ONE WAY BEARING FAILURES

[papa38]

It sounds like the centrifugal force is pushing the rollers away from the shaft they are supposed to grip(overcoming the spring tension on the locking fingers in the cage) I have my original OWB in my T-Rex, and It's probably been spooled up a thousand times without problems. Gaui should put the OWB on the shaft that drives the main blades like everyone else. I think the X5,X7 does this?

[fusionsx00]

If I could find a lower tooth count rear main, I could lower the first stage rpm
On stock gears my owb rpm on the 15t pinion is 9000 rpm
and all those bearings

But on a 13t pinion 50t front, 20t owb and a 54t rear main
My first stage would be at 7838 rpm owb /first stage bearings
still high but I would get my 2900 head speed.

Time to look for compatable gears

I guess I could also go to a 500 size blade, stretch the tail
Be the easiest way out,

Either way a lot of work

[papa38]

Too much work I think. 9000 rpm is probably way too fast for the one way setup.Not a very well engineered system in my opinion, and I have one due in a week No wonder so many peeps are having problems.

[gpraceman]

Originally Posted by fusionsx00

The gear is metal, the vxb owb has delrin or similar inside
But it has a metal housing

So its metal on metal

The main gear is plastic, owb gear metal

That sure looks like a plastic gear to me. The only metal gear that I see is the brass one for the tail belt drive. All the rest look like plastic.

Originally Posted by fusionsx00

I'm gona email vxb and see what they think the max rpm of the owb is

It would be interesting to hear if their bearing can handle that RPM.

[fusionsx00]

Looks plastic, but I smashed one already, and dented the edge of the owb gear
And I used my grinder and a file to smooth the gear out

Unless plastic sparks when you grind it

[fusionsx00]

Here is boca owb specs

ace
Material Chrome Steel 52100
Rolling Element Mat. Chrome Steel 52100
Dimension Type Metric ID (Fw) 8 OD (D) 12 Width (C) 12 Knurl No Weight(g) 4 Torque Rating (N.m) 3.15 RPM
Max Shaft Rot. 17000 RPM
Max Housing Rot. 12000 Rolling Element Roller Spring Plastic

[Mikej]

Originally Posted by papa38

Too much work I think. 9000 rpm is probably way too fast for the one way setup.Not a very well engineered system in my opinion, and I have one due in a week No wonder so many peeps are having problems.

At the risk of being shot down in flames - I think that there is a bit of "Forum fever" creaping, there are lots of people using the 425 in various guises and not having any issues. As has been mentioned the Gaui OWB has been known to be a bit fragile, however the VXB has generally been very reliable. Unfortunately Fusionsx is having a big problem with his OWB shaft and bearings and a few more have had issues - it sounds like a bad batch of Gaui OWBs and some related issues, not an epidemic or design flaw, people have been flying the 425 for a couple of years now and this has only come to light recently.

I really feel for you guys that are having issues - but hang in there - it's a great heli

[fusionsx00]

Im trying to, I guess im trying to solve my issue mainly,
and ease the preasure the owb has to deal with.

Still can't say that there are no problems at all
but I agree its not as bad as we are making it seem

I wish I was back on the" my owb is fine" boat

[spootman]

Geesh, 2900rpm! Lol, I run that on my 450! The high head speed might be what is eating up your bearings. I've had a good run with my setup besides the gear rubbing the frame, but I'm only running around 2600rpm.

[fusionsx00]

Well its a target head speed, and my castle ice only gets me to
2615 governed
I spent 2 days on the phone with castle,
believe it or not its slower than the 14t ungoverned

And I thought 2500 is the recommend head speed?
I wanted a 3d setup, not sport

But I do see where that would eat my bearings

So to sum it up, I ran the 15t governed, and did not set my end points on my tx
so I was at 80% max which was around 2700 according to my phones app
now it is set properly and the cc ice 75 logs have me at 2600 max
except for 2 test/setup hovers

I was thinking I use a 15t with gov and I get 3000rpm, well I was wrong according to castle

So I had 6 flights since I backed down on the rpms, and another owb failed .
I know something else has to be bad, the struggle continues

[Milde Shag]

Just a mention,
The bearing blocks can be overtightened on the plastic frames, causing premature..
bearing failure. Also I have ruined a few OWB' due to this and powerful motors.
When replacing OWB's Use a new 204582 8mm One Way Gear Shaft Set(L43)otherwise pointless.
The new 425 plastic frames seem to clamp the bearings tighter even for the main shaft and tail counter gear. I use a small amount of red locticte on the frame screws. Position the shafts in the bearings for assembly spin the shafts while increasing the torque on the bearing block fasteners, you will feel the friction on the shafts. It is a good idea to clamp the bearing block without creating any deformation or friction on the bearing, causing binding

[fusionsx00]

Carbon frame on mine, so at least that's one less thing to worry about

I've gone thru 5 shafts and sets of bearings so far

[papa38]

You should use CA on all screws going into plastic. It's a known fact that Loctite reacts with,and destroys plastic.

[gpraceman]

Originally Posted by papa38

You should use CA on all screws going into plastic. It's a known fact that Loctite reacts with,and destroys plastic.

Yes, but the frame screws go into metal nuts.

[papa38]

Ok ,sorry

[Stoats]

Fusionx, did you run a governor on the first 150 flights or so that your original OWB survived? I'm kind of wondering if that would kill a OWB faster with how governors cause engage/disengage cycles or pulse the powertrain like an impact wrench. Maybe that could cause the tiny roller pin "brakes" to wear out and fail eventually.

I've been nervous about putting the extra strain on the OWB system so I've held off on the governor so far on my Gauis. For what it's worth, running V curves has provided 60ish flights without any issues on VXB bearings but only doing smooth sport flying - very few pitch pumps or tictoc attempts since I didn't want to kill my 550. I've read about mixed results on OWB survival with governor vs curve from other Gaui fliers... seems to be completely left up to chance.

Has anyone tried a light silicone grease?

[fusionsx00]

It was not the original owb that came in the kit, it was 1 given to me by a team pilot
It looks like the vxb, but it was smooth and did spin freely

i did run a gov, but it was not running fast headspeed or
Any dramatic change in head speed, I thought I was but my log says diffrent
I did not understand all the settings in the cc ice gov, but now I do.

I lowered the gain on my gov, and I could hear the head speed changing

Castle told me everything was right, except my tx endpoints
on my logs my head speed is very consistant and not going up and down
It does sometimes but not constant.

I have isolated 2 culprits, my shaft on the first stage moves up and down
That's with 2 washers installed under and above the owb
2nd is my cf frame it allows my bearing blocks to move up and down about .01mm
Does not seem like much but when you stack the 3 blocks holding the shaft its a lot.

So I need to find a way to keep my blocks from moving, dowel pins or more screws under the blocks
Or buy new frame sides
No crashes, one hard landing when my first owb gave in flight
Only thing broken was a skid no cracks in the frame, nothing visualy wrong

[gpraceman]

Originally Posted by fusionsx00

I have isolated 2 culprits, my shaft on the first stage moves up and down
That's with 2 washers installed under and above the owb
2nd is my cf frame it allows my bearing blocks to move up and down about .01mm
Does not seem like much but when you stack the 3 blocks holding the shaft its a lot.

So I need to find a way to keep my blocks from moving, dowel pins or more screws under the blocks
Or buy new frame sides

Are you putting two washers on both ends (4 washers total)? It seems like Gaui designed it so the OWB would have room to float around. If you are putting in extra washers, then maybe that is causing some binding of the OWB.

I mentioned the OWB issue to a guy at our local flying field that has a 425 and he said that he saw on one of the forums people recommending to leave out one of the washers. I haven't come across that myself, but then again, I just started building my kit recently.

[fusionsx00]

No 2 total, one under and one above

But when the blocks are moved away from eachother
I bet I could fit 3 easy,

I talked to the owner of the store where I bought the kit
He said he will get one of his"experts" to help me fix this

But I have already experienced how helpful those guys are,
they do have alot of knowledge but they only help who they want to

I see alot of people get help there, even get there kits built by them
But there unwilling to help me?

It all started with this guys work ethics, he was supposed to get a 13t pinion for me
he called me and said it was there I showed up and he had sold to another customer already, I knew the other customer. So that's how I knew, but he lied right to my face and said it never showed up. So he got chewed out and has held this grudge agaisnt me for months. This is the manager im talking about.

It was nice having 2 gaui stores by me, but now I don't go to the closest one by me, and there always out of parts.
also gaui is having growing pains, there seeing more customers and releasing new helis and parts, that's why there having parts shortages.

It was nice while it lasted, im looking around

[beenflying]

Interesting! Received the VXB bearing today. The stock OWB has very similar markings to the VXB OWB, in fact it's hard to tell them apart, however, the VXB bearing has 10 rollers, whereas the stock OWB, only has 9.