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[phrankhansen]

I'm in need of help (ask my wife).  Specifically, I bought a harbor freight tile saw to cut slabs.  (I know - that was the first mistake, but the price was very persuasive)  I tried free-hand cutting some slabs from rocks that were flat or fairly flat.  The cuts would start great and then the blade would begin to bind.  I suspect rock movement, so I rigged up a clamp.  I drilled through the table, stuck some bolts through the holes, lock nuts and then a piece of 1X4 with washers and wing nuts.  Hopefully, the pics show it adequately.  I don't think the rocks are moving, but the blade "pulls" in whenever I cut rocks thicker than about 1".  The deflection seems to be both in the blade and "looseness" in the bearings.  If I force the cut, I get a break like shown in the pic of obisidian.  Any suggestions will be very much appreciated

[Redrummd]

I think the blade has cupped a bit, usually from too much pressure on the cutting face of the blade.  Use less pressure.

Two things:

1) Flip the blade around - I do not think it is a directional blade.

2) Sharpen it!  Use a small 4 ounce to 6 ounce hammer.  Use an edge of the hammer to tap the blade lightly to put tiny dimples in the sintered edge.

[phrankhansen]

thanks I'll do those today if it quits raining.

[Slabbercabber]

A thicker blade or blade stabilizers would help.  But if the blade is not cupped then the only other things that can cause your problem are to much force or not moving exactly parallel to the blade.  Parallelism is best checked with a dial indicator attached to the vise but can be done with a pencil.  You can check for a cupped blade by laying it on a flat surface like a table saw.  If you must use a countertop for this be sure to try it in several locations as countertops are not very accurate.

[johnjsgems]

Are you sing a HF tile blade?  I have an MK101 10" commercial tile blade.  I use BD/MK 301 blades normally.  To cut thicker/odd shape rocks set rock on a 1" or so Styrofoam board packing piece.  Stops rock from rocking. 

[Jhon P]

Is it a harbor freight blade? I cut a lot of rocks with the 10" tile saw and the harbor freight blade wouldnt do it. Try a better blade. I get the blades at Home Depot. Cost about $40. I preform spheres 4" and smaller on the tile saw be cause it is faster and less mud in the oil, I also cut geodes.  I think Covington makes a tile saw blade designed to cut rocks but I haven't wanted to pay the price.

[phrankhansen]

Thanks for the suggestions.  Here is a pic of the blade type I'm using,  I tried cutting some jasper? and agate pieces tonight for tumbling material.  It worked much better with the blade reversed, but still wanted to grab a bit even after sharpening with a resin stone.  The jasper (or whatever it is) seemed to grab more than the agate did for whatever reason. 

I'm going to try tapping the blade in the next few days. 

I think the idea of using the styrofoam underneath will help also.

thanks again for the great advice.

[johnjsgems]

If the blade is directional it should have an arrow.  If a standard tile blade the matrix material is generally too hard to expose the diamonds to hard rock.  If it is a 5/8" arbor most lapidary blades will work at high tile saw speeds but will dull quickly. 

[Phishisgroovin]

i say cutting a fire brick ( brick for INSIDE a fireplace) and then tapping the cutting edge of the blade with a tiny flat faced hammer, then more soap in the water.
I think you havent got a slippery enough lubricant. the tile saws are meant to cut up to 1/2 inch thick tiles.
so, with that you need less force on the blade also to cut thicker stuff.

[Jhon P]

soap is a good idea, I have used the high efficiency laundry detergent.(or you will be in a big bubble bath) and I would feed the rock by hand . you can get a feel for how it is cutting so you don't use too much pressure. I used to slab up a lot of obsidian on the tile saw when I was doing a lot of napping.