How to use thin slitting saws?

carlquib

carlquib

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I've used a lot of slotting and slitting saws over the years and they have always worked very well until I was trying to cut some deep narrow slits. I'm making some specialty collets and was using a 5" x 1/64" slitting saw cutting about 1 1/4" deep. I was going full depth with a cool mist running to clear chips and provide lubrication. All was going perfectly for the first couple cuts and then bang, no more slitting saw. I thought hmm maybe that is just too deep for a saw that narrow, so I switched to a 5" x 1/32" slitting saw. I finished the slit the other blade broke on with a jewellers saw by hand. I managed to finish slotting the next collet with the 1/32" saw but on the first cut of the third collet bang, gone. So my question is how do you make deep narrow slits. Obviously it can be done because I have collet sets with the narrow slits but obviously I don't know how to do it. The blades both broke when I was almost all the way through the bore with the slit, both times it was when I was almost finished. I was running at 60 rpm feeding slowly by hand. For my next attempt I got a left handed arbor so if the saw gets stuck hopefully the nut will nut come loose instead of grenading the blade. I haven't tried to finish yet with the new arbor. Any suggestions? The material is O1 drill rod and 1045 steel?

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Have you checked the run out on your saw arbor, the arbor and blade? I think some will say you're running the blade too slowly. 60 rpm?
 
I have checked run out, about .0002" and the slitting saw was running out about .001" . For a slitting saw it sounded really good, hitting probably 80-90% of the teeth on the blade. If I did the math right on a 5" diameter cutter that gives me about 80 sfm, which is about what I usually run hss at when I'm cutting high carbon or tool steel.

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The way I use slitting saws is to center the saw on the part and plunge it to depth, then clean up the bottom if needed. I learned this from my 1st job, operating B&S screw machines. The slotting arm on them picks up the piece when it's cut off and plunges it into the saw.
 
I think my broken slitting saws are related to the interrupted nature of the cut, since I am cutting through the already cut bore of the collet. It appears I'm getting chips jammed as the blade tries to carry them through the second wall of the collet. I think I will try having the mister directed into the bore of the collet to try and clear the chips before they can jam the cut.

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