New Products for 2016: Speculation, Wants

[Nathan Streeter]

Originally Posted by Mike Marandola

If they are the same wheels that they had at IRI, they are pretty neat. There are two new compounds, a "one match" and "one event" wheel. Unfortunately, I forgot the exact durometers. The "one match" wheel was very soft and grippy so I would imagine it would be great for non-drive uses.

I'm eager to see these unveiled!

[Cory]

Originally Posted by Rob Stehlik

But I don't see what the obsession with hex is all about. What's wrong with a nice round keyed shaft?

The obsession with hex is because round keyed stock is completely inferior in every way (except perhaps availability).

Strength (massive stress risers)
Ease of use...no keys to lose during installation. No struggling to get the key in/out of the keyway on either mating part. No need to cut keys.
Torque transmission (which goes into strength)
The list goes on and on.

[marshall]

Originally Posted by Cory

The obsession with hex is because round keyed stock is completely inferior in every way (except perhaps availability).

Strength (massive stress risers)
Ease of use...no keys to lose during installation. No struggling to get the key in/out of the keyway on either mating part. No need to cut keys.
Torque transmission (which goes into strength)
The list goes on and on.

It's true! It's all true! I was against hex for a while but I have to say, I've been converted.

[safiq10]

Originally Posted by Mike Marandola

If they are the same wheels that they had at IRI, they are pretty neat. There are two new compounds, a "one match" and "one event" wheel. Unfortunately, I forgot the exact durometers. The "one match" wheel was very soft and grippy so I would imagine it would be great for non-drive uses.

I heard the same thing at Worlds when I got to talk to them. I believe it was 30 and 45 durometers, but don't quote me on that.

[Munchskull]

What I would love to see is an output for the versa planetary gearbox that is a 1/2" hex clamp. That way tears can make the output shaft as long as they want. Ideal for intakes and power rollers.

[Scott Kozutsky]

Originally Posted by Munchskull

What I would love to see is an output for the versa planetary gearbox that is a 1/2" hex clamp. That way tears can make the output shaft as long as they want. Ideal for intakes and power rollers.

This is why vex came out with the hex shaft coupler. http://www.vexrobotics.com/vexpro/ha.../217-4008.html

[jman4747]

Originally Posted by Cory

The obsession with hex is because round keyed stock is completely inferior in every way (except perhaps availability).

Strength (massive stress risers)
Ease of use...no keys to lose during installation. No struggling to get the key in/out of the keyway on either mating part. No need to cut keys.
Torque transmission (which goes into strength)
The list goes on and on.

Well outside of FRC and just so students who might be mechanical engineers one day know, round shaft has its perks.

1. Round shaft is available in any material that can be put on a lathe

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

3. Machining internal features for round shaft is (depending on the tolerances required) easier, faster, more precise, and cheaper than for hex

Round shaft is not "completely inferior in every way" to hex. Hex shaft is easier to use and commonly meets the needs of most FRC applications but when your're in the real world there are times when you may need something else.

[Cory]

Originally Posted by jman4747

Round shaft is not "completely inferior in every way" to hex. Hex shaft is easier to use and commonly meets the needs of most FRC applications but when your're in the real world there are times when you may need something else.

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.

[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?

[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.