Servo bench testing

[SnowDog]

Tell me how to do it and I can accomodate. I am guessing I will have to use a high speed camera as there is no way I can do a stop watch that quickly. The quickest camera is have is only 60 fps I think which would not be real accurate. I think the measure is per 60 degrees of travel, and each frame would be .016 seconds.

Also which servo you want tested as this will be a PIA as I will have to measure say 30 degrees up and down and set the end points and then setup the camera rig.

that sounds like too much work. :|

figured it was worth asking though...

at what point does the speed become irrelevant to a mediocre 3D pilot such as myself? I'm not sure I could tell the difference from 0.12 and 0.10 or 0.08 anyway! Now that I think about it, perhaps around 0.14 or below becomes hard to tell for me...above that and I can "feel" a difference.

What do others think about this? I know it is pretty subjective...

 

[TimP]

that WOULD be a cool test. But what camera can you get that does highspeed and how much are they!? Maybe RW can do some testing like this

 

[Enterprise]

I would use my gopro first. I have a hero 3 white edition which only does 720p/60. The hero 3 black, and hero 3+ silver and black do 720p/120. Beyond that you are probably going to have to get a more specific camera. My nice camcorder does 60 fps, but that is for interlacing. Anyways that would be a whole other project. I will talk to [MENTION=443]ghoffman[/MENTION] about it. I think he has a better gopro than me and his own test rig.

 

[Ohio AV8TOR]

at what point does the speed become irrelevant to a mediocre 3D pilot such as myself? I'm not sure I could tell the difference from 0.12 and 0.10 or 0.08 anyway! Now that I think about it, perhaps around 0.14 or below becomes hard to tell for me...above that and I can "feel" a difference.

What do others think about this? I know it is pretty subjective...

Mike I also will fall in that mediocre 3D pilot description and let me share what I have found. When I went to the 7245's in HV (0.11sec) I really noticed the speed. At first I was over controlling but adjusted some of that out with expo and slowly worked my way back out of that expo. Where I really saw the difference was in rolling circles, there the extra speed seemed to help. At this point I will never go back to 6v servos as the HV really shins. If you are using HV now change it to 6v and then you can compare for yourself if the speed helps.

 

[Enterprise]

The issue with going to 6V is that the servo is geared to 7.4V. That would be like running 6V servos at 5V. HV servo were the new thing when I started doing 3D setups, so I have very few 6V servos. 90% of those are minis and below. The cool thing with HV is that they can gear the servo to have more torque in the same size, using the voltage to keep the speed.

 

[skibum44]

Just did some further testing with the improved rig.

Brand new Savox 2231 was 500 oz-in
Brand new Futaba BLS-172 was 450 oz-in
Brand new Turnigy 3509 was 470 oz-in
several season old Hitec 7954SH was 370 oz-in

[MENTION=2470]RedwingRC[/MENTION] gave me a few servos to test back at Toledo and I did not believe the first tests. Redid them today

XQ 4113D was 240 oz-in which is better than spec
XQ 4120D was 280 oz-in which is a little under spec, but I am going to redo this one as the 4113 got better once I tweaked the rig and I did this one first.

All of these are tested using a Spektrum RX fed by a Castle BEC pro set to 8.5V

Don't know if there were any differences with servos but it leads me to believe that the power safe RX on two a lipos is a better power supply then the BEC pro set to 8.5v. I had 516oz-in on a the fresh lipos vs your 450oz-in on he BEC.

 

[Enterprise]

I did testing over the winter using a powersafe and got worse results. When I did the BLS-157 I was using that RX. I have one spare for future use. With the BEC pro I have 2 inputs into the RX. Maybe next time I will use a capacitor to help with sag. I had a issue with my heli and this fixed it.

I use BLS's on my flagship 104 extra and in a few rudder applications. I do know for a fact that they don't have the same torque as a Savox 2230 as I had it on my 110 yak and got very bad blow back. I replaced it and still get some, but not nearly as much. I tried both a 157 and 172 in that application.

 

[skibum44]

Interesting... What lipos were you using when you did testing with the power safe?

 

[Planecraz3d]

The Hitec brushless sevos have a bulletin out saying not to use them with a powersafe receiver without a PAD device they send with the servo. I don't know if the Futaba brushless servos have the same issue with powersafe or not but it may be worth looking into.

Here is the bulletin:

June 2014: Brushless Servo Service Bulletin

While compatible with most radio control devices, the regenerative braking feature of the HSB-9XXX series servos may cause a problem if the device cannot accept a backflow of current. The types of devices that cannot accept this backflow are: Voltage Regulators, Power Safe Receivers and certain BEC circuits whether stand alone or integrated within an Electronic Speed Control. Check with the manufacturer or the Hitec website for a list of compatible models. If your device cannot accept a current backflow, then you must install a PAD (Power Absorbing Device - Hitec PN# 55756) as described in this manual. A PAD is included with every Hitec brushless servo.

http://hitecrcd.com/support/service-bulletins

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[SnowDog]

Servo voltage...what would happen to a servo if you ran 7.4v through a servo that was rated for only 6v? Would it kill the servo?

I've tried this on some cheap servos and it did not seem to harm the servos...just wondering about higher quality ones.

I don't want to put a HV high torque servo in for a throttle servo, but the whole system is running at 7.4v so I don't want to run the throttle servo only at 6v and I'd prefer not to add a regulator between the RX and the throttle servo...