PP: Hitec Servo Programming Fixture and Motor Thrust Shims

[Boulder]

Hitec Servo Programming Fixture and Motor Thrust...

Click here to read the entire review

[bob_nj]

So, are the units available?
I should have one for the shop, and some engine shims too

[1bwana1]

I got mine oh Friday. I will be using it next week. In the mean time I can say that this is a very well built product.

[bob_nj]

Do you know if the shims are available yet?

[757Driver]

	Quote: Originally Posted by bob_nj
	It would be excellent if someone could figure out how to make it work with more than just the servo the modeller cuts it out for.

What are you referring to when you say "cuts it out for"?

You lost me.

[ddlstang]

Bob nj ; the servo degree plates are available and can be ordered on my web site.

The engine shims are in the process of being cut, Im gonna try and get some laser cut real quick.

Dale Lathem
www.LA-Hobbies.com

[bob_nj]

"LA-Hobbies claims it's only for the Hitec 5955, but to tell you the truth, I've used it for HS-6965's with good results and I've also been able to use it for 5645's and 5925's"

"Keep in mind, if you attempt to use this device on any servo other than the one that it's intended for, you may get results less than optimum. The 59XX and 56XX series servos that I used on this fixture were an extremely tight fit, it worked, but it's not recommended by the manufacturer."

[rcflyer]

How does this fixture compare with the servocity protractor? http://www.servocity.com/html/servo_protractor.html

[Boulder]

	Quote: Originally Posted by bob_nj
	"LA-Hobbies claims it's only for the Hitec 5955, but to tell you the truth, I've used it for HS-6965's with good results and I've also been able to use it for 5645's and 5925's" "Keep in mind, if you attempt to use this device on any servo other than the one that it's intended for, you may get results less than optimum. The 59XX and 56XX series servos that I used on this fixture were an extremely tight fit, it worked, but it's not recommended by the manufacturer."

Just so you know Bob, the part that gets tight are the locating pins, not the servo opening. Using the fixture for other servos I was able to drop the servo into the opening then needed to force it on the locating pins. This is not recommended by the manufacturer, however, I found that I was able to use it with excellent results on all of the Hitec programmable servos I have.

Again please note: This is not recommended by the manufacturer.

[Boulder]

	Quote: Originally Posted by rcflyer
	How does this fixture compare with the servocity protractor? http://www.servocity.com/html/servo_protractor.html

In my opinion this unit is much easier to use and more accurate, since the servo is held in place by the locating pins.

[bob_nj]

Dale -> Sent you an email to let me know when the shims are available.
I'd like to make one order for both items.

Thanks
Bob

[crhammond]

	Quote: Originally Posted by 757Driver
	The really great thing about this fixture is that it garuntees perfect geometry between paired servos. A common issue when using a Futaba radio with these servos is that the end points "Shift" from where you set them with the programmer. The GREAT news is that with this degree setting fixture you can tweak the endpoints (by changing the exact point with the Hitec programmer) and then check the end result with the radio while the servo is in the fixture. ALL servos will have exactly identical throws and thus eliminating any binding between groups of servos (given the distance from the horn to hinge CL is identical).

I have a method for calculating this shift and a spreadsheet for anyone who is interested. It takes out the guess work. I have found ALL radios have a different pusle output and this is what makes the servos move "not quite the same distance" when you use the programmer vs. the radio.

It works like this:
1. You set your ATV/ETL to some high number for maximum resolution (I use 140)
2. You use the Measure Pluse for each channel on your radio using the programmer
3. You program the servos either on the wing or using a fixture of some type
4. You use the spreadsheet to correct the throws based on your radio's output

Example:
When measuring the pulse on your radio for ailerons you find that the readings are:
911us (clockwise) 1498us (center) 2076(CCW)

You program your aileron servos - lets say the values are -50 0 and 50. (totally unrealistic values but they are just to keep things simple)

Now your servo expects a signal of 900us 1500us and 2100us... so some simple math and we can find the correction needed.

For clockwise:
Expected us / Actual us
= (1500 - 900) / (1498 - 911) = 102.215%

For counter clockwise:
Expected us / Actual us
= (2100 - 1500) / (2076 - 1498) = 103.806%

The center is calculated like this:
Center error = Expected value / Measured value
= 1500 / 1498 = 100.134%

Now to correct simply take the values you programmed and multiply by the correction factor:
for CW -50 * 102.215% ~ -51
for CCW 50 * 103.806% ~ 52
for Center 0 * 100.134% = 0 (note if your center is actually zero this formula won;t work... but it has never been 0 in my experience)

Now re-program the servos with these end points.

IF your geometry is symmetrical then the servos will move to the dergee you programmed in. If your geopmetry is not 100% symmetrical then you can either fix it or tweak the programmer a tiny bit more.

Spreadsheet would be attached... but it won't let me upload a XLS file...

[bob_nj]

I have a spreadsheet that I use with my AeroPerfect meter that works pretty good.
It's on their site.

Send me yours if you will.
I'd like to take a look at it.

bob_nj@hotmail.com