EXI head shaking problem

[thayghetucsb]

This thread is mainly for those who bought EXI 450 and its parts from Xheli. The main shaft offered on Xheli as replacement part for EXI 450 is very cheap in price (3 for $3.68) and unfortunately quality as well. it's made of very soft aluminum material. No matter how much i fine tune it, the head always wobbles uppon throttling down. And it's visually shown on the tail fin considerably vibrating at mid to high headspeed. Every crash, no matter how light it is results in a bent main shaft. After running out of EXI replacement main shaft, i used the harden shaft from the Outrage G5. There was no vibration nor head wobbling. I strongly recommend anyone that bought the EXI450 kit to replace the main shaft with the harden one. Align Trex 450 sells 2 for $11 (have not tried these yet) but Outrage G5 harden main shaft from Helidirect is 3 for $5.40. It doesnot say harden shaft from the website but i already talk to the Helidirect rep to comfirm that it is. I crashed my bird 3 times already and the G5 mainshaft is still flawless. Don't get me wrong i love my Trex clone but the main shaft gotta go.
By the way, i set my own record yesterday: 7 pairs of main blades down the drain in one afternoon. ;D

[Solitaire]

Seven pairs in one day? Yeow. Sounds like a record to me.

Thanks for the heads up on the main shaft. So far, out of the members here that bought the EXI 450SE on sale, I think only one is actually in the air. The rest of us are still waiting for parts.

Nice find on the Outrage alternative. I know what'll be added to my next HeliDirect order.

[Doozer]

Let me just toss an idea at you. I had a bad head wobble problem at throttle down that I couldn't figure out. I'd pull the head off the shaft and the shaft would spin true. I put the head back on and bam... there it was again. I finally started checking the bearing mounts. It seems that the frame screws that go into the mounts had shaken loose several turns and the mounts themselves were sitting loosely in the frame. I tightened these up and I was good to go. No more wobble.

You may have already tried this, but if not check that out and see if it helps.

[akent]

Solitaire, if you are talking about my Exi being in the air, it is no longer. It is waiting on 'real' servos now.

The Exi's do indeed have some soft shafts.
In fact, of the three Exi's that I have, only one came without a prebent shaft!!!
The Exi Squadron had a bent tail shaft.
The Exi T-450SE CF had a bent front belt pulley shaft.
The Exi 450SE was Ok.

The Align replacement shafts are nice and hard. They work well, but are not the cheapest.

Doozer, I actually had that exact same thing happen to the Squadron. It has plastic bearing holders, so I didn't loctite them. I found out later that they have metal inserts inside them, so the screws backed out. They are loctited now!

Kent

[thayghetucsb]

Mar 18, 2009 10:12:16 GMT -6 Doozer said:

Let me just toss an idea at you. I had a bad head wobble problem at throttle down that I couldn't figure out. I'd pull the head off the shaft and the shaft would spin true. I put the head back on and bam... there it was again. I finally started checking the bearing mounts. It seems that the frame screws that go into the mounts had shaken loose several turns and the mounts themselves were sitting loosely in the frame. I tightened these up and I was good to go. No more wobble.

You may have already tried this, but if not check that out and see if it helps.

I check srew tightening often, just to make sure that nothing is loose. i find that vibration or wobble is often caused by loose nuts/srews if the bird acts weird out of nothing. EXI shaft is ok for low -mid headspeed. Last time i put a 4s pack on my bird with EXI mainshaft which wasnot able to handle the new power and bent itself. yeah, shaft bent just for spooling up. ;D. The G5 harden shaft, exactly the same in every spec to Align shaft, is a worthwhile investment. I actually save money for not having to replace the mainshaft after the last 3 crashes. I checked, double checked and have my brother rechecked the shaft... Still flawless.
Anyone try the 4s zippy on this EXI 450 yet? Much longer flight tiime and power. I have 12 mins on mine and room to spare. Could go for another 2 if i wanted to. I don't do 3D. So that could be a big factor.

[Solitaire]

I had considered a 4S on the EXI, but was concerned with the weight factor. Not only that, with the 3S-2200 LiPo on there now, there's a lot more battery than there is tray.

I don't know what kind of flight times the 3S will give (Kent can interject on this) as I'm still building.

[thayghetucsb]

Mar 18, 2009 19:16:05 GMT -6 Solitaire said:

I had considered a 4S on the EXI, but was concerned with the weight factor. Not only that, with the 3S-2200 LiPo on there now, there's a lot more battery than there is tray.

I don't know what kind of flight times the 3S will give (Kent can interject on this) as I'm still building.

i have a couple of 2200mah 20C flightmax batt from hobbycity. just for basic hovering (11T pinion) i get around 9-10mins. I can go further but don't really want to damage them. The 4S 2100mah 25C is great, the bird feel much more powered. I get 14 mins out of each pack. These are also zippy's.