In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

Tim Wescott fired this volley in
:

On 05/26/2010 10:47 AM, wrote:
On May 26, 11:38 am, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
I've got a tough-dog clamping job to do.

I want to mill my lawnmower blades, rather than grind them.

The blades must be mounted at an angle to the table (tilting the
head just wouldn't work well in this app, because my Y travel isn't
enough), and the jig/workholder must be "indexable" in the sense
that I must flip the blades end-for-end to grind both ends, yet get
the same position from center each time.

No problem on the indexing, but has anyone a good idea for a very
simple way to clamp the blades at a "tilt", yet still hold them well
enough to reduce the chatter? There is a requisite overhang of
about 6" from the jig to the end of the blade, because there's
nothing on the ends you can clamp to -- little "lift wings"&
turbulence slots get in the way.

LLoyd


This seems to be a post in need of a question, "why?". Takes me
about 5 minutes to sharpen blades and balance using a belt grinder.
Using a mill would seem to be a use of an inappropriate tool.

Ditto. Not only would a mill -- if you could use it properly -- be
way more precision than is ever necessary to whack a grass stem in
two, but if the blade is decently hardened at all you'd have to use
some fancy extra-hard cutter and hold the work a lot closer to the cut
than you're proposing.


To both of you. These are high tip speed blades for a commercial mower.
The manufacturer _recommends_ milling them instead of grinding, and
offers suggestions for cutter inserts -- which I have. The tool and the
mill are already in my shop. I just need a way to hold the blades.

(and if you've ever looked, all commercial blades are milled, not ground)

Well, I have a 21" commercial Honda mower, and yes the blade edges were milled,
but I clamp them with a bench vice and sharpen them with a BIG mill file. The
file has no problem cutting the blade metal, which is quite soft, so the blades
won't shatter when they hit a rock. Anyway, I would make a fixture out of a
hardwood like Oak (for the damping) with metal clamps of some kind, and use an
ordinary HSS cutter.

Joe Gwinn