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Posted in response to Slab Saw vs Trim Slab Saw???? from Cindy Patrick on March 12, 2008 at 08:05:22:

Re: Slab Saw vs Trim Slab Saw????

Hi Cindy,

"Trim Saws" are generally regarded to be light duty saws designed to make cuts in slabs, preforming faceting rough and other applications that do not entail cutting thick pieces of rock. Cutting a cabochon outline to shape from a 1/4" thick slab of rough material prior to dopping and grinding it is a typical application for a trim saw. Saws with blades from 4" to 8" in diameter are typically classified as trim saws.

"Slab Saws" are generally regarded to be medium to very heavy duty saws designed to cut slabs from rough rock, slice geodes, preform spheres, bookends and other larger lapidary projects, cut down large rocks to a size that can be handled by smaller saws, and other applications where cutting thicker material is involved. Saws with blades from 14" and up are typically regarded as slab saws.

Between "Trim Saws" and "Slab Saws" are 10" and 12" saws that can be used to slab relatively small pieces of rough rock in addition to trimming type work and it is probably saws in this size range that you have heard referred to as a "Trim Slab Saw". Some of those saws incorporate a removable table for trim work.

Besides the larger blade size and capacity, slab saws are also distinguished by some kind of vise or clamping mechanism and guide bars or rails to hold the rough rock and direct it along a straight path as it is fed into the blade. Most slab saws provide some kind of self-feeding mechanism that more-or-less automatically transports the rough rock into the blade. There are various approaches and mechanisms for self-feeding including gravity feed where a weight is attached to the vise/clamp via a cable and pulley arrangement, as well as worm screw drives and hydraulic piston drives.

The size saw required to make you happy cutting a given size rock depends on a number of factors, so is difficult to generalize with universal rules of thumb. One rule of thumb I've heard that is reasonably consistent with my own experience is the diameter of the blade should be at least three times the diameter of the rocks you want to cut. Does a 6" rock really require an 18" saw? Well, if you are going to cut a lot of 6" rocks, my experience is yes. You actually have less than half the blade diameter to cut with due to the diameter of the arbor and blade flanges. If the blade flanges are 2" in diameter, that leaves you with an 8" maximum depth of cut on an 18" blade. So why not an 8" rock? Well you can cut through an 8" rock with 8" of blade, but if you want your blades and saw to last, you need the durability that comes with extra capacity. If you are slabbing 6" rocks for a living you really want a 24" saw. If you only slab a 6" rock once in a blue moon you can probably get by on a 14". If you only use a saw for trimming cabs out of slabs, a 6" saw works for that.

My experience is that the drive on a slab saw has a great deal to do with its capacity, versatility, durability and all around owner satisfaction. The vise or clamp on a slab saw also greatly impacts the ergonomics of using the saw. Quality vises are rare birds on "Trim Slab Saws" and many I have seen and used are just plain Mickey Mouse.

For most users, I think it is a mistake to try to compromise and do the job of trimming and slabbing with the same saw. Get a 6" saw for trimming. Get as large a saw as you can afford and have room to accommodate for slabbing unless your application is very specific and niche, such as slabbing turquoise. I know very few people in the hobby who do not covet a larger slab saw.

Hope this helps some and keep on rock'n!

From Bob Keller - March 12, 2008 at 16:18:59

Message: 66179

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Bob Keller