On Mon, 22 Nov 2004 11:31:10 -0800, "Harold & Susan Vordos"
wrote:


"John Albers" wrote in message
. com...
I am looking for basic info and advice on using reamers. I have a few
questions:

1. What types of reamers exist? The ones that I have herd of are
D-bits, non adjustable straight flute, adjustable straight flute, and
taper.

Two classes are of concern. Chucking, or hand. There are variations of
flute design, one of which you left out is the helical flute.

2. If and when should reaming be done under power? I know that you
are not supposed to ever turn them backwards.

When using a chucking (machine) reamer.

3. Should the reamer be allowed to "float" or should it be rigidly
supported?

Unless a (chucking) reamer is 100% in dead alignment with the hole being
reamed, it is very best to float it. That permits the reamer to seek
center. Imagine reaming from a tailstock of a lathe that is somewhat low, a
common condition on older lathes. If one does not have a floating device,
to minimize the amount of influence a reamer has over the hole that is
reamed, it's a good idea to hold the reamer by a short distance of the shank
(¼") so it can easily center on the hole. When chucked that short, they can
move about freely, yet hold for reaming under all but the most severe
conditions without spinning in the chuck.

4. I believe that that reamers are for a finishing cut and not to
remove large amounts of metal. Is this correct?

Yes, that is correct. Most reamers have little ability to deal with chips,
so they accumulate in the flutes (unlike drills, which tend to discharge
them via the helical flute). A fully loaded reamer is troublesome, and
flutes have limited capacity, so leaving too much to ream is a bad choice.
Best is to remove a maximum of .015", and less can be better. The larger
the cut, the more influence it can have over the finish diameter, often the
result of one tooth of a reamer being dull, deflecting the cut away. That
tends to yield tapered holes. The less material left behind to ream, the
better the chance the hole won't clean up, due in part to drill's ability to
drill anything but a straight, round hole.

Any help would be greatly appreciated. Thank You

The best help I can offer is for you to learn to bore holes instead of ream
them, assuming you have a mill from which you perform your work. Reamers
are, at best, not a great tool. They have the potential to do good work, but
are not predictable. They often yield holes that are multi-sided or
tapered, and don't have the ability to locate a hole where it is desired,
unlike a boring head. A well bored hole won't display any of these
tendencies. Further, (fixed, not adjustable) reamers are good for one
size, and one size only. A boring head will yield any size desired. I
suggest the use of reamers for certain operations, one of which is when
building tools with dowel pins. I rarely rely on reamers for critical
dimensions otherwise.

Harold

Good answer and I know nothing about reamers and someone asked...
I figured that the hole is drilled then reamed without moving the set
up or by hand , I like the partial chuck part.