9.07

KINEMATICS KIT USERS MANUAL

INCLUDED PARTS LIST

Standard parts -

1. ground plane enclosure which includes stepper motor with control circuits, press fit motor shaft adaptor, and link attachment plate.

2. 2 each links from 1" to 6"

3. slider assembly with both fixed block and pivot bars

4. y.. - 20 flat head screws (2)

5. 8/32 x Y2 screws (3)

6. y.. - 20 Phillips screws in 5/8" (10) , 1" (5) , lengths

7. 1/16 steel washers (10)

8. nylon spacers 118 (6) , 3/16 (6) , and 7/16 (4) ,

9. springs for slider and cams (3)

10. double dwell cam and translational follower

Advanced mechanisms - choice of one

1. Geneva mechanism

2. Ratchet and pawl

3. Scotch yoke

Warranty The Python Kinematics Kit is guaranteed for three

years. Anything that breaks in normal use will be replaced . Damage caused by accident or abuse, i.e. stripped threads , cracked bearings, dropped case is not covered.

NOTE: STEPPER MOTORS ARE DESIGNED TO RUN HOT.

THE PROGRAMMED CUTOFF IS 140 DEG. F. THE TIP OF THE SHAFT AND THE MOUNTING SCREWS ON THE GROUND WILL GET HOT AFTER EXTENDED RUNNING!

The stepper motor will not be damaged if it stalls or is stopped , but may heat more rapidly. It is important to check that the mechanism is assembled correctly.

The motor has thermal protection and will shut off if over temperature, the red LED will blink in this condition . When cooled sufficiently, it will reset but the motor won 't start until the switch has been turned off first.

The motor drive will also automatically turn off if left in locked position for more than approx. four minutes.

Mechanism assembly

It is generally easier to assemble the entire linkage assembly first before attaching it to the motor plate and ground . Many of the links must be screwed in from the bottom and they are more accessible when still free .

The link assembly should first be attached to the motor adaptor, the adaptor attached to the motor plate, and then the ground point(s) can be attached .

It may be convenient to store favorite demonstration mechanisms assembled as a unit rather than disassembling them after each class.

BEFORE STARTING MOTOR,

1. BE SURE THE LINKS ARE PARALLEL IN CORRECT PLANE ABOVE GROUND.

2. CHECK RANGE OF MOTION Be sure the links move freely without binding or locking .

3. CHECK FOR COLLISION

Check the orientation of the bearings in each link.

The first link will always be bearing up. The link adaptor is attached to the link from the bottom using 2 flat head %-20 screws. It will always be on the recessed bearing side.

The link adaptor is attached to the motor plate using 2 or 3 half inch 8/32 screws.

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The cams, geneva mechanism, and several other advanced mechanisms are attached directly to the motor plate using the 8/32 screws without the link adaptor.

The bearing screw is always inserted through the recessed side of the bearing without any washers . It will always need a steel washer on the other side against the bearing . The steel washer has one sharp side and one rounded . Put the sharp side against the bearing and the rounded side against the plastic of the next link.

The last link to ground wil l always be bearing down and will usually need a 3/16 nylon spacer to keep it in plane.

In simple mechanisms the bearing side will usually alternate top and bottom.

Because of the shape of the link adaptor, a 1" link cannot be attached directly to the motor. If a 1" link is needed, use a 2" link mounted backwards .

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.. ... . standard four bar linkage

SLIDERS

The slider and cam blocks are the same except for the spring . The spring should be removed when using the block with a slider.

The fixed slider block is usually best attached directly to ground. Assemble the sl ider first, then the rest of the links; the slider block bearings should be down. Use whatever size or combination of washers that are needed between the slider and the coupler link to be sure they are parallel.

For a pivoting slider, the slider pivot bar should be attached to ground first, then the slider inserted into the bearings. Picking the point on the ground for attachment may be largely trial and error. The pivot bar needs a 3/16 spacer and a steel washer. Then attach the slider block to the pivot. Be sure to check for range of motion and collisions .

CAMS

Cams are attached directly to the motor adaptor with 8/32 screws. The followers always need a spring that must maintain tension throughout the range of movement. .

• The translational follower is generally set centered with the motor shaft. It uses the sl ider block with the spring attached. The block will be attached to ground with bearings down, using 1" screws and metal washers. The spring will go toward the bearing end of the follower .

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The rotational follower also must have adequate spring tension throughout it's motion . Pick an attachment point for the follower and the spring to give desired motion with continuous tension .

RATCHET AND PAWL

The ratchet mechanism requires links at three levels; be sure they are kept parallel. To be sure there is free motion , the levels need extra space between them.

It will need a 1/8" washer inside the o-ring under the output arm, attached to ground at the bearing side. The ratchet is attached to the output arm with 2 large nylon washers between them in the center and 2 steel washers at the outer attachment screw. There are 2 steel washers between the input arm and the ratchet and between the input arm and the pawl , A 1 3/4 " screw is needed to reach through the three levels to ground.

Attach the ratchet to the output arm first. When tightening the outer screw, be sure the center is lined up and the 1 % screw does not bind. Attach the pawl to the input arm, then complete the assembly.

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The frictiona l resistance to rotation at the output, provided by the o-ring , keeps the ratchet from turning backwards. If needed , adjust the tightness of the screw to give the best performance

SCOTCH YOKE

The scotch yoke is mounted on the slider block with the bearings up. Use 7/16 " spacers under the block. First mount the yoke in the slider block, and the drive arm to the motor, then insert the drive pin . . The maximum arm length on the motor to drive it is 2 ".

Note that the drive arm is mounted to the link adaptor such that the bearing is not used. Be sure there is clearance between the drive arm and the sl ider block.

GENEVA MECHANISM

The driver is mounted directly to the motor plate . Use an extra washer under the output to keep it in the correct plane.

NOTE: The serial port is connected on th is version of the kit, but conrol software is not ready.