bman
off to a rocking start
Member since March 2010
Posts: 4
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Post by bman on Apr 2, 2010 12:55:41 GMT -5
I am new to the message board and have just recently dug out my old 18" Covington with a screw feed. I have had the blade bind on a couple of the harder rocks and even put a larger pulley on the screw feed to slow it down but still have the same binding issue. I am using transformer oil as the coolant which is a highly refined mineral oil with high temperature stability, so I;m sure that is not the problem. But then again, maybe it is. I have read several posts stating converting the screw feed to a gravity feed. How is that done? Do you use the same guide rails and add a weight and pulley system or what? Thanks for the help. Blake
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Post by johnjsgems on Apr 2, 2010 13:41:53 GMT -5
First step would be to dress your blade. Cut a slice or two of a dressing stick, old silicon carbide wheel, etc. I use broken pavers on my big saws. Dressing will expose new diamond surfaces and any glazing. Another thing to check is alignment. Put a magic marker in vise so it just touches blade core at rim on leading edge. Manually slide the vise along blade. If aligned you should have line full length of blade. Also check edge of blade rim. If rounded you could get binding. If rounded you can flatten edge by carefully hammering. If blade is dished or otherwise lost tension you may be needing a new blade.
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Post by Rockoonz on Apr 4, 2010 1:32:30 GMT -5
Obsidian also is an excellent blade dresser.
Lee
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Post by catmandewe on Apr 4, 2010 20:49:30 GMT -5
If you are binding that bad, then the obsidian will not work very well. You will need to dress it with an a dressing stick, an old grinding wheel, or a firebrick. Use Obsidian occasionally to keep your blade fresh, so it doesn't need dressing as often. It is kind of like the fine stone in a sharpening kit, works good if you don't let it get too dull.
Some transformer oil has PCB's in it, so be very careful how you handle and breathe it.
Have a great day..........Tony
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Post by snowdog on Apr 4, 2010 22:32:07 GMT -5
the jaws that ride on the threaded screw shaft -- do they have a spring that holds them tight -- if so, you can loosen it when you are cutting harder rocks -- it lets the jaws bounce over the threads and doesn't push so hard into the blade --- also sounds like what the others said , maybe need to dress the blade up a little ( it could also be warped some but if it will cut soft rocks then it is prob just putting to much pressure on when cutting hard ones )
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bman
off to a rocking start
Member since March 2010
Posts: 4
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Post by bman on Apr 8, 2010 9:08:25 GMT -5
Thanks for all your input on this. After dressing the blade and doing some other minor maintenance, it cuts like a it's supposed to now. I have cut quite a few rocks with it now and will post some pics with questions on what they are, soon I promise. Thanks Blake
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slabbercabber
starting to shine!
Member since March 2010
Posts: 30
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Post by slabbercabber on Apr 10, 2010 18:46:00 GMT -5
Bman, all transformer oils are considered class two carcinogens. They no longer contain pcb's but are nonetheless very dangerous. Please find another lubricant. Water can be used with a rust inhibitor like sodium nitrite and a surfactant such as borax, but if your bearings are not sealed they will fail before long. It's a tradeoff between the cost of bearings and the cost of mineral oil.
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