Cheap servos worth the risk?

[Martin Harris - Moderator]

Martin makes a good point - the Futaba 148 (or 3001 ball raced equivalent) is adequate for the majority of sport and reasonable sized scale models and pretty much bulletproof. The "standard" JR591 is another good choice if you can still find them - they have very smooth mechanics and are a little more powerful - but only if you're running a 4 cell pack or on a 5V BEC.

Here's an example representative of an aileron on something quite large which is well within the capability of a 148 (33 oz.in on 4.8V):

Edited By Martin Harris on 28/06/2017 16:33:38

[Don Fry]

Or I have a quarter scale Dr1 Triplane. 20 cc power plant. Mix of Futaba 148, 3001, all working off a 1400 maH LiFe battery. Or my mate, quarter scale cub, same servos, 2000 4.8 volt Eneloop.

And it all works without hassle.

[Nigel R]

The torque requirements of 'sport' or regular aerobatic models flown through regular maneuvers are, to put it bluntly, piddling small. A quality standard servo easily copes with even quite large models.

3d models, different kettle of shrimp.

Edited By Nigel R on 28/06/2017 17:55:30

[Robert Parker]

Hi Tony,

I have used Hitec servos for many years using a variety of sizes with good results. I prefer to use 425 for every day use .

However, recently I have built / building some electric models in which I needed to keep the weight as light as possible, 54" Catalina and 60" Wellington both designed for speed 400 size motors and in their day were very under powered. So I upgraded the electrics to Lipo and brushless and used Turnigy 113mg servos, these are tiny 12g and have a torque of 2.2kg/cm. They are noisy in operation but I have no problems with them in use £7 each.

My present build I have used a mixture of the Turnigies and Corona DS 329 metal gear slim wing servos £7 each. I managed to strip the gears on first use, my fault, I centred the servo arm and fitted it through the ply plate on the wing, I moved the stick for the aileron and it fouled the ply plate just for a few moment but that was all it took to strip the gears. I have had stronger plastic ones Plate altered new servo ordered.

Hope this is some help

Regards

Robert

[Cuban8]

I bought a couple of Hitec, high torque, metal geared servos a couple of years back (can't remember the model number, but they were fifty quid for the pair). They were terrible with bad overshoot around centre and an age to settle. They also went nuts at anything slightly over 6V. Returned them to the on-line supplier (model shop) who said they were fine but would exchange them as I was unhappy (can't complain at that).

The replacements were a bit better around centre (still went crazy at anything over 6V) , but still not as good as a ten quid standard Futaba!

Eventually sold them for half price to a club mate who was more than happy with them and wasn't bothered by their poor performance - and as he ran standard 4 cell RX batteries, the voltage issue didn't crop up.

Had a couple of Hitec retract servos that emitted the magic smoke after a short period of use as well - no overload protection which I found surprising.

On the other hand, I had standard Hitecs in a twenty years old model until recently, with not a hint of bother in all of those years, until the pots started to get a bit erratic - so swapped them for Futabas

 

Edited By Cuban8 on 28/06/2017 21:56:33

[Nightflyer]

Some great comments which I would concur with. I have tended to favour Futaba or Savox where quality and reliability are concerned, or Hired or others when cheap is desirable. I am not wild on SD200s as had issues with them on an electric Hurricane and my Simprop Excel. They seem 8k at first but after time give trouble. Hs55 comments elsewhere on here I agree with comments on.

[cymaz]

of my pI use Hitec 645mg for my petrol planes. Always found them great.

[Rich too]

It depends on the model. In have used lots of these from HK without a single failure:

**LINK**

And for larger models (50cc) I use Hitec..

[Former Member]

[This posting has been removed]

[Tony Kenny]

HI guys,

Just following up on some old threads. I ended up buying decent servos from a reputable model supplier but didn't go overboard.

Thanks for the advice, this forums is really helping my learning curve!

[Sam Longley]

Posted by Braddock, VC on 28/06/2017 09:35:45:

I bought a servo tester from HK at the same time bought 8 metal geared corona digital servos. Put them on the servo tester and left them running (3 at a time)

3 were warmer than the rest so got them replaced by HK, new ones are ok. Generally any faults show up on the servo tester after 15 mins, I allowed about that.

Way off thread here--- but I have been having servo inconsistencies & someone suggested i get a tester. may i ask what sort you have. I have not researched the subject yet but a start suggestion would be handy

Edited By Sam Longley on 29/07/2017 10:24:33

[Nigel R]

I think they will be talking about one of these:

**LINK**

Available in various places from about £1 (slow boat from Shenzen region) to £10.

[TartanMac]

I've been out the hobby a while and have noticed an increase on price on everything but good servo's are quite expensive. I drive 1/8 rc race trucks and buggies and fly aeroplanes also. The first thing I prioritise is how it will withstand vibration the cheap brands don't do that well a new power servo I got lasted 15 mins then packed in I have had Hitec pack in also. Hitec seem to prioritise the motor then gear it up then industrialize the parts some of there servos are good but some they take too far and the circuit boards can't take the current. Or they get jittery. MG996R get jittery and sloppy over time. After vibration I look at Speed then look for the torque I need.

Savox are great never had an issue of reliability but they draw more current than the top brands and not quite got the resolution of Futaba JR or Hitec. But they are very fast and Torquay for the money and stand up to very high levels of vibration. Got 2 in a 1/8 scale buggy 30,000 rpm engine solid mounted to chassis over rough various terrain stands up to jumps also. Broke a hitec doing the same thing.

People told me not to bother replacing std servo's but once you have flown an aeroplane with high speed high res servos you want that plush direct instant response but not twitchy feel in all your planes even in a trainer you can get more out the air frame and gets rid of the sluggish feel of 0.2 sec servos. 0.14 is the slowest I would go now for airolons. Got 2 savox servos @ 0.09 sec for my Velocity I think they are 9 kilo gonna be great.

I know you got your servos but just in case anyone else is interested I posted this. Cheaper brands I worry about vibration be carefully with Hitec I just bought HS-225BB x2 and then read they go faulty quick. Futaba are pricey so are JR but savox are solid servos. I just bought 2 hpi ss-20WR servos £15 each but the spec looks good I know that HPI used to rebrand the Futaba S3003 servo so hopefully they are good. Water-resistant 6.5kg @ 0.11 sec on 6v. It is hard to get a fast servo with good torque for a fair price that stands up to vibration. I think you just have to pay the money especially if running an engine. And that's coming from a Scotsman lol.

[Former Member]

[This posting has been removed]

[Rich too]

TartanMac, it would be great to use servos that fast, but you will pay a fortune for them once you have specked the torque req'd

[Nigel R]

"Cheaper brands I worry about vibration be carefully with Hitec I just bought HS-225BB x2 and then read they go faulty quick."

Everything I've read suggests the main problem is a weak gear train that doesn't stand up to the rated torque, otherwise they're ok. Personally I would happily use these all round on a 20 size sport, or one-per-aileron up to about 60 size, and simply wouldn't go near them for a 3d model.

 

"I always hook them up to the tester for a good 30 minutes plus"

Likewise - also for any second hand gear.

I still have a bundle of nylon gear JR 507/517 servos that still work perfectly after years of use. The cheap stuff is false economy (mind you, my opinion is similar on the use of tiny servos to save a few grams).

Like the maxim for cars; cheap, fast, reliable - pick any two.

 

Edited By Nigel R on 01/08/2017 09:56:38