I work for a printing company, and our paper cutter has developed an
unusual problem-- the blade cuts OK at both ends, but not in the middle.
I think the sharpening service is suddenly not grinding them straight
anymore. Before I accuse them of screwing up our blades, I'd like to
know what a typical tolerance would be for a blade that's 43" long and
I measured one of the blades with my Chinese digital caliper, and found
that it was .02" wider at both ends than it was in the middle. Even
assuming some error in my measuring, that seems like too much,
considering that some of our paper is only .003" thick. The blade cuts
into a sacrificial plastic "cutting stick" which is replaced
frequently-- I found a note that says it should cut into the stick by
about .004". I'm sure we're setting it deeper than that to get a clean
cut, and it's making the blades get dull faster.
The blade is adjustable for angle, so it's OK if it's slightly tapered,
as long as the edge is straight. The last person who changed the blade
told me that when she adjusted the angle so it cut at both ends, she
could still see daylight under the middle of the blade. I haven't
checked the cutter's table with a straightedge, but I'd be surprised if
it was warped that much.
Any guesses as to how they managed to grind a curve into our blades?
If I'm right, they've done this more than once, over a couple of months.
- posted 15 years ago