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Servo's keep stripping gears

Old 04-05-2002, 06:37 AM
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shess65-RCU
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Default Servo's keep stripping gears

Mike,

I wrote you not long ago about a std. bb servo that I had new on an Ultra Stick .40 plane. It was on a single flap. I had only a couple of flights and noticed it was not working. I checked it and the gears were stripped. I had questioned if there were any know problems in a run of gears or something.

As you advised, I sent the servo off to service and sure enough they fixed it and returned it to me. Unfortunely, my new plane was pretty much out of service, or at least limited for about 2 1/2 weeks. When I got the servo back, I put it in the plane and went to the field. I flew a few flight and the plane started acting strange. I landed and found that the other flap servo was now stripped out.

I figured the service people would not believe my story so I tore it apart and it just happened the gear that was stripped was the same as a gear in a bad Futaba std. bb servo I had junked out. I used this gear and fixed it myself. The servo has done great for about a month now. These were new servos from the same flightpack I had purchased this year and this was their first plane and only used for flaps which were hardly deployed except for landing in crow mode which is really slow so should be low stress.

Well, I now have the problem again...

At the suggestion of many people on this site, I bought 5 605's for my new Hanger 9 120 size Cap 232. I finished it two weeks ago and took it to the field Saturday to test fly. This was my first big plane and the engine was new so I took it easy and never wrung it out at all. At the end of the fourth flight when I landed, I noticed I had no steering control. When I checked the rudder would move freely.

Tonight I took the servo apart and low and behold a gear is stripped. I checked my junk Futaba servo and this gear is just slightly different in size that the Futaba gear so I cant fix it. I guess I probably will have to order some metal gears to fix it.

My question for you again is this. Are there any known recent problems with gears stripping under low stress conditions. I have eight flyable planes and all have Futaba std. servos except for these two and I have never had this type of problem before. I have had multiple people at the field check and double check to see that everything is ran correctly and not binding or anything out of the ordinary.

I am really concerned at this point and almost afraid to fly either of these planes for fear of reoccurrance. I know these servos have a good name and a competive price and would like to continue moving to them but this is really a concern as I am sure you can understand. I have over $900 in the Cap and more hours that I would ever care to admit.

What would you recommend I do? I know service will fix the servo if I send it in but I am then out of flying my NEW plane for another two weeks besides this week.

Is there someone I can talk to send me the gears so I can fix it myself? Can I get some type of replacement for all the gears in my current servos providing I send in the old ones? They are all under warranty and pratically new.

I do understand Hitec's position as far as sending out parts vs. in-house but this has already cost me freight to ship out one servo, down time, and loss of use of my planes. Can someone please help me out...

I appreciate your service on this site and taking the time to read this book I have written.

To all others who may read this... Have you had similar problems?

My email is [email protected] and if needed I can provide a number to be reached at and can provide names and numbers of people who were present and can collaborate the accuracy of my account.

Thanks again,

Steve Hess
Old 04-10-2002, 08:19 PM
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MikeMayberry
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Default Servo's keep stripping gears

You should consider going to a metal geared servo on any aircraft with large control surfaces, especially on a 120 size aircraft.

Metal gears are available for the 605's as an upgrade.

Contact me @ (858)748-6948 x 302 if you wish to discuss this further.

Mike.
Old 04-11-2002, 12:44 AM
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aerolou
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Default Servo's keep stripping gears

hmmmm, I have a Byron Pitts 1/3 scale using 605's on all control surfaces that I stuffed in the ground once because of a temperamental engine. It hit at a 30 degree angle at a pretty good clip and flipped over on its back HARD and sufferred no servo damage at all. It is still flying (about 25 flights) with the same servo's.

Lou
Old 04-11-2002, 01:41 AM
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shess65-RCU
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Default Servo gears

Mike,

Thanks for answering.

I called service while your were in Toledo. The guy told me gears were not warranty items and whoever repaired my first servo should not have done it. He too recommended metal gears. I asked if the gears were not covered, then, since these were brand new, could he sale me replacements. He said Hitec did not sale direct and I would have to go back to my dealer. I have since ordered metal gears from Tower where I got the servos and after the cost of the gears and the S&H charges I am out around $9 per servo x 5=$45 over the cost of the servos had I ordered them with metal gears originally. This is for servos less than a month old, only two trips to the field, maybe 7 flights tops, none at wide open, no aerobatics at all, just scale-like 1/2 throttle, level flight. Additionally this kit is not the 1/4 scale version, it is the 73" and the manufacturer only recommended std. servos. I went with the higher torque just for assurance that this would not happen.

From a customer stand point it would be a great service to offer gears without the big markups and S&H costs as a service part if the servos are within a certain time period, ie. 30 days or 60 days or maybe during the servo warranty period.

I still do not know about the std. bb servos I have in the .40 size plane. These are the ones that have stripped two times on the flaps. Should all these be converted to metal as well?

Also, I would like to suggest if the recommendation for the high torque servos is to use the metal gears then have the tech notes reflect such on web sites where they are sold. Most all proudly show the tourqe rating and other specs but if the servo has more torque that the gears can bear then should not the servo only come with gears that will work reliably or at least have a notice to let the customer know the recommendations.

Had I had this information, I could have saved the expense by ordering what I need the first time.

This causes negative impressions for end users for what I truely believe is basically a good product.

I realize it is probably too late to help my situation but hopefully this feedback will provide feedback for future consideration.

Thanks for listening,

Steve
Old 04-16-2002, 08:12 PM
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MikeMayberry
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Default Servo's keep stripping gears

Steve,

I understand your frustration. To be honest... the metal gears are recommended but many people do use the nylon geared servos in larger aircraft without any problems like lou. Since you have also stripped other servos in other aircraft there may be another issue. It just doesn't make sense that you would be stripping servos so easily.

One of the reasons I maintain a presence on R/C bulletin boards such as this is to help the customer get the right product the first time and eliminate any pit falls like the ones you have experienced by using a product that is not optimum for the application.

I would be happy to help you anyway I can. Perhaps an E-mail to me directly would have had a different outcome. I will typically go out of my way to give that extra effort to help the people who post here. That's not to say we don't give our customers a high level of service, because we do. It's just that the service guys have to stick by the rules, where I will sometimes bend them a little.

Good luck!

Mike.
Old 05-14-2002, 07:06 PM
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Johng
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Default control geometry

Just to butt in here a little, but Mike's addressing your problem with your radio - and doing a good job of it. If he suggested that you might want to look at your pushrod arraingements, it might seem like he's blowing off your problem. So, I will.

Things like different control geometry can cause the servo to have significantly greater or less leverage against the control surface, and likewise see greater or less force. SOme pics of the problem airplane setups wouold be good to see.

I have a stinger120 - a similar size plane- that I intended to use large control throws on large surfaces. For this reason, I chose the 5645's, digital with metal gears. If I had wanted to set this plane up with surface travel for sport/sunday flying, I could have gotten away with nylon gears.

Mind you, that this comparison is made by leaving the servo travel at 100% for both cases. If you leave the control geometry the same and vary travel with your computer, of course there would be no difference in leverage - or the forces seen by the servo at the same deflections.

The best way to take it easy on your servos is to increase the servo throw to the maximum possible, >100% if you can, then either move the pushrod attachment closer to the hub on the servo, or farther out on the control horn at the surface, INSTEAD of just hooking stuff up and then cutting the travel back with programming. Once you get close to the travel you need by changing the geometry, then tune it exactly thru programming.

Hope this helps.

FWIW I'm completely comfortable flying the 605's with nylon gears with outrageous throws on my 60 size planes. They weigh around 10 lbs and I would expect the heavy duty nylon servos to take that treatment.
Old 05-14-2002, 07:29 PM
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shess65-RCU
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Default Servo gears

Thanks for your advice. For the most part, I think I try to do the things you suggest to releave the torque loads as much as possible. There are cases, as I'm sure you know, where extreme throws are desired and this conservative approach is not always possible, but I agree that as much as possible one should take steps to releave the work load. If nothing else, it should help extend the battery's usable time on a charge and add to the life of the servo.

Just to clarify in case I was not clear in my longwinded previous post. I had checked and rechecked these things and had other people with much experience double check me. None of us could see anything that would have been out of the normal or uncommon practice. I actually had the servos set up on the 2nd hole from the inside of the servo arm on the on high torque servo on the Cap 120. However, I did have the servo linkage on the outmost servo arm and about 1/2 down on the control surface on the 40 size Ultra Stick flaps which stripped 2 servos. This was necessary to get the throws needed for the crow function. I have since replaced the servos on the Ultra Stick and maxed the throws out to their limits on all controls and have had no further problems. I replaced the servo gears with metal gears in the Cap and have had no problems. There is a guy in our club with the identical plane and a larger engine and flys much more extreme stuff than I could ever do and gets by with standard servos.

These are the only servos that I had ever had strip or break, and have had none since, so hopefully is was just a streak of bad luck.


Thanks again as I am always anxious to learn more about this great hobby of ours.

Steve
Old 05-15-2002, 03:00 PM
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Default Servo's keep stripping gears

Just a quick FYI. You can order servo gears from www.servocity.com at low prices with FREE shipping. I have been using them for quite a while now. Free shipping on any order.

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