joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 2, 2014 10:07:32 GMT -5
Hello, I am a new member of this forum, and new to the wonders of lapidary! Im currently in the design / material gathering phase of building my own cabbing machine based off of Lynn's design here on the forums. Im wondering if a galvanized steel pipe would work for a shaft, with the threads on the outside? Im leaning towards a solid carbon steel rod with drilled and tapped ends, but the galvanized pipe is so much cheaper! Also, what size pulleys should be used on both the shaft and motor? Thanks a lot!
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Post by johnjsgems on Jan 2, 2014 10:27:31 GMT -5
No. Pipe is not round enough to use with bearings. Also 3/4" pipe is 3/4" ID, not OD. You need cold rolled steel.
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 2, 2014 10:32:17 GMT -5
Thanks a lot! Any idea about pulley sizes?
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Post by jakesrocks on Jan 2, 2014 12:20:02 GMT -5
Use cold rolled, or preferably stainless steel for your shaft.
Most commonn motors turn at 1725 RPM's. This is also the speed you'll want your arbor to turn at. Use the same size pulley on both the motor and arbor.
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 2, 2014 21:01:53 GMT -5
Thanks for the info! Now one last question about the arbor. Is it necessary for the shaft to have one regular thread and one reverse thread? Or can they both be regular threaded?
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Post by jakesrocks on Jan 2, 2014 21:07:11 GMT -5
You need the reverse thread on the left end, to prevent the nut from loosening while the arbor is spinning.
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Tommy
Administrator
Member since January 2013
Posts: 12,652
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Post by Tommy on Jan 2, 2014 23:21:21 GMT -5
Hello, I am a new member of this forum, and new to the wonders of lapidary! Hi Joshua glad to see you made it over :-) You're in good hands here with the mechanical questions - these guys are amazing.
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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 Jan 2, 2014 23:29:56 GMT -5
Another thing to consider: To help give good belt life [likely you will use a 1/2" wide or 4L belt], use pulleys at least 2" in diameter.
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 6, 2014 9:24:54 GMT -5
Thanks so much for the useful info. I plan to order my wheels today, and my shaft should be here any time. Ill surely post pics in the near future of the completed machine. And Tommy, Im going to start on that piece I got from you just as soon as this crazy cold front moves along (Im in Texas, its not supposed to be in the 20's).
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cccbock
spending too much on rocks
Member since December 2011
Posts: 498
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Post by cccbock on Jan 6, 2014 23:13:07 GMT -5
I bought a ready made shaft from Lortone for 38 dollars when I built my machine....it came with appropriate threads on the ends , A flat gound mid shaft for the pulley set screw , and appropriately place grooves for snap rings that set the center spacing for the wheels and pulley. I also bought from them spacers , snap rings , wheel spacers and end nuts. The total package plus shipping was arounf 80 dollars. I used 6 diamond wheels. When I was done and grinding I had around 700 dollars in the machine. Have been happy with it's performance ever since.
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Post by johnjsgems on Jan 6, 2014 23:26:20 GMT -5
Sounds like you have the shaft coming. As far as left hand thread on left side the only way to avoid it is to center drill the shaft and tap it 1/4"-20 (or other) and use a bolt and over sized washer. Left hand thread would be easier. I would have right side threaded and center drilled and tapped to 1/4"-20 to use spin on polish pads.
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 7, 2014 11:57:19 GMT -5
Thanks for the idea. I was trying to figure out how to attach a flat lap disc or hard grinding wheel to the end of the shaft. Threaded AND drilled and tapped, awesome idea.
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Post by johnjsgems on Jan 7, 2014 16:42:53 GMT -5
It has to be centered.
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Post by jakesrocks on Jan 7, 2014 16:49:23 GMT -5
As John said, the end hole has to be centered. Best to have a machine shop drill and tap it in a metal lathe.
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Post by pauls on Jan 9, 2014 15:33:06 GMT -5
One of my arbors has just a bare shaft at the left hand end, I have made up bosses that are bolted to the back of various laps, sanding disks etc that just slip on to that bare shaft and a screw is tightened down onto a small flat spot ground onto the shaft. Much like a pulley is held onto a shaft.
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zarguy
fully equipped rock polisher
Cedar City, Utah - rockhound heaven!
Member since December 2005
Posts: 1,791
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Post by zarguy on Jan 13, 2014 1:51:05 GMT -5
I used left & right handed bolts, not nuts on my machine that you referred to. The right side bolt is also tapped with I think 1/4x20 threads for spin-on laps. The bolts are fairly beefy, but I don't remember their size. Lynn
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 16, 2014 8:32:19 GMT -5
Thanks a lot guys and gals! Lynn, I finally talked to the guy you got your shaft from. He told me the same thing; the bolts are 1/2" with the left one being left hand threads. I plan on getting one similar to yours (46" - 48") in may when he gets back from winter break. I took my 36" cold rolled steel rod to a machine shop to have them drill and tap the ends for me to a 1/2" thread (left hand thread on one side). It should be done today...and I am super excited. I have only 3 wheels, but more are on the way as we speak. At least I have enough now to mock it up and work out any kinks that are unforeseen as of now. Thanks again for all yalls help!
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 26, 2014 8:53:17 GMT -5
my progress so far.
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Post by 1dave on Jan 26, 2014 10:45:11 GMT -5
Your picture didn't show. Did you use the right(direct)link?
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joshua
off to a rocking start
Member since January 2014
Posts: 13
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Post by joshua on Jan 26, 2014 11:10:24 GMT -5
it wont let me attach an image. says the forum has exceeded its attachment size limit
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