H550 metal blade grip options

[lightbulbjim]

Hi all. I maidened my Hurri 550 the other day, it was a bit windy so I couldn't really trim it out and tweak the gyro like I was hoping, but it's flying sweetly. The power surprised me (running a Z20A 980KV motor with the stock 14 tooth pinion on 6S), it has a lot more zip to it than I was expecting :).

Anyway, I'm pretty keen to replace at least the plastic blade grips with metal ones (I'm a little paranoid about plastic head parts after the plastic rotor hub seperated in flight on my T-Rex). Only thing is from what I've seen and heard (and Finless has described) on the Gaui metal grips the outer bearing is not allowed to float, meaning it ends up taking the axial load rather than transferring it to the thrust bearing.

Has anyone yet tried putting the thrust bearing on the outside? To my mind having the radial bearings either side of the thrust bearing is a good design, as twisting forces in the grip would put less leverage on the bearing the further out it is seated. But obviously for that to work the outer bearing needs to float so that the axial load is transferred from the screw/washer at the end of the spindle, through the inner race of the outer radial bearing, to the thrust bearing.

Ok so I've already written way more than I intended to, but the question's in there anyway. :wink:

Alternatively, has anyone tried the Helidirect grips, or better yet had a chance to compare them to the Gaui metal grips? From some pictures I've seen they appear to be compatible with the other Gaui head parts. I've seen mention of the fact that they do have thrust bearings, I assume they're set up correctly unlike the Gaui ones?

[Pinecone]

Finless mentioned trying it, but he never has.

But if you press the outer beaing in using the outer race, you should be preloading the inner race against teh thrust bearing, allowing the thrust bearing to take the load.

Or you could just relieve the grip a bit to allow the outer bearing to float a bit, but even so, it will bind with side loads on it.

And if you put the thrust bearing on the outside (thinking aobut it) then the inner race of the outer bearing will still be taking the thrust loads, and binding that bearing. You need to transer the thrust loads from the bolt to the grip through solid metal, and the current setup does this, as long as there is some play in the outer bearing in the thrsut direction for the inner race to float a bit.

[Mikej]

And if you put the thrust bearing on the outside (thinking aobut it) then the inner race of the outer bearing will still be taking the thrust loads, and binding that bearing.
But if the thrust bearing inner flange was mating on the outer race of the outer bearing though presumably - wouldn't this be the optimal arrangement ??

Cheers,
Mike.

[lightbulbjim]

And if you put the thrust bearing on the outside (thinking aobut it) then the inner race of the outer bearing will still be taking the thrust loads, and binding that bearing. You need to transer the thrust loads from the bolt to the grip through solid metal, and the current setup does this, as long as there is some play in the outer bearing in the thrsut direction for the inner race to float a bit.
Well normally the thrust bearing pieces are the same diameter as the radial bearings. Doesn't that mean the the axial load would actually be transferred from the grip to the thrust bearing via the outer race of the radial bearing, hence it shouldn't bind.

If the thrust bearing only contacted the inner race of the radial bearing then it would bind under load, but then that is the same as having no thrust bearing at all as the inner bearing races don't need to turn against the feathering shaft.

You could have a thrust bearing that only contacts the inner race of the radial bearings, but it would have to sit closest to the main shaft, and the radial bearings on the outside. Which should transfer all the forces correctly, provided the radial bearings can float in the grip. The axial loads would be transferred to the thrust bearing via the inner races of the outer two bearings butting up against each other (maybe with a spacer between them or whatever). But I think it would just get unnecessarily complicated.


EDIT: Just noticed Mikej said what I meant... in way less words. :o

[Pinecone]

I don't think so. Because the loads from the spindle are on the INNER race of the outer bearing. So the axial load would go from the spindle screw, through the inner race, to teh thrust bearing to the grip.

And that point is, the inner race doesn't move on the spindle, but it moves in relation to the grip. If you get the loads into the outer race, the thrust bearing (in the stock location) won't do anything because the outer rae doesn't move in relation to the grip.

Thinking about it, if you put the thrust bearing on outer most, it would work, but you would have to make sure that the only contact is the outer race of the radial bearing. The load wold go from the spindle bolt to the thrust bearing, to the outer race to the grip.

And thinking about it, the outer race of the thrust bearing, either way, should be close fit to the shaft for the ID, and loose in the grip for the OD. And the reverse on the inner race.

The outer race should move WITH the spindle, and not have contact with the grip. And the inner race should move with the grip and not make contact with the shaft.