How is a hand reamer identified
Reamer Basics
there are some things that every
machinist should know about twist drills
they always make an oversized hole they
generally leave a rough surface finish
on the sides of that hole and the holes
they make are not necessarily straight
in thicker material or round and thinner
material in the case of clearance holes
these things tend not to matter but when
you need an accurately sized round hole
with a good surface finish you should
reach for a reamer
reimers are a fast and relatively
inexpensive way to get a precise
diameter on a hole they are available in
almost any size
most industrial suppliers sell them in
thousandths of an inch
and hundredths of a millimeter
increments so you can get just the fit
you need one of the most used tools many
machine shops as an over-under reamer
set which consists of Reimers one
thousandth of an inch over and under
each fractional size from an eighth of
an inch up to a half an inch this lets
you get either a slip fit or press fit
on dowel pins this is useful for
applications where you have two mating
parts that need to be able to move but
also need to stay in relation to each
other like this by stop or these ball
out molds for rounding out tubing
the most common type of reamer is called
a chucking reamer it has a very long
shank in relation to the flute length
this makes sure it's flexible enough to
follow the pilot hole the flutes are
most often straight but they can also be
spiral either right-handed to pull the
chips out or left-handed to push the
chips forward pay attention to the
direction of the cut though because a
left-handed spiral can still have a
right-handed cut like most tooling
Reimers start to get quite expensive in
larger sizes so large Reimers are often
sold as shell dreamers one shank is used
to hold a range of interchangeable
reamer shells this not only makes the
tooling more affordable but it takes up
far less space than a drawer full of
very large Reimers just like twist
drills reamers come in a wide array of
styles materials and shank types many of
these are the same options you would
have with drills they're available in
high speed steel and carbide as well as
carbide tipped so you get the hardness
of carbide on the leading edge and the
flexibility of a high speed steel shank
they also have both straight and taper
shanks like drills but additionally
there's a variety with a square shank
like a tap these are hand Reimers and
are not meant to be run under power on a
machine instead these are meant to be
turned with a tap wrench hand Reimers
have longer flute lengths than normal
and the flutes are slightly tapered at
the beginning to aid in getting the
reamer straight into a hole there are
also some special purpose rumors that
deserve to be mentioned Morse taper
Reimers are available to either cut or
clean up Morse taper sockets taper pin
Reimers are for cutting a seat for
tapered dowel pins these pins are used
in all kinds of machinery to accurately
locate removable partes there are also
adjustable reimers which use opposing
nuts to slide the reamer blades and
tapered channels to make the reamer
larger or smaller these are always hand
reamers and the surface finish that
create leaves a lot to be desired these
are mostly used to open a hole slightly
rather than trying to
a precise fit there are some rules of
thumb that should be followed when
reaming the most important one is that
riemer's should never be run backwards
either under power or by hand doing so
dulls the Reimer the next thing you need
to know is that Reimers should be run at
half the speed and double the feed of a
similarly sized drill simply put if a
drill of the same size should be run at
1,400 rpm the reamer should be run at
700 likewise your feed rate would be
doubled although on manual machines that
comes down to a sense of feel next use
cutting oil when using a reamer this not
only helps achieve a better surface
finish but it affects the size of the
finished hole reaming a hold dry tends
to leave it oversized and somewhat
rough-looking lastly if you are reaming
a blind hole make sure to stop before
you reach the bottom of the hole Reimers
are flexible but generally continue
straight into a workpiece once they're
started the same cannot be said for the
drill used for the pilot hole which will
start to wander sideways quickly if you
hit the bottom of a blind hole
especially a deeper one the reamer will
immediately center itself on the
depression left by the drill tip and
make the hole oversized
if you have to ream a blind hole make
sure to drill a little deeper with the
pilot drill to give yourself more room
at the bottom and utilize a quill stop
to make sure you don't go too far with
the reamer the flutes of a reamer do not
have much space in them so the pilot
hole needs to be closed to size but
still leave enough material for the
reamer to remove otherwise it'll just
rub and dull the reamer how much stock
leave depends on the size of the reamer
so please refer to this stock allowance
chart I've also put this down in the
description and it's part of my class
handout that's linked down there as well
thanks for watching and I'll see you
next time
