If you have a Nennos TR pulley check the width of the teeth!

[OICU812]

Well today brought some big pain. Aileron tic tocs 10 feet under off the deck, belt broke and not time or room to recover, a near writeoff, and the second near writeoff in the last month to make matters worse. Getting to be expensive to say the least, lol.

Anyhow... in investigating why it broke as I check my belts and all my stuff to the point of being anal almost I found something interesting which I think may have definetly played a role in this belt issue.

In looking at the Nennos tr hub or to some known as pulley I noticed a distinctive wear on the pulley itself. In fact it looked like the teeth are getting narrowed or worn in a matter that they are too wide, so I looked into it further. In taking a digital caliper I measured the teeth width to be 2.70mm in width at half height of the teeth. Then measuring the Mikado one it came in at 2.37 on every tooth, that is quite a difference when you are talking about belt cog spacing! Now I also noticed that the depth of the teeth is approx .4-.6 of a mm deeper on the Mikado one as well.

So I may have got a bad pair of these or this may be a problem.

I bring this up so anyone who has one of these nifty pulley/hubs can look at theirs and see if they are in risk or if their is different in measurements.....

If anyone has one or more of these please let me know your measurements. Meanwhile I emailed Nenno to see what the deal is on these.... I love the setscrew idea and metal but not at the risk of wrecking belts and helis. :?

[OICU812]

Oh and to clarify the 2.70 mm I measured was on the already "worn part" of the nennos pulley, the "non worn" part is more like 2.80 which would bring in a difference of .43mm between the tooth width of Nennos and Mikados, that is a fair bit I would think!

[Lorents]

Thanks for sharing, and my condolations :(

[WillJames]

Sorry to hear Shawn. :(

[OICU812]

Hey no biggie, these things happen, only thing that gets me is when I crash from failures of parts etc, that's always a bummer. :roll: I am hoping someone who has these pulleys will verify their measurements on the tooth width... :dontknow

[mudbogger2]

Were you running a black belt or a tan colored belt on there?

[Rick NT]

The comparance of these 2 dimensions doesn't say everything. Better is to measure the diameter on top of the teeth, can be dificult if the hub/pulley has a uneven number of teeth. The diameter should be the same for pulley's with the same number of teeth.
The dimension you now measure you should compare it with the width of the gaps on the belt.
It can be that the original plastic pulley has 'narrow' teeth on the pulley which have a lot of free play when mated to the belt.

Rick

[OICU812]

All originals measure exactly the same and this measurement is from top to bottom of each individual tooth, the measurement I referred to on the Nennos hub is from the very top of the tooth, at the bottom it widens more. The stock one is the good fit from cog to cog, this is not a special or new style belt or anything different, only the pulley is.

And Jon, the belt I am using is the Logo 20 "black" belt. I do not know of a different belt out there in this length that would be better, do you?

[Daniel Jetschin]

There you go with "necessary" upgrades ... :roll:

[epc2]

Shawn,

Checked mine , 2.43mm.

epc2.

[OICU812]

There you go with "necessary" upgrades ...


Hmmm...... how did I know that was coming? LOL. :badair: The only reason I put one of these in first of all was I had darn near lost tail control one day when a small peice off a stock on came flying off creating an uncontrollable vibration, took forever to find that it was even that. Now that aside if these teeth were same as Mikado it would be better as you do not need a pin nor do you need to take apart the tailcase just to change out a tr shaft, so I do not think it is all that bad, I think I got a bad pair is all. 2.43 is not far off, if mine were that I'd be ok with it, mine are far off and Nenno is going to replace them for me upon inspection so all is good. He said that the measurement can be off on some by .04-.10 but that us at most where for example Eds is .7 which is not much at all.

And honestly in looking at my other L14 with the Nenno hub the belt really does not seem to be unseating itself or anything odd, it could very well be that I just got a bad belt or prematurely had one break and that this small difference in tooth width is nothing to worry about. However......to be safe I am going to run the stock one for now to take that out of the picture and wait for some new ones with the "exact" dimesnsions tooth width and depth wise.

Someone here had pm'd me on premature belts breaking the Logo 20 black ones and that very well may be the case. The stock Logo 14 ones however to me look to be the same material etc as the Logo 20 ones. Is there a vendor out there or a belt manufacturer I wonder who would make better ones somehow than what we get in our kits...?
Hmmmmmm :roll:

[OICU812]

12.5 - 13 hrs later the L14 is reborn. Next time I put one in that hard I will either buy a full kit or try a different heli since I have 2 anyways, only thinig I did not change was one frame, a few frame parts, and a tailcase, rest is pretty much all new now. Good greif, now need the snow to stop here. We just had record snowfall for 20 years of nearly 3 feet in 48 hrs! :shock: That is more snow than the last 3 years combined. In looking at my other L14, the pulley the belt etc, I am starting to think it was the belt and maybe the pulley difference is no big deal. I would love to know if there is an alternative "stronger" belt in the Logo 20 length, 592xl,,,anyone know of one???

[Lorents]

Wow, you are a fast builder Shawn! You probably can deassemble and assemble a L14 blindfolded by now...

I think these guys have all kinds of belts and pulleys. You could see if there are a belt that fits from their selection:

http://www.sdp-si.com/

If its any better than the Mikado ones is hard to tell though :dontknow

[OICU812]

Well I replaced both belts brand new now, I am not going to lube them with nothing to see what happens. I also for now have put in the stock rear pulley even though I am convinced that is not an issue however I want to take that out of the picture. I will look into other belts when I have time, yes Lorrents no manual needed for me on any Logos, lol pretty much can throw it all on a table and build away now days. Heh :glasses2: