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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
			May 1, 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
- KB-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  (
KA-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 the bottom bearing,
but this can  easily be done  by slipping on  another retaining  ring
before 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
bearing  will  push  the  retaining  ring up  to  the  right  point.  
Carefully  removing the tube  will keep  the ring at  the right 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-ring squash to act as a spring.  Don't put any more
preload than
.015 with this method.  If in doubt- just forget the O-ring and leave
at least  .005 clearance between retainer and  bearing.  The bearings
are of the type which require 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.  The  flange end  bearing is retained  with a retaining
ring as in  joint 1, while  the other bearing  floats on the  tubular
shaft.  The rear bearing  is retained on it's O.D. by the housing and
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 and phenolic rings.   Epoxy the  rings to the bearings  with
two bands of cement - one on  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 with  the extra center  hole in the  center of the  rod before
cementing on the second bearing.   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, shim
the roller blocks with shim stock.  

Joints 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 ressing
in the bearing. 

Installation  of the small  shaft bearings on  the #6  joint and hand
will be discussed  later in the  section on main  assembly.  For  the
present, its good enough to check  that all the main drive shafts fit
together, and the arm structure 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 its
radial mounting screws.  Then put  in the bottom bearing.  Now  slide
in the  drive tube  assembly with  the upper  bearing and clamp  ring
already installed  .  Tighten the clamp ring  screws, and then put in
the drive tube  screws thru  the access hole  in the side.   At  this
point  you should  decide  on  the orientation  of  the encoder  zero
reference  mark with respect to the socket  cutout on the main tube.  
To change it  in the future, just  unscrew the drive tube  screws and
turn the head assembly until the proper orientation is reached. 

	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 which 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  some 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.  Mount the motor
assembly with the wires towards the base of the arm. Also shorten the
encoder shaft so that it doesnt protrude more than .1 inches past the
diaphram  hub.    Just  grind  or hacksaw  offthe  extra  piece  with
everything  in place, as the  encoder shaft is  fragile and will snap
off easily if  bent.   The hollow motor  shaft restricts the  maximum
amount of bending to a safe level. 

	Joint #3

	The 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
screws are socket head and the  use of a stubby wrench is recommended
for  easily working in the  confined inside of the  square tube.  The
wires for the motor come out  the notch in the flage on the  #2 joint
tube.  The boom is slipped in from the front (short end of the square
tube with rollers).  The rack is mounted either on the top or  bottom
side of the  tube.  Top side  mounting is preferred because  it keeps
the rack free of  dirt.  The backlash between the drive gear and rack
is adjusted  by tightening  the rack  screws while  pushing the  rack
against the drive gear.  Later, you will install the #3 joint encoder
in  the hole in the rear of the guide  tube.  The encoder has its own
backlash adjustment.   Glue a  small strip of  1/4 inch thick  rubber
onto the rear boom stop [L shaped piece], and slip an O ring onto the
front boom stop for a cushion.  


	Joint #4


	In this assembly, the improtant thing to keep in mind is that
te motor armature  is supported at the rear  by a bearing and  at the
front  by  the  wave  generator of  the  harmonic  drive.   The  wave
generator is  pre-mounted by  Vicarm,  but is  not supported  on  its
outside diameter  until the harmonic drive  is completely assembled. 
Thus  it is not possible to test the  motor separately.  Also keep in
mind that the  motor comes with  a magnet keeper.   This keeper  must
never  be removed,  even  for and  instant without  either  the motor
armature fully in  place, or  an equivalent piece  of magnetic  steel
with a diameter equal to or greater than that  of the armature in its
place.  Otherwise the magnets will become demagnetized (it takes but
.0001 seconds  to do this) and will have  be recharged to regain full
performance.  The rear  motor bearing is held  in place by the  brake
disk and the center retainer on the  ID.  and by the rear housing and
outside  retainer on  the o.d.   Some  shimming may be  necessary, in
addition to  the spacer,  to reduce end  play to  under .010  inches.
Install  the brake  field.   The motor  brush ring  is slipped  on by
tipping it and springing  apart the brushes a  bit so they clear  the
tach drive gear.   The motor is held together with  six 4-40 screws. 
Two short ones hold the magnet ring in place.  Two medium length ones
hold the brush ring in place.  Two long ones hold the rear case piece
in place.  These last two should  be flat head and countersunk so the
bearing  retainer  can slip  fully into  place.   The  harmonic drive
circular spline is  screwed onto  the front of  the motor assy.  with
socket head or  fillister head screws.  The  flexspline is screwed to
the output shaft and the wire guide tube pressed into the hole in the
center of the output shaf.  This tube  guides the wire bundle through
the center of the motor.  Test the assembly by pushing the flexspline
into the gap between the  wave generator and the circular spline.  It
should slip  in easily.   If it  goes in hard  it means that  its not
correctly  centered.  Try it again.   The harmonic drive works on the
principle that there are 2  more teeth on the circular  spline (outer
ring) than on the flexspline (thin tubular piece).  The flexspline is
deformed to the shape  of an ellipse gy  the wave generator  (bearing
like thing).  The ellipse contacts the  circular spline at two points
and  walks  around slowly  advancing as  it  does.   The  wave motion
proceeds at 72 times the actual motion, thus giving a  gear reduction
of 72/1.  It  is possible to install the harmonic  drive with the two
tooth  difference on one side  and no difference on  the other.  This
lopsided installation  will  cause the  drive to  be  very rough  and
require more  power.  This error  can be prevented by  trying the fit
several times.   If it assembles  easily, its right,  if its hard  to
push together, its wrong.  Some wiggling and a bit of initial pushing
is the normal  method of installation.  The spacing between the motor
and  the  harmonic  drive  flexspline  is  not  to   critical,and  is
determined by the design dimensions.  There should be no interference
of  screw heads when the output shaft is  fully in place.  To get the
output shaft fully in place pull it through the #4 joint housing with
some long screws in the output plate. 

	The  tachometer is installed  by slipping  the unit  with its
gear in thru the hole in the rear motor housing and applying a dab of
epoxy to hold it  in place.  The potentiometer  mounting details will
be discussed later.