Main gear breakin and wear, again

[Rob43]

I don't get the use of WD40 for this application. WD40 isn't a lubricant per se. Are there other properties of WD that are providing a benefit? If not, why not a more suitable gear lube?

[DominicD]

The wd40 is being used as a cutting solution not a lube, this is why it has to be removed after 3 or so breakin flights.

[felborn]

Originally Posted by popokatepetl

Only 100 flights and you need to change the main and pinion? Well it's not good at all. Even my TRex 700E has 300+ flights without ANY maintenance t.

I only changed the pinion, the main gear seems just perfect niw, worn in but no freeplay at all. And I think it's my fault for splashing on to much WD40 and not cleaning it out. To really clean it, you need to remove the gear I think

[felborn]

Originally Posted by DominicD

I remind the jury of your previous post

Out of curiosity the folks who are having premature wear and those that arent did you let the springs in the motor mount auto-tension your motor belt or did you add alittle tension to it yourself ?

I added tension, do you recommend letting the springs do all the work?

[snemi00]

You should not be adding any tension to the motor mount by pulling on it. No need to add additional bending load to the motor shaft. Its a very thick belt and there is more than enough wrap around the pulleys to allow for good power transfer without much tension.

The springs in the motor plate are there to set the correct tension. Just leave the nuts a little loose allowing the plate to still slide freely. Spin the head around a few times to make the motor turn and find its natural place an then tighten the nuts down.
Watch the video SAB put out, it shows exactly.

[ame]http://www.youtube.com/watch?v=tCsJlqsgOu0[/ame]

[Azlum]

Originally Posted by snemi00

You should not be adding any tension to the motor mount by pulling on it. No need to add additional bending load to the motor shaft. Its a very thick belt and there is more than enough wrap around the pulleys to allow for good power transfer without much tension.

The springs in the motor plate are there to set the correct tension. Just leave the nuts a little loose allowing the plate to still slide freely. Spin the head around a few times to make the motor turn and find its natural place an then tighten the nuts down.
Watch the video SAB put out, it shows exactly.

http://www.youtube.com/watch?v=tCsJlqsgOu0

Both the manual and the SAB video you posted suggest that you should add a little extra tension by hand. Watch the video closely, he pulls the motor back slightly while he tightens the mount for the final time.

[snemi00]

If you look at the video at about 0:54 you can see he just squeezes the frames together a few times to just set the plate in place and then tighten the nuts down to finish. No pulling back or adding any significant force.
The manual states:
"The springs keep the belt in tension.
Help the springs by pulling the motor slightly"

This is just to overcome any "stiction" of the assembly to make the plate find its natural place. The video was released after the manual and the new technique as shown is to spin the head around a few times to free things up and find their place.
At about 1:30 in the video when he pushes in with his finger you can see the belt is actually quite loose.
A belt in a power transmission system should always be run as loose as you can without skipping teeth or flapping. Overtensioning is never a good thing.
It puts extra load on the bearings and motor shaft, prematurely wears the belt, and adds friction.

[Azlum]

Originally Posted by snemi00

If you look at the video at about 0:54 you can see he just squeezes the frames together a few times to just set the plate in place and then tighten the nuts down to finish. No pulling back or adding any significant force.
The manual states:
"The springs keep the belt in tension.
Help the springs by pulling the motor slightly"

This is just to overcome any "stiction" of the assembly to make the plate find its natural place. The video was released after the manual and the new technique as shown is to spin the head around a few times to free things up and find their place.
A belt in a power transmission system should always be run as loose as you can without skipping teeth or flapping. Overtensioning is never a good thing.
It puts extra load on the bearings and motor shaft, prematurely wears the belt, and adds friction.

I think perhaps you should watch it again and pay a little more attention. You can clearly see the belt get more tension when he pulls back on the screws, and he HOLDS this tension while tightening the mount.

No offense, but I'll go by what I see and exactly what is written, rather than interpreting the text of the manual in a different way.

[DominicD]

Stock up on motor shafts azzy

[snemi00]

No offense taken, just trying to point out a couple of things for people to consider.
There is no quantitative way for people to know how much tension the belt is under, and it is a very subjective thing.
One person will say his belt is tight and another may say loose, but it could actually be exactly the same, just their perception of what tight or loose is.
The nice thing about the Goblin design, is that it really does remove much of the guess work. The tail belt tension is very easy for people to quantify by looking at the position of the tensioner arm relative to the frame.
The motor belt tension is held by the springs in the plate.
And there is no gear mesh for people to worry about either.

The thing that prompted me to post is reading in the other threads about the squeaking noise and how relieveing the belt tension made it go away. It makes me wonder how some people may interpret setting tension and could be pulling back on the motor with significant force and holding it in order to set tension then having the belt as tight as a guitar string.

[gww528]

Originally Posted by Azlum

I think perhaps you should watch it again and pay a little more attention. You can clearly see the belt get more tension when he pulls back on the screws, and he HOLDS this tension while tightening the mount.

No offense, but I'll go by what I see and exactly what is written, rather than interpreting the text of the manual in a different way.

+1 a little tension is given when pulling back on the motor... then the video shows how much deflection the belt should have by poking it with a finger.

Manual v1.3 Page 29

•Assemble the motor and pinion to its mounting plate.
•Fit the motor assembly into position.
•Compress the springs by pushing the motor toward the main shaft.
•At maximum compression, temporarily tighten one of the slide screws.
•With the minimum centre distance it is easy to install the belt. First put the belt on the motor pinion.
•Then put the belt around the big pulley.
•Rotate the motor several times by hand.
•Release the screw that locks the slide.
•The springs keep the belt in tension.
•Help the springs by pulling the motor slightly.
•Lock all screws.

[gww528]

Originally Posted by snemi00

No offense taken, just trying to point out a couple of things for people to consider.
There is no quantitative way for people to know how much tension the belt is under, and it is a very subjective thing.
One person will say his belt is tight and another may say loose, but it could actually be exactly the same, just their perception of what tight or loose is.
The nice thing about the Goblin design, is that it really does remove much of the guess work. The tail belt tension is very easy for people to quantify by looking at the position of the tensioner arm relative to the frame.
The motor belt tension is held by the springs in the plate.
And there is no gear mesh for people to worry about either.

The thing that prompted me to post is reading in the other threads about the squeaking noise and how relieveing the belt tension made it go away. It makes me wonder how some people may interpret setting tension and could be pulling back on the motor with significant force and holding it in order to set tension then having the belt as tight as a guitar string.

The belt tension is a learned art. Springs loose their tension & belts stretch. The best rule of thumb is to learn how much deflection the belt should have by pressing it with a finger from the side... this is how its been done with heli's without mechanical tail belt tensioners

[popokatepetl]

So I did use the WD40 for a few first flights just to get the right mesh. Then I've cleaned everything and after evry 4th flight used tooth brush to clean the main gear and the pinion from the black dust comming from main gear.

After 34 flights my pinion is EATEN all the way down!

Now what. It looks like we should lubricate the main gear after breaking in process. I'm so...

[pitchandyaw]

I'm going to do the first few flights without any lube and once the mesh has settled in a little I will lube with silicone spray.

I'll let everyone know hoe that goes....

[popokatepetl]

Originally Posted by pitchandyaw

I'm going to do the first few flights without any lube and once the mesh has settled in a little I will lube with silicon spray.

I'll let everyone know hoe that goes....

Now I'm pretty sure that main gear have to be lubed once the mesh is set. I just hope my main gear isn't dead as well

But we should use to lube it? I have some PTFE grease here so this is what I'll use next time.

[felborn]

Even after wearing the pinion down to knifeedges, the maingear itself seems just fine. Replaced the pinion and the fit is perfect, so I dont think you have to worry about that. But after putting in 6 flights today with new pinion and zero WD40 or lub, I'm seeing more of that damn black dust... Temped to try triflow silicon or somethibg. Really hoped I was done with that black dust, but sadly not it seems

[popokatepetl]

I don't think new pinion will solve that. Just gives you few more flights before the new one dies as well. We really must lube it with something.

I've just ordered steel pinion for my Goblin It's custom made.

[felborn]

Originally Posted by popokatepetl

I don't think new pinion will solve that. Just gives you few more flights before the new one dies as well. We really must lube it with something.

I've just ordered steel pinion for my Goblin It's custom made.

But will lub oil the damn thing, or like the WD40 just help in cutting and causing even more black gunk to be trown about in there?

[tott]

Is the gear made of a cheaper soft "plastic"........ Or something like delrin ?

If it is not delrin I could only imagine it will only be a mater of time before there will be an "upgrade" offered either from SAB or a outside company for this heli.

There has been previous concern and discussion when using slanted gears as well....this creates an extra load of sort by a direction force which COULD "help" explain the excessive wear of this system. I know here are several heli systems that use slant gears without this problem....but this is a unique geartrain......just something to think about...

Herringbone seems to give the benefits of slanted gears but no extra "load".....

Of course most of this is subjective and opinionated so take it for what it is worth...

Jason

[OnTheSnap]

I used wd40 a few times for the first 20 flights then stopped lubricating my gear. After 100 plus flights it's holding up well. I never cleaned it off. The pinion had worn in a bit but doesn't look worn out.