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C00002 00002 NOTES FOR ASSEMBLY OF STANFORD ARM KIT COMPONENTS
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NOTES FOR ASSEMBLY OF STANFORD ARM KIT COMPONENTS
by VICTOR SCHEINMAN- VICARM
MARCH 20, 1975
The Stanford arm kit of components consists of all the parts
mentioned in the purchased parts list plus all the custom
manufactured parts denoted with an "S" in the set of arm drawings
supplied with the kit. In addition, all modifications to the
purchased parts, if necessary, are completed by Vicarm.
The kit is shipped in three or four separate shipments. The
first shipment is the bearing shipment. Not all bearings are
shipped, as some are used in the subassemblies supplied later. The
bearing shipment should allow the user to assemble most of the basic
arm components. Joints 1,2,3,4,5, and 6 can all be connected
together for fitting purposes.
Notes on the installation of bearings.
Joint 1: First slip the clamp ring (9-9a) onto the drive tube(9-5)
. (The drive tube should have the screw access holes already
drilled, as noted in the latest drawing set. Then the upper bearing
- KA-040-XP0 is slipped on the drive tube. Then the retaining ring
(9- ) is slipped on. Using machinists clamps, clamp the retaining
ring-bearing -drive tube flange together tightly and dowel pin the
retaining ring in place. Mark the ring and tube so it can be removed
and replaced in the same spot in the future. The lower bearing (
KB-040-XP0 )is tipped sideways and dropped into the main tube. It
should be a light slip fit on both the main column and the drive
tube. Seat the bearing at the bottom of its seating diameter. Then
drop the main tube into the column. The clamp ring is screwed down
with socket head screws inserted thru the access holes in the top of
the drive tube. If the arm is going to be used in an upright
position, it is probably not necessary to retain bottom bearing, but
this can easily be done by slipping on another retaining fore putting
on the bottom bearing and dowel pinning it in place. The exact
position can be determined by squashing the ring a bit so it sticks
the the drive tube. Then when the tube is inserted, the earing will
push the retaining ring up to the right point. carefully removing
the tube will keep the ring at the t point until it can be dowel
pinned in place. Some bearing preload can be added by putting an
O-ring between the retaining ring and the bearing with about .015
O-riing squash to act as a spring. Don't put anyy more preload than
.015 with this method. If in doubt- just forget the O-ring and leave
at .005 clearance between retainer and bearing. The bearings are of
the type which quires little or no preload anyhow.
The second joint is assembled in a similar manner. In this
case, the rear (motor end) bearing acts as a pilot for the motor
mount plate.
Joint #3-
The square tube boom rides on 16 rollers. Only about 6
rollers are actually needed to guide the tube, so dont worry if all
dont contact at the same time. The rollers are made up from the 34KDD
bearings supplied and phenolic rings. Epoxy the rings to the
bearings with two bands of cement - one one each side. The rollers
are sttached to the shafts with Locktite adhesive. Use Locktite #35
or #40 adhesive (available from bearing supply firms),and place one
of the roller clamps in the center. The spacing of the rollers
should be about 2.30 outside to outside. This will insure that there
is no interference with other rollers. The boom should fit tight
enough so that it springs the rollers out a bit. If it fits very
loosly, shimm the roller blocks with shim stock.
Joint 4, 5 and 6. The installation of the main shaft bearings is
self explainatory. It is advisable to make some simple plugs to
install and remove these bearings, as acrewdriver blades and knives
are not good for the bearings or the parts. DO NOT hammer bearings
into place- press them in, on a drill press if an arbor press is not
available. Also, plan on having tooling for removal before ining the
bearing.
Installation of the small shaft bearings on the R6 joint and Hand wil
be discussed later int he section on main assembly. For the present,
its good enough to check that all the main drive shafts fit together,
and the arm shructure assembles properly.
Shipment #2.
This consists of most of the purchased components and
critical assemblies. The only mechanical parts not included are
those with an electrical function. (Such as the drive gear on the #6
joint, and the #3 encoder or pot.]
You will probably want to assemble joint #1 first. Test fit
the motor assembly in the column. It should drop into place. It
should also slip into the drive tube. You will note that because of
the coaxial nature of the assembly, it is not possible to just fit
everything together and bolt it into place later. You must screw
things together while assembling arm.
The addition of an access hole in the side of the main column
allows for easier assembly because with it, you can assemble the #1
joint by dropping the motor assembly in place and putting in the
screws. Then put in the bottom bearing. Now slide the drive tube
assembly with the upper bearing and clamp ring already installed .
The access hole allows you to screw in its bolt circle. There are
access holes in the top plate of the drive tube to allow you to screw
down the clamp ring.
Joint #2 is assembled in a manner similar to joint #1. Note
that the rear (motor end) bearing serves to center the motor mounting
plate also. The #2 motor assembly is not complete as the motor mount
plate is not part of the kit. You must first mount this plate to the
motor, and then bolt on the harmonic drive. It may be easier to get
the harmonic drive screws in place if you remove the three small
phillips head screws shich hold on the diaphram assembly. The motor
drive system has a slip clutch on the hollow drive shaft. The slip
torque has been preset, so dont adjust the two locking nuts on the
drive shaft. The shaft thru the center of the motor comes from the
encoder. it is connected to the output thru the thin diaphram to
allow for som axial play during assembly and due to motor heating.
When assembling the unit, make sure that the diaphram is not
bottomed, but has free travel in both directions when the encoder
shaft set screw is tightened. Also remember that to remove the
encoder or get access to the motor brake( under the black motor end
bell at the encoder end), you must first loosen the encoder shaft set
screw. Only after doing this is it safe to remove the brake cover
screws and slip off the encoder and brake assembly.
Joint #3 motor is first mounted on the square tube (9-20).
The front motor bearing acts as the centering device too. Now wire
up the motor, brake and tach and slide the motor into the head
assembly. If it doesnt go all the way in, the encoder shaft on joint
#2 sticks out too far, so cut it off flush with the diaphram hub.
The mounting scre are socket head and the use of a stubby wrench is
recommended for easily working in the confined inside of the square
tube.