Using HSS power hacksaw blades for tooling ?

"Andy Dingley" wrote: (clip) I'm thinking of using these to make scrapers, such as a side-cutting scraper for inside boxes and a dovetail scraper for making a chucking recess. My concern though is whether the blades are thick enough (clip) ^^^^^^^^^^^^^ Scraping inside a box requires a certain amount of overhang (reach) off the tool rest. I am afraid with only 1/8" thickness, the tool will chatter. As a dovetail scraper, you should be able to position the tool rest to minimize overhang, so it will probably work, if you watch what you are doing.

Blades like this would make excellent parting tools.

Drill rod is usually sold unhardened, but is easy to harden. The two common types are oil-hardening and water-hardening, for the quenching medium. After shaping the point or edge, heat to cherry red--a good indicator is just after it loses it's magnetism. Hold at that temp for 1 hour per inch of thickness to ensure thorough heating into the core then plunge into quenching fluid (olive or peanut oil, or water). It will be glass hard and brittle, so it needs to be tempered back to a slightly softer, less brittle state. First, polish the metal bright then gently and slowly heat with a low flame until the oxidizing color appears-- first is a dark yellow or straw color, then brown (almost too far for a woodturning tool), followed by purple then blue which are both too far. Shoot for a golden yellow or light brown then quench in water. The tempering flame should be played evenly over a large area but not concentrated on the edge or point since that will heat up much quicker and lose it's hardness before the shank even begins to lose it's brittleness. When sharpening on a grinder, avoid heating past the boiling point of water by quenching in water often.

Many blades of this type are HSS on the teeth only. Do a spark test on a grinder--if the sparks are small and dark red, it's HSS. If bright yellow and long, it's carbon steel. Usable either way, but if I wanted to use them as a flat scraper, I'd epoxy a blade to a stouter bar which can be plain old cold-rolled from the hardware store--1/4" of 3/8" thick, and 1" wide. And as Leo said, they make great parting tools in a vertical, on edge orientation.

Ken Grunke

Use the tips sold for metalworkers installed at the end of cold-rolled rod. If the wood's fairly consistent, even carbide will work.

I got some from the machine shop up the way to fit to my Stewart system handles.

If it's truly hss it will work great but must be supported underneath. I have done it often and have used epoxy to glue the thin hss to some mild steel. Very tiny pieces I have silver soldered in place, but that's just me being cautious. I have never had a failure with epoxy. Keep your tool cool when grinding by dipping in water often.

-mike paulson, fort collins, co

Andy, it'll vibrate like crazy, but you could always braze it on top of a piece of milder steel and have a sharp cutting surface with a softer substrate. Just grind your scraper with a slight overhang and you're all set.