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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Machining a shaft for a redneck style rock tumbler



 
 
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  #1  
Old May 21st 05, 05:29 AM
Leo Lichtman
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Default Machining a shaft for a redneck style rock tumbler


"Ignoramus32374" wrote: (clip) I will use a used tire as the rotating
vessel. (clip)
^^^^^^^^^^^^^^
Would you be interested in a simpler, totally different way to use a tire?
Mount a V-belt pulley your gearmotor shaft, and just hang the tire on the
pulley by one of the beads. By sizing the pulley properly, you can get RPM
in a suitable range. If the tire hangs too "slanty" by a single bead, you
can always use two pulleys.


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  #2  
Old May 21st 05, 05:49 AM
Cydrome Leader
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Ignoramus32374 wrote:
I would also like to make a rock tumbler, like another poster. My plan
is as follows.

I will use a used tire as the rotating vessel. I grew fond of used
tires after my generator project.

The tire will be bolted to a large plywood ring that will have a hole
larger than the internal diameter of the tire, just enough to go a
little bit over the widest point of the tire.

There will be a board screwed to plywood and serving as a "diameter"
of the plywood ring.


I'd say the ouside of a tire might make a good surface to run directly on a motor shaft of some sort, letting you skip all the gears and nonsense. Why does this need to complicated?




There is going to be a horizontal shaft, mounted in bearings. (see
below). The shaft will be made either from a steel pipe nipple, with
flanges on both ends, or from a solid 3/4" diameter piece that I
already own. On one side, a sprocket will be bolted to the flange. On
another, there will be an adaptre plate to attach the "diameter" board
securely, but it will be removable for cleaning purposes.

The sprocket will connect via chain to a 3/4 HP 60 RPM gearmotor with
a keyed shaft and another (smaller) sprocket. My friend will give me
that gearmotor (I gave it to him 3 years ago, but he did not use it).

My expense will be sprockets, nipples and the shaft (maybe).

My question is about bearings. I have a variety of bearings, about
100-150 lbs of bearings. I have some sealed bearings, some needle
bearings 1 1/8" ID. Huge stuff for tractors and tanks, tiny ones etc.

I also have something I like, spherical bearings 3/4" ID. They are not
pillow blocks because they do not have a "base" to be screwed to
something. Nevertheless, they are nice because they can survive
misalignment. (I also have some 1/2" ID spherical ones, but I need a
bigger shaft).

My misgiving about them is that I am not sure what shaft to use. I
have a solid steel 3/4" shaft. But how would I mount a sprocket on one
side, and a plate holding the wheel, on another? I can easily drill
and tap a coaxial hole on both sides. But I have great doubts that the
bolt's tension would be enough to hold it during days of operation. I
do not have a welder.

I could try to thread both ends on my lathe, but I expect this to
become a pathetic failure. And I do not think that there will be a
suitable NPT flange at my home improvement store (although I am not
sure).

I can probably drill smaller parallel holes and tap them and put in
little 8-24 screws or some such.

i

  #3  
Old May 21st 05, 07:16 AM
Leo Lichtman
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Default

yhgdc
"Ignoramus32374" wrote: (clip) can you explain a little bit more in detail?
(clip)
^^^^^^^^^^^^
Sure. You have a horizontal shaft coming out of the gearmotor, turning 60
RPM. I visualize the tire hanging vertically from this shaft, with rocks
inside, at the bottom. To get the RPM you want, you have a couple of V-belt
pulleys on the shaft, turning at 60 RPM. Lets say you want the tire to turn
at 20 RPM, and the tire fits a 15" rim. If the v-belt pulleys are 5"
diameter, you will have a 3-to-1 reduction to give you 20 RPM. The
smallelopr you make the pulleys, the slower the tire will turn. 65 The
weight of the tire and rocks will create the contact pressure for the
pulleys to drive the tire beads.

If I have managed to make this too confusing, feel free to ask more
questions.


  #4  
Old May 21st 05, 08:01 AM
B.B.
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In article
,
"Leo Lichtman" wrote:

yhgdc
"Ignoramus32374" wrote: (clip) can you explain a little bit more in detail?
(clip)
^^^^^^^^^^^^
Sure. You have a horizontal shaft coming out of the gearmotor, turning 60
RPM. I visualize the tire hanging vertically from this shaft, with rocks
inside, at the bottom. To get the RPM you want, you have a couple of V-belt
pulleys on the shaft, turning at 60 RPM. Lets say you want the tire to turn
at 20 RPM, and the tire fits a 15" rim. If the v-belt pulleys are 5"
diameter, you will have a 3-to-1 reduction to give you 20 RPM. The
smallelopr you make the pulleys, the slower the tire will turn. 65 The
weight of the tire and rocks will create the contact pressure for the
pulleys to drive the tire beads.

If I have managed to make this too confusing, feel free to ask more
questions.


Or he could get his paws on a kiddie bike with the 12" wheels and a
long chunk of all-thread. The axles in those wheels are just short bits
of all-thread anyway. Remove the spokes and rims, keeping just the
hubs. Screw them along the length of the shaft until they're where the
beads will ride on them. One will come with a sprocket pre-installed.
If he goes with a multi-speed bike instead of a single-speed he could
even adjust the rpms by moving to different sprockets. Could probably
repurpose the leftover frame to support the whole mess.

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/
  #5  
Old May 21st 05, 10:53 AM
Gunner
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Default

On Sat, 21 May 2005 04:29:04 GMT, "Leo Lichtman"
wrote:


"Ignoramus32374" wrote: (clip) I will use a used tire as the rotating
vessel. (clip)
^^^^^^^^^^^^^^
Would you be interested in a simpler, totally different way to use a tire?
Mount a V-belt pulley your gearmotor shaft, and just hang the tire on the
pulley by one of the beads. By sizing the pulley properly, you can get RPM
in a suitable range. If the tire hangs too "slanty" by a single bead, you
can always use two pulleys.

Damn Leo..thats exactly what I was thinking. Great minds DO think
alike. G

I would suggest a pvc plug and close nipple and pipe cap in the
sidewall for fluid drainage though.

Gunner

"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown
  #6  
Old May 21st 05, 11:48 AM
Christopher Tidy
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Default

Leo Lichtman wrote:
yhgdc
"Ignoramus32374" wrote: (clip) can you explain a little bit more in detail?
(clip)
^^^^^^^^^^^^
Sure. You have a horizontal shaft coming out of the gearmotor, turning 60
RPM. I visualize the tire hanging vertically from this shaft, with rocks
inside, at the bottom. To get the RPM you want, you have a couple of V-belt
pulleys on the shaft, turning at 60 RPM. Lets say you want the tire to turn
at 20 RPM, and the tire fits a 15" rim. If the v-belt pulleys are 5"
diameter, you will have a 3-to-1 reduction to give you 20 RPM. The
smallelopr you make the pulleys, the slower the tire will turn. 65 The
weight of the tire and rocks will create the contact pressure for the
pulleys to drive the tire beads.


That's a smart idea Leo. I'd like to see a tumbler built like that.

Chris

  #7  
Old May 21st 05, 03:31 PM
Larry Jaques
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Default

On 21 May 2005 12:55:38 GMT, the inscrutable Ignoramus14511
spake:

On Sat, 21 May 2005 04:49:06 +0000 (UTC), Cydrome Leader wrote:
Ignoramus32374 wrote:
I'd say the ouside of a tire might make a good surface to run
directly on a motor shaft of some sort, letting you skip all the
gears and nonsense. Why does this need to complicated?


Good question. In my opinion, 60 rpm is too much for a used tire.


Let's see, 60rpm too much? Take your 15" tire (Mine are 28" tall.)
1 mile is 5,280' or 63,360". One rev is 88", 60mph is 1mpm, so
dividing 63,360 by 88 gives us 720rpm at 60mph. I think a used tire
(even a 12-incher) can take that beating, Iggy.

But 60rpm would likely stick the rocks and all else to the drum, not
allowing any movement or tumbling. Speed probably has to be 30rpm or
less, lower on larger diameters due to centrifugal forces.

(Oops, I meant to say "centripetal forces." Sorry.

-
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so that I could hear heavy breathing again. || Programmed Websites
  #8  
Old May 21st 05, 03:41 PM
Ecnerwal
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Posts: n/a
Default

In article
,
"Leo Lichtman" wrote:

yhgdc
"Ignoramus32374" wrote: (clip) can you explain a little bit more in detail?
(clip)
^^^^^^^^^^^^
Sure. You have a horizontal shaft coming out of the gearmotor, turning 60
RPM. I visualize the tire hanging vertically from this shaft, with rocks
inside, at the bottom. To get the RPM you want, you have a couple of V-belt
pulleys on the shaft, turning at 60 RPM. Lets say you want the tire to turn
at 20 RPM, and the tire fits a 15" rim. If the v-belt pulleys are 5"
diameter, you will have a 3-to-1 reduction to give you 20 RPM. The
smallelopr you make the pulleys, the slower the tire will turn. 65 The
weight of the tire and rocks will create the contact pressure for the
pulleys to drive the tire beads.


Well, the actual systems in use at the rock shop were a bit different,
but still a lot simpler than what's been talked about here previously.
One problem with what you describe above might be excessive grit
transfer to the drive system, but it's heading the right direction.

A more detailed description of a system which was in use for decades at
a rock shop near where I grew up, and may yet be in use (I haven't
visited recently).

A motor drives one, or better two shafts through some sort of chain or
belt or gear reduction. If only one is driven, the other is an idler.
The shafts are as long as you like, and may have intermediate bearings
or support wheels (psuedo-bearings) as needed. The bearings should be
well-sealed, and you might want to arrange covers for them, too. You may
want to texture the shafts a bit between bearings, but probably don't
need to. The shafts should not be too small, at least on the
tire-contact area. 2" would be a lot better than 5/8", though I can't
say where, exactly, it would stop working. 1-1/2" strikes me as about
what the rock shop used, might have been pipe with smaller shafts welded
or pressed into the ends for the bearings.

On the shafts sit one or more tires. Just tires, no seals, no plywood
covers. I forget, there might have been some arrangement to help keep
any drips inside the tire, but if so, it was a fixed arrangement (like a
reverse fender), not something attached to the turning tire. The turning
of the shaft(s) turns the tire(s). I vaguely recall that there might be
a particular SFPM range that works pretty well for this (rock tumbling
gets a lot of its science from ball-milling), so the same set of shafts
can turn larger or smaller tires at the appropriate speed (same SFPM,
different RPM for each size tire). Inside the tires are rocks and grit
and water. In multi-tire systems, those can be different grits in each
tire. If you want to check progress, you reach in and pull out a handful
of rocks. If the rocks (or if you care to sort them, some of the rocks)
are ready for the next grit, you wash them carefully and move them to
the tire with the next grit.
  #10  
Old May 21st 05, 06:24 PM
JohnM
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Default

Ecnerwal wrote:



Well, the actual systems in use at the rock shop were a bit different,
but still a lot simpler than what's been talked about here previously.
One problem with what you describe above might be excessive grit
transfer to the drive system, but it's heading the right direction.

A more detailed description of a system which was in use for decades at
a rock shop near where I grew up, and may yet be in use (I haven't
visited recently).

A motor drives one, or better two shafts through some sort of chain or
belt or gear reduction. If only one is driven, the other is an idler.
The shafts are as long as you like, and may have intermediate bearings
or support wheels (psuedo-bearings) as needed. The bearings should be
well-sealed, and you might want to arrange covers for them, too. You may
want to texture the shafts a bit between bearings, but probably don't
need to. The shafts should not be too small, at least on the
tire-contact area. 2" would be a lot better than 5/8", though I can't
say where, exactly, it would stop working. 1-1/2" strikes me as about
what the rock shop used, might have been pipe with smaller shafts welded
or pressed into the ends for the bearings.

On the shafts sit one or more tires. Just tires, no seals, no plywood
covers. I forget, there might have been some arrangement to help keep
any drips inside the tire, but if so, it was a fixed arrangement (like a
reverse fender), not something attached to the turning tire. The turning
of the shaft(s) turns the tire(s). I vaguely recall that there might be
a particular SFPM range that works pretty well for this (rock tumbling
gets a lot of its science from ball-milling), so the same set of shafts
can turn larger or smaller tires at the appropriate speed (same SFPM,
different RPM for each size tire). Inside the tires are rocks and grit
and water. In multi-tire systems, those can be different grits in each
tire. If you want to check progress, you reach in and pull out a handful
of rocks. If the rocks (or if you care to sort them, some of the rocks)
are ready for the next grit, you wash them carefully and move them to
the tire with the next grit.


That's the idea I like..

John
 




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