| Note:
Do not use Loctite or thread locks on the assembly.
They are not necessary and may cause damage to the
Lexan. |
Image of arm
without base, or gripper.
|
Step
1.
Assemble
the forearm structure as illustrated. Use four of
the .250" 4-40 screws and four of the
.750" hex spacers. Tighten these down snugly.
|
Figure 1. |
Step
2.
Attach
the wrist servo as shown. Turn over the forearm
assembly, sandwich the servo mounting tabs in
between the forearm assembly and the plastic
panel with the Lynx logo on it. Use two of the
.375" 4-40 screws for this step. Tighten
these down snugly.
|
Figure 2. |
Step
3.
Attach
the elbow servo as shown. The servo wire goes
inside the forearm assembly in the opening
provided. Use two of the .375" 4-40 screws.
Tighten these down snugly.
|
Figure 3. |
Step
4.
Install
the servo hinges as shown. Remove the green
plaid cover from the double sided tape and press
it firmly into place. The hinge should be lined
up with the edge of the servo, directly across
from the servo output shaft.
|
Figure 4. |
Step
5.
Drill
the servo horn with the 3/32" drill in the
indicated positions. These holes are by the 2
and the 4 molded on the horn. Do this to both
servos.
|
Figure 5. |
Step
6.
Next,
we need to rotate the elbow servo's output horn
by 90 degrees. Remove the screw from the center
of the elbow servo horn (the one on the right)
and pull it off of the servo. Move the servo to
its center of rotation using a servo controller
or a microcontroller.
The SSC-12 will automatically produce the proper
1.5mS pulses when powered up. It is not
necessary to connect it to a PC or
microcontroller for this procedure. Consult the
documentation that came with your electronics if
you are using something other than the SSC-12.
Reinstall the servo horn as illustrated.
|
Figure 6. |
Step
7.
You
should have a small bag of parts packaged with
your servos. Locate the four small rubber
bushings and install them onto the servo as
illustrated in figure 7. These parts are
polarized, meaning they can only be installed
one way. If you have difficulty, try turning the
part around. The other components in the
servo parts bag are not needed. Do this for the
remaining two HS-475 servos.
Note:
These servos will make up the shoulder of the
arm. They will receive the same control signals
via a "Y" cable. Therefore, they will
both move to the same commanded position.
|
Figure 7. |
Step
8.
Mount
the servos to the servo bracket as shown. Use
four of the .375" 4-40 screws and four of
the 4-40 nylon insert lock nuts. Make two of
these.
|
Figure 8. |
Step
9.
Now
we need to rotate these servo horns by 90
degrees. Remove the screw from the center of the
servo horn, and pull it off of the servo. As
before, position the output shaft to its center
of rotation and reinstall the servo horn. Drill
the servo horn with the 3/32" drill in the
indicated positions. These holes are by the 2
and the 4 molded on the horn. Do this the both
servos.
|
Figure 9. |
Step
10.
Attach
the arm upright panels to the servos as
illustrated. Be careful not to over tighten
these screws as they can strip out the nylon
servo horn. The assembly on the right is
adjustable. It will go on the robots left side
to allow adjusting the dual servo arrangement
later in the setup.
|
Figure 10. |
Step
11.
Make
two 1.875" cross members using the
.375" and 1.500" nylon spacers. Attach
them to the arm uprights as illustrated in
figure 11 using four of the .250" 4-40
screws. Make sure the upright with the enlarged
adjusting holes is on the outside so it can be
adjusted later.
|
Figure 11. |
Step
12.
Attach
the forearm to the uprights as shown. The
uprights can be spread apart without worrying
about breaking something. Install the two
.250" #4 screws and tighten them snugly.
|
Figure 12. |
Step
13.
Attach
the 7" nylon wire ties to strengthen the
forearm assembly. Do this two both ends of the
forearm. Pull these tight.
|
Figure 13.
|
Step
14.
Now it's time to align the shoulder servos. Plug
both shoulder servos into the "Y" adaptor,
and plug the other end into any channel on the
SSC-12 servo controller. Power it up and the two
servos should move to their center of rotation. They
probably will not be lined up at this point. Now
loosen the two .250" #4 screws on the
adjustable upright. Place the arm on the table so
the two shoulder servos are sitting flat. Then
carefully tighten the two screws. Now the two servos
that make up the shoulder are mechanically aligned.
Also add the 6" extender cable to the wrist
servo cable. Plug the elbow and wrist servos into
the SSC-12. The arm should look like figure 14. If
not then the servos probably were not properly
aligned during the construction. Remove the servo
horn screws, pull the horn off the servo, align it
properly, push the servo horn back onto the servo,
then replace the servo horn screw. |
Figure 14.
|
Step
15.
Now the arm can be mounted to one of the
optional rotating bases or a mobile robot such as
the CRL5 or the 4WD2. The .375" 4-40 hardware
is used for this purpose.
|
Figure 15. |
