Sherline Products WETTROTH 8100 User manual

SHERLINE/WETTROTH
Mill Digital Readout
P/N 8100 (Metric P/N 8160)
SHERLINE
PRODUCTS
INCORPORATED 1974
SHERLINE PRODUCTS INC. • 3235 Executive Ridge • Vista • California 92081-8527 • FAX: [phone] • Toll Free Order Line: [phone]
Local, International and Tech. Assistance: [phone] • Internet: www.sherline.com • E-mail: [email protected]
1/17/08 Page 1 of 6
The Digital Readout in the modern machine shop
Digital readouts are popular on full size mills because they
make the life of a machinist much simpler. They make
it easier to accurately set or change the table position
and eliminate errors caused by misreading handwheel
increments or losing track of multiple rotations. Now that
same convenience is available on tabletop size machines
with the availability of a D.R.O. (Digital ReadOut) for
Sherline mills. The compact electronics package and
clever backlash compensation feature were designed by
John Wettroth.
On industrial DRO’s, a sensor reads a highly accurate
external scale. On Sherline’s DRO, the sensor reads rotation
of the leadscrew. Because of the accuracy of Sherline’s
precision rolled leadscrew threads and the short travels
on a machine of this size, this system makes it possible to
provide a DRO with sufficient accuracy while maintaining
a price appropriate for a machine of this size and cost.
The kit can be installed on any Sherline mill, regardless of
age and is very easy to use. Remember that the directions
of movement of the mill are referred to as the X-axis (table
side-to-side), Y-axis (table in-out) and Z-axis (spindle up-
down). The readout of any axis can be set to zero at any
time with the push of a button. As you move the handwheels
you can read the table position to three and a half decimal
places on the digital readout. It is not necessary to keep
track of the number of handwheel rotations to figure the
stopping point on larger dimensions. This will be especially
appreciated when cranking in “negative” amounts. Backlash
is compensated for by setting it into the unit’s electronic
memory in increments of .0005". As a bonus, the package
also includes an electronic readout of spindle RPM at all
times.
Installing the D.R.O. components on your Sherline mill
The following instructions describe the steps required to
remove the existing handwheels and thrust collars and
replace them with the D.R.O. encoder/handwheel units.
It is suggested that you remove the headstock and motor
assembly from the mill to make it easier to install the D.R.O.
components. (“Left” and “Right” refer to the operator's
left and right sides when facing the mill with the X-axis
handwheel on your right.)
1. Move the table all the way to the left. This will limit
movement of the leadscrew and help center the new
collar.
2. Move the table all the way to the front toward the
operator.
3. Raise the headstock all the way to the top of its travel.
4. Using a 3/32" hex wrench, remove all three handwheels
by releasing their set screws and sliding them off their
leadscrews. (If your mill has resettable “zero” handwheels,
loosen the collar locking knob and rotate the collar until
the hole lines up with the set screw. Then use the 3/32"
hex wrench to loosen the set screw and remove the entire
handwheel/collar unit.)
5. Using a 3/32" hex wrench, remove the 5-40 screws
holding the thrust collars on the X- and Y-axis leadscrews.
Remove the collars.
FIGURE 1—Installing
the new thrust collar on
the X- and Y-axes
NEW COLLAR
EXISTING SCREW LEADSCREW SHOULDER
LEADSCREW

6. Clean each grooved thrust collar with a solvent like
acetone or lacquer thinner to remove any oil from the surface.
(You will later lock them in place in relation to the plastic
housing with "instant glue" and it will not stick to an oily
collar.) Using the existing screws, install new grooved thrust
collars on the X- and Y-axes, making sure the leadscrew is
centered in the collar. Make sure the screws are secure, but
do not overtighten. If a shim washer was present on your
existing leadscrew, reinstall it as it was before.
7. Install a new handwheel and encoder ring on the X- and
Y-axes. (The encoder ring has been factory installed on
the handwheel for easier assembly.) Note that the X and Y
handwheels are similar except on the X-axis, the numbers on
the handwheel face away from the handwheel. On the Y-axis
they face toward the handwheel. Make sure the shoulder at
the end of the leadscrew thread is seated against the thrust
collar and the handwheel is pushed in tightly to remove end
play before tightening the set screw. On the X-axis, push
the table AWAY from the handwheel while pushing the
handwheel onto the leadscrew shaft. On the Y-axis, hold the
table (not the base) with one hand and push the handwheel
onto the shaft with the other. Rotate the handwheel so that
the set screw tightens on a new part of the shaft. If you
don't, it will tend to pick up it's old indentation making it
difficult to tighten it in a new position.
See Figure 3 for orientation of the encoder housing. The
thicker shoulder inside the encoder should be facing
toward the thrust collar. It is easier to tighten the screws if
you install the units upside down with the screws coming
down from the top. Place the two halves of the shell over
the thrust collar and over the encoder ring and install the
four #2 x 3/8" self-tapping screws. Draw the screws down
until they seat snugly, but DO NOT OVERTIGHTEN or
you will strip the threads! Once tightened into position, the
unit can be rotated around until the screws and cable are
on the bottom.* When finished, the cable from the X-axis
encoder should come off to the rear, and the cable from the
Y-axis encoder should come off to the right.
*NOTE: The unit should be tight enough so that it doesn't
move accidentally once positioned. If it rotates too easily
1. First the shell is installed over the thrust
collar and handwheel upside down. (Left)
2. Then the shell is rotated into position
with the cable lead on the bottom. (Below)
P/N 8100, Page 2 of 6
FIGURE 2—Making sure the leadscrew is centered
FIGURE 3—(Above) Detail of the encoder housing showing
direction of installation
FIGURE 4—Installing the encoder unit over the thrust
collar. The unit can be installed upside down to make it
easier to put in the screws. It is then rotated into position
and tightened to lock it in place.
TOWARD THRUST COLLAR
THICKER SIDE OF HOUSING
FIGURE 5—Rotating the unit into its proper position. (Note:
Handwheel/encoder unit not shown for clarity.)
CENTER LEADSCREW BEFORE TIGHTENING SCREW

when the screws are tightened, you can remove the housing
shell and sand the mating surfaces on a piece of sandpaper
on a flat surface until they grip the collar tightly enough.
8. Using a 1/8" hex wrench, remove the flat head screw
that holds the Z-axis thrust collar to the column. Remove
the collar by lifting it up and off the Z-axis leadscrew. If
the spacer washer sticks to the bottom of it, remove it and
reinstall it on the leadscrew shaft. Then remove the ball
bearing thrust and two washers from the collar and reinstall
them in the new Z-axis thrust collar in the same order. (See
Figure 6.) Install the new collar on the leadscrew shaft and
secure it to the bed with the flat head screw.
9. Install the remaining handwheel and encoder unit onto
the Z-axis leadscrew. Lift up on the saddle assembly until
the washer and shoulder of the leadscrew are all the way
up against the bottom of the collar. Then push down on the
handwheel and tighten its set screw, being sure to tighten
it against a new spot on the shaft. If installed on your
machine, reinstall the 5-40 x 3/8" flat head screw through
the center of the Z-axis handwheel and into the end of the
leadscrew. See "Adjustment the Z-axis handwheel" on page
4 for more details on adjusting this screw. Install the pickup
housing over the handwheel unit as shown in Figures 4
and 5. When finished, the cable should exit toward the left
when viewed from the front.
10. The sensors that read geartooth position as you turn
the handwheel are located in the bottom of the handwheel
housing. If the housing moves, it is the same as if you
moved the handwheel, because it changes the relationship
between the sensor and the geartooth. Therefore, the
housing should be anchored in place so that it cannot be
inadvertently moved. The screws that hold the two halves
together go into plastic, and overtightening them can strip
the threads out of the hole. A good solution is to place a
drop of "super glue" between the plastic housing and the
metal collar once the housing is positioned where you want
it. This will keep it in place but can still be broken loose
if you need to later.
Installing the RPM sensor
1. Reinstall the headstock/motor/speed control onto the
mill.
2. Peel off the backing and apply the 2-1/2" round decal
to the pulley. (HINT: A little liquid window cleaner on
the pulley allows the decal to be repositioned and bubbles
squeezed out before it sticks. Once the liquid is squeezed
out and dries, the adhesive on the sticker will stick fine.)
3. Locate the RPM sensor by holding it in the position shown
in Figure 7. Mark the center of the hole on the plastic belt
housing and drill a 1/16" hole. Fasten the sensor to the belt
housing using the self-tapping screw provided. (Do not
overtighten or you can strip the threads.) A plastic tie-wrap
is provided to secure the sensor lead to the motor’s power
cord to keep it out of the way.
NOTE: If you have a mill with an older AC/DC motor that
does not have a plastic belt guard, the RPM sensor can be
mounted in the proper position over the pulley by attaching
it to the motor mounting bracket. Locate and mark where
the hole should be drilled. Remove the motor and drill a
hole through the bracket. You can use a self-tapping sheet
metal screw or a bolt and nut through the hole or you can
tap the hole to match the thread of the bolt you use.
Hooking up the connecting cables
Plug the cable connector from each encoder unit into is
respective port on the display unit. The telephone type cable
connectors go in with the locking tab facing up when the
unit is lying on its back. The RPM sensor cable goes into
the port marked “Tach In”.
Plug the power adapter into the bottom hole marked
“DC In”, and plug the transformer into a 115 VAC (60 Hz.)
source. Check to make sure all three axes are functioning.
Turn on the motor and check to see that the RPM indicator
is functioning.
Initializing your display for inch or metric leadscrews
When you press the “Power” button to turn your system on,
the upper right corner of the display will read either “inch”
or “metric” mode. Normally, the DRO will be set up properly
when you receive it, but there is always a possibility it could
be set wrong. To set or change the system of measurement
your unit displays, follow these steps:
1. With the power off, unplug the power cable from
the display unit.
2. INCH—Hold down both the “Power” button and
the X-axis button while you plug the power cord
back into the display unit. After the display comes
up, release the buttons. The display should now read
in inch dimensions.
3. METRIC—To initialize your display unit to read metric
dimensions, hold down the “Power” and “Y”buttons
while plugging the power cord back into the display
unit. Once initialized, the unit will always read in your
chosen system of measurement each time it is turned
on unless you change it.
Drill 1/16" hole and mount
sensor head using the self-
tapping screw provided.
PLASTIC TIE-WRAP
RPM SENSOR
VINYL DECAL
P/N 8100, Page 3 of 6
FIGURE 7—Mounting the sensor to the belt housing

P/N 8100, Page 4 of6
NOTICE! THE DISPLAY DOES NOT CONVERT
DIMENSIONS FROM INCH TO METRIC!
The DRO reads rotary handwheel movement and
converts it to a linear dimension based on a formula
assuming a certain leadscrew thread pitch. The DRO
must be set to agree with the leadscrews installed on
your machine to provide accurate measurements.
The only difference between the inch and metric packages
is the number of divisions engraved into the handwheels.
The electronics package is the same for either and can be
set to read in either measurement system depending on the
leadscrews of the machine on which it is installed.
Setting the backlash compensation values
To set backlash compensation for each axis, you must
first measure to determine what the backlash is. Use a dial
indicator to determine how far the handwheel on each axis
rotates before the table starts to move. (If this amount is
excessive, see your instruction manual for instructions
on setting backlash. It should ideally be in the .003" to
.005" range.) Once the amount is determined, the backlash
is compensated for by setting it into the display unit’s
memory.
To set the measurement system to correspond to your
machine's leadscrews, complete the following steps for
each axis:
1. Turn the handwheel for each axis one full turn
clockwise. This assures that the software starts the
backlash compensation at the proper initial point.
2. Hold down the “Power” button for longer than a
second until the display changes.
3. Now you can set in the backlash for each axis by
pushing the button for that axis. Each time the button
is depressed, .0005" (or .01 mm on metric units) is
added to the reading. Set in the amount of backlash
you measured previously for each axis. Amounts
up to .015" (.50 mm) can be set. (Note: You cannot
cycle backwards to a lower number. If you go past
your desired setting you must continue pushing the
button until the reading passes .015" or .50 mm and
returns to zero. Then start over.)
4. Once the backlash for all three axes is set, briefly
push the “Power” button again to return the display
to its normal reading. The backlash setting can be
checked or changed at any time by holding the
power button until the display changes. The amount
can then be reset as described in instruction number
3 above. Once set, backlash settings are held in a
special memory chip even if the unit is turned off and
unplugged. They remain until you change them.
Adjusting the Z-axis handwheel screw
To adjust tension on the screw, first remove all Z-axis
backlash in the conventional manner by lifting the motor/
speed control unit by hand while tightening the handwheel
set screw on a “fresh” quadrant of the leadscrew to avoid
picking up any previous indentations. Once adjusted, tighten
the center screw* only until it is “finger tight”. Use a very
small amount of Loc-tite® on the end of the screw to keep it
in place. (Do not coat the threads or the screw may become
impossible to remove.) Overtightening the screw will cause
the handwheel to become hard to turn. The purpose of the
screw is not to adjust backlash, but rather to keep it from
increasing once it is properly adjusted. Do not try to use
the screw to pull out additional backlash. The small 5-40
threads are not strong enough for this task.
*Note: If installing the Z-axis DRO handwheel on an older
machine that does not have a 5-40 hole in the end of the
leadscrew this screw is not used.
A few more tips
When in use, shield the unit from chips so they don't
accumulate around the telephone jack connections on
the side. Do not use an air hose to clean the unit.
A metal stand is included with your DRO so you can stand
the unit up on your workbench. This makes it easier to
read while you work. If you wish to secure the box to the
stand, a piece of double-sided foam tape or hook-and-loop
(Velcro®) tape are good methods.
Reversing the direction of the reading on the X-axis
The X-axis readout is designed to read negative numbers
when the handwheel is turned in the clockwise direction
and positive when turned counter-clockwise. Should you
wish to change your readout so that it uses a standard x-
y plot, you can do so by switching two of the four wires
coming from the encoder for the X-axis.
To do so, unplug the X-axis cable from the readout box.
Remove the four screws that secure the lower housing to
the upper housing and then remove the encoder halves from
the handwheel. On the bottom of the half with the encoder
is a cover plate secured by three screws. Remove these
screws and the cover plate. This will expose the soldered
connections for the four wires coming from the encoder.
To reverse the direction of the readout, unsolder the green
and black wires. Reverse their position and re-solder to
the encoder leads. Reinstall in reverse order. The diagram
below shows the factory locations of the wires before the
swap is made.
Figure 8—The drawing on the left shows the encoder hous-
ing and wires coming from the plug. The diagram to the
right shows a schematic of where each wire is connected.
Swapping the black and green wires will change the + and
– directions of the readout.

NOTE: The wires and solder joints are small and delicate.
If you don't have a suitable soldering iron and a little
expertise along these lines you may return your encoder
housing to the factory and we will make the change for you
at no charge. Call first for a return authorization number
and instructions on how to return your housing.
Getting the most out of your DRO
When using a machine equipped with a digital readout, I
find it is best to use either the readout or the handwheels,
but not both. If the displayed accuracy of .0005" (.01mm)
is satisfactory for the job you are doing, use just the digital
readout and disregard the handwheel settings. In cases
where you might want to interpolate to a higher degree
of accuracy, the markings on the handwheels will allow
you to do this.
An example of this would be where you have located the
center of a bored hole and then changed the table position.
To return the spindle exactly to the hole's center again using
the digital readout could leave you a few ten-thousandths
off, which may not be acceptable. In this case, you should
write down your handwheel settings and direction the
handwheel was last turned before moving from the desired
location. This will allow you to return to the same spot
with great accuracy. The handwheel marks are .001" or
.01mm apart. By reading the space between the marks on
the handwheel and interpolating your position, you can
achieve a high degree of accuracy. Knowing your machine
is an important part of achieving this kind of accuracy, and
as you get more familiar with your machine, your accuracy
will continue to improve.
Sherline's DRO brings modern machine shop technology
down to tabletop size and makes your Sherline tools easier
and more fun to use. I think you will find the digital readout
to be a great addition to your Sherline machine shop.
Joe Martin, President and Owner
Sherline Products Inc.

P/N 8100 Mill Digital Readout
REF PART
NO NO DESCRIPTION
1 81010 Mill DRO box and electronics (complete)
2 81320 X-axis handwheel, inch (Metric 81322)
81330 Y-axis handwheel, inch (Metric 81332)
81340 Z-axis handwheel, inch (Metric 81342)
3 81100 Encoder housing w/ wheel and cable
4 81110 Encoder housing upper cap
5 81120 Encoder housing body
6 81130 Encoder housing lower cap
7 81300 X- and Y-axis thrust collar
8 81350 Z-axis thrust collar
9 81280 #2 x 3/8” Self-tapping pan head screw
REF PART
NO NO DESCRIPTION
10 81270 2-56 x 3/8" pan head Phillips screw
11 81500 Tachometer encoder & cable asby.
12 81510 Tachometer pickup decal
13 40440 #2 x 1/4” Self-tapping pan head screw
14 81310 Encoder star gear
-- 81080 Black tie-wrap (not shown)
-- 81050 115 VAC Power supply/transformer(not
shown)
– 81150 Stand for readout display box (not shown)
– 45010 Z-axis handwheel support screw (not
shown)
Exploded View and Parts Listing
2
14
4
5
6
7 (X- and Y-axes)
8 (Z-axis)
Cable
9
Sensors
NOTE: Some numered items are complete assemblies. Items
not for sale individually do not have part numbers listed.
12
1
Asby. 3*
*Assembly includes housing,
sensors, cable and screws but
not handwheel and gear.
P/N 8100, Page 6 of 6
10
11
Assembly
Tach sensor
Cable
Sensor housing
13
* NOTE: The Z-axis handwheel has a hole through the center and comes with a 5-40 x 3/8" flat head screw that goes into the
end of the Z-axis leadscrew. The screw is P/N 45013.