New Products for 2016: Speculation, Wants

[jman4747]

Originally Posted by Cory

We're not in the real world. This discussion is clearly about FRC and there really can be no debate that for FRC hex is a superior product.

Looks real to me.

I would argue that we are in the real world and that our application has parameters that support the common use of 7075 anodized hex shaft. I believe the best practice not to make a blanket statement about material usage and instead to state it's usefulness in terms of our application.

Saying round shaft is always inferior isn't true. Even in FRC there are times when we may be better served with round shaft. I would never tell my students to always use hex or round shaft or aluminum or steel. I train them to pick the best thing for that application. If we have sponsor that will buy half a robots worth of hardware from mcmaster and machine shop that doesn't have hex broaches then round shaft might be a better choice that time around.

Oh and...

4. round shaft couplings and collars are easier to produce (again depending on required tolerances/features)

[R.C.]

Originally Posted by jman4747

Looks real to me.

I would argue that we are in the real world and that our application has parameters that support the common use of 7075 anodized hex shaft. I believe the best practice not to make a blanket statement about material usage and instead to state it's usefulness in terms of our application.

Saying round shaft is always inferior isn't true. Even in FRC there are times when we may be better served with round shaft. I would never tell my students to always use hex or round shaft or aluminum or steel. I train them to pick the best thing for that application. If we have sponsor that will buy half a robots worth of hardware from mcmaster and machine shop that doesn't have hex broaches then round shaft might be a better choice that time around.

Oh and...

4. round shaft couplings and collars are easier to produce (again depending on required tolerances/features)

Your not really at at a real world job. Your in a HS competition where the best choice is clearly ThunderHex or Hex Shafting for most applications if not close to all.

While I agree on the blanket statement, the round shafting is clearly the 1%/minority here. Round shafting + key ways are a major pain and I can't think of a situation where in FRC I'd really want to use round. Most likely if we come to a situation where do we want to use Key'd shafting we'd probably redesign or re evaluate our design.

[page2067]

Why we need this:

A 3/8" hex bore bearing with a 0.875" OD

[asid61]

Originally Posted by page2067

Why we need this:

A 3/8" hex bore bearing with a 0.875" OD

Because when I'm using 3/8" hex shaft it's very convenient.
Also I forgot to mention: 3/8" hex versahubs and sprockets! Or a 3/8" hex to 1/2" sleeve if that's not possible.

[Jared]

Originally Posted by Cory

We're not in the real world. This discussion is clearly about FRC and there really can be no debate that for FRC hex is a superior product.

I'd take hex over round 99 out of 100 times for transmitting torque, but I don't agree with a blanket statement that says hex is always the way to go, especially considering budget. It's undeniably cheaper to drive a McMaster Carr Sure-Grip wheel with a round shaft than a hex shaft.

Putting a hex in a 1.25" hardened steel worm is impossible for most teams that don't have access to a wire edm. Using a keyed shaft would be a better solution, especially if there isn't room in the worm for a 3/8" hex.


If you have a set of two driven rollers or wheels with a pair of bearings in between, you're forced to use a hex bearing here. The inner race of the hex bearing is much weaker than the inner race of the round bearing and has a sloppy fit. I'm pretty sure 254 solved this problem in the past on their outer wheels by using 1/2" keyed shaft...

[MichaelBick]

Originally Posted by Jared

If you have a set of two driven rollers or wheels with a pair of bearings in between, you're forced to use a hex bearing here. The inner race of the hex bearing is much weaker than the inner race of the round bearing and has a sloppy fit. I'm pretty sure 254 solved this problem in the past on their outer wheels by using 1/2" keyed shaft...

No, they used 7/16" hex at the wheels.

[MichaelBick]

Originally Posted by jman4747

2. Round shaft depending on how it's machined will hold tighter tolerances than hex shaft which can be unbelievably important in various real world applications

In the "real world", could you also just clamp the shaft instead?