The magic behind Sandvic scraper blades? How to replicate factory edge.

bmikkalson said:

Does any one know the voodoo behind the factory Sandvik machine tool blades and the factory keen edge.
I have used a rotary sharpener with 600 and 800, and have tried hand lapping with diamond compound. Nothing comes close to the out of box edge.

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You need a diamond lap. That diaamond stone is too coarse. The scraper edge needs to be almost mirror smooth and dead keen for handsome results and efficient scraping.

Lessee, you're hand sharpening? Grab most any hunk of steel or cast iron having a smooth finish (a piece of cold rolled flat bar 1/4" x 1 1/2" x 8 or so will do).

Obtain a tube of 9 micron (green) diamond lapping compound (lapidery shop, catalog house, or industrial supply for about $20) apply a smear of lapping compount to the clean smooth steel and lap as though your were sharpening, taking care to lap "away" from the edge so as not to ding the metal.

Preserve the 95 degree included angle. The edge geometery is easy to blur when hand sharpening a scraper

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mixdenny said:

These are the woodworking scrapers? Don't they traditionally sharpen them with a microscopic hook by burnishing them against a hardened rod?

Dennis

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Mcgyver said:

Most guys develop cast iron laps and charge with say 10 micron diamond paste - a cast iron disk on an old motor or bench grinder is common (pic of mine is below).

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paul39 said:

Nice looking lapping rig. I presume you built it.

Paul

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Mcgyver said:

because the DOC is so small, the edge on a scraper has to be exceptionally fine. The chip can be .0001 for example so if the edge isn't finer than that, it will skid across the work. Most guys develop cast iron laps and charge with say 10 micron diamond paste - a cast iron disk on an old motor or bench grinder is common (pic of mine is below). I make make own carbide scrapers and before silver soldering, lap the two sides manually with 10 micron paste, then sharpen the end......you need two perfect surfaces to make a perfect edge. I'd be quite surprised if any off the shelf sharpening was as good as you regularly get with a lap as I described....search around, there is lots here on sharpening scraper blades

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swatkins said:

Nice job on your laping rig.. What RPM is that motor and what size are those wheels?

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