Gr4yb3ard
06-02-2008, 11:42 AM
All,
This is going to be mostly text. Wish I had time to figure out how to embed and annotate photos, maybe next time...
A lot of us have found a "click" in the head. Fell victim to bent grip screws. Found dampers not working quite right. Even one case where it seems the spindle wallowed out the head.
I found the click myself, and decided to get down and dirty on this, here's what I found....
First off, the "click" is simply the grip moving in, or outboard along the bearings it houses. Figures 1 & 2 demonstrate this, you can see the gap between the two bearings in the small hole on the bottom of the grips. One shows the grips pushed together, the second pulled apart "CLICK".
The movement of the bearings is NOT a sign of slop in the damper system. Note the picts of the mounted spindle and brass spacers. Everything is lined up on the end of the spindle as the bearings "close" it up.
If these brass, stepped spacers are at the end of the spindle on assembly, there's not much reason to worry, lacking the discussion on adjustment below.
Again, the inside grip bearings "close" the damper system, and the grip screws make sure of that. All the click means is that the grips basically "hang" on the bearings, and are allowed to move inward, sliding over the bearings with pressure, but in flight, they will move out to the proper location, no problems....
It would be nice to have some small washers to adjust the damper pre-load, but they'd be really thin. I've demonstrated this in one illustration of the head on it's side,showing the smallest washer I could find inserted into the system. You can see the large amount that would have to be compressed into the dampers in order for the bearings to seat on the ends of the spindle.
BTW, One gotcha I found, is that one of my stepped-brass-spacers was pretty much welded to the spindle with locktite from the factory. Having gone through this dissasembly and cured that, it flies quite a bit better, watch that one....
Grinding material from the end of the spindle would allow you to compress the dampers as material is removed, but this can only to one way, and a big caveat here as well!!!
If you don't grind the spindle end exactly 90d to the plane of rotation, the grip screw arrangement will tend to take your grips to some angle out of plane.
So, I'd say mess with damper dimension first to adjust. Little, itty bitty washers? Might work, but at this scale I think it would difficult. Grinding the end of the spindle?, I give that a big thumbs down.
From most of these pics, you can get the drift that the grip bearings flush up against the end of the spindle. This is contrary to most heli's, where the spindle goes through the bearings, further into the grips.
This is where the both the reliability of the spindles, as well as the notorious bending of the grip screws comes from.
There is nothing supporting the grips in any direction but outwards, than the strength of the bolt against bending.
Having thought about it a bit, I'm not unhappy with this. I'd rather replace little screws at every crash than the spindle, as most require. And as the spindle is pinned into the head, you really don't need, or want to! Just replace the dampers and screws as needed. It would take quite a crash to bend this spindle, I think...
I've lastly included a mock-up of the spindle, spacer, bearings and bolts to let you see how the bearings sort of "hang" off the end of the spindle. Again, this system seems to work okay, and buying a bag of 2x10mm screws beats buying a bag of spindles any day.
Synopsis: The "click" is normal. The bent grips screws are pretty much a weak link that allows us to save spindles. Damper adjustment is best handled by working with the dimensions and properties of the dampers themselves. If you find a spindle too long to slightly compress the dampers, try a newer one to save yourself some time and trouble.
Gr4yb3ard
"....tool-using pirates... ...scary!!..."
This is going to be mostly text. Wish I had time to figure out how to embed and annotate photos, maybe next time...
A lot of us have found a "click" in the head. Fell victim to bent grip screws. Found dampers not working quite right. Even one case where it seems the spindle wallowed out the head.
I found the click myself, and decided to get down and dirty on this, here's what I found....
First off, the "click" is simply the grip moving in, or outboard along the bearings it houses. Figures 1 & 2 demonstrate this, you can see the gap between the two bearings in the small hole on the bottom of the grips. One shows the grips pushed together, the second pulled apart "CLICK".
The movement of the bearings is NOT a sign of slop in the damper system. Note the picts of the mounted spindle and brass spacers. Everything is lined up on the end of the spindle as the bearings "close" it up.
If these brass, stepped spacers are at the end of the spindle on assembly, there's not much reason to worry, lacking the discussion on adjustment below.
Again, the inside grip bearings "close" the damper system, and the grip screws make sure of that. All the click means is that the grips basically "hang" on the bearings, and are allowed to move inward, sliding over the bearings with pressure, but in flight, they will move out to the proper location, no problems....
It would be nice to have some small washers to adjust the damper pre-load, but they'd be really thin. I've demonstrated this in one illustration of the head on it's side,showing the smallest washer I could find inserted into the system. You can see the large amount that would have to be compressed into the dampers in order for the bearings to seat on the ends of the spindle.
BTW, One gotcha I found, is that one of my stepped-brass-spacers was pretty much welded to the spindle with locktite from the factory. Having gone through this dissasembly and cured that, it flies quite a bit better, watch that one....
Grinding material from the end of the spindle would allow you to compress the dampers as material is removed, but this can only to one way, and a big caveat here as well!!!
If you don't grind the spindle end exactly 90d to the plane of rotation, the grip screw arrangement will tend to take your grips to some angle out of plane.
So, I'd say mess with damper dimension first to adjust. Little, itty bitty washers? Might work, but at this scale I think it would difficult. Grinding the end of the spindle?, I give that a big thumbs down.
From most of these pics, you can get the drift that the grip bearings flush up against the end of the spindle. This is contrary to most heli's, where the spindle goes through the bearings, further into the grips.
This is where the both the reliability of the spindles, as well as the notorious bending of the grip screws comes from.
There is nothing supporting the grips in any direction but outwards, than the strength of the bolt against bending.
Having thought about it a bit, I'm not unhappy with this. I'd rather replace little screws at every crash than the spindle, as most require. And as the spindle is pinned into the head, you really don't need, or want to! Just replace the dampers and screws as needed. It would take quite a crash to bend this spindle, I think...
I've lastly included a mock-up of the spindle, spacer, bearings and bolts to let you see how the bearings sort of "hang" off the end of the spindle. Again, this system seems to work okay, and buying a bag of 2x10mm screws beats buying a bag of spindles any day.
Synopsis: The "click" is normal. The bent grips screws are pretty much a weak link that allows us to save spindles. Damper adjustment is best handled by working with the dimensions and properties of the dampers themselves. If you find a spindle too long to slightly compress the dampers, try a newer one to save yourself some time and trouble.
Gr4yb3ard
"....tool-using pirates... ...scary!!..."