Trex 700 at Charmouth

[Smoothound]

Dunno if it's been mentioned before, or if anyone's thought of it yet, but it could be that it needs a 3rd bearing block... you know - under the main gear

LOL
Cheers,
Rob

Personally I think a 3rd bearing block will help but the real problem is a main gear designed for a less powerful machine(pitch is too fine), very limited mesh adjustment and probably not particularly round main gears

I really think the 3rd bearing is more belt and braces than a root cause

[Ade_Law]

considering trev is still doing main gears on his 700e which isnt using the 700 clutch stack and has adjustable mesh i think we can say its not mesh related.

-1 gear apparently is slightly bigger, this is basically just trying make the mesh tighter which unless they have changed the material too wont fix the problem.

i agree that the gear should be a mod 1.0 rather than 0.7 i didnt like it on the 600 either give me a nice mod1 gear on 50/90 any day of the week, its prooven to be reliable!

Ade

[stmpngrnd]

I've still to do one myself..must be around 15 gallons. One question for those experiencing the problem consistantly. When does the stripping generally mostly. Fast stop on Pitch, sideways tic/tocs, forward tic tocs etc

I still think the 3rd main brg block is the answer. I wonder how much fuel Electricsceudo has been through now since modifying?

I got my 700 last summer when the first batch hit the states.
Living in California I've flown in temps from 40f to 90fplus. My 700 was flawless for the first 10 gallons through it. Then on a mild 55F day started to hear an odd ticking only to find several teeth were torn but still attched. Fitted a replacement gear(before the -1 came out) and got several more flights without issue.

Next up, fitted the rock solid miro cnc clutch block(this thing is perfect , no problems with it) and the microhlei cnc delrin gear. That didn't last but 3 minutes tops! Just did a few circuits to feel it out then went into some mild 3D. While doing some backwards traveling tumbles all but about 10 teeth sheered off in an instant while inverted. I saved it execpt for a bent head link. I couldn't get it back onto the runway and it tipped over in some very soft snow on the ground. This is californis so don't let the snow fool you..its was a beautiful toasty 65Fplus day.

I then put the previous replacement gear back in and got another 4 trouble free gallons worth of flying until this past saturday. Oh, first flight out after that repair I purposefully beat on it to try to strip the gear and all seemed good...full power vertical descents from 200ft to full power stops, and any combination of power and torque moves I could muster to try to either get a failure either from instant applied power or by twisting the frames under load. All seemed well. But last saturday it stripped again, this time costing a pretty penny in repairs..200USD not counting blades! Had a great warm up flight to start the day. Seccond flight, was coming accross the flight line at about 20ft about as fast as she can go doing consectutive rolls. On the forth roll while inverted the gear let go. I didn't react in time and she went down inverted full speed. I did a brain fart trying to descide which to do first..to roll out then hit thold or hit thold then roll out. Well in a blink she was in the dirt..thank god no chicken dance! The evidence on this last strip is odd. There are both teeth that where sheered and others that were run over by the pinion in different areas of the gear but not touching each other.

So, not counting the microheli gear as everyone is in agreement it is just pure junk, I've had two align gears strip. Both in warm conditions and both while doing rolling or tumbling moves. Both show signs of frame twisting pulling the gears out of alignment and only one shows signs of just pure stripping. From my experience its more the lack of a third mainshaft bearing than poor gear mesh or gear material. I've picked up a suitable Quick UK block to use as a third on the mainshaft and going to do the trick reported over on thetrexforums.com about using a 8mm shaft inside the hollow 700mainshaft to connect to the third block.

I love this bird beyond anything I've built and flown in the last 15yrs. Really hope this third block fixes it becuase no other 90 right now floatss my boat and I really don't want to pull the Fury out of its fuselage.

[Tim Procter]

Welcome to the forums.

Interesting read.

[mattie-lodge]

Hi,

As Busterboy said welcome to the forum.

Is anybody else over there having the same problem? If so, see if you get ask them to join in this debate. We are trying to raise the awareness of this issue to a greater height.

Thanks for your support

[stmpngrnd]

Hi,

As Busterboy said welcome to the forum.

Is anybody else over there having the same problem? If so, see if you get ask them to join in this debate. We are trying to raise the awareness of this issue to a greater height.

Thanks for your support

There are about 5 T700s at our field and so far I think I'm the only one to strip a gear. I'm not too sure though because i haven't been flying much there so far this spring. At our fun fly last october nearly 15 T700s came out and not one stripped a gear that week end and there was some serious flying going on

[Stuart]

While doing some backwards traveling tumbles all but about 10 teeth sheered off in an instant while inverted.

Seccond flight, was coming accross the flight line at about 20ft about as fast as she can go doing consectutive rolls. On the forth roll while inverted the gear let go.

Both in warm conditions and both while doing rolling or tumbling moves. Both show signs of frame twisting pulling the gears out of alignment and only one shows signs of just pure stripping. From my experience its more the lack of a third mainshaft bearing than poor gear mesh or gear material. I've picked up a suitable

It certainly sounds like you've hit the nail on the head as our Barney has been asking for age's to have a 3rd bearing block - ironically give him his dues on the very first pic's of the 700 he was surprised not to see a 3rd block.

The thing is the 700 was launched in July 2008 and got bigger in the market later in the year, getting into the colder UK weather, now we are into spring and soon summer with warmer temps coming and this could make matters worse with more flex getting into the frames.

[Ads]

I think being the UK expert on stripping gears I should kick in here. When I first saw the 700 I knew there were going to be problems with the tiny mod0.7 gear.

First, mod 1 gears will still strip if the material sucks!

Just b4 I left Century we were testing some carbon filled mod1 main gears that were injection moulded, they were much stronger because we were striping the normal mod 1 gears on 6S through wear and tear.

So how many flights do you guys get before the gear goes? Has anyone had 1 go rite away?

[mchristyuk]

Guys,

Maybe a temporary fix that might be worth a try..

Back in my Schluter days (NOT Robbe.. proper Schluter!) we used to boil the main gear (and undercarriages..and other plastic bits!) to de-stress them otherwise they broke quite easily.

I'm wondering whether it's worth a try?

From what I can understand there are several problems with the current gear 1) too fine, 2) too much flex in the mechanics and 3) non adjustable gear mesh.

Whilst all these may be contributing a 4th might be is that the gear is highly stressed out of the factory and a good boiling may release the stress in the gear.

This won't fix the underlying issue but may make the gear more durable and lengthen it's life a bit.

Of course if this has already been tried and helped none then please ignore me and I'll go back in to my hole

Cheers

Mark

[stmpngrnd]

I finished the third bearing mod and now its off to the field to put it through its passes. It was really quite simple to fix the new block. electricsceadu on ttrexforums.com pointed me in the right direction as far as what was needed. I posted a build thread over on helifreak for those that want to checck it out.-E

[Made2Fade]

it dont work

[kuss.72]

i just got the 700 only weeks ago have only run 1 1/2 tanks and just buy looking at the gear its only meshing on half of teeth wonder if the pinion gear on the bell could be just a hair bigger or teeth little longer looks like a problem to me but i've only flown for a year and first nitro heli for me.

trex 450/trex 600e/and unsure trex700 but still proud

[3dhiro]

"Align have brought a 90 size helicopter to us which is affordable for a lot more people through kit prices spares radio gear and engines." I am not too sure about that. So far the 700 has cost me more on crashes due to broken gears and two cyclic servo failures. If I could start over I would have gone for a proven better quality heli and I have already gone back to Futaba servos. h3R0

[ChrisB]

Fast Lads have the new Align main gear

http://www.fast-lad.co.uk/store/hn70...n)-p-6587.html

[StuSmith]

Can we cut down on align bashing on this furum at what seems to be any oportunity it's getting a bit boring.. If you dont like it sell it. Every manufacturer has its problems aligns are just advertised more as more people use align products..