Effect of grinding heat on jigsaw blades?

Re: Effect of grinding heat on jigsaw blades?

Derek Cohen (in Perth, Australia)

>Dave

I use these blades to make marking knives. I believe that they are HCS. I first surface grind the blades on a disk sander. The large magnet I use to hold them tends to absord much of the heat so they run fairly cool. I then grind the bevels carefully (with frequent dunking in water) on a belt sander, which is a lot cooler than a high speed grinder. BUT they are still most definitely burnable on a belt sander, so be very careful on a white wheel. With care, however, they retain their temper and hold an edge very well. I have not needed to hone the marking knife I use in some months.

Regards from Perth

Derek

Re: Effect of grinding heat on jigsaw blades?

thomd

>I assume this is an inside curve, or you could just grind it? I make tight inside curves by drilling them, filling them etc... Otherwise i think Derek has you covered.

Re: Effect of grinding heat on jigsaw blades?

Ernie Miller

>I love them marking knives I used your idea and made Chico one for Christmas He said he liked it as well.

Re: Different problem

Dave Mount

>I'm actually not profiling the cutting edge, I'm trying to get two irons out of a single piece of steel by having the flags at opposite ends and the tangs side by side. The geometry is such that I have very little room for waste in the middle -- so I need to come in at 90 then turn 90 degrees to rip down between the tangs. I'm making way too big a deal of this trying to save a few dollars on steel. . .

For everyone's info, someone else e-mailed me off board and said a jeweler's saw would cut annealed O-1.

I'm off to the grinder for now, might as well learn something. . .

Thanks to all.

Best,

Dave

Re: Different problem

thomd

>Jewlers saw would be slow cutting though, and would make a very narrow kerf your larger saw might not fit into. The other option would be an abrassive cut off wheel.

Re: Different possible answer

Bill Houghton, Sebastopol, CA

>Although they're an excellent aid in teaching patience, the carbide grit "wire" saws that fit hacksaw frames will cut any which way. You do wind up with a wide kerf, if that's the word, but you could probably accomplish almost any cut you wanted that way.

They're sold for cutting hardened steel, and they do (it's how I've made my one custom plane iron from an already-hardened bench plane iron) - I don't know if they'd load up with annealed steel.

Good luck

jim reed @ tallahassee

>I have learned the hard way that you cannot expect to draw layouts and cut steel like plywood. For that you need a plasma or waterjet cutter. If you are careful, however, your large pieces of scrap can be reused on other projects. By the time I finish cutting, my scrap pile is full of strips that are less than 1/4" wide. Good luck with your plane projects.

Dr*mel Tool

Sandor in middletown, DE

>I've done this. Use a cutoff wheel on a dremel tool. Drill a hole at the corner of each tang, then use the dremel tool to cut your blades out. Don't worry about getting the blanks hot. You'll heat treat them later.

For making 1/16" mortise chisels?

Bill Houghton, Sebastopol, CA

>Jim, you may be missing an opportunity here...

Re: Epilogue -- success in spite of myself

Dave Mount

>Well, Derek was right, there was no problem grinding the back of the blade to make a narrower jigsaw blade. The problem, I realized partway into it, was that the back of the blade, which I was busy grinding away, is where the blade contacts the blade support in the jigsaw. So I made a wonderful narrow jigsaw blade that chattered so badly that it wouldn't cut. However, I also realized after I laid out for the irons that if I just lived with a slightly shorter tang than I had planned I could just nibble out a void to make the turn with a full width blade (lucky they're sold in packages of 2!).

Heat treating tomorrow -- if all works out (big if), I'll post pictures of the final products (planes and irons) tomorrow evening. I made two identical planes figuring I'd make a fatal mistake somewhere along the way. . .so far, both are still in the running. . .can't believe I'd jinx myself by saying that.

Thanks for the advice,

Dave

Using scraps

Jim Reed @ tallahassee

>I did not learn much ww from my dad, but I did learn how to make a board squeak with economy. I use that technique on steel and by the time it hits the scrap pile it is mostly dust and tiny ribbons.