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Post by mohs on Dec 11, 2010 9:16:02 GMT -5
Greetings All
Would like to set up a variable speed motor on my Lortone 8” cabber. I haven’t done any real research, yet.
Anyone have any experience with variable speed motors ?
Thanks Ed
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Post by johnjsgems on Dec 11, 2010 9:47:47 GMT -5
It would be much less expensive to use a three step pulley. Variable speed motors are DC with a built in converter to allow them to plug into AC current. Some tool motors with brushes will run with a router speed control but generally motor runs hot, has less power, and shorter life. Another option would be to buy a 2 speed swamp cooler motor. Pulleys worked back in the Jurassic days for a lot less. By the way, my Genie runs at 1725 rpm and I've never had a need to have it run slower.
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Post by jakesrocks on Dec 11, 2010 10:32:13 GMT -5
I agree with John. For most lapidary uses, 1725 RPM works just fine. I do have a pair of metal buffing wheels set up on a double shaft, 2 speed industrial fan motor, but seldom use the low speed.
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Post by mohs on Dec 11, 2010 10:40:03 GMT -5
The reason I was looking to slow down the speed was that I buff by hand on the expandable wheel leather belt. It gets slick trying to hold the stone and thought that a slower speed would be better.
But haven't thought out all the variables, yet so was just wonder'n
Thanks Guys ! ed
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guitarc
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Post by guitarc on Dec 11, 2010 10:47:12 GMT -5
John if you were to put together a 3 step pulley cab machine, how would you go about doing that? What motor would you use? How and to what would you mount the motor the arbor etc?
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Post by johnjsgems on Dec 11, 2010 10:58:39 GMT -5
Slickest set up I've seen is the now discontinued GP-8 unit. It had three step pulleys on both motor and unit. The motor pulley was turned opposite way so speed changes could be made by simply moving belt. With just one pulley motor would have to be mounted with slotted holes o adjust allignment and tension.
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guitarc
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Post by guitarc on Dec 11, 2010 11:35:38 GMT -5
Ok, the GP-8 is a cab machine that was commercially made and sold.
What about making a 3 step pulley cab machine? Could a 3 step pulley be attached to the shaft of a 1725 or 1750 RPM motor which that pulley then connects via the belt and drives the drive pulley on the shaft of an arbor mounted a few inches away?
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Post by jakesrocks on Dec 11, 2010 11:47:47 GMT -5
No problem. Just turn the motor pulley the opposite direction from the arbor pulley. You'll end up with 3 speeds. If you only want 2 speeds, use 2 step pulleys. I built one years ago, when motors were super heavy. I hinged the motor, and to change speeds I'd just lift the motor and move the belt over. With the newer and lighter motors, a person could probably attach a bungie cord to the motor, to keep it from bouncing.
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guitarc
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Post by guitarc on Dec 11, 2010 12:04:34 GMT -5
Thanks!
So from the ground up what motor, what arbor (or would you make your own) and would you just mount everything to thick plywood?
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Post by jakesrocks on Dec 11, 2010 12:30:32 GMT -5
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guitarc
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Post by guitarc on Dec 11, 2010 13:14:12 GMT -5
Thanks! That looks like a killer cab machine! Way too elaborate for what I need(right now).
I was looking for something really basic so I could do some very basic shaping of trimmed out 2-3mm thick pieces of agate. I had read on these boards about some people using their tile saws with tile saw blades as grinders but several members here frowned on that. Then I saw posts about the "Supergrinder" and I thought I could get a bench grinder and modify it with either a 6" 80 grit diamond wheel or go the Supergrinder route with 6-8 tile blades. Then I would make a water system including a water tray and shield to prevent water spraying everywhere (including the motor which I know is not intended for use with water).
I am still confused by the direction I should go and feel that for now I don't need much as far as a means to grind. A one wheeled grinder or some other way to grind millimeters off of small preforms to shape them before going into a tumbler is all I need for now. My searches for such machines have not been that successful. The closest I have come is a machine like the $350+ Rock Rascal but I don't need the saw part. I would think I could easily get a 1/3 HP, 1725 RPM motor for $75, an 80 or 100 grit diamond wheel for $60 and the rest (switches, adapters, material to make a water tray and shield etc) for another $40. So for $175 I think I could make a very basic one-wheeled grinder. Maybe I just have not found a basic one wheeled cab unit and there is one out there for $200? Money really is not the issue because if I thought I would use a 4 or 6 wheeled cab machine a lot I would go for that. However, I feel it would be stupid for me to buy a $1000-$2000 cab machine to use it a total of 30 or 60 minutes a month.
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Post by jakesrocks on Dec 11, 2010 13:32:39 GMT -5
Lortone makes a very nice 2 wheel arbor for $250.00. You'd have to get a motor and wheels for it. I have one that I use expando drums on. My first grinder was a converted bench grinder that I bought for $15.00 at a yard sale. Most of the newer bench grinders have sealed motors and bearings. If you go that route, check the motor speed before you buy the grinder. Many of the grinders meant for metal grinding turn faster that 1725 RPM's. Lapidary wheels are designed to be run at 1725 RPM or less. I'll add that the Lortone arbor comes with the motor mount attached to the back, a belt guard, belt and motor pulley all included. A salvaged 1/3 hp motor will be all you need.
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guitarc
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Post by guitarc on Dec 11, 2010 14:04:02 GMT -5
Thanks! When I was looking into modifying a bench grinder I had found some variable speed grinders that went down to 2000 RPM. I think I found a new Delta 6" for $90 and someone told me that if I put a $20 Router Speed Control on it would slow the rpm down to less than 1700.
A 2 wheel arbor definitely gives me more options
What is the name or model number of that Lortone 2 wheel arbor?
Do most 1/3 HP motors come so that they could be easily attached via the motor mount on the Lortone?
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Post by jakesrocks on Dec 11, 2010 14:39:37 GMT -5
The Lortone is a BA62. Don't know if John carries them, but they're in the Kingsley North catalog. The motor pulley that comes with the arbor is for a 1/2" motor shaft. The motor mount attached to the motor should bolt right to the Lortone mount. Lortone also makes a 4 wheel model, and both in 8" size as well. They come pre-drilled for water supply and drain line.
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Post by mohs on Dec 11, 2010 14:59:15 GMT -5
I like that 3 step idea I was wondering if they made a quick change pulley ? my idea was 2 half’s of a pulley remove front half of pulley change belt remove back half of the pulley reverse the process for the new size pulley this would eliminate having to adjust the motor I think ![::)](//storage.proboards.com/forum/images/smiley/eyesroll.png)
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Post by jakesrocks on Dec 11, 2010 15:19:22 GMT -5
John Deere had something on their old 110 and 112 lawn tractors that was a 2 piece pulley. One half of the pulley moved in and out on the shaft, to adjust the tractor speed. With the 2 halves wide apart, it was a small pulley and low speed. As the sliding half moved in, the belt rode higher in the pulley, making it a larger pulley. As I remember, there were 4 speed adjustments, all linked to the shift handle.
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Post by mohs on Dec 11, 2010 19:28:19 GMT -5
Hey Don that's a really cool write up ! I've worked with similar machinery in saw sharpening trade
O.K I know this subject has been beaten to death.
How much we'll doubling up the size of the pulley on my motor slow the speed down? I'm running two 2" pulleys. If I double up the motor pulley to a 4" we'll I notice a appreciable slowness in speed?
I know there a chart out there by Covington. Ugghh! I'm too lazy to search for it on my slow internet connection...
ED
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Post by jakesrocks on Dec 11, 2010 19:51:27 GMT -5
Put the small pulley on your motor. If you put the big pulley on it, you'll speed your arbor up. With a pair of 2" pulleys, Your arbor will turn at the same speed as your motor. If you put the 4" pulley on your motor, your arbor will turn at 3450 RPM. With the 4" pulley on your arbor, and 2" on the motor, your arbor will spin at 850 RPM.
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Post by johnjsgems on Dec 11, 2010 19:59:08 GMT -5
I have an adjustable pulley that came with a used motor somewhere. I think it only changed about an inch overall. We used adjustable pulleys on all our belt drive motors when I did commercial HVAC work but those gave you about 1/2" adjustment. The double or triple pulleys (on each side) gives you easy adjustability.
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Post by mohs on Dec 11, 2010 20:15:37 GMT -5
Wow Thanks Again Don ! So in theory there’s no way for me to slow down the arbor on this Lorton BA-82 by the pulleys? Because there’s not enough clearance on the arbor side to put a bigger pulley than 2 inches. Watch out! Serious modifications ahead… ![:o](//storage.proboards.com/forum/images/smiley/shocked.png)
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