Redshift Project Depot

General Topics => Arcadia => Topic started by: Louis L on February 15, 2017, 03:16:20 PM

Title: Hardware design and implementation - strategy and goal
Post by: Louis L on February 15, 2017, 03:16:20 PM
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Highlights
Title: Re: Hardware design and implementation - strategy and goal
Post by: Ed B on February 24, 2017, 11:59:07 AM
Related to overbuilding:

connecting parts to other parts ---> modular design

Other items (use what seems appropriate for the message):

Use ad-hoc bearings like a bolt through a hole only where wear is going to be minimal and precision is not important.  Otherwise use proper bronze bushings, ball bearings, appropriate plastic bearings, etc. Never use Aluminum on Aluminum for bearings.

Don't overload gear boxes.  Particularly with high ratio planetary gearboxes, it is possible to develop enough torque to break an output shaft.  Keep in mind that during interaction with the field, other robots, and game pieces, actuators can apply dynamic torque that far exceeds the torque provided by the motor/gearbox.

provide two bearings on shafts longer than 5 or 6 times the diameter of the shaft or when actuator side forces can be large.  This can include the motor or gearbox output bearing.

remember that motor and gearbox mounts see all of the torque their output shafts see.  Build accordingly.

Mount motors and gearboxes the way they were designed to be mounted, not with u-bolts, hose clamps, etc. Do not use the motor part of a gear/motor combination for mounting.

Chain drive bearings should be in the same piece of metal or at least in the same module of the design. Use pins to prevent slippage between bearings.

Don't use limit switches or other sensors as mechanical stops. They will break. Locate limit switches where they can be adjusted.  Account for coasting or backdrive where limit switches stop a mechanism. Use limit switch features on motor controllers where you can.

Avoid set screws for fixing pulleys or sprockets to shafts.  Use keys or clamping collars where possible. Sprocket and pulley bores MUST match shaft size or an appropriate shaft adapter.

Plastics: Polycarbonate for strength and flexibility.  Avoid acrylic if possible and certainly where strength/flexibility is needed; acrylic cracks at edges and holes. HDPE is tough and makes a good bearing surface with aluminum or steel. LDPE is almost as good, but softer. Delrin makes good bearings, too.