9x20 Lathe Collet & Jawed
Chucks
Last updated on
Tuesday, September 19, 2023 04:35:01 PM
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5C Collet Chuck,
Keys & Bars,
Chucks
with 5C Mounts,
ER-40 Collets & MT3 Chuck,
MT3 Collets,
4-Jaw Chucks,
3-Jaw Chucks,
Total Indicated Readout,
MT3 End Mill Holders,
MT3 to Taig Adapter
5C Collet Chuck
Tramming (centering) a
5C collet chuck that has
4-way
built-in set screw adjustability in its adapter plate.
This is an important feature as this lathe has a
threaded spindle nose which
introduces setup variability.
A Swiss-made, jeweled, Brown & Sharpe dial test
indicator (0.0005" resolution)
is being used to tram.
I stamped each position with a number. Use the
4-jaw alignment method to tram the
5C chuck.
See instructions on how to
set tip geometry
&
illustration.
Introduction to lathe chucks.
One of four adjustment set
screws for tramming the 5C chuck.
A 5C collet set has a larger range of sizes when compared
to
ER-40 or MT3 collet sets but seventy
5C collets are
needed to make up a
complete set of 3/64" through 1-1/8"
sizes by 1/64". A 5C collet has a relatively small range
for gripping a part. Best accuracy is +0 to -0.002". For
a part above +0.005" you may damage the work, a part
below 0.010"
you may damage the
collet. 1/32" (0.03125")
increments are too large of steps & you will not get
continuous coverage. Most 5C collets are open all the way
through & thus
allow holding long stock up to
the
maximum of the lathe spindle
hole, e.g., 25/32" (0.78125")
for the 9x20. By comparison, an ER-40 chuck limits
the depth at which a part can be seated
into its collet to a
few inches. Collets, in general, do not mark the metal
stock like jawed chucks & the total indicated
runout (TIR) is
low if it is a quality tool.
See Collets Section for more
information
Keys & Bars
Every chuck comes with a key.
Fabricated steel Tommy bars to tighten &
loosen spindle chucks.
Bottom two are supplied with the Jet lathe.
To tighten or loosen a 5C
collet requires about 40 turns
of the T-wrench. Mounted a hex to 3/8" (hardened)
adapter bit into the
5C square fixture &
diamond
ground the sides/corners
down a little until it fit.
Using the cordless screwdriver now allows much
faster operation.
Start by installing the
collet by
hand to avoid cross-threading.
Final tightening &
initial loosening should be done with the T-wrench.
Chucks with 5C Mounts
4-inch, 3-jaw 5C chuck supplied with both inside &
outside hardened jaw sets &
a T-wrench.
The one-piece, integral 5C back plate is strong & accurate.
3-inch, 4-jaw, 5C mount lathe chuck &
key.
4-jaw 5C
specifications.
MT3
Spindle Collets & Adapters
A collet is safer to use than a chuck &
typically has a lower
total indicated readout (TIR). The ER-40 double-angle
collet is an industry standard affording
Each ER-40 collet has a wide
(0.04") clamping range so a 23 collet set provides
continuous size coverage
from
0.12" (nominal
1/8") through 1.02" (nominal
1")
or 3.05mm ~ 25.9mm. The 15 sizes that come in the set (fitted
case included) are shown in
the table in bold numbers; the other eight collets (all
n/32nds sizes) were purchased
separately. Specifications: wide holding range, accuracy 0.0001",
self-releasing design, high precision collet
chuck with different
shanks available (MT3,
MT-4,
MT-5, R-8) &
a
spanner wrench. The
MT3 collet chuck I
received had a 1/2-12
TPI tapped hole for the drawbar (not a common
thread). I made a drawbar from rod threaded
1/2-12 TPI on one end & 1/2-13 TPI on
the other end. There are milled flats for a wrench.Snap the collet into
the nut's
eccentric ring before screwing it onto the spindle. This
ring is the collet
extraction mechanism.
Do not tighten the nut onto an empty collet as damage
could easily result.
ER-40
Collets & MT3 Chuck
ER-40 collet set (above).
Collet chuck
shown with
an MT3 shank. The plugs are used to fill the collet when
holding very short
parts;
allows good clamping without
distorting/damaging the collet or part.
Each plug is
stamped with the collet's nominal size.
There are
other types of ER-40 collet chucks, e.g.,
R-8 shank.
Threaded aluminum drawbar. Steel end plug machined
to fit the spindle hole & a
flare nut with a washer.
Collet table (below) showing continuous size coverage.
White sizes were the original set &
green sizes were added.
| ER-40 COLLET SIZES | ||
| COLLET SIZE | DECIMAL EQUIVALENT |
WORKING RANGE |
| 1/8" | 0.12500 | 0.12 ~ 0.16" |
| 3/16" | 0.18750 | 0.16 ~ 0.20" |
| 7/32" | 0.21875 | 0.200 ~ 0.236" |
| 1/4" | 0.25000 | 0.236 ~ 0.275" |
| 5/16" | 0.31250 | 0.275 ~ 0.316" |
| 11/32" | 0.34375 | 0.316 ~ 0.354" |
| 3/8" | 0.37500 | 0.354 ~ 0.393" |
| 13/32" | 0.40625 | 0.393 ~ 0.433" |
| 7/16" | 0.43750 | 0.433 ~ 0.472" |
| 1/2" | 0.50000 | 0.472 ~ 0.511" |
| 17/32" | 0.53125 | 0.511 ~ 0.551" |
| 9/16" | 0.56250 | 0.551 ~ 0.590" |
| 5/8" | 0.62500 | 0.590 ~ 0.629" |
| 21/32" | 0.65625 | 0.629 ~ 0.669" |
| 11/16" | 0.68750 | 0.669 ~ 0.708" |
| 3/4" |
0.75000 |
0.708 ~ 0.748" |
| 25/32" | 0.78125 | 0.748 ~ 0.787" |
| 13/16" | 0.81250 | 0.787 ~ 0.826" |
| 27/32" | 0.84375 | 0.826 ~ 0.866" |
| 7/8" | 0.87500 | 0.866 ~ 0.905" |
| 15/16" | 0.93750 | 0.905 ~ 0.944" |
| 31/32" | 0.96875 | 0.944 ~ 0.984" |
| 1" | 1.00000 | 0.984 ~ 1.020" |
MT3 Collets
MT3 collet set
& a
3/8-16
drawbar made from threaded steel rod.
MT3 collet set from
Phase2+.
Drawbar made from
3/8-16
threaded stock.
Collet sizes range from
1/8"
to 3/4" by 1/16ths (no
continuous size coverage).
To remove a part, make the nut
flush to the end, hold the part & collet
while
gently knocking out the bar using a hard plastic-faced mallet or brass hammer.
3/4" MT3 collet mounted into the
Jet's spindle.
A collet in a lathe spindle is much safer &
accurate than a
spinning chuck with protrusions.
4-Jaw Chucks
4" (above)
manual
& 6"
(below), 4-jaw chucks
on
a
standard 1-1/2-8 Jet
threaded
mount.
6-inch,
4-jaw instruction manual.
Massive for this sized machine, it weighs over 26 lb.
Tramming
(center)
the
part using a
digital
indicator
gauge.
Use steel letter stamps to mark each jaw position on all
chucks.
I also indexed the adapter plate to the body.
How to center a
round work piece in a 4-jaw lathe chuck
1 - After rough alignment using the chuck-face rings, put
a dial indicator on the work piece.
Then, rotate the spindle through one complete revolution noting the
highest & lowest indicator readings.
2 - Continue
rotating the spindle & stop
exactly midway
between the high & low readings, then zero the indicator.
3 - Rotate the spindle to bring jaw #1 on plunger & iteratively
adjust jaws #1 & #3 to re-zero the indicator.
4 - Finally, rotate the spindle 90 deg & adjust jaws #2 & #4 to
re-zero the indicator once, again.
Making a new compound pivot.
A
six-inch, 4-jaw chuck from
with a 1-1/2-8 threaded adapter plate. Screws
right onto spindle of the Jet BD-920N.
Weighs about 26.4 lb (12 kg. Clamps part more tightly than a 3-jaw & allows perfect centering.
It
can easily
hold a 4" x 4"
(square)
part.
A far more accurate
& easier to use modern design when compared to
the
Jet-
supplied 7-inch, 4-jaw
chuck. Note, even the empty chuck is quite heavy. Its
momentum makes for extra nice
cuts. This chuck is at the
upper limit of the machine in terms of both weight &
size.
Verify everything clears
(e.g., the carriage) before starting.
Make sure to slip the belt idler, especially when
starting fast &/or heavy
loads,
otherwise you can break the V-belt. Reduce
belt idler tension
by installing an
S-link. This large chuck
can also be mounted onto a
6" rotary table.
3-Jaw Chucks
The
Bison 5", 3-jaw chuck
(Poland) is smooth
& accurate.
The jaws are
reversible. The counter bore of
the
threaded back
plate was undersized
& had to be bored to fit
the
spindle shoulder.
The chuck weighs
about
10 lb Faced
the adapter
plate to achieve best total indicated runout (TIR).
Verify your lathe is in
alignment before
facing a chuck adapter plate or a
faceplate.
Specialized rule that can be used on lathes &
mills.
Stop-Loc instructions.
To measure
total indicated readout where
TIR
= (Maximum reading - Minimum reading), clamp a dowel pin in
the chuck
(or collet)
& put a dial gauge on it. Slowly rotate the spindle
& note max & min values.
Dividing the
TIR in half yields the +/-tolerance. For example, a part having a 0.004" TIR has
+/-0.002" tolerance. The
magnetic
base
shown
(Noga) is
very easy & quick to use. Loosening
a large knob makes all the joints movable.
Just position indicator &
tighten; the whole arm's position is then fixed. It can hold instruments
with either a
3/8" stem or a dovetail. It has a fine adjustment feature, too.
The large Jet OEM
independent
4-jaw chuck is 7-3/8" in diameter.
Adjustments of the
jaws' rear
attachment bolts are troublesome.
Note the spindle safety set screw
(center-right).
This
OEM chuck is more
suited for wood applications
as its accuracy is unacceptable for metal work.
There are no relief cuts in the jaw corners. One could
use a surface grinder to
clean it up, if needed.
MT3 End Mill Holders
These MT3 end mill holders from Phase2+
each
have
a
set screw that engage the end mill
flat.
These holders
are
for both
3/8"
& 1/2" shank end
mills. For use with the Jet
BD-920N lathe
spindle.
MT3 to MT2 taper adapter sleeve.
MT3 to 3/4-16 TPI taper, allows using
Taig or Sherline
chucks & other
accessories on the
Jet
BD-920N or
other MT3 machines. Allows accurate fabrication of
large-shank end mill holders
for use on the Taig mill &
lathe. I've made end mill holders by both reaming &
boring. Boring is very
accurate (0.0005" TIR) but a
slower process. It is better to mount the arbor by its
threads before boring
than to grip it on the outside.
Taig collet on
the Jet 9x20. Taig collets are size
limited & made of
soft steel but can be easily customized
e.g., threaded for 10-32 to turn down screws. The 5C
collet chuck, ER-16, or
ER-40 are superior alternatives.
A
Sherline
3.1-inch, 3-jaw
chuck
&
a Taig 3-1/4-inch,
4-jaw chuck
using
a
MT3 to 3/4-16 adapter.
A finished end mill holder for the
original-design
Taig
lathe/mill.
Blank arbors (steel) #1132, from Taig.
3/8"
shank end mill shown. Milled flats for a
7/8" wrench &
uses a
1/4-20 set screw. This type of arbor
is not needed
(nor mountable) if you use the (superior) upgraded
Taig mill ER-16 spindle
but is still usable for the lathe.
CAUTION: Large end mills easily exceed
a
Taig mill's capacity thus requiring small cuts.
For extra small
parts, combine the MT3 & stubby holder
to allow use of the
ER-16 collet set on the
Jet lathe.
There is a left-hand set screw in the shank
that controls an end mill's depth in
the collet.
The total indicated readout
5C Collet Chuck,
Keys & Bars,
Chucks
with 5C Mounts,
ER-40 Collets & MT3 Chuck,
MT3 Collets,
4-Jaw Chucks,
3-Jaw Chucks,
Total Indicated Readout,
MT3 End Mill Holders,
MT3 to Taig Adapter
