TowerPro/Hextronic MG995 servo

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TowerPro/Hextronic MG995 servo

Postby RCModelReviews » Tue May 04, 2010 4:57 am

This review can be found at: http://rcmodelreviews.com/mg995review.shtml

Comments, feedback and questions on this review can be posted to this topic
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Re: TowerPro/Hextronic MG995 servo

Postby Stuka » Wed Jul 28, 2010 4:42 am

Completely agree with you about the overall review of these servos, glad that I only paid small dollars for the few I purchased from an EBay shop that hadn't put it's price up to nearly $18.00.

Looking forward to putting the "guts" into other servos as per your article.

This is a very good site that will be fantastic as it progresses
Cheers Geoff
OZ
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Re: TowerPro/Hextronic MG995 servo

Postby pejay » Sat Aug 07, 2010 4:10 am

Thanks for very good review. Had me worried so I opened up one of my Hextronic HX12K metal servos - and same thing here. The wires to the motor as well as the wires to the potentiometer are unsupported. See attached picture. Looks very much the same as your reviewed servo MG995. My question is - how is it supposed to look like? And would it not be enough to just put some silicone or even epoxy on the wires were they are soldered? On my servo the three wires going down to the pot has a blog of silicone covering the pot which I suppose will give enough support to the wires. :?
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Re: TowerPro/Hextronic MG995 servo

Postby RCModelReviews » Sat Aug 07, 2010 10:31 pm

I'm doing a big servo-shootout and I'll include pictures of "good" servo designs. Quite often these have the servo motor soldered directly to the PCB so there's no way (short of breaking the PCB) that the connection can fail.

Providing support by way of some kind of glue would help but don't use regular caulking silicone, it contains acetic acid that will corrode the wires (hint.. if it smells even vaguely of vinegar, a silicone adhesive/compound contains acetic acid and should not be used).
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Re: TowerPro/Hextronic MG995 servo

Postby Roger » Sun Aug 08, 2010 1:23 am

try hot-melt glue, works well for me...
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Re: TowerPro/Hextronic MG995 servo

Postby JensR » Mon Sep 20, 2010 12:39 am

Thanks for this review, which I found after buying 12 or so on ebay...
;)

Well, to be fair, it is a non-flight-related project - a slow moving model of an earth-moving machine. Also, I converted two of the servos to geared motors, so the problems don't really affect those and I can make use of the rather decent drive train - or so I thought.
On some of the servos, I notice a certain slack of the gears already (I am still in the testing phase).
This might be due to me backdriving some of them - stupid of me, I guess - it hasn't yet affected other servos and I am not sure this is the real cause, but wanted to send out the warning to be sure. Will update when I get to test my machine for real.
If anyone has a suggestion for a powerful and rugged servo that is cheap and may be slow: I'm all ears :)

Cheers
Jens
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Re: TowerPro/Hextronic MG995 servo

Postby RCModelReviews » Mon Sep 20, 2010 1:42 am

JensR wrote:
If anyone has a suggestion for a powerful and rugged servo that is cheap and may be slow: I'm all ears :)

Cheap, powerful, reliable

Choose any two of the above.

My servo shootout is nearly finished (I wanted to include the new coreless digitals from Turnigy). That'll give you a lot more in the way of clues as to what's good and what's not.
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Re: TowerPro/Hextronic MG995 servo

Postby JensR » Mon Sep 20, 2010 5:30 am

RCModelReviews wrote:Cheap, powerful, reliable
Choose any two of the above.


True, Bruce :)
I guess I sounded a bit too demanding - My point was that I would be willing to give up speed (and weight).
It's a bit frustrating as a machinery modeller that virtually all servos are so fast...
But I fully understand that such slow servos are not really in the focus of a plane-focused website and to be fair,
only few people seem to ask for them or else the market would have answered by now...
As I have them already, I might as well run the 995s as long as possible...
It also seems there is a large gap between the TowerPro Servos and the Bluebird Servos in price,
but I will be very interested to read your servo shoot-out!

Cheers
Jens
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Re: TowerPro/Hextronic MG995 servo

Postby Gadgets » Thu Sep 23, 2010 9:47 am

I've been using the Turnigy 9150MG for 1/8 steering.
The 995 has a plastic holder for the centre gear idle pin (I think thats the correct name)
The plastic goes oval or break easily.

The Turnigy has a brass bushing.

No complaints so far. Centres well enough strong and reliable for about a year of racing in a truggy.

I am thinking of using them in my 50 Heli.

To slow down try this:
http://www.laureanno.com/RC/picaxe-slowdown.htm
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Re: TowerPro/Hextronic MG995 servo

Postby JensR » Thu Sep 23, 2010 4:40 pm

Thanks very much for the info!
That looks like a better servo indeed. However, this goes into the price region of the Bluebird 620MG and similar, which I can get overnight without custom charges. Thanks for the option and pointing out this weak point of servo design!

As to the slow down:
A forum colleague in the machinery forum is building my a "hydraulic-simulator" module, which does what your linked PIC does. Also, there is a German e-store www.flymotec.de (english site not currently operational) who sells one plug'n'play module for this.
In general, I was more talking about translating speed into torque through gearing - which keeps the power equal (minus losses). Whereas this PIC reduces speed with keeping torque constant - and hence reduces output power.

Cheers
Jens
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