fann 280 User manual

Rheometer Calibration Fixture
Instruction Manual
Model 280 & 286
Instruction Manual Part No. 204210 Revision B

Copyright 2009
Fann Instrument Company
Houston, Texas, U.S.A.
All rights reserved. No part of this work covered by the copyright
hereon may be reproduced or copied in any form or by any means -
- graphic, electronic, or mechanical without first receiving the written
permission of Fann Instrument Company, Houston, Texas, U.S.A.
Printed in U.S.A.
NOTE
Fann reserves the right to make improvements in design, construction and
appearance of our products without prior notice.
®FANN is a registered trademark of Fann Instrument Company.
Fann Instrument Company
P.O. Box 4350
HOUSTON, TEXAS, U.S.A. 77210
TELEPHONE: [phone]
TOLL FREE:[phone]
FAX: [phone]

TABLE OF CONTENTS
Section Page
1 Description................................................................................................................1
2 Calibration Check Procedure Rheometer.................................................................3
3 Spring Calibration Procedure Model 280 Rheometer...............................................7
4 Spring Calibration Procedure Model 286 Rheometer.............................................11
5 Parts List.................................................................................................................15
Table
1 Calibration Weight vs Dial Reading..........................................................................4
Figure
1 Typical Torsion Shaft Assembly...............................................................................5
2 Model 280 Set Up.....................................................................................................6
3 Model 286 Set Up...................................................................................................10

1
SECTION 1
DESCRIPTION
The Rheometer Calibration Fixture is designed for calibration verification and calibration
adjustment of the torsion spring in either the Model 280 or the Model 286 Rheometers. This
instruction describes checking and adjusting the strength of the torsion spring such that a known
torque will produce a known deflection, (dial reading). In this calibration known weights will be
used to produce a known amount of angular rotation of the bob shaft, or dial reading. The
Newton-cm of torque/degree of dial deflection is known as the K1factor. The K1(spring factor) is
adjusted by adjusting the active length of the spring.
The Calibration Fixture may be used for:
Calibration of a replacement spring when it is being installed.
Verification of the calibration of the spring already in the instrument.
Re-calibration of the spring already in the instrument.
Check the following parts of the Rheometer for runout or damage. If any of these parts are bent
or otherwise damaged, repairs must be made before a successful calibration can be performed.
Check the following:
Bob Shaft and Bob for runout -- Straighten or replace.
Maximum total runout allowed is 0.005 in. (0.127 mm)
Sleeve for runout -- Straighten or replace.
Maximum total runout allowed is 0.005 in. (0.127 mm)
Deformed or damaged spring -- Replace.
Mis-aligned dial "0" -- Readjust zero, (Refer to Sections 3-F7 or 4-F9)
Torsion Shaft bearings defective --Replace

2

3
SECTION 2
CALIBRATION CHECK PROCEDURE
The Pulley Support, Pulley, and Calibration Spool are removed from the Calibration fixture and
mounted on the Rheometer base and bob shaft to check its calibration. Dis-assembly of the
Rheometer Sleeve, Bob, and Dust Shield is required.
If a Calibration of the spring is required, it will be necessary to remove the Torsion Shaft
Assembly. A typical assembly is shown in Fig. 1. Dis-assembly, spring re-calibration, and re-
assembly procedures are described in Section 3 for the Model 280 Rheometer and Section 4 for
the Model 286 Rheometer.
A. Rheometer Set Up for Dead Weight Calibration
1. Unscrew and remove the Sleeve, Bob, and Dust Shield from the Rheometer.
2. Remove the Pulley Support [8] from the Fixture by removing the two 6-32 x 1/2
long screws holding the Pulley Support to the Calibration Stand Base.
3. Slide the Pulley Support over the center of the front edge of the Rheometer Base.
Secure the pulley support by installing one of the screws just removed. This screw
is installed from under the Rheometer Base into the hole in the Pulley Support
closest to the pulley for the Model 280 Rheometer and away from the pulley for the
Model 286 Rheometer.
4. Screw Calibration spool [5] onto bob shaft, threads down, until it tight. Wind two to
three turns of thread around the drum clockwise as viewed from the top of the
spool. (Refer to Fig. 2 for Model 280 and Fig. 3 for Model 286) Route the thread
over the sheave, and allow it to hang. Make sure the thread does not lap over
itself on the spool.
5. Adjust the height of the Rheometer head up or down such that the thread [6]
coming off the spool and going to the pulley is
horizontal.
6. Verify the hairline on the Rheometer jewel is aligned with "0" on the dial to an
accuracy of +/- 1/2 division. If not the Rheometer should be zeroed. Refer to
Section 3-F7 for the Model 280 Rheometer or Section 4-F9 for the Model 286
Rheometer.
7. Operate the Rheometer at 300 RPM and observe that there is less than +/- 1
division of dial movement. Excessive dial movement probably indicates dirty,
corroded, or defective bob shaft bearings. This defect must be corrected before
running the calibration check.
8. Attach weights to loop in thread. Make sure that thread does not roll over itself as
it spools of and onto the drum.
9. Take readings as shown in the table 1.

4
B. Take readings as shown in the Table 1.
TABLE 1
WEIGHT
DIAL READING
25 GRAMS
103-104
50 GRAMS
204-206
75 GRAMS
309-312

5
Fig. 1
Typical Torsion Shaft Assembly

6
Fig. 2
Model 280 Set Up

7
SECTION 3
SPRING CALIBRATION PROCEDURE
MODEL 280 RHEOMETER
This procedure requires the removal of the Torsion Shaft Assembly, shown in Fig.1, from the
Rheometer, and mounting it in the Calibration Fixture.
A. Torsion Shaft Assembly Removal
1. Unscrew and remove the Sleeve, Bob, and Dust Shield from the Rheometer.
2. Place Rheometer speed shift lever in 300 RPM speed setting.
3. Remove flat head screw from center of Gel Knob.
4. Holding Gel Knob loosen hex set screw 1/4 turn using a hex key wrench and, then
unscrew and remove Gel Knob.
5. Move Speed shift lever to the STIR position and pull shift arm, cam, and bearing
off shift rod.
6. While holding rotor from turning, turn crank backward thereby unscrewing and
removing it.
7. Remove four 6-32 x 1/4 long screws holding cover to frame, then pull cover up and
off Rheometer.
8. Remove flat head screw [79] from top center of dial, then carefully lift dial straight
up and remove.
9. Loosen two Zeroing screws that act as set screws against the flat on the Torsion
Body, sufficiently to clear and allow removal of the torsion body.
10. Remove the large retainer ring on top of the Torsion Body.
11. Lift the torsion shaft assembly up and out of the Rheometer frame.
12. Re-assemble the Dial [60] onto the top of the Bob Shaft and secure it with screw
[79].
B. Preliminary Spring Setting
A preliminary setting of the torsion spring should be made prior to mounting it in the fixture.
Make this setting as follows:
1. Set the torsion spring assembly for approximately 9-1/4 to 9-1/2 pair turns by
rotating the outer collet [67-3]. (Refer to Fig. 1) on spring [67] to the proper point.
2. Grasp the flats on lock collet [64] with needle nose pliers between lower spring
coils. Holding the dial [60] turn it, torsion shaft, and collet [65] clockwise to loosen
the thin notched portion of lock collet [64] from the spring [67]. and collet 67-3].
3. Slide the spring, with the outer collet [67-3] on it, over lock collet [64] until top of
collet [67-3] is approximately even with top of lock bushing [65].

8
4. Grasp the flats on lock collet [64] with needle nose pliers between lower spring
coils. Holding the dial [60] turn it, torsion shaft, and collet [65] counterclockwise to
tighten the thin notched portion of lock collet [64] against spring [67]. and collet 67-
3].
C. Mounting Torsion Shaft Assembly in the Calibration Fixture.
Re-assemble the Calibration Fixture and set it up for the Model 280 torsion shaft
assembly. (Refer to Fig. 2).
1. Install the pulley [3] into the top hole of the Pulley Support Bracket.
2. Loosen the two screws holding the lower bearing support bar, [1] and position it at
the top of the slots for the 280 Rheometer and re-tighten the screws.
3. Slide torsion shaft assembly into fixture from the top. Position torsion body hub into
the hole in the top of the fixture and bearing [68] in the hole in the lower bearing
support bar [1]. Rotate the torsion body to align the flat of the torsion body cross
wise of the fixture. Secure the torsion assembly into the fixture by locking the lock
bar [4] over the flat of the torsion body.
4. Remount the Dial [60] onto the top of the torsion shaft [66] with screw [79].
5. Position the hairline/magnifier [2] in the lower groove of its support. Rotate the
hairline/magnifier [2] so the hairline aligns with the divisions on the dial and lock in
place. Loosen set screw [81-B] to loosen collet [67-2] in the torsion body [61], then
rotate the dial and bob shaft to align Zero with the hairline. Lock collet [67-2] in this
position with set screw [81-B].
6. Screw Calibration spool [5] onto bob shaft, threads down, until it is tight. Wind two
to three turns of thread around the drum clockwise as viewed from the top of the
spool. (Refer to Fig. 2.) Route the thread over the sheave, and allow it to hang.
D. Taking the Readings
Hang the 25, 50 and 75 Gram weights each in turn on the loop in the end if the thread and
note the dial readings obtained. (Refer to Table 1). If the dial readings are higher than
shown in Table 1 - shorten the active part of the spring. If the dial readings are lower than
shown in Table 1 - lengthen the active part of the spring.
E. Adjusting Torsion Spring:
1. Loosen hex set screw [81-B] holding upper spring collet [67-2] in torsion assembly
body [61].
2. Loosen torsion spring adjusting collet as described in Section 3B-2. If the readings
were too high, screw the threaded outer collet [67-3] up the spring pairs (1/4 turn
will drop 3-5 dial units). If the readings were too low, screw the threaded outer
collet [67-3] down the spring pairs (1/4 turn will change reading 3-5 dial units).
3. Align top of outer collet [67] slightly above top of widest section of lock bushing
[65]. Tighten torsion spring adjusting collet as described in Section 3B-4.

9
4. Push upper spring collet [67-2] into torsion assembly body [61] and lock it with hex
set screw [81-B] in a position so that dial zero aligns with the hairline.
5. Check calibration as described in Section 3D above. If still incorrect, repeat this
section.
F. Re-assembly of the Torsion Shaft Assembly into the Rheometer.
1. Loosen and rotate the hairline/magnifier out of the way of removing the Torsion
Shaft Assembly.
2. Unscrew the Calibration spool [5] and the thread [6] and remove them.
3. Remove screw [79], then remove dial [60].
4. Loosen and remove the lock bar [4] holding the Torsion Body, then lift the Torsion
Body out of the Calibration Fixture.
5. Place the Torsion Shaft Assembly in the Rheometer with the flat on the Torsion
Body toward the crank end of the rheometer, then install the retainer on top of the
Torsion Body.
6. Assemble the dial [60] and secure with screw [79].
7. Temporally place the cover, with the hairline jewel in it, in place and observe the
position of the hairline with relation to the "0" on the dial, then remove the cover
and adjust the two zeroing screws against the flat on the torsion body to slightly
rotate the torsion body as needed to align the "0" with the hairline. Recheck using
the cover and repeat if necessary. Both zero adjust screws should be tight against
the torsion body.
8. Place cover in place and install the four 6-32 x 1/4 long cover to frame screws.
9. Position shift arm in the STIR position, then install the shift arm, cam, and bearing
onto the shift rod. Move shift arm to the 300 RPM position.
10. Turn crank forward while holding rotor from turning, screwing it into place and
tighten.
11. Screw Gel Knob onto speed shaft as far as the hex set screw will allow. Use hex
key wrench and holding Gel Knob tighten the hex set screw. Test the operation of
the rheometer at 600 RPM and adjust the speed to 600 +/-3 RPM. If the
rheometer is running too slow loosen the set screw 1/4 turn, then screw the Gel
knob 1/4 turn further on. Re-tighten the set screw and retest. If the Rheometer is
running too fast, loosen the Gel knob using the above procedure.
12. When the 600 RPM speed is properly set, install the flat head cover screw.
13. Assemble the Dust Shield and the Bob onto the Bob Shaft, then screw the Sleeve
onto the Rotor.
NOTE: This spring calibration should be verified after assembly of unit in silicone
calibration fluid.

10
Fig.3
Model 286 Set Up

11
SECTION 4
SPRING CALIBRATION PROCEDURE
MODEL 286 RHEOMETER
This procedure requires the removal of the Torsion Shaft Assembly, shown in Fig.1, from the
Rheometer, and mounting it in the Calibration Fixture.
A. Torsion Shaft Assembly Removal
1. Disconnect the Rheometer from the power source.
2. Unscrew and remove the Sleeve, Bob, and Dust shield from the Rheometer.
3. Use hex key wrenches loosen the set screws holding the power ON/OFF switch,
the speed selector switch, and the knob for the variable speed control, then
remove these three knobs.
5. Remove the speed selector switch nut and the variable speed potentiometer nut
holding these parts to the stainless steel cover. Use socket wrenches or nut
drivers.
6. Remove two 6-32 x 1/4 long cover to frame screws on the sides near the front of
the Rheometer.
7. Remove two 6-32 x 1/4 long cover to power supply bracket screws in the back of
the Rheometer.
8. Carefully lift the cover up and off Rheometer.
9. Remove flat head screw [79] from top center of dial [60], then carefully lift dial
straight up and remove.
10. Remove printed circuit board by removing screws as follows:
Two 4-40 screws mounting the printed circuit board to the frame. These two
screws go through the circuit board from the top. One is near each side of the
board about 5 inches, (12.7 cm), from the square end.
One 1/4 inch long screw that attaches the power transistor to the frame on the right
side as viewed from the curved front of the Rheometer frame.
One 3/8 inch long screw that attaches the voltage regulator to frame on the left
side as viewed from the curved front of the Rheometer frame.
11. If the heat sink sealer has the power transistor or the voltage regulator stuck to the
frame, pry them loose.
12 Lift the printed circuit board upward and allow it to swing out of the way hanging
near the front left side of the instrument.
Loosen two Zeroing screws that act as set screws against the flat on the Torsion
Body, [item 6, Fig 1] (right hand side of frame) sufficiently to clear and allow
removal of the torsion body.

12
13. Remove the large retainer ring on top of the Torsion Body.
14. Lift the torsion shaft assembly up and out of the Rheometer frame.
B. Preliminary Spring Setting
A preliminary setting of the torsion spring should be made prior to mounting it in the fixture.
Make this setting as follows:
1. Set the torsion spring assembly for approximately 9-1/4 to 9-1/2 active pair turns
by rotating the outer collet [67-3] on spring [67] to the proper point. (Refer to Fig.
1)
2. Grasp the flats on lock collet [64] with needle nose pliers between lower spring
coils. Holding the dial [60] turn it, torsion shaft, and collet [65] clockwise to loosen
the thin notched portion of lock collet [64] from the spring [67]. and collet 67-3].
3. Slide the spring, with the outer collet [67-3] on it, over lock collet [64] until top of
collet [67-3] is approximately even with top of lock bushing [65].
4. Grasp the flats on lock collet [64] with needle nose pliers between lower spring
coils. Holding the dial [60] turn it, torsion shaft, and collet [65] counterclockwise to
tighten the thin notched portion of lock collet [64] against spring [67]. and collet 67-
3
C. Mounting Torsion Shaft Assembly in the Calibration Fixture.
Re-assemble the Calibration Fixture and set it up for the Model 286 torsion shaft
assembly. (Refer to Fig. 3).
1. Install the pulley [3] into the bottom hole of the pulley holder bracket.
2. Loosen the two screws holding the lower bearing support bar, [1] and position it at
the bottom of the slots and re-tighten the screws.
3. Slide torsion shaft assembly into fixture from the top. Position torsion body hub
into the hole in the top of the fixture and bearing [68] in the hole in the lower
bearing support bar [1]. Rotate the torsion body to align the flat of the torsion body
parallel with the fixture. Secure the torsion assembly into the fixture by locking the
lock bar [4] over the flat of the torsion body. For the Model 286 the bar [4] is
parallel with the fixture with its notched side holding the torsion body. (Refer to Fig.
3).
4. Remount the Dial [60] onto the top of the torsion shaft [9] with screw [79].
5. Position the hairline/magnifier [2] in its upper groove of the support. Rotate the
hairline/magnifier [2] so the hairline aligns with the divisions of the dial and lock in
place. Loosen set screw [81-B] to loosen collet [67-2] in the torsion body [61], then
rotate the dial and bob shaft to align 0 on dial with hairline/magnifier. Lock collet
[67-2] in this position with set screw [81-B].
6. Screw Calibration spool [5] onto bob shaft, threads down, until it is tight. Wind two
to three turns of thread around the drum clockwise as viewed from the top of the
spool. (Refer to Fig. 3.) Route the thread over the sheave, and allow it to hang.

13
D. Taking the Readings
Hang the 25, 50 and 75 Gram weights each in turn on the loop in the end if the thread and
note the dial readings obtained. (Refer to Table 1). If the dial readings are higher than
shown in Table 1 - shorten the active part of the spring. If the dial readings are lower than
shown in Table 1 - lengthen the active part of the spring.
E. Adjusting Torsion Spring:
1. Loosen hex set screw [81-B] holding upper spring collet [67-2] in torsion assembly
body [61].
2. Loosen torsion spring adjusting collet as described in Section 3B-2. If the readings
were too high, screw the threaded outer collet [67-3] up the spring pairs (1/4 turn
will drop 3-5 dial units). If the readings were too low, screw the threaded outer
collet [67-3] down the spring pairs (1/4 turn will change reading 3-5 dial units).
3. Align top of outer collet [67] slightly above top of widest section of lock bushing
[65]. Tighten torsion spring adjusting collet as described in Section 3B-4.
4. Push upper spring collet [67-2] into torsion assembly body [61] and lock it with hex
set screw [81-B] in a position so that dial zero aligns with the hairline.
5. Check calibration as described in Section 3D above. If still incorrect, repeat this
section.
F. Re-assembly of the Torsion Shaft Assembly into the Rheometer.
1. Loosen and rotate the hairline/magnifier out of the way of removing the Torsion
Shaft Assembly.
2. Unscrew the Calibration spool [5] and the thread [6] and remove them.
3. Remove screw [79], then remove dial [60].
4. Loosen and remove the lock bar [4] holding the Torsion Body, then lift the Torsion
Body out of the Calibration Fixture.
5. Place the Torsion Shaft Assembly in the Rheometer with the flat on the Torsion
Body toward the right side of the Rheometer, then install the retainer on top of the
Torsion Body.
6. Reposition the printed circuit board on the top of the Rheometer. Be especially
careful to make sure the following are not damaged.
Make sure the encoder disc on the motor flywheel fits into the groove of the
photo transistor sensor assembly. DO NOT BEND THIS DISC.
Make sure the heat sink surfaces on the power transistor and the voltage
regulator and the corresponding surfaces of the frame have been cleaned
and new heat sink compound has been applied.

14
Make sure all holes in the circuit board are in line and nothing is binding the
circuit board as it is assembled into place.
Make sure the two top mounting holes are in line and the holes for the
power transistor and voltage regulator are in line.
7. Mount the circuit board by installing the following screws:
Two screws from the top of the PC board into the frame
One screw holding the power transistor to the frame
One screw holding the voltage regulator to the frame
8. Assemble the dial [60] and secure with screw [79].
9. Temporally place the cover, with the hairline jewel in it, in place and observe the
position of the hairline with relation to the "0" on the dial.
Remove the cover and adjust the two zeroing screws on the right side of the frame
and against the flat on the Torsion Body. Loosen one and tighten the other to
slightly rotate the torsion body as needed to align the "0" with the hairline.
Recheck using the cover and repeat if necessary. Both zero adjust screws should
be tight against the torsion body when adjustment is complete.
10. Install Cover be installing the following fasteners:
Two 6-32 x 1/4 long cover to frame screws
Two 6-32 x 1/4 long cover to power supply bracket screws.
Nut cover to speed selector switch
Nut cover to variable speed potentiometer. (Use socket wrenches or nut
drivers).
11. Install switches. Use hex key wrenches to tighten their set screws. Make sure
these set screws are seated on the flats on the switch shafts.
Power ON/OFF switch
Speed selector switch knob
Variable speed control
12. Assemble the Dust Shield and the Bob onto the Bob Shaft, then screw the Sleeve
onto the Rotor.
13. Connect the Model 286 Rheometer to the power source and test its performance.
NOTE: This spring calibration should be verified after assembly of
Rheometer by the silicone oil calibration method. Refer to
Model 286 Instructions.

15
SECTION 5
PARTS LIST
A. Calibration Stand Parts List
Part No.
Description
207096
Weights, 25 grams & 50 grams
207849
Thread
204210
Instructions
205683
Bearing, bob shaft
B. Optional Calibration Fluids
PART NO.
DESCRIPTION
207124
Calibration Fluid 10 cP
207119
Calibration Fluid 20 cP
207120
Calibration Fluid 50 cP
207121
Calibration Fluid 100 cP
207122
Calibration Fluid 200 cP
207123
Calibration Fluid 500 cP

Warranty
Fann Instrument Company warrants the product to be free from defects in material and
workmanship for a period of twelve months. If repair or adjustment is necessary, and has not
been the result of abuse or misuse within the twelve month period, please return, freight prepaid,
and correction of the defect will be made without charge.
For your protection, items being returned must be carefully packed to prevent damage in
shipment and insured against possible damage or loss. Fann will not be responsible for damage
resulting from careless or insufficient packing.
Out of warranty products will be repaired for a nominal charge.
Return of Items
Before returning items for any reason, authorization must be obtained from Fann Instrument
Company. When applying for authorization, please include information regarding the reason the
items are to be returned.
The correspondence address is:
Fann Instrument Company
P.O. Box 4350
Houston, Texas 77210
U.S.A.
Telephone: [phone]
Toll Free: (800)-347-0450
Fax: [phone]
The shipping address is:
Fann Instrument Company
15112 Morales Road
Houston, Texas 77032
U.S.A.