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Post by captbob on Sept 24, 2014 23:58:05 GMT -5
I do have one build question.
Why mount the shaft vertical instead of horizontal? I'm thinking that with a horizontal shaft, you could grind on one side of the spinning wheel and direct the dust towards the ground. With the shaft vertical, the dust is going to be up at your level, won't it? Also, if you lose your grip on a stone, a horizontal mount could direct the now dangerous projectile towards the ground, instead of putting everything within several feet of you at risk.
Have you tried grinding both ways and vertical is better?
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jamesp
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Post by jamesp on Sept 24, 2014 23:59:45 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. You will like what it does captbob.
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jamesp
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Post by jamesp on Sept 25, 2014 6:14:02 GMT -5
I do have one build question. Why mount the shaft vertical instead of horizontal? I'm thinking that with a horizontal shaft, you could grind on one side of the spinning wheel and direct the dust towards the ground. With the shaft vertical, the dust is going to be up at your level, won't it? Also, if you lose your grip on a stone, a horizontal mount could direct the now dangerous projectile towards the ground, instead of putting everything within several feet of you at risk. Have you tried grinding both ways and vertical is better? It would work either way. You can push fairly hard on the stone which made my shoulders tired. With hands resting on 2"X10" it keeps the work steady and control in your fingers. Your hands grounded so to speak. Rolling rocks up to 3-4" against the outside edge in your fingers gives good control. And my forearms get tired doing that. I have one mounted vertically too. Mainly for grinding a flat spot on the bottom of larger specimens. Was looking to go horizontal ever since. It is not like grinding metal that grabs the work piece, much less friction. The dust issue is better vertical, like you said. The most control for me anyway, is rotating the rock upward into the bottom of the edge. Grinding cup can be installed upside down for that motion. Diamond cup wheels have various grits. Usually 30 or 40. they make 16. The 4 inch wheel I have must be 24 or 30. Cuts very fast. The 7 inch wheel shown cuts slower, must be 40 or 54 grit. I don't like it for agate, fine for glass and obsidian. Made in China, it is not easy to know what grit the diamond is. Both are from Harbor Freight. I ordered 9 inch wheel through Aliexpress according to the photo. 4 inch cups as cheap as $5, but in 10 packs usually. They shipped one that is probably useless as it has large gaps between the sintered diamond blocks. This wheel says it has 30 grit. The photo shows large diamonds. Correct hole. Is that what you are going to get ? Maybe www.aliexpress.com/item/M14-thread-5-Diamond-Aluminum-matrix-sintered-grinding-disc-125mm-stone-Turbo-grinding-CUP-wheel/1664991845.htmlMore wheels from Aliexpress: www.aliexpress.com/premium/diamond-cup-wheels/1.html?g=y&needQuery=n&SearchText=diamond%2Bcup%2Bwheels&CatId=0&shipCountry=us&initiative_id=AS_20140925025918
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Fossilman
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Post by Fossilman on Sept 25, 2014 9:00:48 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? Looks like he has it hollowed out for an easy fix....Thumbs up..
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jamesp
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Post by jamesp on Sept 25, 2014 9:28:41 GMT -5
Just went from a 3 inch pulley on the shaft to a 2 inch. And a 2 inch pulley on the motor to a 3 inch. From 1200 RPM to 2500 RPM. Cuts much better. I think the Max speed rating for the 7" wheel is 6000 RPM. 12,0000 for the 4 inch wheel. take note
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Post by Rockoonz on Sept 25, 2014 13:43:03 GMT -5
Sweet looking creation, would work excellent for smoothing all the flats off a sphere preform before grinding @shotgunner . I would have to devise a wet version, I don't do much outdoors here in the cold Pacific North WET.
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Deleted
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Post by Deleted on Sept 25, 2014 21:49:22 GMT -5
Thanks Lee; for spheres we use stacked 6" saw blades vertically. for my purposes that looks like a knuckle buster.
Be safe Mr. Jim!
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Post by captbob on Sept 25, 2014 22:07:08 GMT -5
Thanks lee; for spheres we use stacked 6" saw blades vertically. Do you have a picture of that?
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Deleted
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Post by Deleted on Sept 25, 2014 23:07:46 GMT -5
captbob Sorry. Mine is not up and working yet. I have the blades and an arbor.... it's been a crazy year. Visualize a regular bench grinder with a regular bonded abrasive wheel on it. Now stack 5-6ea 6" diamond saw blades and replace the grinding wheel with those. Now visualize the lapidary equivalent with hood, tray, recirculating water..... Some put CD's between the blades for a very aggressive cut. Some call them "super grinder's". Google is our friend. Here is one without the spray hood When I make mine, I plan to put a trim saw blade on the other end!
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Post by captbob on Sept 25, 2014 23:33:29 GMT -5
Ah, I gotcha. Interesting. Thank you, sir!
A couple more questions if you have the time.
Is this a more aggressive grind than a diamond wheel? And, what kinda life can you get out of this set up?
okay 3 questions!
Are you using the cheapest blades available or do better blades give better results?
Thanks!
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jamesp
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Post by jamesp on Sept 25, 2014 23:55:49 GMT -5
Thanks Lee; for spheres we use stacked 6" saw blades vertically. for my purposes that looks like a knuckle buster. Be safe Mr. Jim! Saws made to cut, cups made to grind. Gotta have speed dude. And bigger diamonds than clean cutting saw blade. 4 inch cup to 12,000 RPM 7 Inch cup to 6000 RPM Saw blades will come apart long before those speeds. Sintering made for grinding and pressure and heat on cups As mentioned earlier in thread, guards not in place yet. Hell Boy grinding his horns Large diamonds with sintering supporting diamonds instead of rolling over them
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Deleted
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Post by Deleted on Sept 26, 2014 0:26:48 GMT -5
I am watching.
The stacked blades are sintered diamond segments. Maybe not 30grit? I dunno. Spacing makes for a very aggressive cut. If water flow is forgotten sparks fly from agates!
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Post by Rockoonz on Sept 26, 2014 1:36:33 GMT -5
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Post by parfive on Sept 26, 2014 2:34:44 GMT -5
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jamesp
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Post by jamesp on Sept 26, 2014 8:13:03 GMT -5
I have the following diamond cups Diarex Assassins in fine medium and coarse all 4" Harbor Freight 4.5"(large photo above) Harbor Freight 7"(shown in this thread mounted on machine) Chinese made 9" that has to much gap between the segments(they did not send the same cup as the one in the photo) so useless.
The Assassins are crap, diamonds to small. the Harbor Freight 7" wheel does OK, diamonds seem a bit small, won't know till some wear starts.
However, the $15 Harbor Freight 4.5" is wicked. Must have 24 grit diamonds. It must have 300 hours on it. At only 3600 RPM. Chips to much at 11,000 RPM. Can only grind for an hour or two at a time as fingers get tired bearing down so hard on the rock. Was mounted on a 3600 RPM angle grinder and vibration added to fatigue. Vibration eliminated with heavy base and AC motor w/v-belt. Always run dry. It will probably be the wheel I design around. Will go to 4.5" pulley on motor and 2" pulley on shaft for 3900 RPM, 4.5" disc. Perhaps bumping motor from 1/4 HP to 1/2 HP if it bogs down. Draw back is dust and because of the dust it is best run outdoors. But a fan keeps it blown away. Or the wind if blowing. Thought I would like the larger wheels, but they are more likely to vibrate, especially if the wear unevenly. no substitute for speed and deeper cut/pass with bigger diamonds. The newer cups are aluminum with sintered disc bonded to them for heat dissipation. Prefer the steel cup. The Assassins will do preform and slab touchup. The 24 grit diamonds will shatter them. 24 grit wheel for round/oval shapes such as tumbles and spheres only.
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jamesp
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Post by jamesp on Sept 26, 2014 8:46:02 GMT -5
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jamesp
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Post by jamesp on Sept 26, 2014 9:28:34 GMT -5
Re-emphasize note on safety. Rock held against edge of wheel. Bottom of palms grounded to table. Arms extended. Wheel height set so that fingers can present rock whilst bottom of hands grounded against table. If using top of cup then you are at risk unless a block is mounted close to a section of the cup at cup height to rest palm on. Again, presenting rock with fingers, palm grounded. Eye and dust protection mandatory. Gloves may not be a good idea. Contact area small and should be closest point on cup to operator. Turning cups upside down voids Max speed rating cautions.
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Post by rockpickerforever on Sept 26, 2014 10:13:21 GMT -5
Unit in position. Needs a saddle. A saddle? Seriously? Tell me you're not intending to ride that thing? It's not a rat bike, ya know.
And to think that we all were worried about you injuring fingers...
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jamesp
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Post by jamesp on Sept 26, 2014 11:33:22 GMT -5
The way it vibrated with the off center bolt it way be useful in other fields Jean Sorry, off center bolt replaced with what looks like a pressure vessel bolt(has a tall head(Jean gonna give me hell now)). Found the 16 inch bolt(behave Jean) down in the bone yard. rusted, but wire brush cleaned her(yes,it's a her Jean) up. Running dead true w/7 inch wheel. So it is possible to use a bolt. And increase the speed as needed. With 7 inch wheel a pretty heavy pressure will slow it down with fitted 1/4 HP motor. With 4.5 inch wheel more pressure required. Saddle optional, along with wheels and 75 cu in Harley
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Post by rockpickerforever on Sept 26, 2014 11:39:02 GMT -5
Okay, gotcha. But seems you wouldn't get any work done that way...
A her? You sure about that? Never heard of a her with a 16 inch bolt with big head, lol.
(Okay, I'll try to calm down.)
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