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Old Dec 23, 2013, 02:57 PM
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Micro servos. Not all the same.

I Don't know where else to put this. I have recently had a tremendous problem with some micro servos which I bought from HobbyKing. The Servos are their own label but I do realize they are just sticking a label on someone else's product. The servo in question is the 4.3g servo with the HobbyKing # 5458 or EM_43G. I love the servo because of it'size to power ratio. These servos are PERFECT for fitting into slim wings fro individual control surface operation. They are only 8.3mm or .33" wide and have well over 8oz/in of trust I would say closer to 11oz/in. The problem I have been having is that when I buy them, they come with cracked cases, mostly in the output shaft bearing area. Sometimes the cracks are so bad that there is an opening you can see into the servo through. The problem is caused by the secondary bearing shaft being too long and the case is cracked while the top middle and bottom are being screwed together, The shaft cracks through the upper case and causes more damage as it cracks the upper receiver hole. Out of 24 servos I had only five were not cracked when i got them. I wound returning them to HobbyKing. I took a risk and bought, what i thought was the same servo from "Tower Pro". The Tower pro servo was actually 33% cheaper. This I thought was a plus but I still figured i was getting the same servo with a different label and therefore more cracks.
Well I'm happy to report I was wrong in every presumption with the only exception of one. This is that the servo in dead is the same physical size. The Tower Pro servo is much better constructed and the six I bought to try out all came in in perfect condition. There is one other thing which is better about the Tower Pro servos and that is that the mounting hole spacing is the same as on most common 5g servos. On the HK servo they mad the mounting tabs shorter and placed the holes closer in. So---- for those of us who want a decent, inexpensive tiny servo with a lot of power the Tower Pro #302 4.3g servo is the clear winner. If you want to spend a tad more money and go digital than the EMax 9051 is the same size and is the MASTER at about 17oz/in of torque which I measured on a force gauge. the Tower Pro analog servo will cost you under $3 and the EMax servo just over $6. I hope this helps some of you.

Otto
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Old Dec 23, 2013, 08:53 PM
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Awww c'mon.. You simply GUESSED wrong
I too have bought that servo... It's Crappy.... not putting too fine a point on it.
But then with full understanding that buying from a large scale Chinee vender, one needs Know (beforehand) EXACTLY what one is ordering.
Mine too was broken(cracks in the gear case cover) Clearly due to the Simians assembling the thing, broke off one of the wee locating pins and it lodged in the bearing housing .. cracking it in several places.
Easily repaired (by Me) but even so the silly servo proved slooow and imprecise.
Garbage is a single word description .
The HK 3061 IS a better product (same size/weight) in case that is of interest to you.

Hard to be sympatheitic to your whinging.. Mate.
As this is after all..a ~$3 expense/gamble..
A clever man would buy.... one... to 'test the waters' ...FIRST.
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Old Dec 23, 2013, 09:05 PM
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Do you mean the S0361 servo? I did in fact order 6 of those just on Friday. I also have 14 of the EMax 9051 digital servos of the same size coming. The TowerPro is a better servo of the same size also. It is also less expensive yet. I was just looking for the smallest yet strongest servo which I can build into a thin wing. This servo fit the criteria but I did not like the cracks. I shouldn't have to fix something that is NEW. The slight buzzing some of these have do not bother me. OK so they draw a few more mA. I ordered 6 of the TowerPro servos just to try them out. I just ordered 11 more earlier today.
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Old Dec 29, 2013, 09:02 PM
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Well I compared more of these micro servos. The HK S0361 servo is a bit smaller than the 4.3g servos and also quite a bit less powerful. The servos that are equivalent to the S0361 would be the RC Timer 4.4g servos which are about a millimeter taller and also the Turnigi TGY-1370A which are about 2mm lower and a bit smoother and faster. Out of these thre the Turnigi is quite a bit better. On the other hand the Tower Pro 302 4.3g servo is for all intents and purposed identical to the HK 4.3g servos but of better quality of construction. This servo has the same power.
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Old Dec 29, 2013, 09:19 PM
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Not understanding.. What ? your intent is here.
IF... you want wing servos of Excellent function/ pedigree then you would be looking at Hyperion and Futaba product... in order of price
BUT these are bigger than 4.3 grams and cost more than a dozen cheap HK toy type micro servos.
Buy Cheap... buy twice or seemingly ...repeatedly .
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Old Dec 29, 2013, 09:47 PM
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The idea is to get servos which are small enough to fit into a wing which is about 2cm thick or thinner and to be able to build them into the wing permanently. I also have some exquisite EMax digital 9051 0f the same size and only a bit more expensive and also quite a bit more powerful. I was looking for servos though, which I can glue into the wing as you would mount a disposable bellcrank. If I bust up the model I will just toss the whole wing and not even bother with taking anything out. I plan on covering over these servos with fabric and forget hem. Hence a disposable servo.
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Old Dec 30, 2013, 04:32 AM
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I also build servos into wings on a permanent basis, but if I break the wing I can then remove them.
A servo cheap enough to be disposable will probably be the cause of you busting the model anyway, so I would use decent servos and remove when the wing is scrap.

I have used these http://hyperion-world.com/products/product/HP-DS09-AMD
and you can build them into a 1cm thick wing.

Dick
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Old Dec 30, 2013, 07:14 AM
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These are the digital servos I have chosen to go with and am ecstatic with. Plus they won't upset the bank. They are a bit smaller than the Hyperion but not as powerful. However they are MORE than powerful to do the job and reliably. They are about 25% the cost of the Hyperion and definitely more than good enough. I think they are brand new on the market and still a bit hard to find. I took two of the first batch of five I bought and placed them on an automatic servo cycler with a spring load on them and let them run for a full 24 hour period on 5v to see how they would do. Short of developing a "minutely" detectable extra gear slop they are still working the same as when started. For a $5 servo I am extremely happy. I might even go as far as saying "ecstatic". These are my firs digital servos. Since I am a builder more so than a flyer and my models never see more than about 20 flights before they are donated to various institutions for display, short term reliability is all I want and need. Normally when I buy servos I buy two for inspection and if satisfied than I buy 20 in one batch. Unfortunately the HK EM_43G servos which I got in the test pair and the bulk order were not of the same quality. The first two were perfect (actually first 4 in the test batch) but out of the bulk buy almost all of them were cracked.
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Old Dec 31, 2013, 01:27 PM
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I just received my big order of EMax 9051 Digital servos. I think I will take one random one and put it on a 72 hour cycle under 33% load and see what happens.
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Old Jan 01, 2014, 01:37 PM
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I want to repot that the servo has now been running NON-STOP for 24 hours and is a bit warm (not hot)(5V). There is no appreciable increase of slop in gear train. I have also ordered some new test servos in the same size group category to try out. These are the Turnagy TGY1440A servos. They are a slightly larger brother to the TGY1370A servo (in height) but the same size as the original 4.3g servo in question. This new servo is an analog servo unlike the Digital EMax servo being tested but unlike its slightly smaller brother the 1370A is twice as powerful (according to it's advertised torque) and should be just as powerful as this EMax digital servo. I will report on this new servo when it is received and placed into test.
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Old Jan 05, 2014, 09:55 AM
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Servo ran for a non stop 96 hour (4 days) period with no failure. This servo is a micro keeper.

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Old Jan 05, 2014, 10:50 AM
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Thanks for your efforts. I'll give them a try.

By the way, after 96 hours I would expect the test servo to be worn out -- but in a good cause.
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Old Jan 05, 2014, 10:57 AM
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Thanks for the information on the Emax 9051 and also the other servos that you have mentioned in this thread. I have found this thread interesting and helpful.

Please keep us informed on your testing results.

J.P.
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Old Jan 05, 2014, 11:00 AM
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What type/size models are you flying with these servos ? seems they are all in the under 5 in ounces of torque size
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Old Jan 05, 2014, 12:17 PM
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That E-Max servo at 4.8V states 0.8 kg-cm or 11.1 oz-in
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