Articulation
Compound Gears
- Create a new folder called Compound.
- Download SpurGear-6-20.SLDPRT from the web and save it in Compound.
- Open SpurGear-6-20 in SolidWorks.
- Do "Save As Copy and Open" and save the part as SpurGear-12-20.
- Click on Manage Equations and set the pitch diameter to 12.
- Edit the hole sketch and set all the hole distances to 0.45 inches.
- Save the part.
- Do "Save As Copy and Open" and save the part as SpurGear-12-40.
- For SpurGear-12-40, click on Manage Equations and set the number of teeth to 40.
- Save the part.
- Make a BackingPlate part 6 inches by 6 inches.
- Add three 1/8 inch diameter holes in an L-shape, spacing 2.5 inches.
- Save the part and create an assembly from it.
- Insert a SpurGear-12-20 and mate it to the left hole.
- Insert a SpurGear-12-40 and mate it to the right hole.
- Add a 20:40 gear mate.
- Create a new part called GearSpacer: a disk 1.25 inches in diameter.
- Add 1/8 inch holes, one at the center and one 0.45 inches above it.
- Insert GearSpacer into the assembly and mate it to the top hole in the backplate.
- Insert a new SpurGear-12-20 and mate it to the top of the SpurGear-12-40 using both holes, so that the two gears are rigidly attached.
- Insert a new SpurGear-12-40 and mate it to the top of the Spacer using both holes.
- Add a 40:20 gear mate betweeen the new SpurGear-12-40 and SpurGear-12-20 instances.
- Verify that rotating the left gear results in a 4:1 reduction for the top gear.
- Verify that rotating the top gear produces a 1:4 speedup in the bottom gear.
Articulated Arms
- Download LittleManVee and save it as LittleManArt.
- Create a new part.
- Sketch a bar 2 inches long and 1/2 inch wide. Add horizontal and vertical centerlines.
- Put three 1/8 inch diameter holes at the center and 1/8 inch in from each edge.
- Extrude to 1/8 inch depth and fillet the corners to 0.2 inch.
- Color the part red.
- Save as ArmSeg.
- Delete the Arms in the assembly.
- Change the link lengths to 6 inches.
- Open the Torso and rescale the part so the shoulder distance is 2.75 inches.
- Replace the arms with pairs of ArmSeg instances mated at the end circles.
- Mate the links to the distal ends of the arms.
- Verify that turning the gears moves the arms.
First Motion Analysis
- Switch to the motion analysis tab.
- Change the type from Animation to Motion Analysis.
- Add a rotary motor attached to the small gear and set it to 40 rpm.
- Run a motion analysis study and observe the chaos.
Pin
- Create a new part called Pin.
- Sketch a cylinder 1/4 inch in diameter and extrude to a depth of 1/4 inch.
- On the back side of the cylinder sketch a cylinder with a diameter of 1/8 inch and extrude to a depth of 1/4 inch.
- Color the pin yellow.
- Place pins on the backplate to limit the travel of the links.
- Mate the links against the backplate and set them to Fixed.
- Return to the motion study tab.
- Add Solid Body Contacts between each link and its pin.
- Click calculate and observe the results.
Slotted Link
- Create a new part called SlottedLink.
- Sketch a horizontal rectangle 1.875 inches long and 1/4 inch high.
- Add a horizontal centerline.
- Sketch a slot 0.75 inches long on the centerline, with one focal point 1/8 inch in from the right edge of the rectangle.
- Set the slot radius to 1/16 inch.
- Add a 1/8 inch diameter hole at the other end of the rectangle, 1/8 inch in from the edge.
- Extrude to a depth of 1/8 inch.
- Fillet the corners with a 1/16 inch radius.
- Switch back to the assembly.
- Put a pin in the central hole of each upper arm segment.
- Add a SlottedLink.
- Mate the hole in the slotted link to the central hole in the distal arm segment.
- Use a slot mate to mate the slitted link to the pin in the upper arm segment.
- Do the same for the other arm.
- Move the parts to check range of travel, and reposition the limit
pins as necessary.
- Return to the Motion Study tab.
- Add Solid Body Contacts between each slotted link and pin.
- Click Calculate and observe the results.
Dave Touretzky
Last modified: Wed Mar 29 16:44:49 EDT 2017