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Canuckle Solar Tracker Version 2 Driver

by Wayne
This page describes the drive unit built for the Canuckle #2 Solar Tracker. The drive unit consist of two DC motors, two spur gears, a worm gear, a Canuckle bearing made from ABS fittings and housings and plates made from ABS flat stock.

When assembling the drive unit alignment of the motors, shafts and gears is critical. Bad alignment will cause the drive to bind when torque is applied resulting in stalled motors and possible burnouts. During assembly test the alignment by driving the motors with 5 volts, at 5 volts the motors will rotate slower and with less torque (In use the motors will run off of 12 or 24 volts).


Top View Cut-Away of Assembled Drive

The Spur gears can be found in most inkjet printers on the end of the paper feed mechanism. The worm gear can be made from a large bolt or threaded rod that matches the thread pitch on the spur gears. The Canuckle bearing is made entirely from ABS fittings, a design drawing is shown below. The height of the Canuckle bearing must be adjusted to fit the dimensions of the drive housing which is in turn determined by the size of the DC motors. The DC motors should be identical and have the same shaft lengths.


Canuckle Bearing



Making The Drive

Cut a bolt or threaded rod for the worm gear shaft to a length slightly longer than the DC motor shafts by adding about half the thickness of the ABS flat stock to its length (see the diagram below).


Shaft Length Detail



The spur gear will be fitted to one end of the worm gear shaft. It is possible the file a perfectly centered shaft diameter by placing the worm gear shaft in a hand drill, lock two nuts to act as a guide for the file and starting with a course file machine the worm gear shaft to match the center mounting hole diameter on the spur gear. The spur gear can then be presses onto the worm gear shaft. Both ends of the worm gear shaft must also be machined to fit the shaft guides.


Worm Gear Shaft



Use ABS flat stock to make the motor mounting plate as shown in the drawing below. The motors are mounted vertically with spur gear/worm gear assembly sitting to the side but centered between the two motors. When drilling the holes for the motors it may be easier to make a template to position the motors. Mount the motors onto the motor mounting plate.


Motor Plate Layout



Cut out two pieces of flat ABS for the front and back shaft guide plates. They will be the exact dimensions as the motor mounting plate. Cut out a bottom plate with a width equal to the length of the worm gear shaft plus 2X the thickness of the ABS flat stock. The length of the bottom plate will be the same as the length of the motor and guide plates. Also cut out some small squares to be used for the shaft guides. Drill two motor shaft guides for the front shaft guide plate. The hole diameters in the shaft guides should provide a snug fit onto the shafts. Later in the assembly process these holes will be drilled again to provide a looser fit.

Tack cement (to be removed later) the front guide plate to the bottom plate and also tack a support bar on each end to hold the two pieces at a perfect 90deg angle. Support bars are simply pieces a flat ABS that can be used during assembly to hold things in place. Tack cement them so they can be easily removed when no longer required. When this assembly has dried place the two shaft guides on the ends of the motor shafts and cement the outer surface of the guides. Carefully position the motor assembly into place so the cemented guide surfaces adhere to the front guide plate. Make any adjustments before the cement has a chance to dry making sure the front guide plate and the motor mounting plate are perfectly aligned. Keep everything still until the cement on the guides has had a chance to cure.


Front Guide Plate Assembly



Cut and drill a square piece of flat ABS for the front worm gear shaft guide. Remove the motor assembly and place the worm gear assembly into position. Use a wide elastic band to hold the spur gear against the two motor gears making sure the gear teeth mesh properly. Place the shaft guide on the end or the worm gear shaft and cement the outer surface. While holding the other end of the worm gear shaft so that it is properly aligned place the motor assembly back into position which will cement the worm gear shaft guide to the front guide plate. Adjust the alignment of the worm gear shaft so that it is perfectly aligned parallel to the two motors then wait for the cement to cure on the shaft guide.


Shaft Guide Plate



Remove the motor assembly and re-drill all the front shaft guides making sure not to drill through the shaft guide plate. This process should only remove enough material to allow the shafts to freely rotate in the shaft guides, there should be little or no play but also no binding.

Put the motor assembly back into position making sure all three shafts insert into their respective shaft guides. Tack cement several support bars to hold the front guide and motor plates in proper alignment. Cut and drill shaft guides for the rear shaft guide plate. Place the two motor shaft guides onto the motor shafts and apply cement to their outer surfaces then place the rear shaft guide plate into position making sure to align it properly using the edge of the bottom plate as a guide. When the cement has cured remove the back guide plate and repeat the procedure for the rear worm gear shaft guide making sure the worm gear shaft remains in perfect alignment.


Assembly Detail



When the cement has dried remove the back shaft guide plate and re-drill the guides as you did with the front shaft guide plate. Place the back guide plate into position making sure each shaft fits into its respective shaft guide then tack cement several support bars on the top and sides of the drive. Once the cement on these has cured you can remove the bottom plate and tack cement several support bars across the bottom of the drive. The entire drive unit should be very rigid at this point and you can test the drive by turning each motor with 5 volts.


Side View Cut-Aways of Bearing, Worm Gear and Motors



Cut another bottom plate from ABS flat stock about an inch wider and longer than the required dimensions. Remove any support bars that are on the bottom of the drive and clean off any dried glue from the bottom of the plates. Place the drive in the center of the bottom plate then place the bearing into position making sure the spur gear teeth on the bearing mesh with the worm gear teeth on the drive. Mark the approximate position of the bearing on the bottom plate. Remove the bottom plate and drill a hole equal to the inside diameter of the bottom skirt of the bearing.

Tack cement the bearing to the bottom plate and place back into position on the drive again making sure the spur and worm gear teeth mesh properly. Mark the bottom plate to the outside diameter of the drive housing. Remove and trim the bottom plate by scoring it with a utility knife and breaking the edge pieces off. Take the new bottom plate and transfer the position of the hole to the old bottom plate which will now be the top plate. Drill out the hole in the top plate.

Cement the bearing to the bottom plate and let the cement cure. Cement the bottom plate to the drive plates by applying cement to the bottom of the guide plates and motor plate and placing the bottom plate into position again making sure the spur and worm gear teeth mesh properly. You can test the drive at this point by applying 5 volts to the drive motors. The motors may struggle a bit because of the low voltage but the torque of both motors should be able to drive the bearing a full 360deg.

Remove any support bars from the top of the drive and again clean up any cement so the top of the guide plates and motor plate are clean. Apply cement to each of the guide plates, the motor plate and the top outer diameter of the bearing and place the top plate into position. After the cement is dry test the drive again.

The drive is now almost complete and the next step is to add the Sun Switch sensors and electronics. Mark the motor wires as required and feed the wires through past the bearing to the back of the drive. Remove any support bars from the front of the drive and cut ABS flat stock to make a front cover and cement into place.

Make a back plate from ABS flat stock and drill a small hole to feed the power supply wires through. Attach the Sun Switch sensor to the top of the bearing and feed the wires into the back of the drive housing. Make all the required wiring connections to the Sun Switch circuit board then place the board into the back of the drive housing making sure the Sun Switch wires have sufficient play for the bearing rotation.

Perform the final test of the drive and then cement the rear cover into place. The drive is now ready to be mounted on a tracker frame.

Pics of Canuckle #2 Drive

The pictures below are of the first build of the drive unit for the Canuckle #2. The above plans have some minor modifications which are not shown in the pictures.

         


Next - the Bearing for Version 2
Return to the Canuckle Solar Trackers

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