[FTC]: Split Clamp vs Axle Hub

[F Elliott]

Rookie coach alert.

The Tetrix Split Clamp (W739078) and the Tetrix Axle Hub (W739172) seem to be two ways to achieve the same purpose.

I read somewhere when using the Split Clamp to only use two of the attachment holes so the clamping mechanism isn't restricted.

When should I use the clamp and when should I use the hub?

THANKS!

[aklego]

We use the split clamp in situations where we want to be able to adjust the angular orientation of one component relative to others. For example, two years ago, we had a cam operated limit switch that needed very precise tuning. We mounted the cam on a split clamp and then could adjust as needed.

[F Elliott]

Got it. That makes sense.

Which one has greater holding power on the axle? Specifically which one would you use to mount a gear and wheel? I seem to see both types in use for that.

[RRLedford]

Mount gears or sprockets with non-split hubs directly onto wheels.
Keep gear/sprocket as close to wheel as possible.
Run four long screws all the way through the entire stack - wheel, hub, and gear/sprocket.
Use flat or button head 6-32 screws where close spacing is needed , and countersink for heads as needed
Then drive wheels directly, with axles merely free spinning in the sleeve bearings. No torque applied to axles.

Tetrix axles bend easily and driving wheels via torque applied to Tetrix axles is a very unreliable concept.

-Dick Ledford

[RRLedford]

Originally Posted by F Elliott

Got it. That makes sense.

Which one has greater holding power on the axle? Specifically which one would you use to mount a gear and wheel? I seem to see both types in use for that.

For just the motor, the 6mm (motor size) split clamping 2-piece 16-tooth integrated sleeve-hub from
AndyMark → S25-16T 6mm Bore Aluminum Sprocket (am-3185)
LINK→http://www.andymark.com/product-p/am-3185.htm
PIC:

are far superior to the set screw hubs for holding/gripping the axle and higher levels of frequent reversing torque power transfer. Only the one 16T size option currently offered though.

We will never use a set screw hub on a 6mm motor axle again if possible.
Their performance justifies the high $20 price IMO.
We are using them on our robot for FTC Res-Q. The non-round wheels cause a lot of shock loading to the motor hubs and no loosening of hubs has occurred so far as long as hubs were properly tightened.






BEWARE though that the clamp screw must be torqued quite highly is prone to stripping if not lubricated !!
Be certain to lube the screw with a tiny bit of good high pressure grease prior to installing, but just a little so it stays away from the bore. A high pressure moly grease is best.

I am about to purchase another (6) of these hubs because the first six are working so well!

-Dick Ledford

[RRLedford]

Originally Posted by F Elliott

Rookie coach alert.

The Tetrix Split Clamp (W739078) and the Tetrix Axle Hub (W739172) seem to be two ways to achieve the same purpose.

I read somewhere when using the Split Clamp to only use two of the attachment holes so the clamping mechanism isn't restricted.

When should I use the clamp and when should I use the hub?

THANKS!

For Tetrix axles, I was not aware that a Tetrix Split Clamp (W739078) existed, and searching does not pull one up for me. Where did you order it? any link?

I found a PIC of it in thr FTC Inspector manual PDF, in the section on legal/illegal parts. They probably both initially hold axle grip at similar level, but the set screw is more prone to progressive loosening than the clamp. The significant amount of hub protrusion that the clamping "fingers" cause, demands that swing clearance around the hub must accommodate this considerably longer radial reach of the fingers beyond just the hub's OD.

-Dick Ledford

[ArtemusMaximus]

Originally Posted by RRLedford

For Tetrix axles, I was not aware that a Tetrix Split Clamp (W739078) existed, and searching does not pull one up for me. Where did you order it? any link?

-Dick Ledford

The original post is 2 years old, so I suspect it existed at that time.