Help with my new Swift Aluminum Blade Grips.

[frankos72]

I just got in my new century aluminum blade grips. They look great! I removed my existing plastic ones and I have ran into a problem installing the al ones.

I can't seem to get the thrust bearing into the grips. The flat washer that goes in just before the inner bearing race barely fit and the inner bearing race will only slip just into the opening then it binds up. I've tried everything short of beating it in with a hammer cause I'd like to be able to get them out someday if needed. I tried the outer race just for kicks and it binds at the same place.

I was thinking of trying new thrust bearings, but I didn't want to if I don't have to cause I'd like to get it back together and flying ASAP and no one around here carries Swift parts in stock.

Any ideas / suggestions from someone with experience installing these would be great.

Thanks!

Jev

[Chris DeSain]

I have not installed them on mine yet so let me give a PM to the taem guys in CA and see if they can help here.

[Lappster]

Jev,

I had the same thing happen,, I believe there is some tolerance issues on the thrust bearings. I took a spare spindle and stacked the thrust washers (small and large alternating) on one end with the screw tightened down against them to keep them tight,, chucked them into a drill and used a belt sander while running the drill to take a few thousands off and they fit fine. I assume the grips were machined with a TB measurement and then the tolerances changed after the fact. Dont hammer them in though,, you actually want a bit of clearance so take enough off to allow them to slip in easily.
You will really like the metal grips,, they add some crispness to the cyclic.

take care,,
Troy

[Dennisu]

frankos72

If you do trim the inner and outer race of the thrust bearings you must make sure that the inner race is loose on the feathering spindle and tight in the grip and the outer race is tight on the feathering spindle and loose in the grip.

[frankos72]

Nice particulars Dennisu. It will be easy enough to do. Can you explain why this is? I am already aware of the way they fit the spindle, but I guess I hadn't noticed the way the fit in the grips.

[Dennisu]

frankos72

Each race has to be anchored to something at each side/end but NOT to the same thing. The outer bearing is attached to the feathering spindle and stays fixed to it and must therefore be separate from the grip. The inner bearing is taking the centipetal load of the grip and blade and passing that to the outer bearing race and so must be fixed to the grip and not drag on the feathering spindle.

[frankos72]

Ah that makes perfect sense!

Thanks!

[smitty240]

Dennisu, I think the need for thrust bearings isn't to take radial loads from the grips to the feathering spindle, it's to take the thrust (centrifugal) loads from the blades/grips to the feathering spindle. Therefore they need to carry the thrust (end) load of the spinning blade/grip to the retaining hardware at the end of the spindle. This doesn't mean that the bearings should be undersize, as the larger bearing surface will dissipate the load over a larger area, but the need for press fit to the grip or spindle isn't that great. The outer race will be held to the retaining hardware by pressure and the inner race will be held to the grip, again by pressure from centrifugal force.
I'm a noobie to helis, but I've worked a ton of full scale aircraft and that's how our prop blades work. Those races seat to a machined face, but they are not a press fit.

EDIT: OK, disregard this.

[DavidH]

Couple of questions.
Do these new aluminum grips come with the radial bearings installed? Or do you use all the bearings from the plastic grips?

If the thrust bearings worked in the plastic grips, they should work in the aluminum grips if the grips were designed to accept them. Tolerances on bearings are normally very precise. So I would not think the problem is with the bearings.
I would NOT modify the bearings by changing the diameter using a sander.
If the aluminum grips are anodized and the inside where the bearings go is anodized. It is possible that the anodizing is thicker than it should be. Most parts that are anodized and require a part to fit precisely. The area where the part fits will usually not be anodized or will have been machined after the anodizing has been done.

David

[Chris DeSain]

David,
This has been brought to Centurys attention (in fact this morning) and you are correct. It appears the thrust bearings had a slightly larger OD than original spec the grip was made for and tested on. The area between the race groov and OD is rather large. On my swift 550 I also had to file down the thrust race to fit as the new plastic grips are to spec with the alum ones.

Not sure of the perm resolution right now.

For those who can't wait
wishing to use the grips and don't mind a little elbow grease can definitly use Troys tip and everything will be smooth and to fit.

[Dennisu]

Dennisu, I think the need for thrust bearings isn't to take radial loads from the grips to the feathering spindle, it's to take the thrust (centrifugal) loads from the blades/grips to the feathering spindle. Therefore they need to carry the thrust (end) load of the spinning blade/grip to the retaining hardware at the end of the spindle. This doesn't mean that the bearings should be undersize, as the larger bearing surface will dissipate the load over a larger area, but the need for press fit to the grip or spindle isn't that great. The outer race will be held to the retaining hardware by pressure and the inner race will be held to the grip, again by pressure from centrifugal force.
I'm a noobie to helis, but I've worked a ton of full scale aircraft and that's how our prop blades work. Those races seat to a machined face, but they are not a press fit.


NO This is wrong. What I said is exactly what is going on in the grips. The thrust bearings are taking the centripetal load from the grip and transfering it to the feathering spindle. My statement had nothing to do with radial load which is taken by the two ball bearings in the grip that were used in the plastic grip. This is exactly the same as the plastic grip except that the metal grips were slightly different bores than the plastic ones which has been noted.

[smitty240]

Well, if radial loads aren't the issue, why do they have to fit tightly on the ID and OD?

This is the statement I am referring to:

"If you do trim the inner and outer race of the thrust bearings you must make sure that the inner race is loose on the feathering spindle and tight in the grip and the outer race is tight on the feathering spindle and loose in the grip. "

[Dennisu]

Well, if radial loads aren't the issue, why do they have to fit tightly on the ID and OD?


I'm not sure what the question about this statement is? My preceeding posts should have covered the question of what has to be attached to what in the grips and the spindle with regards to the thrust bearings. If you are referring to the radial bearings then they have to fit tight on the spindle on the inner race AND tight on the grip on the outer race. The races in each different type of bearing have to attached to one and only one fixed surface. If the race was tight to two surfaces that moved then you would have no movement of the bearing.

[frankos72]

David,
This has been brought to Centurys attention (in fact this morning) and you are correct. It appears the thrust bearings had a slightly larger OD than original spec the grip was made for and tested on. On my swift 550 I also had to file down the thrust race to fit as the new plastic grips are to spec with the alum ones.


So will they be producing bearings that are slightly smaller to correct the problem?

[Chris DeSain]

So will they be producing bearings that are slightly smaller to correct the problem?


Not sure what the resolution will be to the parts fit problem here. Will post as soon as I know.

[tjmitchem]

Not sure what the resolution will be to the parts fit problem here. Will post as soon as I know.

It's been almost a month. Might want to ping them again :wink:

Terry

[Chris DeSain]

There was no response from them on this subject. I will ask again ? :arggg:

I rung the bell again and asked for them to post or fill me in so I can post.

[Chris DeSain]

Ok guys here is the as recieved reply I got. Looks like it is news to them so they need a return or two so they can see first hand.

"There was a slight change in the thrust bearings some time ago and this changed from the brass color to silver colored bearings. If he has questions, send them back and we'll take a look and exchange if needed. If it's a thrust bearing issue, send those back as well and we'll get a set that fit. It's hard to say exactly what's going on. "