Tuesday, April 16, 2013

Grinding without a grinder

I'll admit it.  I'm terrified of powered grinders.  Last time I tried to use one I didn't grip the metal firmly enough, and it caught, shot down towards the floor, left a divot in the concrete between my feet, and wound up halfway across the garage.  Sooner or later I'll have to try again, but not soon, I hope.

But it does leave me with a dilemma.  Everyone occasionally nicks a blade, and chisels and plane irons are a little pricey to just throw away if they get nicked.  And grinding out a big nick on sandpaper is... well, my time may not be worth much, but it's worth more than that.  So what's a cowardly cheapskate to do?

Find a solution, that's what.

Here's how I deal with this problem.  Anyone else who has the same problem may like this solution too.

First, make sure you have a drill press, and that it's set nice and slow.  If you don't... well, go buy one.  They're less terrifying than grinders, and they have more uses.

Next, cut a wedge to the angle you want your iron sharpened at.  Screw that secondary bevel nonsense;  this is for the big bevel.  Make sure it's wider than the largest blade you'll want to sharpen, and not too long.  Also, make sure you can attach it firmly to your drill press table.

Third, go find a 3" or 4 1/2" sanding disk.  These things are moderately rigid, and they've got a hole around 3/8" in the middle.  Make it coarse:  80 grit works nicely, and I've used one at 60 grit that removed an amazing amount of metal in seconds.  Pick up an arbor that fits it;  that shouldn't be too hard.  Worst case, a bolt, washers, and two nuts should work, but try to find the real thing.

Fit the disk to the arbor, chuck the assembly up in the drill press, and fasten your nicked blade to the ramp.  Make sure it's not going to contact the arbor, and set the table so the blade is about an inch from the sanding disk.  More than that, and you'll wear out your arm.  Less, and you won't be able to see what you're doing.

Finally, start the drill press, and start bringing the disk down into contact with the blade.  Short touches:  not more than a couple seconds.  Each time there's contact you'll probably see sparks, and the blade will start heating up.  But at 60 grit and a few hundred RPM, it works fast;  you just need to keep bringing the disk down and checking to see if the blade is too hot.  If it is, spray it with water or stop for a while.

When you're done, the bevel will be heavily gouged by the rough paper, but you can take that out pretty easily with a coarse stone or some 80 grit sandpaper.

So there you have it.  A way to get rid of your grinder!  It's fast, it's easy, and it's pretty cheap, if you've already got a drill press.