RPM) angle grinder with a 4 inch diamond cup wheel. It is noisy and spins too fast. And little hand rest So this one will have a quiet 1700 RPM 1/4 HP motor and a larger 7 inch diamond cup wheel. The 3600 RPM/4 inch wheel turns at about 63 feet per second at the rock. This one will be geared down so the 7 inch wheel turns 1200 RPM and have a speed of about 33 feet per second at the rock. The wheel will sit horizontal out of a table like a flat lap and serve as a hand rest. It is a dry wheel and can remove 1/8" material in one pass. Dust protection about mandatory. Shaft is an 18" bolt with 5/8"-11 UNC threads. Table top height about where green card is: Will build out of wood. Position of rock, top can be used too. Obsidian and glass rounded from some awkward shapes, works on agate as well:
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Post by Drummond Island Rocks on Sept 23, 2014 8:26:45 GMT -5
that thing should work great. I would be on board if it had a water system. I don't mess with rock dust much. I have a respirator for the toxic rocks even with water but I don't like the idea of airborne dust. I know your able to work outside more so you don't have to worry as much.
I did some quick math and it seems it could be made for about $80-$90 if someone already has a motor. Much cheaper then the $400 6" x 1.5" sintered diamond wheel I have been trying to save up for on the genie for pre-grinding tumbles.
chuck
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Fossilman
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Member since January 2009
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Post by Fossilman on Sept 23, 2014 9:32:04 GMT -5
COOL!!!! Great idea James!!! This will be going on my to do list now!! Thumbs up
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Post by Drummond Island Rocks on Sept 23, 2014 9:36:26 GMT -5
Now you got me thinking if there's a way to mount that diamond cup wheel that has a 5/8-11 thread to my flat lap that has water drip. The flat lap has a male 1/2"-13 mounting shaft. Chuck
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 23, 2014 10:15:14 GMT -5
that thing should work great. I would be on board if it had a water system. I don't mess with rock dust much. I have a respirator for the toxic rocks even with water but I don't like the idea of airborne dust. I know your able to work outside more so you don't have to worry as much. I did some quick math and it seems it could be made for about $80-$90 if someone already has a motor. Much cheaper then the $400 6" x 1.5" sintered diamond wheel I have been trying to save up for on the genie for pre-grinding tumbles. chuck That 4 inch wheel surprised me in that it has been grinding hard and dry for 2 years. It is a Harbor Freight special for 14.99. I weld so I have fans. I could never use it indoors, and the fan is a point source that blows the dust away. Still have to go w/the wind. Will be happy to get a table under the bottom of the hands. For light grinding 'dip and grind' greatly lowers the dust. But it is usually grinding deep and makes lots of dust. It is a trick getting a dry shroud around it. I am happy with it running dry since it fires the dust in a stream to the right, never slinging it on my chest. It chips, but that is good for many applications as it removes material fast. It chips less if you feed the ground side in, the grind slows chip propagation way down. It grinds that dang coral....It will grind a 3 inch ball pretty quick if the rock was close to round. And goes thru obsidian like butter. I think the 7 inch wheel was $39.99. I did grind the back of the diamond cup so the rock is exposed to the diamonds using a steel angle grinder while the diamond cup was spinning. Like a poor man's lathe:
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Post by captbob on Sept 23, 2014 11:28:48 GMT -5
What's the ETA on completion? I'm really looking forward to seeing it all assembled and the beast up and running.
This is a super idea!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 23, 2014 11:58:00 GMT -5
What's the ETA on completion? I'm really looking forward to seeing it all assembled and the beast up and running. This is a super idea! I woke up to a stack of fire pit orders captbob. Getting chilly in Atlanta. Will get to it in a week or so. I will sure post photos. I thought those wheels had left hand threads, but not. I have ground 100's of pounds on the 4 inch wheel. It sure works. Never tumble w/out it anymore. Thanks
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 23, 2014 12:00:22 GMT -5
COOL!!!! Great idea James!!! This will be going on my to do list now!! Thumbs up Speaking of thumbs, keep them clear of that wheel. And no neck ties !! You can do wood Michael.
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Post by mohs on Sept 24, 2014 16:51:29 GMT -5
quick planing of rock can't get enough of that
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Post by mohs on Sept 24, 2014 16:53:57 GMT -5
That S/C wheel set up Chuck as there is what I use on my Ameritool
I invested in some industrial grade S/C wheel 60g & 220g they plane some rock quick
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 24, 2014 17:32:07 GMT -5
Finished it today. Started with used lumber, 15 year old plant beds of treated southern yellow pine Building a box, 3 helpers on break, carrion Finished unit, laying on side. Unit in position. Needs a saddle. Guards and blocking for safety and feed rests needed, operation unacceptable do to wobble. Must replace bolt that serves as shaft. It is galvanized and the coating must have thrown it off center when the threads were chased. It runs dead flat, but the edge is out of round. Will replace with 18" bolt that is not galvanized. Hopefully threads will be lined up with center line of new bolt. It runs quiet and could spin faster. Easy to change to bigger motor pulley for speed increase.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 24, 2014 17:44:26 GMT -5
Pre-ground glass and obsidian tumbled in 30 grit after 4 days Dry: Wet: Mahargony obsidian(southern spelling), thank you Larry(quartz):
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Post by mohs on Sept 24, 2014 17:47:38 GMT -5
u ain't noth;n but hound dog ly'n around all the time ain't ever caught a rabbit
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Post by rockpickerforever on Sept 24, 2014 20:00:05 GMT -5
You got it going on with that grinder, James! Something like that is going to make the pregrinding go lickety-split.
And to think I just passed up half a dozen pillow block bearings at the swap meet on Sunday. Probably could've had 'em for a song. Maybe they'll be there next Sunday... Got a nice 5HP 3 phase Baldor motor just sitting around, that could really turn a diamond wheel. (Just kidding, I know that's way too much. I do have the motor though, a phase converter and another 5 hp 3PH for an idler motor.)
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panamark
fully equipped rock polisher
Member since September 2012
Posts: 1,343
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Post by panamark on Sept 24, 2014 20:29:02 GMT -5
You got me started on my next project James. One question: isn't that belt captured in the wood recess? Hard to change?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 24, 2014 21:28:57 GMT -5
You got me started on my next project James. One question: isn't that belt captured in the wood recess? Hard to change? I got to change the shaft Mark. Threads are offset. When I do I will open hole. Yes it is trapped. Just prototyping to see if it all gels. I already want to put a smaller pulley there. so may not have to open it up. Need more speed.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 24, 2014 21:30:05 GMT -5
You got it going on with that grinder, James! Something like that is going to make the pregrinding go lickety-split. And to think I just passed up half a dozen pillow block bearings at the swap meet on Sunday. Probably could've had 'em for a song. Maybe they'll be there next Sunday... Got a nice 5HP 3 phase Baldor motor just sitting around, that could really turn a diamond wheel. (Just kidding, I know that's way too much. I do have the motor though, a phase converter and another 5 hp 3PH for an idler motor.) Could spin a 6 foot diamond wheel w/that motor.
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Post by captbob on Sept 24, 2014 23:16:41 GMT -5
I love it. That's more than enough to get me going on one.
Hope you keep posting updated pictures is you continue to MacGyver on it.
Outta start a contest to see who comes up with the craziest final build!
PS... I'm thinkin' you're overpayin' them guard dawgs.
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quartz
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breakin' rocks in the hot sun
Member since February 2010
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Post by quartz on Sept 24, 2014 23:39:10 GMT -5
Like the looks of that project, should make quite a rough grinder. Experience has shown few die cut bolt threads are concentric, and also be attentive to face runout on the nuts. Good ones are available. That thing will have to run pretty smooth.
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jamesp
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Member since October 2012
Posts: 36,154
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Post by jamesp on Sept 24, 2014 23:57:49 GMT -5
Like the looks of that project, should make quite a rough grinder. Experience has shown few die cut bolt threads are concentric, and also be attentive to face runout on the nuts. Good ones are available. That thing will have to run pretty smooth. May end up having to get the threads chased on a lathe. Thought about using an old worn out 8" grinder just for the shaft. Fastenal distributer just up the road, may try one of their bolts. Yes, with the aggressive grit it needs to run dead true. I could not figure it out at first, roll the shaft on a table and it was dead straight. the top of it runs dead flat. Thread the diamond wheel down the shaft and it would spin on dead true. spin the diamond wheel w/the shaft and orbital rotation. Has to be the threads center line not lined up w/bolt shaft. hells bells
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