General Help withTrex 450 pro dfc setup

[VFRLuke]

Hello,

I've been lurking a little bit her and using the setup guides for setting up a dfc head and 3gx. I appreciate the hard work that went into making these help threads and videos.

I've finished putting together my 450 pro dfc and have ran into some issues setting it up.

My equipment:
New 450 pro dfc kit with ds415m servos
3gx that came with it
Spektrum DX7s

I've went through and tried to setup the head 2 different ways:

I've used the guide on this forum: 90 servo's before installing and level the swash by adjusting the links.
I've used the freddy can fly videos: get horns as close as possible, make all linkages same length, level swash with sub trim.

I'm having no issues getting the swash level, but my problem comes when I move the collective stick up/down in DIR mode. At the positive end of travel, the pitch servo is a little bit higher than the aileron. At the negative end of travel, the pitch servo is a little bit lower than the aileron.

I can set a leveling tool on top of the swash and see it rock back and forth as collective pitch changes.

I've asked for help on another forum, but I've heard advice that you don't level the swash at high and low stick, just mid...but I think there's something wrong. One of the freddy can fly videos showed that the swash should be level all the way through collective travel.

so I think I got the servo's pretty close to 90 before installing them and it looks like the pitch moves more than the aileron when looking from the front of the heli. With the soko helitool pitch gauge and the swash leveled within 0.2 degrees at mid stick, it's like 2 degrees off at high and low stick. This is at 10 degrees of pitch, it gets further off with more.

I took a little video with my phone to show the guys on the other forum:
[video=youtube_share;ODPULdbcqEM]http://youtu.be/ODPULdbcqEM[/video]

So I got to thinking about it today, and wondered if the 3GX might have been to blame...I keep reading that they are evil. I hooked up the cyclic servos to a normal receiver (no gyro) and had the same exact issue. so the 3gx has nothing to do with it.

now with the servo linkage legngth I can't get them exactly the same, because you are limited to + or - one turn. The balls are in the inside holes on the servo horns.

Any ideas?

 

[Tony]

Am I the only one seeing nothing but black on that video? lol

First off, welcome to RCH!

I have heard of quite a few people having this issue. On the 3GX, you cna get away with a little more than you can on the ikon or BX. In this case, I would test and see if you can adjust your travel at high and low to get it to level out. I'm thinking something like 105-107 top and bottom will even it out. Just make sure when you are done, reinitialize the gyro (not in DIR mode) and make sure the swash is going to stay level and not want to wonder off.

 

[Tony]

And then when you get fed up with teh 3GX as many do, get you an AR7200BX and call the issues done lmao.

 

[VFRLuke]

I was playing with the servo travel in the transmitter and on the pitch i had it at 80 one way and 70 the other to get it to stay level. seemed like a lot.

I can't blame the 3gx because it did the same thing hooked up to a normal receiver.

Starting to wonder if I have a bad servo or something.

Here's a link to the video on youtube:

 

[coolgabsi]

I had this issue with my bird, had about the same experience as you are having but with Align 610's.. I have a whole thread on that asking a similar question frantically, as I have been doing this for 3 years and hadnt seen this before. luckily I am using Ikon and it has a way to correct that to make all the servos equal. One of your servos is not centerd somehow, As far as i remeber from when I used to have a 3GX based 450, my servo arm had the ball links on the outer most link to where the the links going to the swash were perfectly perpendicular.

Make sure the three servos have the ball on the arms at the same place on all three arms. One servo with the ball too far out than the other two will cause such behaviour also. I never saw this happen on my 450 before, but I have been told that one out of a 1000 servos will do that.

Now I cannot tell you how to fix it if everything else checks out, but to tell you to start by replacing one servo at a time with a different one and see which one was your problem. Sorry cant be of help, but atleast an encouragement nonetheless

Check your ball links, and your radio settings to make sure the limits are equal on all sides. reset the 3GX to factory and start over. Thats what I would do .

But others might have a different opinion

 

[VFRLuke]

the balls are in the proper holes on the horns, and the mechanical setup is as close as I could get with the horns that came with the kit. I tried hooking up a spektrum receiver and had the same behavior so it's not the 3gx.

I agree that it's just a weird servo on my pitch. I even tried swapping it to a different channel with the same results. for now I leveled the swash at mid stick and will let the 3gx do the corrections for the rest of it. I have hovered it and it seems ok. If issues persist I will get another ds415m

 

[coolgabsi]

Cool