Incorporating Bearings into This...

[TIves]

Hello all,

Sorry if this is not the best forum to use, but I'm not sure where else to find bearing experts.

I would love to receive some direction on how one would incorporate bearings into this (not sure what to call it)...

(I hope the .gif file animates ok)

As can be seen, this is a shaft which will rotate 180 degrees, always in the same direction, each time the hub is moved back and forth along the length of the shaft (totaling 360 degrees).

I'm not a mechanical engineer and I have never incorporated bearings into any of my designs previously, so I apologize if this is a stupid question.

I assume I could place bearings in the front and back of the hub, but I'm concerned that as the bearings cross the helical channel that they may get hung-up. Is that just wrong? If not, what's the solution?

Thanks kindly!

Trip

 

[MikeHalloran]

If it had a pitch closer to one diameter, it would be called a 'level wind' or a 'ball reverser'.
They are found in fishing reels and in winches, with the shaft being driven in sync with the drum, and the hub prevented from rotating by a rail, and driven axially to move a rope/line guide.
I think they are available as assemblies from some specialist manufacturers.

Normally the hub slides/rotates on the part of the shaft that's not grooved. If the hub is lined or made of a coppermetal and the shaft is steel, a little oil or grease will be sufficient, because there's a lot of bearing area. I.e., the hub/shaft bearing is normally a 'plain' bearing. ... which you may not think of as a bearing, but it is. There are usually ball bearings on the ends of the shaft, but the balls never ride over the grooves.

Congrats to whoever made that 3d model, and whoever made the numerical model that generated it.

I'm not sure it would work as nicely in practice, e.g. in a machine, as it seems to work in the hand. You might need some sort of trapdoor ramp inside the groove in order to make sure that the hub rotates in the desired direction when the thrust on the shaft reverses. Without that assistance, the hub might just reverse its rotation so that the internal ball would go back down the groove it just left.





Mike Halloran
Pembroke Pines, FL, USA

 

[TIves]

Mike,

Thank you so much for your reply and the education! As I did a little more research I figured it is closer to a bushing solution rather than the use of bearings. I believe what you said aligns with that thought.

I made the 3d model (using Sketchup) and then printed it on a 3d printer that I built. Thank you for the complement

As for the issue you brought-up about potential reversal of the rotation, I was hoping a flywheel, at the tail-end of the entire assembly, would keep the momentum moving in the desired direction.

I appreciate the help!

All the best,

Trip