Canadian Contractor - July-August 2015

MAXWELL’S
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all. It’s really something to experience. The tool will be magic.
Another test involves shaving hair. If you’ve got enough hair
on your hand or arm to spare, a truly sharp blade will cleanly
cut that off better than a new razor.
What If It Doesn’t Cut?
If a buffed tool edge is shiny right to the edge but doesn’t cut
cleanly, it always means you held the tool tip at too steep of an
angle relative to the buffing wheel.
The solution is to reshape the tool on a grinding wheel,
creating the proper bevel angle. This process is no longer called
honing, but grinding. It’s a much coarser technique than honing
and it removes more metal. The good news is that you shouldn’t
have to grind tools very often once they’re working well with
edges ground to the correct angle and honed skillfully. So, what
is the correct angle? That depends on the tool involved.
The edges of general-purpose woodworking tools like bench
chisels and hand planes should have a bevel angle between
25º and 30º for proper performance. Block planes and chisels
you’ll use for slicing and paring work better with a shallower
bevel of about 20ºC. The trick is making this happen without
overheating the tool. If the metal gets too hot it won’t be able
to hold an edge any more.
Bench grinders are cheap and effective at removing metal, but
they can cause huge heat build up in tools, too. The simplest and
cheapest way to grind without too much heat is using a
cool-running, soft-bond wheel on your bench grinder. Soft-bond
wheels aren’t very common, but it pays to track one down for
delicate, heat-sensitive applications like tool grinding. I buy
mine from Lee Valley Tools (800-267-8767; www.leevalley.com).
Want a really simple grinding option? A woodworking belt
sander performs surprisingly well. Clamp it upside down in a
portable workstation after putting on a 120- or 180-grit abrasive
belt. There will be a few sparks as you grind, so be careful.
Remove the dust bag and blow off all sawdust before you begin
so nothing catches fire. The trickiest part of using a belt sander
for tool grinding is getting the precision you need. Since there’s
no opportunity to install a tool rest, you’ve got to get good by hand
and eye. It’s no big deal, though.
You can still overheat tools on a white wheel or a belt sander,
so you need to be cautious. Don’t make sparks for more than two
or three seconds before dipping the tip of the chisel or plane iron
into cold water for five seconds. Keep the grinding and cooling
process going until the entire bevel area shows an even, fresh
surface, with a small burr of rough metal formed at the tip. With
this done, you can hone and have a better-than-razor-sharp edge
in a minute or two.
Building your success as a contractor always comes down to
hundreds of details done right. Chisels and planes might only be
a small part of your tool collection, but sometimes they’re the only
things that can make you look like a hero where it really matters.
As long as they’re sharp, that is.
cc
www.canadiancontractor.ca July/August 2015 55