5945 "Too Tight"?  
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All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> Radio Manufacturer Direct Support >> Hitec/MultiPlex Radios- Ask Hitec Customer Service >> 5945 "Too Tight"?
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5945 "Too Tight"? - 5/23/2004 11:52:34 PM   
macanaw


 

Posts: 39
Joined: 11/16/2003
From: Draper, UT, USA
Status: offline 		I recently purchased a number of Hitec 5945's for my 27% Extra 300. Since the time I took these servos out of the box I noticed the servos where unusually tight. After installing them in the plane I noticed that when the plane was switched off it required and great deal of preasure to move the surfaces. All other 5945's that I have used in the past have had much less resistance to the point of turning off the plane and all the surfaces would slowly lower.

This causes me a great deal of concern for a couple of reasons.
1. Is something wrong with these servos that may cause me a great deal of greif soon?
2. If a servo connection were to disconnect or become loose, the force of the air against the control surface would not be enough to push it to a neutral position. It would be "stuck" in whatever position it was in when it lost power or signal. Needless to say that would be very bad.

Another pilot I fly with had a number of 5945's with the same behavior which developed into a large amount of "slop in the servo yet still held alot of "resistance". Recently "flutter" began to appear and he was forced to replace all the 5945's with JR 8411's. The 5945's were bought at the same time mine were which was approx. 4 months ago. Any feedback on this would be appreciated.
       Post #: 1

RE: 5945 "Too Tight"? - 5/27/2004 6:32:30 AM   
mglavin



Posts: 5203
Joined: 11/29/2001
From: Elverta, CA, USA
Status: offline 		To be safe if your concerned return the servo to Hitec for service with a note of your concerns.

You might simply run the servos in and see if they loosen up. Manufacturing tolerances allow for some run out and this maybe whats being realized.

I have yet to see any 5945's realize a signifiacnt amount of slop, certainly nothing that would cause flutter. JR's 8411 are well known for this very attribute and premature gear train slop while the 5945's are NOT...

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Michael Glavin
RCU Community Moderator
Hitec * Multiplex Field Representative

(in reply to macanaw)
       Post #: 2

RE: 5945 "Too Tight"? - 6/17/2004 5:10:16 PM   
fcawth



Posts: 38
Joined: 5/4/2003
From: Beltsville, MD, USA
Status: offline 		Any word on these servos?? I have 2 out of 4 that exhibit the same behavior you are seeing. I bought them in groups of 1 and 2, and I did get the 2 about the same time as yours. I am about to fly my WH 28% extra with these things, but I am a bit concerned about these servos. I just hate it when you ignore something like this and find out the hard way that you should have done something about it...

Thanks,
FC

(in reply to macanaw)
       Post #: 3

RE: 5945 "Too Tight"? - 6/21/2004 7:20:09 PM   
MikeMayberry



Posts: 2864
Joined: 1/15/2002
From: Poway, CA, USA
Status: offline 		I doubt if there is an issue here but I'll pull some units and test them here and see if we see anything. However, if you are concerned you can always send them back to us to check out. As Michael said, some gear trains will be tighter than other but will break in as the gears wear.

As for the gear wear... search on the subject using the 5945 and the 8411 and I think you will find that there is no question that the 5945's are superior in this catagory.

Mike.

(in reply to fcawth)
       Post #: 4

RE: 5945 "Too Tight"? - 6/22/2004 5:48:21 PM   
fcawth



Posts: 38
Joined: 5/4/2003
From: Beltsville, MD, USA
Status: offline 		Thanks for the reply. It seems like something down the line in the gear train is tighter, because there is more noticable "slop", but the motion is tighter once it gets moving. On the smoother ones, when I move the arm with the servo off, it seems like there is very little slop because the motor seems to move whenever I move the arm. On the "tighter" ones, you can click it back and forth a bit with little resistance even with the motor off, then you get more resistance than normal once the motor (or whatever is tight) does move.. When I power it up and move it slow (i.e. cycle function on 9C radio), it seems to oscillate a bit more than I would like, and it really seems like this is caused by the tightness issue coupled with the servo loop controlling the motor oscillating slightly. (You see this kind of thing alot when tuning industrial servo loop PID parameters when there is friction somewhere)

I thought about opening up the case and having a look. Does this void the warranty??

I am thinking about picking up another servo so I can send one of the tighter ones in. I put in a couple of flights without an incident, but it still makes me nervous since the plane that I am using the servo on is by far my biggest money pit yet!! I just have to get that SWB arm off !!!

Thanks again,
FC

(in reply to MikeMayberry)
       Post #: 5

RE: 5945 "Too Tight"? - 6/22/2004 11:01:40 PM   
MikeMayberry



Posts: 2864
Joined: 1/15/2002
From: Poway, CA, USA
Status: offline 		Opening it does not void the warranty.

Mike.

(in reply to fcawth)
       Post #: 6

RE: 5945 "Too Tight"? - 6/29/2004 2:53:08 AM   
Nogyro



Posts: 1992
Joined: 11/30/2001
From: Puryear, TN, USA
Status: online 		I bought a 4 pack of the 5945's. Three are firm to move with the power off, and one will move very easily. It will just about hold up the elevator half of my Wild Hare 28% Edge when the power is off. So far after 20 flights or so, no problems with the easier one. The gear train is just as tight as the others, just moves easier with no power applied. These are my first digitals so I don't know which ones are right.................... They sure do center dead on compaired to the 645's, I know that.

_____________________________

Frank

(in reply to fcawth)
       Post #: 7

RE: 5945 "Too Tight"? - 7/6/2004 6:07:14 PM   
fcawth



Posts: 38
Joined: 5/4/2003
From: Beltsville, MD, USA
Status: offline 		Ok. I opened up one of the tight ones to see what was going on. It looks like the motor itself is what causes the "tightness" The apparent extra slop might be just because it takes more force to turn the motor so you can feel the play in the geartrain more. Everything else was very free, and the motor turned OK, but it did have some resistance to it.. Perhaps the motors have bushings that vary in tightness?? Anyway, I will just keep flying with this thing, since it doesn't seem to be hurting flight performance..

Thanks,
FC

(in reply to MikeMayberry)
       Post #: 8

RE: 5945 "Too Tight"? - 7/6/2004 6:38:58 PM   
famousdave


 

Posts: 2263
Joined: 9/16/2003
From: Bradenton , FL, USA
Status: offline 		Interesting... I was thinking that I got a few "used" servos as a recent bunch (12) I bought from the same company some were loose and some were tight per this discussion. I too opened up one of each to make sure I wasn't getting used stuff... they were all new. My guess is that Hitec went to a different motor design or bushing design. I was a little worried, but as the servos are used, they do loosen up a bit. To me, the tighter servos seem more accurate and less prone to noise. As a result, I have been using all the tighter servos in the wing and elevator and use the looser ones on rudder.... they all center perfectly, work the same and I have had no problems. I guess I'll stop worrying....

DP

(in reply to fcawth)
       Post #: 9

RE: 5945 "Too Tight"? - 7/6/2004 8:03:50 PM   
DENNIS C



Posts: 2965
Joined: 7/8/2002
From: frisco, TX, USA
Status: offline 		Im also having the same problem with my 5945's. infact i just started a thread on this servo. but now that i found this thread i'll just keep track on you guy's as ginney pig's JUST KIDDING. sure would like to hear what mike has found out on the test.


ANY WORD MIKE?????

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       Post #: 10

RE: 5945 "Too Tight"? - 7/7/2004 5:21:10 PM   
DENNIS C



Posts: 2965
Joined: 7/8/2002
From: frisco, TX, USA
Status: offline 		Hey mike are you going to do the test or what i sure would like to know. before i put my $3500.00airplane in the air.

Is there a problem or what??????????????

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"Opinions are like Buttholes EveryBody has one "

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RE: 5945 "Too Tight"? - 7/7/2004 11:01:47 PM   
MikeMayberry



Posts: 2864
Joined: 1/15/2002
From: Poway, CA, USA
Status: offline 		We are in the process of batch testing them to see if the issue shows up in our stock here. I will post my results in the next couple of days. However, we are not experiencing any problems with this servo so I would not hesitiate to use them.

Mike.

(in reply to DENNIS C)
       Post #: 12

RE: 5945 "Too Tight"? - 7/7/2004 11:15:37 PM   
DENNIS C



Posts: 2965
Joined: 7/8/2002
From: frisco, TX, USA
Status: offline 		Thanks for the reply mike, but im still intereted in what you come up with.

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RE: 5945 "Too Tight"? - 7/9/2004 4:36:54 PM   
MikeMayberry



Posts: 2864
Joined: 1/15/2002
From: Poway, CA, USA
Status: offline 		Randomly batch checking our stock of 5945's showed no difference in the effort it took to move the servos by hand.

Mike.

(in reply to DENNIS C)
       Post #: 14

RE: 5945 "Too Tight"? - 7/9/2004 5:45:02 PM   
walton