Hitec Servo Programmer

[Hawkdaddy]

Does anybody have/use one for Heli set-up? if so do you have any useful info to share?
I was thinking that using one to setup your cyclic servos to make them exactly the same
might help them to cut down on cyclic interaction, ie. deadband width, speed, resolution etc... Any ideas or comments appreciated.

[unklpunk]

i have one, for 6965's and 6975's on a raptor and a trex 600n. i mainly just reprogramed deadband width and confirm servo speed. in the end i bailed on hitec and run jr servo's now,.. i think the few extra bux they cost are worth it. hitec are ok,.. but i had an inflight 6965 servo fail with no warning on the 600n,.. exspensive crash. teh programers are also usefull in the manual test mode and to read pulsewidth.

[Hawkdaddy]

Originally Posted by unklpunk

i have one, for 6965's and 6975's on a raptor and a trex 600n. i mainly just reprogramed deadband width and confirm servo speed. in the end i bailed on hitec and run jr servo's now,.. i think the few extra bux they cost are worth it. hitec are ok,.. but i had an inflight 6965 servo fail with no warning on the 600n,.. exspensive crash. teh programers are also usefull in the manual test mode and to read pulsewidth.

Thanks for the reply. Must not be very many heli people use them. I figured there might be more interest in them for fine tuning.

[Windbreaker]

This sounds like a very useful device to get the servos to a perfect center point. Right now with the Futaba 6EX system there's no sub trim. So you're stuck with having the servo arm slightly off if the splines don't align just right -- and they often don't.

If this device does what it seems to claim, then the servo arm can be adjusted to compensate for differences in spline position. And that would be a big help for those who don't have subtrim adjustments, and are trying to eliminate any CCPM interactions on their helicopters.

[Pistol Pete]

I tried finding more info on them as well and got little response. The main thing I found was you can center the servo to get your 90's setup. I didn't see the advantage in using the tool over subtrim so I didn't pursue it. If you don't have subtrim on your radio then it would probably be an advantage to get one. I assumed all radios had subtrim on them.

[ClayK]

Originally Posted by Windbreaker

This sounds like a very useful device to get the servos to a perfect center point. Right now with the Futaba 6EX system there's no sub trim. So you're stuck with having the servo arm slightly off if the splines don't align just right -- and they often don't.

If this device does what it seems to claim, then the servo arm can be adjusted to compensate for differences in spline position. And that would be a big help for those who don't have subtrim adjustments, and are trying to eliminate any CCPM interactions on their helicopters.

Uh, I keep rotating the servo arms until I get it to a 90 degree angle. On a CCPM machine you want 0 subtrim, that's ZERO. If you are using two way servo horns, you might want to look at using something different.

[Windbreaker]

I saw someone suggest something I might actually consider:

With a Dremel tool, grind out the splines of the servo arm and leave a rough texture in the remaining opening.

Coat the spline with a good release agent and fill the screw hole in the center of the shaft with modeling clay. Maguire's makes a hard wax release agent that works well. Be sure to let it dry. You might consider applying more than one coat. Perhaps as many as four or five. Protect the rest of the servo with masking tape.

Briefly connect the servo to the receiver, set the trim to zero and let it center itself. Disconnect the servo and don't do anything to disturb the position of the servo's drive shaft.

Load the inside of the drilled out opening of the servo arm with epoxy and carefully insert the servo shaft. Line up the servo arm so it's perfectly centered and set it up so that the epoxy doesn't flow into the servo. Let it cure thoroughly.

Hopefully you applied enough release agent. The spline should slide off the drive shaft with a little pressure. And I do mean little.

The end result would be a perfectly centered servo arm. Of course that servo arm would be good only for that servo so you might want to mark it to make sure you match it everytime.

If the release agent isn't applied properly, well then, you're stuck with the results.

[Pinecone]

Originally Posted by ClayK

Uh, I keep rotating the servo arms until I get it to a 90 degree angle. On a CCPM machine you want 0 subtrim, that's ZERO. If you are using two way servo horns, you might want to look at using something different.

Why 0 subtrim?

On older radios it would mess up travel, but on most radios now, the entire travel range moves (within reason). You can even subtrim a 401 on the tail.

[Pistol Pete]

I want to know too, why is it so important to have 0 subtrim?

[Pinecone]

Especially since Finless vids specifically tell you to use subtrim to get the arms 90 degrees.

Of course there are a couple of people in another thread (in the Trex 450 section) who claim that you don't need to get the arms 90 degrees.

[Pistol Pete]

Most setup video's, instructions, and people say to use sub trim but use as little as possible by getting the servo horn as close as you can get it to 90 prior to using sub trim. The only thing I can think of is because if you use too much sub trim you loose servo travel on one side, your adding range to one side and taking it away from the other side which may cause you to not have enough travel in one direction. The other thing MAY be the more sub trim the more ccpm interaction you have, I doubt thats true but if someone could clarify this we would greatly appreciate it.

[Pinecone]

On most higher end radios, sub trim doesn't change rang of motion, until you get a LOT of subtrim.

I agree, that you should try to use as little as possible, but question the source of the ONLY ZERO comment.

[ClayK]

There is no substitute for a proper mechanical setup. Set up your model however you want, I'm not the one flying it. However, not good enough coming from me? Perhaps you should listen to Ben Minor. Trust me, you can get a mechanical setup without subtrim.

Which is a better idea Terry? Focusing on getting a mechanical setup or saying subtrim is ok? Subtrim is not okay and should be avoided at all possible costs. If subtrim was a necessity, all the helicopters I've set up would have needed it, which they don't. But guess what? All 11 of my helicopters have 0 subtrim, are mechanically set up, and they fly great. I'm perfecting getting all the interaction out of there that's inherent in CCPM. Want to add more problems to CCPM? Add subtrim instead of focusing on getting a mechanical setup.

[rotary65]

Clay, how do you get the servo arms perfectly level with no subtrim? In the CCPM setups I've used to date, one out of three will need a little subtrim to center due to the servo output shaft splines. Do you just leave them not pefectly level and compensate in the linkages or are you modifying the output shafts as in the previous example (or are you using a servo programmer with digitals)?

[Pinecone]

I am saying you strive to get it as close as possible, then use the minimum sub trim to get it exact. Even with a new high end radio, if you use huge amounts of subtrim, you can lose motion in that same direction. But small amounts just shift the entire range of motion.

You still haven't given a reason WHY sub trim is a problem, only that you have manged to set up your helis without it. And the thread you point to only says to set the arms 90 degrees, not WHY sub trim should not be used.

Oh, and anyway, the arms should be 90 degrees to the linkage, not to the servo case. Now on most helis, it is the same thing, but not all.

[ClayK]

Originally Posted by rotary65

Clay, how do you get the servo arms perfectly level with no subtrim? In the CCPM setups I've used to date, one out of three will need a little subtrim to center due to the servo output shaft splines. Do you just leave them not pefectly level and compensate in the linkages or are you modifying the output shafts as in the previous example (or are you using a servo programmer with digitals)?

I rotate the servo arm until I get it mechanically centered. This means that I put it on, pull it off, rotate it, put it on, pull it off, rotate it until it's centered. I suppose the question is, what servo arm do you use? Depending on geometry, I use a variety of servo arms depending on application. Most of the time I use the large circular wheels and place my linkages so they are geometrically correct. I try every servo horn I have until I can get it right.

Originally Posted by Pinecone

I am saying you strive to get it as close as possible, then use the minimum sub trim to get it exact. Even with a new high end radio, if you use huge amounts of subtrim, you can lose motion in that same direction. But small amounts just shift the entire range of motion.

You still haven't given a reason WHY sub trim is a problem, only that you have manged to set up your helis without it. And the thread you point to only says to set the arms 90 degrees, not WHY sub trim should not be used.

Oh, and anyway, the arms should be 90 degrees to the linkage, not to the servo case. Now on most helis, it is the same thing, but not all.

How about you research it yourself? If me saying that it's bad and should be avoided at all cost isn't good enough, why should you saying that it's perfectly alright be good enough? I think I've provided a link from a verifiable source with years of experience that said exactly what I did, no subtrim unless it's absolutely impossible to avoid. I followed that up with my experience that stated that in all my helicopters I haven't needed it. Logically, what does that say? There are dozens of threads why subtrim should only be used as a last resort after all other attempts have failed. Personally, in the 11 helicopters I currently own and the 2 I previously owned, no subtrim was ever used. How can you explain that? Two words, equal travel or equal throw. You're point is that subtrim should be used to center the arm, while this is may be it's intended purpose, I have found in all the setups that I've done that I've never needed it. This proves that using subtrim isn't a necessity or even a regularity. I know other pilots who don't use it at all. If the people I know, myself included of course, don't need it, why do you suppose it is that you endorse it and they don't?

Originally Posted by BarracudaHockey

While I certainly defer to Ed on subjects such as this let me add again that you usually dont need any sub trim even if the arms don't line up if your using a multi armed servo horn rotate it 90 degrees at a time until you have the one closest to 90 degrees. Then if you must, make minor adjustments with sub trim. Most servo splines have an odd number of teeth so rotating the horn will give you different alingments.

Originally Posted by Dr. Ben

a sound mechanical set up must first be obtained. The radii of all servo wheels must be identical.

Originally Posted by Dr. Ben

2. Locate the mounting point for each ball link on the servo driving the swashplate at EXACTLY ninety degrees relatively to horizontal. Theoretically, this should be ninety degrees to the long axis of the servo's case. In achieving this geometry, the use of subtrim should be avoided if at all possible.

Again, like I stated earlier, not my model and I'm not the one flying it. If the going in position is to not use sub-trim, you are less likely to use it. Telling someone it's ok to use it can lead to them not attempting all possibilities to get a mechanical setup first.

[rotary65]

Originally Posted by ClayK

I rotate the servo arm until I get it mechanically centered. This means that I put it on, pull it off, rotate it, put it on, pull it off, rotate it until it's centered. I suppose the question is, what servo arm do you use? Depending on geometry, I use a variety of servo arms depending on application. Most of the time I use the large circular wheels and place my linkages so they are geometrically correct. I try every servo horn I have until I can get it right.

Gotcha - thanks Clay. For example, you might use the "blank" round arms and drill your own holes using one of those fancy Futaba drill guides. Most of the servos I get have different horns, but they are physically different sizes and strength.

I am also dealing with smaller minis and micros, only recently having disposed of my Raptor 50 in anticipation of the Trex 500.

I guess I should focus on servo arms and ideally find the perfect fit to obtain a true 90 degree geometry without using subtrim. If I don't have ideal horns, then a little subtrim will have to do (but it's not optimal) - but not before optimizing it mechanically (this is what I have historically done). I have also used subtrim and ATV to compensate for servo differences in accordance with Finless' CCPM setup guidelines. With digital servos and a programmer, then it suddenly becomes easier to match the servos.

So I guess I need to google servo horns, especially for my analogue servos.

[Windbreaker]

Regarding the Hitec servo programmer, I got an email from service at Hitec today. The programmer will work only with their digital servos. It won't program a neutral point on analog servos such as the HS-65MG.

So it's essential to get the horn mechanically centered as Clay points out.

[Pistol Pete]

Clay, nobody is disagreeing with you, we just wanted to know why. I guess we could have searched for the info but got talking about it here. I don't know what the big deal is?

[Hawkdaddy]

Well, on my 600N build I bought the Align servo wheels and turned them everyway but loose and couldn't get very close to 90 degrees. I tried every Hitec servo horn I had for my 6965's to no avail. So I decided to buy the servo programmer and set the servo center point myself.