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HelicopterMain Discussion › Why Some Servos Are Junk
06-01-2013 01:29 PM  4 years agoPost 1
icanfly

rrElite Veteran

ontario

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Take these fine examples of modern servo technology,

Take these fine examples of modern servo technology, (take 2, literally)

On the left is the might Hitech hs 5065mg guts with mauled main output gear, that's a lot of aluminum but it, a gear tooth, still nearly broke completely (I know the servo cover says 65mg but the original gear from the 65mg was taken out and put in the 5065 before the pic was taken). It caused more than one crash and about a hundred bucks or more of replacement parts and many hours of frustration before it was replaced, then opened to discover this.

Second servo to the right is the mighty KST 215mg which breaks off right at the output shaft inside the housing and bearing. Now it's totally useless unless the manufacturer supplies that part as a replacement. I have two now.

These are about $35 servos on average, maybe more, the KST is sometimes less, and unless you fork out another $25 for the Hitech gears it's kaput. The Hitech is not worth it. The KST on the other hand IS worth repairing, tough luck finding the output/gear shaft only. Never going back to the hitechs, the KST's are so smooth to control, OH,,,,,EM,,,, GEEE (ohh my got).

How many hours and parts did I go through trying to pinpoint why my 450 was acting up, shutting down in hover, glitchy, wonky, a pita, get it? Very good sir.

Why, because that's what fbl links can do when rotor rpm forces are transmitted to the servo, that's why, servos get the blame.

I like flying helis, don't you?,,,,,,, lots of chuckles. Gonna get a big one one day, easier to fix, er,,,,,,,,,, I mean FLY!!!!!!!

You got a problem, servo? Show everyone what you've discovered then, you might save a few guys from a disastrous and heart breaking end of flight next time out, thanks.

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06-01-2013 02:18 PM  4 years agoPost 2
rpat

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Weirton, W. Va.

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What you forgot to mention was how many crashes these two servos were involved in?

trex 700fbl cal30,minititan,, trx600fbl,trex250,logo 500,Velocity N2

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06-01-2013 05:13 PM  4 years agoPost 3
icanfly

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ontario

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one each.

If the output shaft on the kst was ti or brass or somehow designed with some ruggedness at the weak spot at least only the servo ball link would have popped out and that's all. Mine is ca'd onto the horn and will come out if the heli comes in sideways. The nature of the linkage on a fbl head sends all the leverage into the servo horn and what it's attached to, the servo. When a blade hits the dirt, as heli is landing partly onto it's side, the blade will cantilever the link up or down depending on what side it falls into. There are 3, edit 4, points of leverage on the fbl head/servo, the weakest one will take the brunt of an accident.

It's been only yard high slide offs to the sides that has resulted in a few inconvenient repairs, nothing up high. The eyes adjust to light and dark and up high your pupils close while down below the tree line they open a bit and you must get used to those variables when flying, sunlight, reflections, foliage, shadows clouds, motion. It's a lot to ask if you fly in various outdoor weather conditions. The other night I was flying into the sunset and the heli became a dark object with less and less to reference it's upright position.

Only a bigger heli than a 450 and 25mph winds will be a breeze.

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06-01-2013 11:04 PM  4 years agoPost 4
Riq

rrKey Veteran

ND

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It's been only yard high slide offs to the sides that has resulted in a few inconvenient repairs, nothing up high.
Sounds like your problem.

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06-02-2013 03:22 AM  4 years agoPost 5
icanfly

rrElite Veteran

ontario

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If you shift the blade parallel to the ball link arm on the fbl blade clamp, and pushed blade up or down very quickly with a lot of force, where will the leverage go? To the servo. I ripped out a long ball link and swapped it for the shortest one available, works very well, blade is 90 degrees to the swash ball as always.

One to the left, and one to the right, flying too low with no where to go, simple as that. Those are out of the way, now flight has been minimum 20ft off the ground. I like that "Nap of the Earth" flying, lol.

Took some vid of flying recently, hope to eventually post,

take care.

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06-02-2013 04:46 AM  4 years agoPost 6
ICUR1-2

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Ottawa, Ontario

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an easy problem to fix by using plastic servo arms and better servos

spending time, paying attention

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06-02-2013 05:09 AM  4 years agoPost 7
RM3

rrElite Veteran

Killeen, Texas - USA

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an easy problem to fix by using plastic servo arms and better servos
+++
you get what you pay for most of the time...when it comes to servos on FBL especially.

showing a preference will only get you into trouble, 90% of everything is crap...

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06-02-2013 09:21 AM  4 years agoPost 8
Volcano

rrApprentice

chicago

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Learn to crash. Hit th

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06-02-2013 12:40 PM  4 years agoPost 9
icanfly

rrElite Veteran

ontario

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crashing's not the problem that's easy, hehe, but when the blades touch ground they wrap around while the heli goes onto it's side. Imagine a pair of heli blades folding upward to continue spinning if and when a heli is on its side. Of course it might take out a gear but my first hitech plastic geared 5055s went south from bringing it down hard. Now I have all KST's and a 5065 on the tail.

Knock on something my boom has 3 very small dings throughout the dump events, usually the first thing to go is the boom.

Point is. if manufacturers don't engineer in a sacrificial gear and supply replacements then the servo is a one fail item and how would a consumer know this in advance? Then the consumer might look at a servo with good engineering and support. How can anyone trust the high grade product to hold up better than less costly items? High price product is not immune.

Anyway, there's the flaws on these 2 servos. I would pay $10 extra for a ti output shaft on the kst that doesn't break and made sure the servo arm failed first in any situation.

One thing out of sync here is that my servo arms are the hitech arms and fit very tightly on the kst's. The splines in the kst arms aren't as strong and probably strip making that the weakest point on them.

The learning curve of cp helis can be steep at first. A beginner can start with a pos and wind up repairing and replacing everything many times over, that to me is VERY DISCOURAGING about them. The rewards are high for those who persist against all odds. Considering flying close to the ground and/or objects like trees and shrubs, and learning 3d, that's playing with fire.

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06-02-2013 01:48 PM  4 years agoPost 10
McKrackin

rrProfessor

Lucasville,Ohio

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Learn to crash. Hit th
A big plus one on that.
I know you say crashing is easy but you need to learn to crash well.
Hit TH long before impact and if possible,bottom out the servos right before impact...So they don't have a long run at bottoming out.

Even on 700 size machines...when they hit the ground with TH engaged,the damage is minor compared to hitting the ground under power for even a split second.
an easy problem to fix by using plastic servo arms and better servos
And this too...especially on smaller helis using micro or mini servos.

I literally never use the word literally right.

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06-02-2013 01:50 PM  4 years agoPost 11
McKrackin

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Lucasville,Ohio

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Hitec are not junk servos..far from it.
Just because you broke something AFTER you modified it...that has no bearing on the millions of other servos they produce.

Hitec is one of the most popular and successful servo makers in the world because they make a quality servo at a reasonable price.

There are better for sure but that doesn't mean they are junk.

I literally never use the word literally right.

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06-02-2013 04:53 PM  4 years agoPost 12
ebonicrobot

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East Bay, CA

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Yeah I wouldnt call Hitec junk, but I'm like you I rather use the KST servos on a 450 too. I actually have had some good results with my Turnigy servos (rebadged KST) they have servived two really bad crashes without incident. If I had to do it again I would not hesitate in buying more, just stock up on the replacement gears just in case.

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06-02-2013 05:21 PM  4 years agoPost 13
ICUR1-2

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Ottawa, Ontario

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Icanfly sounds like your doing what most of us did when we started.

trying to save money or trying to mod something (upgrade)

from experience, I can say spend the extra $ on the electronics
it is what makes your heli.

fly the stock kit with as few upgrades as possible
save up for that special kit

spending time, paying attention

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06-02-2013 06:06 PM  4 years agoPost 14
dkshema

rrMaster

Cedar Rapids, IA

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Stuff breaks in crashes. Get over it.

You may not realize it, but your recent history of posts may be gaining you the same notoriety as certain past RR members, notably Foo, and Manny Lalo.

-----

BTW --
A beginner can start with a pos and wind up repairing and replacing everything many times over,
The same thing happens when the beginner buys top of the line stuff and goes it alone. It happens all the time. Entry cost to the sport does not change the outcome.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-02-2013 11:41 PM  4 years agoPost 15
icanfly

rrElite Veteran

ontario

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You may not realize it, but your recent history of posts may be gaining you the same notoriety as certain past RR members, notably Foo, and Manny Lalo.
I don't know those guys and don't pay much attention to any personality clashes. Rc helis are great and ICUR1-2 says it like it is
your doing what most of us did when we started.

trying to save money or trying to mod something (upgrade)

from experience, I can say spend the extra $ on the electronics
it is what makes your heli.

fly the stock kit with as few upgrades as possible
save up for that special kit
I have a 450v2 pro dangling from a wire in the lair, no rush to complete it. Learning on the mod'd se450 is less worrisome in the area of ground contacts of harsher kinds than skids down.

I said in the beginning of this and the tx post I wasn't serious about the junk statement but I am waiting for someone to post pictures of other servo damage and their respective manufacturers.

btw, the damage on the hitech with such a fat spline is a let down, and the broken gear has caused my gyro to shut down which contributed to loss of 3 pair blades, one bust kst, bent feathering and main shafts, many hours of attempts to trace the cause of why gyro shut off (which was not static as first thought) etc. And, the Hitechs were twitchy in flight compared to the kst's I'm now using. Yes the micro line of servos is the low end bracket but I'm fine with things now given what I've learned will help stay out of trouble on a bigger heli, where the consequences can be much more severe in cost and heart break.

I admit it's part of playing with this rc fire, but it's wonderful when everything is working like a well oiled sewing machine. I worked for HP long time ago building typewriters, that's at the time pcs were becoming popular.
Yeah I wouldnt call Hitec junk, but I'm like you I rather use the KST servos on a 450 too. I actually have had some good results with my Turnigy servos (rebadged KST) they have servived two really bad crashes without incident. If I had to do it again I would not hesitate in buying more, just stock up on the replacement gears just in case.
This is the info I wanted to hear, thanks.
Learn to crash. Hit th
A big plus one on that.
I know you say crashing is easy but you need to learn to crash well.
Hit TH long before impact and if possible,bottom out the servos right before impact...So they don't have a long run at bottoming out.

Even on 700 size machines...when they hit the ground with TH engaged,the damage is minor compared to hitting the ground under power for even a split second.
A fine damage minimization tip I should practice McKrackin, good tip to become aware of early in the game, thanks there too

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06-03-2013 12:21 AM  4 years agoPost 16
dkshema

rrMaster

Cedar Rapids, IA

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don't pay much attention to any personality clashes
Neither Foo nor Manny had personality clashes. That wasn't the problem. It was simply how they appeared to many here on RR.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-03-2013 12:42 AM  4 years agoPost 17
ICUR1-2

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Ottawa, Ontario

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^ you mean the noob with swollen head complex

spending time, paying attention

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06-03-2013 08:30 AM  4 years agoPost 18
Volcano

rrApprentice

chicago

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Alot of people cant fathom it but I can crash a 450 15 times if im lucky without replacing a part. Learn to crash.

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06-03-2013 12:05 PM  4 years agoPost 19
RCHSF

rrKey Veteran

NC

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Volcano
Alot of people cant fathom it but I can crash a 450 15 times if im lucky without replacing a part. Learn to crash.
Learn to crash
Better!!! is the key.

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06-03-2013 12:35 PM  4 years agoPost 20
SSN Pru

rrElite Veteran

Taxachusetts

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as heli is landing partly onto it's side
FWIW, heli's don't land on their side. That's called a crash.

Things break when you cresh. They break at the weak point. Introduce an engineered weak point into your system to prevent the servo gears from breaking.

Stupidity can be cured. Ignorance is for life!

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