When the router bit manufacturers refers to a spiral-cut router bit as
up-cut or down-cut, are they consistently speaking with reference to the
router base? Or are they assuming a router-table orientation as opposed to a
The ambiguity being, of course, that a router bit that cuts away from the
router is down-cut when the router is being hand-held, and up-cut if the
router is mounted under a router table.
It's in the handheld position.
Think of when you're looking at the router and reading the brand name.
The letters in DeWalt, Porter Cable, etc can be read in the handheld
That's the position relevant to up and down cutting bits.
It seems to me that they are speaking with reference to the base,
otherwise there would be no reason to have 2 different types of
spiral-cut router bits, and up and a down.
But, being a person with a cattle ranch and only occasionally a wood
butcher, what the heck do I know about anything other than the
gynecology of cows?
The "consistency", and what you need to keep in mind for which to use in
a particular situation -- including direction of feed, handheld or table
use, and whether you want to minimize tear out on the bottom or top --
is in the fact that:
_An up-cut bit pulls the work toward the router, a down-cut bit pushes
the work away from the router_.
There are some general rules that are convenient (up-cut in
table/down-cut in handheld), but these are not hard and fast depending
on the task ... mostly to do with tear out and direction of travel.
Keeping the first above in mind and you can generally figure out from
the task, and how the task will be accomplished (handheld/router table),
which one to use.
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