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Posted in response to Re: Re: Re: Re: Newbie question about saw lubricants from AJ on October 29, 2012 at 22:31:19:

Re: Re: Re: Re: Re: Newbie question about saw lubricants

Hi AJ,

The deeper the cut relative to the diameter of the blade, the more difficult it becomes to maintain sufficient lubrication on the cutting surface of the blade. When you bury a blade too deep in rock, the insufficiently lubricated cutting surface overheats, and the blade then "glazes". Once the blade begins to glaze, the slower it cuts, and the hotter it gets, which of course just further increases the glazing.

Excessive heat is particularly problematic with cheap, electro-bonded (plated) blades. When these get too hot, they don't just glaze over like a sintered blade. They will actually shed the plated-on diamond. Once that happens, it's game over for that blade.

The thicker the rock relative to the diameter of the blade, the more you need to be using oil for the lubricant. I can trim cabs to outline from 1/4" thick slabs all day long on my water-lubricated 6" trim saw. I get good blade life doing that kind of work in water using even very cheap plated blades. And a good quality sintered blade is forever in that application as long as I don't let anyone else try to cut curves with it...

But the thicker the material you're cutting, the better the lubricant needs to be, and the larger the blade needs to be.

People don't like to hear this because of the expense involved, but if you are going to be slabbing a lot of up to 4" thick material as a matter of regular course, particularly so with hard materials like agates and jaspers, or tough materials like jade, then you really need a 14" to 18" slab saw running an oil lubricant.

I've heard an old rule of thumb that your blade needs to be at least 3 times the diameter of the material you are slabbing. Based on my own experience in a production environment, I've concluded that rule should really be more like a minimum of 4 times the diameter of the material you are slabbing.

Can you get away with slabbing a 4" thick rock on a 10" saw? Well, maybe... that depends on the rock, your saw, your blade, your lubricant, your patience, your operating skill, and your tolerance for replacing blades. I'll simply note that a few 10" blades are considerably less expensive than an 18" slab saw...

But unless you slab only very soft materials, this is something you will be getting away with occasionally as a hobbyist. If you are slabbing a lot of 4" (or larger) rock, the bigger the saw and blade you can afford to bring to bear on the work, the better. In production applications, you can't afford not to afford the larger saws. A properly set up 24" slab saw just glides through 4" thick rock... There really is a reason they call the little boys "trim saws", and the big boys "slab saws".

From Bob Keller - October 30, 2012 at 00:43:40

Message: 70514



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