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HomeAircraftHelicopterMain Discussion › Old school
04-14-2018 07:30 PM  69 days agoPost 1
A&J

rrApprentice

Hudson FL 34667

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Help me make up my mind
Past few years I've noticed
People flying there helicopters with no grommets in this servos

Old school was always put them in due to vibration . And we still have vibration today of some type

And allow a little give if something goes wrong
Do people still feel this way today
Is the new rule is install them without the grommets
Makes me feel uncomfortable

Kind of comes down to a builder's choice I guess

Opinion is welcome

Lets do the time warp againnn !

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04-14-2018 07:58 PM  69 days agoPost 2
grimthenoble

rrApprentice

Ketchikan, Alaska

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I have been running servos on everything RC with out rubber grommets since 1998. If a servo is going to fail or cause troubles its because the servo is crap. I have servos in my RC trucks that I bash over and over again (way more abuse than a RC heli) and still perform flawlessly. I think most manufactures put grommets on only to keep people from over tighten the tabs causing them to break. Well with most my servos today that are aluminum bodies there is no worries of that. Just my Opinion!

Never go Full Retard!

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04-14-2018 10:05 PM  69 days agoPost 3
wjvail

rrKey Veteran

Meridian, Mississippi

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I fly mostly larger glow model helicopters and I use the rubber grommets - but I tighten the shiznit of 'em rendering them (nearly) useless. Most of my helis include servos that put out over 500 in*oz of torque and with the precision of flybarless, I want to know exactly where the servo is. The days of 25 oz*in servos squishing around on rubber mounts have passed.

With the above said, I suppose it depends on how you hobby. What servos you use, the smoothness of your model, the way you fly, how long you expect your equipment to last etc. will all play a part.

Like Grim, just my thoughts.

"Well, Nothing bad can happen now."

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04-14-2018 10:52 PM  69 days agoPost 4
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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Grommets
I still use them mostly
On my 600N the front cyclic servos don't have them to get the geometry correct. No issues with them in 6 years.

spending time, paying attention

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04-15-2018 01:46 AM  68 days agoPost 5
HeliMan Dave

rrVeteran

Suburban Chicago

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I've hard mounted servos on my electric helis for over 10 years with great results.

I do this because I don't want the cyclic and collective to feel softer in flight than they already do from blade flex, dampeners, servo arm flex, grip flex, expo, etc.

If I flew nitro, I'd probably use them for a little protection from long-term engine vibrations.

Logo 700 / 600 / 500 V-Bar NEO / Blade 180CFX / mCPX BL / Nano / V-Control

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04-15-2018 03:10 AM  68 days agoPost 6
helitom

rrApprentice

Pine Grove, Calif, USA

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I have always used the grommets with the ferrules. I fly nitro and gassers. I have concerns about vibration damage and have experienced such damage on a few occasions. The most recent occasion was when I thought for sure that my CGY750 FBL gyro was dying. The machine would fly along and then take an excursion in a random direction. It was not an extreme change of direction, but surely got my attention. I had some off line conversations with Dr. Ben and he was scratching his head. I replaced the CGY750 and the problem seemed to go away - for a short while. When it reappeared, I started looking at the cyclics (Futaba S9252's).

This is for those of you who are not old guys like me, some history; I can remember back in the day flying pattern with Kraft KPS-15 servos. At the time, they were the best available. Their feedback pots were very susceptible to vibration, thus losing any remembrance of center position, it was not uncommon to clean/replace the feedback pots in the middle of a competition. It turns out that after only 842 flights, my S9252's also lost memory of center. When I replaced the S9252's the CGY750 problem went away. My point being that there is always some buzzing, somewhere. BTW - I put in some Futaba BLS servos - WOW, it is a completely different machine.

I have also had vibration take out the plastic output gear spline between the servo and output arm. Something to check every so often, and another good reason for grommets.

Finally, if I was a good enough pilot to be able to discern between hard mounted servos and soft mounted servos, I would definitely hard mount. That skill level and me are far apart.

The older I get, the fewer things seem worth waiting in line for.

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04-15-2018 03:23 AM  68 days agoPost 7
PaulBowen

rrKey Veteran

Victoria, Australia.

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Futaba recommend the use of grommets in their servo instructions so I use them unless on an electric model that doesn’t allow for them.

I always use them on glow and gasser helicopters and would never dream of leaving them off. My models are extremely accurate to fly so I’m not sure there are any detrimental handling characteristics with correctly used grommets unless you only ever use full stick deflections.

Futaba T18SZ, JR Propo XG14, Hirobo fanatic!

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04-15-2018 02:48 PM  68 days agoPost 8
KevinB

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Saskatoon, Saskatchewan, Canada

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+1 Paul.

KevinB

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04-15-2018 02:57 PM  68 days agoPost 9
A&J

rrApprentice

Hudson FL 34667

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This is something I've been seeing a lot of it the field guys are not running Grommets

tell me electrics don't need them I don't buy it

Lets do the time warp againnn !

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04-15-2018 03:41 PM  68 days agoPost 10
wjvail

rrKey Veteran

Meridian, Mississippi

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As I said, I use the grommets/eyelets. I do so in part simply to locate the servo. The fitting on the ears of the servo are much too large for the typical M2.5 screw used for mounting. Something has to be used to fill the extra space.

One option I've seen far too often is to not fill the space at all. Folks simply clamp the servo with the washer typically under the screw head. I can't do that. It seems like a particularly bad solution on a plastic case servo. Those screws gotta be tight or the servo will quickly become free to move. Notice in the attached photo the mounting lugs are badly distorted.

I could use the pieces below but at 7 or 8 bucks a servo, I think I'll stick with the recommended grommets.

https://www.amainhobbies.com/protek...tk-3040/p483258

https://www.amainhobbies.com/team-a...sc27128/p682814

"Well, Nothing bad can happen now."

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04-15-2018 04:59 PM  68 days agoPost 11
A&J

rrApprentice

Hudson FL 34667

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Look smarter than what I'm seeing

They just sticking them in there and clamping them down

Lets do the time warp againnn !

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04-16-2018 01:39 AM  67 days agoPost 12
grimthenoble

rrApprentice

Ketchikan, Alaska

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As your original comment about vibration, your rubber grommets do not do any good in my opinion. If the servo fails because of some missing servo grommets than the servos are just crap. I wish they would redesign the servo case to allow a m3 bolt to fit snug eliminating any reason to use grommets.

Never go Full Retard!

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04-16-2018 02:28 AM  67 days agoPost 13
wjvail

rrKey Veteran

Meridian, Mississippi

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Looking at the ProTek servo grommet replacment, they say:
These ProTek R/C Aluminum Servo Grommets are a stronger alternative to traditional rubber grommets, a smart idea over using no grommets, and do an excellent job at completely locking the servo in place.

Traditional rubber grommets do a great job at absorbing slight vibrations and prolonging the life of older, previous generation servos. With current generation of servos being stronger and more powerful, the role of the rubber grommet isn't needed, as evident with the servo saver going extinct in 1/10 scale.

Many people choose to use no grommets on the servo but this comes at the risk of the servo moving around. Without any grommets filling up the dead space in the servo ears, sometimes under certain conditions or impacts, the servo can slightly shift. For a steering servo this can mean losing your center trim and with a throttle servo this can cause frustrating issues with your idle and brakes.
My first reaction was that all sound well and good but of course they are trying to move product. But consider they also sell servos - and I suppose they warranty them too. Apparently ProTek doesn't see traditional rubber grommets as a necessity.

"Well, Nothing bad can happen now."

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04-16-2018 03:34 AM  67 days agoPost 14
eddiscus

rrElite Veteran

Dumont, NJ-USA

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Some heli’s if you use the grommets and rubber you do not get optimal alignment of the linkages. I still think you need to take up the clearance between the bolt and servo ear holes. I made up my own 3D printed solutions where needed.

Logo Xxtreme 800
Logo 700
Citizen 142
Synergy 766
TDR 2

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04-16-2018 05:08 AM  67 days agoPost 15
rcflyerheli

rrKey Veteran

Granbury, TX USA

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Eddiscus, that is a really cool solution to keeping the servos centered with the mounting screws. I suppose that has to be custom printed depending on the specific servo make, but I like it.

As far as using the rubber grommets, the brass eyelets are sized to provide optimal tightness on the mounting screw. If the eyelet is inserted into the rubber grommet from the bottom of the servo, your mounting screw will get tight when it hits the sharp edge of the eyelet. That, technically isolates the servo from the airframe and provides for lowering the vibration to the servo

My larger helis use the rubber grommet and brass eyelet, but I also use CF servo mounting plates instead of just screwing a screw through the eyelet.

Goblin 700, Trex 700DFC, Gaui X7, Logo 690SX, Logo 600SX; Trex 470 Trex 500
Amain Team Rep

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04-16-2018 11:02 AM  67 days agoPost 16
PaulBowen

rrKey Veteran

Victoria, Australia.

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A couple of points.

Cars can’t be compared to helicopters. A car can’t fall from the sky or decapitate someone.

Electric helicopters can’t be compared to glow or gasser helicopters. The vibration is different in frequency and particularly magnitude.

Would we hard mount our receiver and gyro amplifier? Do what you like with electric helicopters but I think they teach very bad habits for IC powered aircraft.

Futaba T18SZ, JR Propo XG14, Hirobo fanatic!

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04-16-2018 02:29 PM  67 days agoPost 17
wjvail

rrKey Veteran

Meridian, Mississippi

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eddiscus
I still think you need to take up the clearance between the bolt and servo ear holes. I made up my own 3D printed solutions where needed.
That is a great solution. Why don't those come with the servo?

"Well, Nothing bad can happen now."

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04-16-2018 02:55 PM  67 days agoPost 18
wjvail

rrKey Veteran

Meridian, Mississippi

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helitom
This is for those of you who are not old guys like me, some history; I can remember back in the day flying pattern with Kraft KPS-15 servos. At the time, they were the best available. Their feedback pots were very susceptible to vibration, thus losing any remembrance of center position, it was not uncommon to clean/replace the feedback pots in the middle of a competition. It turns out that after only 842 flights, my S9252's also lost memory of center.
Funny. I had a Kraft 76 series with KPS-15s. It was my first radio and one of the few that I ever sold. The thing I remember most about it was those servos. The pots would get dirty just sitting on the bench. I swear I could clean them and before I flew 'em next weekend they were chattering and hunting again.

The 9252s lost center and began to hunt after only 842 flights? Only 842?

Kidding aside, I too have a set of 9252s that chatter. They have been in several helicopters over the years and have been relegated to the wing of a large stick airplane. The good news, and it applies to this thread, is that they seem to fail nicely. By that I mean they don't just drive hard over or stop working. They seem to give warning that "time's up."

As I said in post #3, the answer to the OPs question must include answering the question, "how long do you expect a servo to last". I'm certain you can hard mount just about any POS servo in the roughest running gasser - for a while.

"Well, Nothing bad can happen now."

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04-16-2018 03:39 PM  67 days agoPost 19
wjvail

rrKey Veteran

Meridian, Mississippi

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This a bit of a hijack, but what servo does Futaba make that includes a detachable lead? The below picture is the same as the one in post #10 with less cropping.

"Well, Nothing bad can happen now."

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04-16-2018 04:33 PM  67 days agoPost 20
grimthenoble

rrApprentice

Ketchikan, Alaska

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@PaulBowen That is your opinion. Yes we can compare anything we want. In any discussion every persons inputs only helps the people that are seeking help.

Never go Full Retard!

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