Hex vs. Key

[DonRotolo]

Originally Posted by Cory

unlike keys, the hex won't slip.

Nor will it weaken the shaft.

The keyway in a shaft is a stress concentrator, which significantly reduces the strength of the shaft, especially its resistance to breaking under shock loads. Keyways are popular 'cause they're easy, and using a 5/8" shaft where a 3/8" will do isn't an issue if weight is not a consideration.

Einstein says the limit is ~286000 miles per second
Dean says the limit is 120 lbs.

Don

[Salik Syed]

isn't the speed of light closer to 186,000 miles per second...

but regardless.... I think key does pose alot more problems... i think hex shaft would significantly reduce maintainance and wear issues... we have lots of problems with keys walking out, shafts getting worn
if you have the tools i would think hex is the way to go

i wouldn't know but i do know that key kinda sucks

[Richard Wallace]

Originally Posted by Salik Syed

isn't the speed of light closer to 186,000 miles per second...

Wikipedia sez: According to the currently prevailing definition, adopted in 1983, the speed of light <in vacuum> is exactly 299,792,458 metres per second. Since 1 mile = ~1.609344 kilometers, the speed of light is about 186,282.4 miles per second, or in more convenient units about 0.983571 feet per nanosecond. [digression] This gives an upper bound for the speed at which information can be transported using electromagnetism; e.g., lightguide. Actual transmission speed in fiber optic cable is about 30% slower than this, because the fiber has greater electrical permittivity than free space. [/digression]

Short FIRST-friendly summary: remember, Aluminum weighs about one-tenth of a pound per cubic inch, and light travels about one foot per nanosecond. The second approximation has almost no practical significance for FRC robot building. So back to the main topic now:

but regardless.... I think key does pose alot more problems... i think hex shaft would significantly reduce maintainance and wear issues... we have lots of problems with keys walking out, shafts getting worn
if you have the tools i would think hex is the way to go

i wouldn't know but i do know that key kinda sucks

We've been using keys for several years. I'll be ordering a 3/8" hex broach soon. Summer is the time to practice new tricks.

[Gabe]

Machanically speaking, a spline shaft is the best, but that is really hard to get and it is really hard to broach matching splines without laying out some money.