Mill motor upgraded to 1/3 hp. Headstock & spindle upgraded to accept ER-16 collets.
Original mill motor photo GE motor specs
Taig Mill Motor & ER-16 Spindle Upgrades
Last updated on
Wednesday, November 21, 2012 05:23:11 AM
Eastern US Time Zone
ER-16 Spindle,
ER-16 Collets, Locking
Levers, Drill Arbor
Low-speed Countershaft,
High-Speed Pulley,
Motor Mount, Tachometer,
Indicator
Mount
ER-16 Spindle
Mill motor upgraded to 1/3 hp. Headstock & spindle upgraded to
accept ER-16 collets.
Original
mill motor photo
GE motor specs
Caution
Only use a motor that is non-thermally protected or has a thermal overload circuit that requires a
manual reset.
If
the motor automatically shuts down due to excessive heat, it then has the
potential to unexpectedly
start-up again while you are touching/changing sharp end mills,
saw blades, belts or other rotating parts.
The motor that the mill came with was only 1/5
hp, it was surplus, had dual-shafts, capacitor start &
had automatic thermal
protection. The new motor is a GE H164: 1/3 hp, split-phase, continuous duty,
ball
bearing, 1725 RPM, non-thermally protected & has an open case with extended clamp
bolts.
It has a service factor of 1.35 which means that it can deliver a 35% reserve hp
capacity without damage
from overheating. The new motor has 167% (225% in reserve
capacity) more horsepower than the original.
Motor specification
speed is 1725 RPM but measured at 1795 RPM.
A new, larger motor mounting plate was made
based on the
original Taig design.
The motor's
1.75" diameter lower bearing housing passes through & is flush with a very
close-tolerance
hole in the mounting plate. This keeps metal debris from being pulled into
the cooling intake vents.
The plate corners were cut at 45º for safety. The two imported
10-32 cap head screws that held the motor plate
were replaced with high-grade US
manufactured screws. The motor weight increased by only two pounds &
the moment-arm
increased less than two inches. The cradle mount was removed since the motor is
mounted to
the plate using its four extended clamp bolts. The mounting holes were counter-bored for
the nuts.
The original ⅜" motor pulley hole was bored to a 0.5001" diameter
for the new motor shaft.
Use the original belt or a new, longer
Gates belt can be installed; 3M 355
(13.98").
Gates belts can be purchased in a wide range of flat-belt lengths (or
outside circumference)
from any of their local distributors. The first number (3M) is the
belt's (ribbed) back width, 3 mm.
The last number (355) is the flat-belt length, also in
mm's. To measure the needed belt length,
set the motor/pulley assembly to the desired
location & lock it. Then place a single, insulated wire
from lamp cord (split it in
half) around the center pulleys, pull it taught, cut & measure.
The cord fills the
groves enough to give an accurate indication of the required flat-belt length.
The
original wiring connection was duplicated using a computer power cord extension.
A nylon
wire tie was used as the power cord strain relief under the connection box cover.
This
wiring setup allows the entire motor to be removed without having to open the switch box.
On the top right side of the z-axis slide is a
10-32 cap head that protrudes & contacts the lead screw bearing block.
Counter bore
where it contacts the bearing block. This recess for the bolt head then allows an
additional 0.2" vertical travel.
The more powerful motor does not bog down
thereby making more uniform cuts, especially fly cutting, &
is inherently safer since
it does not have automatic thermal protection.
The ball bearing motor, coupled with a low
run-out pulley, runs very smoothly.
Updated
Taig headstock & spindle. One-piece housing,
improved shoe clamp, extra accessory rail, hardened
spindle & nut that accepts standardized,
professional ER-16
collets & end mills.
The hole through the spindle
is now slightly larger than 3/8" diameter.
Both the spindle & collet closing nut use 1" wrenches. Snap the
collet
into the nut's
eccentric ring before screwing it onto the spindle. This ring is the collet
extraction mechanism.
Caution: Do not over tighten the nut onto an empty collet as it might
cause damage.
Shown holding ⅜" shank 45° chamfer cutter. ⅜"
shank end mills are an industry standard. Rigidity & versatility are
greatly improved. After removing the setscrew, I warmed the pulley with a heat gun & then used
drill chuck wedge
pairs for removal. Housing & pulley must be heated (expanded) first before assembly because they
are essentially
a zero-clearance fit.
The upgrade is a big improvement over the original in terns of both
strength & utility.
ER-16 Collets
A set of 10, superior, high-precision ground, hardened ETM ER-16 collets (Israel).
An eccentric ring locks the collet inside of the nut.
Because of the wide 0.040"
holding range of each collet, the set provides a
continuous range of clamping sizes.
This set range allows clamping of multiple tool bits having different
(non-fractional) shank sizes.
ER-16 collets are also very useful on a large mill when used in conjunction with
collet extensions.
ER-16 COLLET SIZES NOMINAL COLLET SIZE (in) DECIMAL RANGE
(inches)METRIC RANGE (mm) 1/32 .0197 ~ .0394 .5 ~ 1 1/16 .0394 ~ .0787 1 ~ 2 3/32 .0787 ~ .1181 2 ~ 3 ⅛ .1181 ~ .1575 3 ~ 4 3/16 .1575 ~ .1968 4 ~ 5 7/32 .1968 ~ .2362 5 ~ 6 ¼ .2362 ~ .2756 6 ~ 7 5/16 .2756 ~ .3150 7 ~ 8 11/32 .3150 ~ .3543 8 ~ 9 ⅜ .3543 ~ .3937 9 ~ 10
ER-16 Taig spindle arbors both
blank & for ½" shank end mills.
Not the most rigid setup & it uses up a lot of Z travel. This
end mill is large for a Taig; only very light cuts.
10-32 die-cast zinc ratcheting locking levers.
The motor-mount lock has an extension & uses two large
custom-made brass washers. The extension allows easier access & lessens the chance of bumping the
Z-axis
crank. The motor pivot has a lever with brass washer. The Z & Y axes
have lever locks, too.
Ratchets allow selection of desired lever
positions.
In general, locking non-translating
axes results in smoother, more accurate cuts.
Drill Arbor
Taig
upgraded spindle now uses a ⅜" straight shank; ⅜-24
drill arbor.
Low-speed Countershaft
Two oil impregnated bronze radial & thrust bearings press-fit
into the Taig OEM pulley.
A
¼" hardened dowel pin is used for the axle. A setscrew holds the axle in
the bracket.
The bearings were drilled & precision reamed to 0.251".
There was not enough room for the thumb knob so a T-nut,
washer, & bolt were used instead.
This design copies that of the
Taig lathe
speed-reduction pulley modification.
A 10-32 tapped hardened steel T-nut locks into in the bracket slot.
Runs very smoothly.
Lowest speed is now 179 RPM. The pulley & bracket are usually removed for regular milling operations.
Lower speeds may be required when I start using involute cutters & the 4th-axis
to CNC brass clock gears.
High-Speed Pulley
A high-speed
motor pulley for CNC engraving.
3¼" aluminum stock for the pulley
mounted in a
4-jaw
chuck.
After a #2 center drill bit, made a 15/32"
(0.4687") pilot hole using a stubby drill bit.
Chamfered the hole before reaming.
Used a
0.4990" undersized reamer for a close fit to the motor's
shaft.
Lowest speed, lots of lubrication, & stop turning before
withdrawing the reamer.
Cut the set-screw shoulder area.
Using the center gage to set up
the 60° tool bit cutting angle which matches the Taig OEM pulley.
Cutting the pulley V-groove. Set & feed the
compound at 29° to reduce chatter; same method as thread
cutting.
Cutting
off the part.
Faced the other side of the pulley &
chamfered the hole.
Mounted in t he RF-25 mill, showing a #2
center drill bit which was then followed by a #21 drill bit.
Held the part in a smaller
2" vise so the setup could be easily
transferred to the hand tapper for threading.
See how to
center a hole on a part.
Hand tapper
used to make the 10-32 threads. This setscrew matches that used
on the OEM pulley.
Ground the set-screw tip smooth & flat so it would not gouge
the motor shaft & leave burrs.
Finished high-speed motor pulley.
Motor Mount
The small OEM spindle motor
mounting post restricted the range of movement when using the
short belt.
The new motor mounting post is 80% larger, held on with 3, 10-32 bolts, & uses
hardened steel T-nuts.
On the bottom of the motor mounting plate, one of the motor
bolts was made flush to clear the new post.
The larger, spindle motor mounting post holds
the motor much more rigidly & it's easier to adjust the
belt.
Top speed is now 8160 RPM. The pulleys are easily
re-positioned via their matched setscrews.
Tachometer
The Fairchild QRB1114
940nm
E-O sensor housing was mounted using Taig, pre-existing 10-32 tapped holes.
Tachometer output showing 8160 RPM (136Hz x 60) using the larger pulley. See
Taig mill tachometer modification.
Indicator Mount
Taig standard tool
post modified with a V-groove dimensioned to hold an 8mm
diameter (40mm long) centering
rod.
Held at 45°, the slot side is milled down to a scribe mark that is 4mm (the rod's radius)
from the bottom of
the original tool post slot. An 8mm rod (Noga arm) then securely rests in the V-groove & touches the
slot
bottom when clamped. The V-groove could have been made to hold a ⅜" diameter
(0.1875" radius) rod, too.
Noga
NF1018 indicator arm with ⅜" clamp held by the modified
V-groove tool post, mounted
off the headstock
side T-slot. Setup shows indicating a work piece before rotating to a
specific cutting angle. The Noga arm is very
good for
aligning mills, lathes & rotary
tables. Do not leave the dial test gage mounted on the head during motor
operation, too much vibration on a delicate mechanism. There is also a
magnetic base Noga indicator holder.
Another example showing a 4° (angled) slot
milled for a steel
cutoff tool holder.
ER-16 Spindle,
ER-16 Collets, Locking
Levers, Drill Arbor
Low-speed Countershaft,
High-Speed Pulley,
Motor Mount, Tachometer,
Indicator
Mount
