"Bill Schwab" wrote in message
nk.net...
Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I still plan to get a boring head, but would rather wait a while to let
my wallet cool off a little. Another reason to wait on the boring head
is that I am not convinced I will take to flycutter. If it gives me the
creeps for facing, I might prefer a face mill to a boring head as my
next purchase.

Bill

Depending on the construction of the fly cutter, you may not be able to
install a tool such that it will serve as a hole saw. Fly cutters are
generally intended for tools that somewhat parallel the face being machined.
If you have one that permits the tool to be installed at a right angle,
parallel to the spindle, it might serve your needs, but you may not have the
option to select the diameter you desire. An operation such as that is
called trepanning, where you remove a core piece without reducing it to
chips. It can be accomplished easier with a boring head, but even that can
be challenging---especially when machining tough materials like the majority
of the 300 series stainless alloys or the chrome moly series.

Regards clamping the piece that comes loose---it's usually a good idea to
use a slightly angled tool, so the cut will be quite thin at one edge, the
outer one preferred, so you don't leave a lot in the hole. When it's about
to break through, you stop cutting and remove it manually. By setting a
quill stop, that's easy. Often, when you break through, the core piece will
shift enough to bind and break the tool, so it's not a good way to get the
piece out. If stop cutting at the right point, it's real easy to remove
the core with a light tap of a hammer on one side. Needless to say, you
should be on parallels, not working off the table face. Be mindful of the
tapered edge remaining--it can be quite sharp if you stop at the right
place.

Using a boring head for fly cutting isn't likely to work much better than
using a fly cutter for trepanning. For one, it may not run smoothly if you
are running at reasonable speed. The advantage of fly cutting is the
ability to run fast, so your single point tool will permit a faster feed
rate. As mentioned in a different thread, you're limited by the tool's
ability to cut at the limits of the material, but some materials have
literally no restrictions. Aluminum, for example. If speed isn't a
concern, you might get away with the boring head, but I'd advise keeping the
slide locked to avoid movement sideways, under cutting pressure. Surface
finish would likely suffer otherwise.

If you don't have a boring head now, and you're debating between a face mill
and the boring head, that should be a no-brainer. Buy the boring head.
You can face mill with a fly cutter, which can be shop made with ease, or
even end mills, A face mill won't bore holes, so running without the
boring head would be the greater restriction.

Harold