quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Sept 18, 2017 12:13:05 GMT -5
captbob, Roy and woodman's machines are rotary table machines rather than vibrating machines. The table rotates under the "near stationary" rocks rather than shaking the rocks around on the table. The sweeps above the table add to the action of the process by forcing the rocks in the opposite direction of table rotation. We visited Roy two years ago, that is the first machine with a sweep I had seen, impressive. jamesp, why do you need a 1/3hp motor on that machine just to swing a weight, I do see the 1725 R.P.M. though.
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Post by captbob on Sept 18, 2017 12:31:57 GMT -5
Yup Jim, like those on the website. Roy had another name for that overhead thingy. Not sure sweep is the proper term. Tried to find a pic of Roy's machine, but he was using photobucket and his pics are all *poofed*. Seems like such a thing would be easy enough to make. The perfectly flat disc would be the expense. Wonder if your pans would be close enough. I NEED MORE SHOP SPACE !!!
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Post by rockpickerforever on Sept 18, 2017 13:36:37 GMT -5
There is a used ROSE Tool ROCIPROLAP 24" Lapidary Flat Grinder Polishing Machine on eBay right now. Only $1750, plus freight, shipping out of Montana. This one is pretty close to the large one I have, only mine is 20".
I have tried to find what they call the ones that do not vibrate, only spin. Like this -
So far, I have seen them called sanders, and grinders. I like sweeper, as that is pretty descriptive. It does not oscillate or vibrate.
This one they call a rock grinder. That'll take up a bit of space!
Here's one someone made, calling it an easily made flat lap More like jamesp 's design.
I've ran across some large (18" or better) laps, but without the sweepers. The glass hobbyists seem to use them (the large non-sweepers) a lot. Think stained glass preforming.
Anyway, some more pics to look at
ETA - Someone had mentioned Woodman and how he polished his large petwood specimens. Here is a link to a thread that he posted a while back with a video of his polishing/lap in action. His is not a sweeper, so flat slabs are held stationary, while the lap rotates underneath them. Hmmm, wasn't even thinking about it - Do some of them have a spinning flat lap, in addition to a sweeper moving the rocks on the surface? So many possibilities!
ETA #2 - A still photo of woodman flat lapping a slab o' wood.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Sept 18, 2017 13:47:56 GMT -5
Seems like there are several names for what I call a rotary lap, maybe we need a directory of terminology on the forum. The sweep part of it, in my opinion, would be an optional accessory rather than the name of the whole unit as it can be removed from operation as desired. As I remember, Roy said he uses the sweep on his while roughing, but not during the polishing cycle. As long as we can all get on the same page, all is good.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Sept 18, 2017 13:55:24 GMT -5
captbob, Roy and woodman's machines are rotary table machines rather than vibrating machines. The table rotates under the "near stationary" rocks rather than shaking the rocks around on the table. The sweeps above the table add to the action of the process by forcing the rocks in the opposite direction of table rotation. We visited Roy two years ago, that is the first machine with a sweep I had seen, impressive. jamesp, why do you need a 1/3hp motor on that machine just to swing a weight, I do see the 1725 R.P.M. though. I remember you having mentioned a giant lap like these rotary table jobs. One of the biggest ? I sure would like to use a 1/6 or 1/8. I have no idea how to calculate HP required for an off balance. I read engineering articles. They only discussed bearing wear. The load articles went over my head real quick. I was always curious why they used a big 1/3 HP motor on the Vibrasonic vibe. Figured it must be needed. I guess you could ask the question- Why can't you swing a 50 pound off balance shaft with a tiny motor with motor sitting vertical. I believe there are forces in rotating out of balance shafts. There is a force. It looks like this in math: Calculating the Imbalance Force. F= I X r X w X w where F = the imbalance force, Im = the mass, r = its distance from the pivot, and w (omega) is the angular frequency, equal to 2p times the frequency in Hz.. and here is the only article that I could come close to understanding(prepare for headache) lol: azimadli.com/vibman/calculatingtheimbalanceforce.htmIt may be called centripetal force. note they said "the force is born by the bearings", which I interpret is purely the friction in the bearings. which sounds bad for the bearings. We already knew that !
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Post by rockpickerforever on Sept 18, 2017 14:43:01 GMT -5
Seems like there are several names for what I call a rotary lap, maybe we need a directory of terminology on the forum. The sweep part of it, in my opinion, would be an optional accessory rather than the name of the whole unit as it can be removed from operation as desired. As I remember, Roy said he uses the sweep on his while roughing, but not during the polishing cycle. As long as we can all get on the same page, all is good. Larry, that is pretty much what he said in the thread a thread by woodman Moving rock to a saw. back in February of this year.
When I Googled "rotary" or "rotating lap", I came up with a lot of small (8 - 10") flat laps. Didn't realize the arms were an optional accessory, and removable. But it makes sense. Most things have a purpose.
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Post by woodman on Sept 18, 2017 17:36:45 GMT -5
There is a used ROSE Tool ROCIPROLAP 24" Lapidary Flat Grinder Polishing Machine on eBay right now. Only $1750, plus freight, shipping out of Montana. This one is pretty close to the large one I have, only mine is 20".
I have tried to find what they call the ones that do not vibrate, only spin. Like this -
So far, I have seen them called sanders, and grinders. I like sweeper, as that is pretty descriptive. It does not oscillate or vibrate.
This one they call a rock grinder. That'll take up a bit of space!
Here's one someone made, calling it an easily made flat lap More like jamesp 's design.
I've ran across some large (18" or better) laps, but without the sweepers. The glass hobbyists seem to use them (the large non-sweepers) a lot. Think stained glass preforming.
Anyway, some more pics to look at
ETA - Someone had mentioned Woodman and how he polished his large petwood specimens. Here is a link to a thread that he posted a while back with a video of his polishing/lap in action. His is not a sweeper, so flat slabs are held stationary, while the lap rotates underneath them. Hmmm, wasn't even thinking about it - Do some of them have a spinning flat lap, in addition to a sweeper moving the rocks on the surface? So many possibilities!
ETA #2 - A still photo of woodman flat lapping a slab o' wood.
I have always called them flat laps. the one I am using in the picture is just a lapping table with no sweep. My other 24" has the sweep and works great.
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Post by woodman on Sept 18, 2017 17:52:30 GMT -5
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Sept 19, 2017 16:18:10 GMT -5
Looks like other duties have moved in on the homemade vibe lapper. I saw this caterpillar. Any ideas rockpickerforever ? It put out red juice when I messed w/it. Liking the pop eyes.
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Post by captbob on Sept 19, 2017 17:28:44 GMT -5
oooh... look at all those future flat laps!
frightening bug!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Sept 19, 2017 18:00:29 GMT -5
oooh... look at all those future flat laps! frightening bug! I'll donate one of those pans to someone doing a lap build on RTH. 27" weighs 23 pounds(I said 30, an error) 30" weighs about 27 pounds. 37" weighs 38 pounds the caterpillar turns into a common looking grey moth.
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Deleted
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Member since January 1970
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Post by Deleted on Sept 20, 2017 15:05:13 GMT -5
captbob, Roy and woodman's machines are rotary table machines rather than vibrating machines. The table rotates under the "near stationary" rocks rather than shaking the rocks around on the table. The sweeps above the table add to the action of the process by forcing the rocks in the opposite direction of table rotation. We visited Roy two years ago, that is the first machine with a sweep I had seen, impressive. jamesp, why do you need a 1/3hp motor on that machine just to swing a weight, I do see the 1725 R.P.M. though. I remember you having mentioned a giant lap like these rotary table jobs. One of the biggest ? I sure would like to use a 1/6 or 1/8. I have no idea how to calculate HP required for an off balance. I read engineering articles. They only discussed bearing wear. The load articles went over my head real quick. I was always curious why they used a big 1/3 HP motor on the Vibrasonic vibe. Figured it must be needed. I guess you could ask the question- Why can't you swing a 50 pound off balance shaft with a tiny motor with motor sitting vertical. I believe there are forces in rotating out of balance shafts. There is a force. It looks like this in math: Calculating the Imbalance Force. F= I X r X w X w where F = the imbalance force, Im = the mass, r = its distance from the pivot, and w (omega) is the angular frequency, equal to 2p times the frequency in Hz.. and here is the only article that I could come close to understanding(prepare for headache) lol: azimadli.com/vibman/calculatingtheimbalanceforce.htmIt may be called centripetal force. note they said "the force is born by the bearings", which I interpret is purely the friction in the bearings. which sounds bad for the bearings. We already knew that ! I read it to mean the bearings are taking a pounding from the oscillating load. The heavier the off center weight, the more vertical load on the bearings. This, to me, means that easily replaced pillow blocks with better than harming the motors bearings. I'm not an engineer, nor do I play one on TV.
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jamesp
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Member since October 2012
Posts: 36,155
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Post by jamesp on Sept 20, 2017 15:37:55 GMT -5
@shotgunner
More load means more HP. Regardless if load is on pillar blocks or on motor bearings. Granted , motor bearings are more likely to get damaged than heavy duty pillar blocks. But if you are calculating horsepower in an off balance situation you have to account for varying centripetal (not centrifugal) forces in the bearings. Be it motor or motor driven pillar blocks.
Reversing forces due to off balance reverses the grease in the bearings and that alone can make a lot of friction. The balls in the bearing are continually plowing thru grease being squeezed out in cyclically varying thickness = more HP. Hard on grease, hard on balls, hard on races. Massive or big enough bearings in motor or pillar block and all is OK. All bearings designed w/safety factors relative to loading, regardless of type of loading.
worse thing you can do to a ball bearing is run it slow. Slow enough that the balls are not hydroplaning on the grease and making ball to race contact.
the load may alternate thru many angles depending on the type of imbalance. Not necessarily vertical. Pure vertical forces would actually be rare. thrust bearing roller bearing ball bearing, taper roller bearing, are designed for various angles of forces. Use tapered roller bearings in cars as the take loads from many angles. motor driving an inline load- ball bearings
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