Newbie needs help with servo centering

[dij74]

Hello,

I've just built my first heli, a TREX450 V2 and i'm now doing the setup. I've been going through Finless's excellent videos, however I have checked the pitch and i'm only getting +6deg and a -12deg.

I thought that i had centred the servos correctely has finless video.

Centre stick and trims.
Power on
Put on arms in as horizontal position as possible.
Correct any horizontal error on the arms using subtrim.I does look has though all the CCPM servos are not moving up as much as they are moving down.

I'm using Hitec HS-65MG servos.

Can anybody help please.

Darren

[LAMAR COOLEY]

dij74
Take another look at the "Finless" 450 SE set-up video, please.
Also you want to adjust your links from the swash plate to the mixing levers so that they(levers) are even with each other and parallel.When the stick is at 50%. With the servo horns as close to centered on the servo case as possible. The HS65 servos come with several horns and I found one that was just about perfect for each servo. If you have to use a lot of subtrim to center than try other horns for a better fit. Also you want your end points for the pitch channel to read 100 at top and 100 at bottom.Or 100 at top and 0 at bottom depending on the radio in use Once you have a horn on the servo do not connect the link.
Example: Move the swash plate to the top by hand. Then move the throttle stick to the top and see witch hole on the servo horn matches the link. Then move the swash to the bottom and the stick to the bottom and see if you can match the same hole as at top.
You may have to shorten or lengthen the link to get the same hole to work at top and bottom.
I hope this may get you one your way.
Regards

[vera]

Check your pitch curve. If you want mid-stick to center the servo then the pitch curve point corresponding to mid-stick (point #3) needs to be set to a vaue of 50.

[Finless]

You don't say what radio you are using but on some radios watch out for any sliders or knobs as they maybe enabled and thus mess with pitch (hover pitch and pitch hi/low). If you do not center those or disbale them in the radio menus (you can't on hitech radios) they will mess you up when doing servo center and you will see more movement one way than the other.

This has really messed up many people.
On Futaba radios like the 7 and 9C they are turned on by default. Go turn them of. Hitech you cannot turn them off so you have to make sure they are centered. JR radios they are off by default usually.

Bob

[dij74]

dij74
Take another look at the "Finless" 450 SE set-up video, please.
Also you want to adjust your links from the swash plate to the mixing levers so that they(levers) are even with each other and parallel.When the stick is at 50%. With the servo horns as close to centered on the servo case as possible. The HS65 servos come with several horns and I found one that was just about perfect for each servo. If you have to use a lot of subtrim to center than try other horns for a better fit. Also you want your end points for the pitch channel to read 100 at top and 100 at bottom.Or 100 at top and 0 at bottom depending on the radio in use Once you have a horn on the servo do not connect the link.
Example: Move the swash plate to the top by hand. Then move the throttle stick to the top and see witch hole on the servo horn matches the link. Then move the swash to the bottom and the stick to the bottom and see if you can match the same hole as at top.
You may have to shorten or lengthen the link to get the same hole to work at top and bottom.
I hope this may get you one your way.
Regards
Thanks for the reply. I will check the videos again.

When I did the centreing, I only needed to put in 2 clicks ofsub trim on one of the servos, the others were spot on.

I does appear that all the servo movements are the same, ie, all of them don't rotate as such in the up direction.

Cheers

Darren

[dij74]

Check your pitch curve. If you want mid-stick to center the servo then the pitch curve point corresponding to mid-stick (point #3) needs to be set to a vaue of 50.
Hi Vera,

You might be onto something here. I did play with the pitch curves in the past, when playing with my new radio.

I checked the pitch curves for Norm ST1 and ST2 they all default at the moment:

1 0%
2 inh
3 50%
4 inh
5 100%

But the graph for Norm shows a kink upwards at point 3!

I will try setting up using a new blank model in the radio.

[dij74]

You don't say what radio you are using but on some radios watch out for any sliders or knobs as they maybe enabled and thus mess with pitch (hover pitch and pitch hi/low). If you do not center those or disbale them in the radio menus (you can't on hitech radios) they will mess you up when doing servo center and you will see more movement one way than the other.

This has really messed up many people.
On Futaba radios like the 7 and 9C they are turned on by default. Go turn them of. Hitech you cannot turn them off so you have to make sure they are centered. JR radios they are off by default usually.

Bob
Hi Bob,

Thank you for your great videos, they are a fanatastic resource to newcomers like me.

I am using a SpektrumDX7 radio, so i assume it will be setup like a JR radio.

Cheers

Darren