| Parameter | Dimension | Units |
| Encoder Base Plate Thickness |
.135 |
in. |
| 3 Mounting Screw Size |
0-80 |
in. |
| 3 Screw Bolt Circle Diameter |
.823 ±.005* |
in. |
| 2 Mounting Screw Size |
2-56 or 4-40 |
in. |
| 2 Screw Bolt Circle Diameter |
.750 ±.005 |
in. |
| 2 Screw Bolt Circle Diameter |
1.280 ±.005 |
in. |
| 2 Screw Bolt Circle Diameter |
1.812 ±.005 |
in. |
Required Shaft Length With E-option* With H-option |
.445 to .525** .445 to .670** >.445** |
in. in. in. |
* Only for shaft diameters <.472".
** Add .125" to the required shaft length when using M-option.
| Parameter | Max. | Units |
| Vibration (5 to 2kHz) |
20 |
g |
| Shaft Axial Play |
0.01 |
in. |
| Shaft Eccentricity Plus Radial Play |
0.004 |
in. |
| Acceleration |
250,000 |
rad/sec² |
Note that radial play translates directly to position inaccuracy.
A leads B for clockwise shaft rotation, and B leads A for
counterclockwise rotation viewed from the cover/label side of the
encoder (see the EM1 / HEDS page).
Be sure to keep different diameters, resolutions and options separated.
The resolution of the optoelectronic modules and the code wheels must
match. Index and non-index parts cannot be mixed since the optical
patterns are different. An identifier is stamped on each optoelectronic
module.
For Agilent Modules (HEDS): The 2-channel (non-index) version can be identified by a 9100 or 9200.
The 3-channel (index) version can be identified by a 9140. One suffix letter
specifies the resolution as shown in the table below.
For US Digital Modules (EM1): The first number identifies the size of the disk this module is to be
used with. The second number identifies the resolution as shown in the
table below. The 3-channel (index) version is standard and not denoted
unless the module is non-index. The 2-channel (non-index) can be
identified by a -N.
| Disk | Standard | Index |
| 64 |
- |
2-64 |
| 100 |
S |
S |
| 200 |
C |
C |
| 400 |
E |
E |
| 500 |
E |
F |
| 512 |
A |
- |
| 1000 |
B |
B |
| 1024 |
J |
J |
| 1800 |
- |
2-1800 |
| 2000 |
T |
T |
| 2048 |
U |
T |
| 2500 |
2-2500-N |
2-2500 |
Index
Provides a single pulse per revolution.

3-option
3-option makes all five of these hole diameters .125". If desired, the two .096" diameter recesses will mate with matching aligning pins. The .438" diameter center hole can also mate with a motor boss. If a motor boss is lacking, a centering tool is usually required to mount the base in proper position to the shaft.

E-option
The E-option provides a cylindrical extension to the cover allowing for longer shafts of up .670". This option is only for shaft diameters <.472".

H-option
The H-option adds a hole to the cover for the shaft to pass through.
- Shafts <=1/2", a 0.55" diameter hole is supplied.
- Shafts >1/2", a 1.05" diameter hole is supplied.

M-option
These adapter plates are for mounting to a 3" diameter bolt circle. Use two 4-40 x 1/4" screws (sold separately) to attach the E3 base to the plate. Comes attached when ordered with encoder.

T-option
When mounting holes are not available, a pre-applied transfer adhesive (with peel-off backing) is available for "stick-on" mounting. Use the centering tool (sold separately) to slide the base into position. T-option specifies transfer adhesive on the standard mounting base.
Instructions: To use transfer ahesive, peel off paper backing and slip tool into center hole of the base and slide both down shaft as one piece. Press to form a good bond, then slip tool off and continue with the standard mounting instructions. A centering tool is highly recommended when using transfer adhesive.
Centering Tools
* May need to order separately, only included with PKG3-packaging option.
Part #: CTOOL - (Shaft Diameter)
Description:This reusable tool provides a simple method for accurately centering the E3 base onto the shaft in order to promote concentricity and thus, higher accuracy. It is recommended for the following situations:
- When using mounting screws smaller than 4-40.
- When the position of the mounting holes is in question.
- When using the 3-hole mounting pattern.
- When using the T-option transfer adhesive.
Instructions: When mounting encoder base, slide centering tool down shaft until it slips into centering hole of encoder base. Tighten mounting screws, then remove centering tool.
Hex Tools
* May need to order separately, see below for more information.
Part #: HEXD-050
Description: Hex driver, .050" flat-to-flat for 3-48 or 4-48 set screws. Only included with default or PKG1-packaging options.
Part #: HEXW-050
Description: Hex wrench, .050" flat-to-flat for 3-48 or 4-48 set screws. Only included with PKG2 or PKG3-packaging options.
Spacer Tools
* May need to order separately, see below for more information.
Part #: SPACER-265
Description: For shafts <=.394".
Part #: SPACER-260
Description: For shaft sizes 12MM or 1/2 IN.
Part #: SPACER-555
Description: For shafts >=.551".
Screws
* For base mounting only, screws for mounting the housing to the base are already included.
Part #: SCREW-080-250-PH
Description: Pan Head, Cross Drive 0-80 UNF x 1/4"
Quantity Required for Mounting: 3 per encoder
Part #: SCREW-256-250-PH
Description: Pan Head, Cross Drive 2-56 UNC x 1/4"
Quantity Required for Mounting: 2 per encoder
Part #: SCREW-440-250-PH
Description: Pan Head, Cross Drive 4-40 UNC x 1/4"
Quantity Required for Mounting: 2 per encoder