Beware of cheap dangerous servos sold online.

[Engine Doctor]

Hi Robin. The lack of rubber mounts with the 9 gram servos isnt the issue. The servos refered to are the standard sized servos like the Futaba  3003 or older 148 etc that are not fit for aircarft use.

[kc]

On 16/11/2021 at 10:15, Engine Doctor said:

Plane flew one flight OK then servos decided to lock over with inevitable results. 

I note this says  "servos"  -plural-  Surely it must be something else that went wrong if multiple servos all lock over at same time?   Worth investigating other items if it really is several servos.  But perhaps it was just mis-typed as plural.

[Martin McIntosh]

MG 60R or MG 90s are the main culprits because the central connection to the pot is of inferior material and when it fails to connect the servo runs to one end and burns out.

A long time ago though, I bought a dozen or so MG 995s for £2.99 each and never had a failure.

[Engine Doctor]

A touch pedantic ? Or is it a case of "There are none so blind as those who will not see".

[Paul De Tourtoulon]

I bought an unflown Esm Stuka with a Saito FG-30 in it, with Mg 995 servos throughout, 6 in the wing, he had installed the flaps with 4 of them,when lowering the flaps the 4 servos moved at different speeds,,

 

yes for the specialists it was made for 2 servos in each side of the wing 1 servo actions each of the split flaps ,now with Futaba S 3001 servos,,

 

 I also bought half a dozen thin metal geared servos ( corona ) for my 4 metre glider, not cheap at the time ( 2014 ) all but one packed up before I actually finished building it, yet my Corona 929 and 939 metal gear mini servos are everywhere and all work well,,

[Wilco Wingco]

If we are, inadvertently, flying with fake servos and have an accident due to servo failure. Would that invalidate our BMFA insurance. ???' 

[Paul De Tourtoulon]

A member of our club bought some fake Futaba S 3003 servos 4 for 12€, I opened one up it was like going back 50 years and all the wiring inside was white,,,

[Martin Harris - Moderator]

5 hours ago, Wilco Wingco said:

If we are, inadvertently, flying with fake servos and have an accident due to servo failure. Would that invalidate our BMFA insurance. ???' 

No. 

[Wilco Wingco]

Thanks Martin that's good to know. Still better to be sure to check the origin of your equipment though. 

[Paul De Tourtoulon]

On 20/11/2021 at 11:40, Wilco Wingco said:

Thanks Martin that's good to know. Still better to be sure to check the origin of your equipment though. 

Many aren't capable and don't know the difference, the only way to be sure is buy from a proper dealer or get someone in the the club to open up your servos,,

 

 Cheap is expensive,,,,?

[Nigel R]

"buy cheap, buy twice"

[Ace]

If unsure about a servos credentials/durability you could cycle it though a servo tester for say 10mins with a load on the servo arm over the bench edge?

Chances are if its going to fail it will soon be evident.

[Nigel R]

Yes, no, maybe. Cheap copies 'might' also miss the mark on

 

general mechanical durability (motor quality / parts life e.g. brushes, bushes, bearings )

inferior mechnical accuracy (slop, lash)

speed of wear over time leading to more of the above quicker

load holding ability (both accuracy and force thereof)

bad electrical behaviour (oscillating, buzzing)

inferior electrical parts (e.g. low quality caps) affecting power/speed/positioning after a while

bad physical build quality, e.g. susceptibility to vibration related failures in crap solder work

a warranty of any sort

 

sadly, very little of which will be made evident by initial examination or by moving it about on a servo tester for 10 minutes, (although Ace I do get the sentiment and that 10 minutes is worth a lot because it weeds out any DOA type problems and I do it anyway as it costs little and is a decent enough acceptance check).

 

To a large extent we have to trust (or don't) the manufacturer to get the above (and probably more) right. Personally I don't really trust Anonymous of Kazakhstan selling ProTower900s via BangGood to get much of any of that right or even know or care about it in the first place. Whereas by contrast I have some 30 year old JR (and the odd Futaba) servos that are only now showing signs of gear train wear.

[J D 8]

   After reading the above I am pleased to have recently got my mitts on a bunch of little used old Futaba 148 and 3003 servos.

[Tosh McCaber]

I thought that Banggood was an online shop, similar to HobbyKing.  Reading your post above Nigel, am I right in thinking that Banggood actually sell items on their website which may not be sold from Banggood itself, rather, stuff similar to Amazon's Marketplace items?

[Don Fry]

Don’t know what Bangood do, but last time I looked, they were selling fake Spektrum receivers. One fake, what else? If you sell something you have made, and can’t be bothered to put your name on it, or indeed trash a reputable builder’s name to flog it,  your little gem is suspect.

Observations, but I bought a dozen, and they worked is irrelevant. If it’s cheap, you have to cut corners, and quality control has got to be an early casualty

[Nigel R]

Exactly that Tosh, Bang good are mainly a warehouse operation.

[Jason Channing]

17 hours ago, Don Fry said:

Don’t know what Bangood do, but last time I looked, they were selling fake Spektrum receivers. One fake, what else? If you sell something you have made, and can’t be bothered to put your name on it, or indeed trash a reputable builder’s name to flog it,  your little gem is suspect.

Observations, but I bought a dozen, and they worked is irrelevant. If it’s cheap, you have to cut corners, and quality control has got to be an early casualty

That's why even the Genuine Tower Pro are total crap, The only ones I have ever used are from Banggood which are the MG92's and these have have decent centring and the correct torque, Why some company wants to make a copy of an already crap servo such as MG90 is beyond me.

[Graham Davies 3]

35 minutes ago, Jason Channing said:

Why some company wants to make a copy of an already crap servo such as MG90 is beyond me.

Simple answer Jason; volume. These things are everywhere. You wouldn't believe the quantity the raspberry pi/ arduino community get through. Never mind modelling use...

[Paul De Tourtoulon]

5 hours ago, Jason Channing said:

That's why even the Genuine Tower Pro are total crap, The only ones I have ever used are from Banggood which are the MG92's and these have have decent centring and the correct torque, Why some company wants to make a copy of an already crap servo such as MG90 is beyond me.

I am running at least 10,  Mg929 and 939 servos they are good,,,

[gangster]

So is it possible to identify a fake Tower Pro MG90S. ?
I am not a micro servo person but did buy 4 MG90S servos from a reputable source and put these in my Dawn flyer. I subsequently bought 4 more from eBay. That model has had hours of flying over the last few years. At least 3 years ago when doing pre flight checks the elevator did not work the servo was hot and the case bottom melting. I replaced it with one of the ebay ones and have flown happily since. I did however get a bit of concern about the servos and rang a reputable  company with a view to changing them all. He talked me out of changing them saying he used them all the time and there was no reason not to use them. I bought a couple more from him.  After reading this I got the servos on the bench to look at them,the four from eBay three are identical to the originals including the QC label. One however is completely different the MG90S is in larger font and the micro servo ina smaller font and the label much pinker.  The label was not on straight either Interesting enough I had put this in a separate bag and labelled it “noisy pot ?”  It performed effortlessly on a servo testertoday. Looking at the two later ones I bought from a reliable source these are labelled MG90D. And Torqpro.

[Don Fry]

My take, on this horror story, is I’ve been in this game of blood a long time. I want my stuff from people who put their own name on the stuff they sell. 
I don’t see the point with the argument, “but the cheap stuff I’ve bought hasn’t broken.”

I accept, bit of foam hits the ground, some money is lost.

Self built airframe, money and a lot of soul gets lost in that crunch.
And as you get deeper in this vale of tears, the box of bits you acquire gets bigger, and the problem grows, is there any false friends in there. As in, skip the box, start again.

Sorry I bang on. May the fake brake pads on your car serve you well.

 

[Nigel R]

I concur. 

 

Lifes too short.

 

Also there is the quote, quality is remembered long after price is forgotten. 

[Martin McIntosh]

Somewhere on here, maybe a couple of months or so ago, somebody put a pic of a genuine TowerPro alongside a fake one. I was able to identify the ones I have as fakes. They are unusable for various reasons. Shame because the spec. is very good.

[EarlyBird]