Tight tail belt

Thanks for reporting back. If I ever have to replace my belt I suppose I'll have to buy a new boom also since I shortened mine. For now I'm going with what I've got.

I ended up cutting my boom about 1/8", I had an Align tail belt in my spare parts box but didn't want to break into it. The belt that came with the 500CMT seems to be good quality. Shortening the boom is easy, just sand it on a sanding block (to keep it square) with 120-200 grit paper, only takes 1-2 minutes of sanding to take enough boom off for a better belt fit. 

The HK belts do stretch during the first flight or two. Score some cross-hatch marks on the end of the boom with a fine hacksaw and this will stop the boom moving in the clamps during use keeping the tension constant.

Engineering problem? Just like the gear stripping problem that the slotted holes fixes, a little trimming and filing should give us an adjustable tail box heli that will run HK or Align parts that are properly adjusted. I am current building a 500GT and have a CMT TT waiting. My GT so far has been very good and the tail boom/belt drive is right on but I have added the gear mesh/slot fix. So what is your solution to make the tail box adjust? We need to be able to use HK, Align, old and new don't we? And to afjust the belt as it ages. A real redneck solution to a short belt would be to make a "stretcher" that puts the belt in tension overnight.

I had to cut 8mm or so from the tail boom (alloy one). It is much cheaper to do that than buy an Align belt (costs 5x more almost), seeing the HK belt seems good (just short). A CopterX belt is only 2x the price, but I don't know if it is any better or not.
If you cut the boom then the tail servo pushrod is too long and you can't move the servo any further towards the main body as it hits the boom holder before it is far enough.... sigh.... so that needs adjusting too then.
And it means I will need to cut all booms I ever need to use. (which should be none ever, lol).

So the best solution is if Hobby King starts getting proper length belts! But this seems like it has been a long term problem (over a year?) and they still have not corrected it.

I also noted that the main belt drive gear is quite high up on its shaft and thus the belt is not lined up at the centre of the boom "hole" - which is the widest part of the circle of course. So it actually rubs lightly at its top edges, against the boom holder opening hole. That can't be a good thing!
Can the drive gear be moved and loctited lower on that shaft?

I am thinking I should have got the Torque Tube tail version!!
Does anyone know if the TT tail system has any notable issues to make it not such a good idea to have that?
It would have cost $4 more to get that right away... and $20 (plus postage) to do it now, sigh again.



Edited by PeterVau - 27/Sep/2011 at 6:59pm