PLANER BLADE ATTACHMENT SVH-320 PROBLEMS--MY EXPERIENCE

[MATPTTDAT]

I HAVE OWNED MY TORMEK SUPERGRIND 2000 FOR 16 YEARS AND HAVE GROUND AND HONED MY 13"PLANER BLADES AND BOTH MY 6" AND 4" JOINTER KNIVES WITH FANTASTIC SUCCESS IN 20 MINUTES PER SET. I HAVE JET BRAND LAMINATED KNIVES FOR THE PLANER--3 SETS TOTAL AND 6 SETS OF KNIVES FOR THE JOINTERS IN EITHER DELTA, ROCKWELL, CINCINNATI, OR AMANA BRANDS. NONE OF THEM WERE IN-EXPENSIVE.
THEY ALL SHARPEN QUICKLY AND HONE TO BE ABLE TO DRY SHAVE MY ARM--JUST LIKE THE INSTRUCTION MANUAL RECOMMENDS.

THE OTHER DAY, A PERSON GAVE ME ANOTHER 6" JOINTER AND A SPARE SET OF BLADES. I AM GOING TO DONATE IT TO PERHAPS A TOOL LENDING LIBRARY TYPE OF ORGANIZATION AND DECIDED TO SHARPEN BOTH SETS OF BLADES WHILE REFURBISHING IT.


WELL.......I GOT NOWHERE IN AN HOUR AND A HALF------THEY DID NOT GRIND NO MATTER HOW HARD I PRESSED ON BLADE HOLDER OR USED THE STONE GRADED AND USED THE DIAMOND TIP STONE RE-SURFACER.  I TRIED DIFFERING ANGLES THINKING MY EFFORTS MIGHT BE DIRECTED AWAY FROM THE VERY EDGE KNIFE--NO LUCK. NEEDLESS TO SAY, I WAS NOT HAPPY.

I QUIT IN DISGUST AND FRUSTRATION. WHAT WAS GOING ON? I READ ON THIS FORUM ABOUT THE EXACT KINDS OF PROBLEMS I WAS HAVING. THE NEXT DAY, I SET THE "PROBLEM CHILDREN KNIVES" ASIDE AND DOING NOTHING ELSE, MOUNTED A SET OF MY 13" JET PLANER KNIVES THAT NEEDED SHARPENING IN THE JIG AND AS USUAL--20 MINUTES LATTER WAS DONE WITH GRINDING, HONING, AND DRY SHAVING MY ARMS.

THE KNIVES BEING ATTEMPTED TO BE SHARPENED WERE THE PROBLEM--NOT THE JIG!

AS A WELDING ENGINEER AND AT TIMES A WELDING METALLURGIST--I HAVE SOME EXPERIENCE WITH FERROUS METALLURGY AND TOOL STEELS. MY GUESS IS THESE KNIVES HAVE A COURSE GRAIN STRUCTURE WITH LARGE BLOCKY CARBIDES AND REALLY ARE INTENDED TO BE DISPOSABLE ITEMS RATHER THAN SOMETHING THAT IS  INTENDED FOR RESHARPENING SINCE SUCH MICROSTRUCTURES LEND THEMSELVES TO DEVELOPING GOOD HARDNESS WITH LOWER MANUFACTURING PROCESSING AND COSTS UPFRONT.

WHEN I SEE  KNIVES SELLING FOR ABOUT $1 USD PER INCH--THAT TO ME  IS A PRETTY GOOD INDICATOR OF THE INTENT OF THE MANUFACTURER WITH RESPECT TO WANTING TO SELL YOU MORE KNIVES RATHER THAN YOU BEING ABLE TO SHARPEN THEM OVER AND OVER AGAIN.

HAS ANYONE ELSE HAD A SIMILAR EXPERIENCE TO MINE?

[Herman Trivilino]

MY GUESS IS THESE KNIVES HAVE A COURSE GRAIN STRUCTURE WITH LARGE BLOCKY CARBIDES AND REALLY ARE INTENDED TO BE DISPOSABLE ITEMS RATHER THAN SOMETHING THAT IS  INTENDED FOR RESHARPENING SINCE SUCH MICROSTRUCTURES LEND THEMSELVES TO DEVELOPING GOOD HARDNESS WITH LOWER MANUFACTURING PROCESSING AND COSTS UPFRONT.

What confuses me is how the manufacturer gets them sharp to begin with. Do they deposit a layer of some kind on the surface that wears away when they are used or sharpened? Or are they sharpened before they are fully hardened in the manufacturing process?

I've heard of hack saw blades that are manufactured something like this. They sharpen them and then heat treat only the teeth.