Building A Robotic Arm


Page 2


Next we want to make a wooden reel for the arm. Using a 1- 1/2" circler hole blade, cut two holes in a 3/4" thick piece of wood. Take out the wood. Drill a 3/8" hole in the center of the rollers. Now see if the metal shaft will fit thru the holes. If the hole is too small, use a file to make the hole a little bigger. Now take one of the rollers and cut off 5/16". Put the 3/4" thick roller and the 5/16" thick roller on the motor shaft. Make the 3/4" thick roller even with the end of the motor shaft. Put the shaft into the motor and move the 5/16" thick roller so that it is next to the motor. Mark a line on the shaft next to the 3/4" thick roller. You are going to drill a .099 hole in the shaft where the line mark is.




NOTE: If you don't have a drill press and don't have the skill to drill the hole using a hand drill; you can make a jig for the job. Just drill a 3/8" hole thru a block of wood. Mark off the center of the hole. Now you can easily drill the .099 hole thru the center of the hole because the drill bit won't slip on even wood like it would on the curved metal shaft. Now put the shaft into the wooden block and use the .099 hole as a guide for the drill bit. Here are two phots of a jig I made to drill a hole in a much larger shaft but the photos will give you the idea of what I am talking about.








Take the cover off the motor. Take the motor out of the bottom cover.



Drill a .140" hole in the bottom cover so that the #6 1-1/8" drywall screw will fit thru it.



Put the covers back on the motor. Put the reel into the motor. Cut off 8" from a stock 1" by 4" piece of wood. Place the motor on top of the wood and make sure that the reel comes even with the front of the wood. Now mark off where the motor would go. Take the covers off the motor again. Now place the bottom cover where you mark it off. Drill a pilot hole where the cover hole is. Screw in a #6 1-1/8" drywall screw thru the cover into the wood. Put the covers back on and mount the motor. Cut off the end of the screw if it sticks out.





Put the cord thru the .099 hole in the shaft and out the end openning. Tie a knot at the end of the cord so that it can not be pulled out of the shaft. Glue the rollers on to the shaft. Glue the shaft into the motor. Hot glue the end of the shaft and around the motor. It will take about a week for the glue to dry, so DON'T go testing to see if the reel will hold.



Now cut a piece of wood that is a 1/2" thick, so that it is 1-6/16" wide and 3-1/4" long. Now glue that to the motor's wooden base.



Drill two pilot holes thru the rail and into the motor's base. Using the two pilot holes as a guide, drill two .140" holes in just the rail so that a #6 2" drywall screw can fit thru. Now using a 1/2" drill bit, drill just enough so that the heads of the drywall screws will be flat with the rail wood. Using two #6 2" drywall screws, screw the rail to the motor's base. If the motor and motor's base looks parallel then hot glue the motor to the base.





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