Thread Tools
Old Apr 29, 2016, 04:09 PM
LWeller is offline
Find More Posts by LWeller
Registered User
Holland, Michigan
Joined Dec 2006
542 Posts
Question
How to remove a servo tray in this wing

A few years ago I bought this glider and the recommended servos. I installed the flap servo trays for what was a new and powerful metal gear micro servo and exclusive to this U.S. glider dealer. It was against my better judgement to be a guinea pig buying this new servo but I went ahead anyway...so no one to blame but me.

I soon saw in the magazine adds that the servo tabs were redesigned for this brand of servo and then a while later I noticed the dealer no longer carried the servo at all and it doesn't exist anywhere else under the brand name on the servo.

Checking all my gliders out before flying this spring I decided to readjust the linkage to get close to a "0" sub trim. When the job was finished and checked out to be working perfectly I planned to put the servo hatch cover back on the next day. When that time arrived I checked it out one more time and the flap froze in the down position.

The bottom line is I need to remove both flap servo trays held in place with thin CA. The frames are mounted to a piece of carbon fiber cloth bonded to the inside of the molded fiberglass center section of this 3.5m glider wing. The CF cloth was laid in the wing as a stiffener by the Mfg. I am uncertain about trying debonder or other products and not at all sure they will work now that the CA has been set for a few years but I'm about ready to try anyway. The only other alternative is to grind them out with a Dremel. The glider is in perfect condition and I hate to screw it up.

I figure somebody on this forum has had experience with this and can guide me to a solution. Thanks for your help.

Larry
LWeller is offline Find More Posts by LWeller
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 29, 2016, 04:46 PM
exf3bguy is offline
Find More Posts by exf3bguy
Registered User
United States, CA, Sacramento
Joined Oct 2011
2,962 Posts
Other then grinding it out with a Dremil the only other suggestion I would have is to try some freeze spray. It's used for electronics troubleshooting. What you would do is get some very thin steel sheet maybe even a feeler gauge set and starting at a corner freeze the frame with the spray and try to work the feeler gauge between the frame and the CF. CF is very thermally stable and the plastic not so much. The hope would be that the cold will cause the plastic to shrink enough to fracture the cold CA. I have done this at my day job with honeycomb laminates with .010 skins and the brackets I was removing came off clean. They were however originally bonded with Hysol 9330 but the CA should work the same.
exf3bguy is offline Find More Posts by exf3bguy
Reply With Quote  (Disabled)
Old Apr 29, 2016, 04:59 PM
Kiesling is online now
Find More Posts by Kiesling
Registered User
San Diego
Joined Aug 2004
3,021 Posts
I have removed trays glued in with CA using acetone and a razor blade.

First you need to make sure the wing isn't made of stuff that the acetone will dissolve. If it isn't, and most decent molded models are not, then you can use the acetone to soften the CA. I suppose debonder should work too, but I don't have much experience with it. As the CA softens work the razor blade between the tray and carbon. Take your time and add more acetone as needed.

Have patience and you'll be able to get it out with this method.

Tom
Kiesling is online now Find More Posts by Kiesling
Reply With Quote
Old Apr 29, 2016, 05:41 PM
SteveK123 is offline
Find More Posts by SteveK123
Hates Palm Trees
United States, CA, Torrance
Joined Jan 2013
435 Posts
Not easy but better than grinding

- heat up a #11 exacto blade and bend the tip 90 degrees from vertical
- put it back in the kinfe holder
- use a butane torch to heat the blade tip
- work the blade between the servo frame and the carbon plate. CA will liquify under sufficient heat
- keep re- heating the blade and working along the joint until the frame comes out.

The extra carbon plate under the frames will be slightly damaged by the heat but the wing skin should be OK

Good luck
SteveK123 is offline Find More Posts by SteveK123
Reply With Quote
Old Apr 29, 2016, 08:11 PM
G_T is offline
G_T
Find More Posts by G_T
G_T
Registered User
Joined Apr 2009
6,654 Posts
CA solvents are acetone and nitromethane. The stuff which you use when you glue your fingers together? It has more of the latter... I'm thinking it is safer for the wing than acetone. Something like this http://www.amazon.com/Cyanoacrylate-.../dp/B00JWTWLA2 Now I didn't read about this one so I have no idea if it is any good. But I'd start with something like that and let it soak to see if it will break it free. If not, then dry very thoroughly and let it air dry for a while so the nitromethane evaporates.

Will your replacement servo drop into the opening of the frame, or nearly so? That is, do you really have to remove the frame, or just slightly adjust its size and shape?

I'm used to doing more F3K han F3J but for both I tend to epoxy the servos in.

I wrap the servo with cling wrap, make up some rather thickened epoxy, and pot the servo against the top skin. If there is thickness and the skin is not stiff, I add a bit of fabric in the process for extra reinforcement. I use something like West Systems for this job, with additives.

When the epoxy is cured I remove the servo then remove the cling wrap. Now the servo should fit into the custom pocket. A bit of 15 minute epoxy will bond the servo in place. Often a bit of persistence flexing the skin will pop it out if absolutely required in the future. I've done that and it worked for a hollow moldie.

Gerald

PS - I realized I simplified the potting description too much at least for solid core wings. For those, I cut the pocket, then cut some 1.7oz Kevlar as a rectangle with tabs that will fit in the pocket and the tabs go up towards the bottom skin. I put the blob of thickened epoxy against the top skin, lay in the fabric, put the cling wrapped servo in position, and push it in place. I leave it lightly weighted. Periodically I check and remove any epoxy which oozed through the skin.

PPS - I've used nitromethane debonders and though they are slow they eventually get the job done.
G_T is offline Find More Posts by G_T
Reply With Quote
Old Apr 29, 2016, 08:51 PM
Batmanwpg is offline
Find More Posts by Batmanwpg
Boar? I'm a Thermal Pig!
Batmanwpg's Avatar
Winnipeg, Canada
Joined Aug 2004
979 Posts
Two things you can try. CA will break down with heat also. Try a covering iron on the top skin to heat the servo area and then pry off the servo frame. Works for epoxy too.
The other method would be to try SteveK123 method but use a soldering iron with a number 11 blade mounted in it. Sometimes you can find small 15-20 watt soldering irons that come with an adapter to hold blades. I use these irons to trim plastic covering such as Monokote and Ultracote. http://www.hobbylinc.com/htm/hca/hcahcar0770.htm
Good luck
Batmanwpg is offline Find More Posts by Batmanwpg
Reply With Quote
Old Apr 29, 2016, 09:23 PM
Kiesling is online now
Find More Posts by Kiesling
Registered User
San Diego
Joined Aug 2004
3,021 Posts
If you go the heat method (which I have no experience with), be careful since the epoxy used in the wing skin won't tolerate a lot of heat.

Like I said in my previous post, I have success removing frames using acetone without damaging the wing.

Tom
Kiesling is online now Find More Posts by Kiesling
Reply With Quote
Old Apr 29, 2016, 11:18 PM
pigly is offline
Find More Posts by pigly
PaulG
Newcastle, NSW Australia
Joined Dec 2004
424 Posts
The servo frames look like those made by Servo Rahmen in Germany. They have a web site with all their products on it. If you look through their product line and find yours they often show that one servo frame will fit more than one servo. It is not normal for them to produce a special servo frame for experimental servos. You might be able to find a servo that will fit the frame that you have thus saving you all that effort.
Most servos made by the big manufacturers are reliable but you do get duds some times. My favourite have been Airtronics 94761 but now I use JR 189 HV mostly as well as the odd MKS. You might find that another servo can be made to fit, even if the frame is not exactly right. Better than sniffing all those toxic solvents!
Paul
pigly is offline Find More Posts by pigly
Reply With Quote
Old Apr 30, 2016, 06:42 AM
Tuomo is offline
Find More Posts by Tuomo
Registered User
Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
2,628 Posts
Just dremel it out.

Dremelling creates heat and will nicely soften the epoxy that has been used to glue the frame. Never had any wing damage when doing this.
Tuomo is offline Find More Posts by Tuomo
Reply With Quote
Old Apr 30, 2016, 07:27 AM
Soarmark is offline
Find More Posts by Soarmark
Mark LSF # 3792
United States, TX, Garland
Joined Nov 2008
845 Posts
Looking at the picture it looks like a frame for the Airtronics 94809, don't know the Sanwa model number. The number ATX 11.5 matches the frames I just put in my X3 on ailerons. I may be wrong, but I believe Graupner also has a servo, (DES-428?) that can use the same frame.

If you really want to remove it try the small saw burr that Dremel sells. Looks like a flattened mushroom with teeth. It allows you to cut the plastic right at the wing skin if you are careful.

BTW, the 809 is a great servo, but not my first choice for flaps on an unlimited ship.
Soarmark is offline Find More Posts by Soarmark
Reply With Quote
Old Apr 30, 2016, 10:32 AM
DrFragnasty is online now
Find More Posts by DrFragnasty
Thermal Wrangler
DrFragnasty's Avatar
Launceston Tasmania
Joined Mar 2004
2,454 Posts
94809 = Hyperion 11AMB
https://www.aircraft-world.com/en/p1005232-hp-ds11
DrFragnasty is online now Find More Posts by DrFragnasty
Reply With Quote
Old Apr 30, 2016, 10:43 AM
jtlsf5 is offline
Find More Posts by jtlsf5
Registered User
jtlsf5's Avatar
United States, CA, Folsom
Joined Jul 2007
2,775 Posts
Why make this so difficult? Take an Xacto spade blade and carefully get it between the frame and carbon skin, just enough to get a start. Take your time and don't force it. I would pick the right side in the picture above. Once you get it started, a chemical spatula or anything thin, blunt and metal can be worked along to just pop the frame loose. Once its out, use a dremel or a small (like 1/2" square) sanding block to remove the rest of the CA. Shouldn't be that hard to do.
jtlsf5 is offline Find More Posts by jtlsf5
Reply With Quote
Old Apr 30, 2016, 11:21 AM
Ken Barnes is online now
Find More Posts by Ken Barnes
Registered User
S.F. Bay Area, California, USA
Joined May 2005
995 Posts
It is quite possible that the servo you have is available under more than one "brand name".

Why don't you tell us what servo you currently have, and maybe someone here knows of that servo being sold under a different "brand name", from a different source. Or someone might be able to recommend a comparable servo that will fit the frames currently installed in your model. Why modify the model before verifying that you have no other options?
Ken Barnes is online now Find More Posts by Ken Barnes
Reply With Quote
Old Apr 30, 2016, 02:37 PM
LWeller is offline
Find More Posts by LWeller
Registered User
Holland, Michigan
Joined Dec 2006
542 Posts
All of you guys have been a great help!!!! There isn't a bad idea in the group. One of my favorites for the removal process is freezing and prying...or just prying but the other suggestions are equally meritable.

I have attached a few more pictures. One shows the original flap servo on the left wing. It still works. I found the same servo through HobbyKing, see the picture of the red servo. I ordered and received 2 of these. The tabs were redesigned with the result it won't allow the hold down wedges to fit in the servo frame. Then in my search I discovered it is advertised as metal gear but really is called a hybrid using both plastic and metal gear.

At breakfast this morning a fellow sailplane pilot suggested I cut off the tabs and epoxy the Hobbyking servo in place. This is a good idea and will work...but I am not crazy about these servos at all. Really I would like to go to a more powerful flap servo - not that these have given me any problem until one locked up.

The question in removing both servo frames, is the juice worth the squeeze? I could grind down the bottom part of the servo frame and use a Dymond mg d160, which is just about an 1/8" longer. I have had no problem with these servos. See the Photoshopped picture showing the bottom part of the frame removed.

This servo frame I'm using is carried by Icare-Icarus in Canada and does list the Hyperion 11AMB and Airtronics 94761 as fitting this frame. I also found the KST DS315MG Metal Digital Mirco Servo or the KST DS115MG Metal Digital Mirco Servo to have the physical dimensions I think will fit.

I'm a sport flyer. I don't couple the flaps to the ailerons except for launch, reflex and camber. They aren't subject to a lot of use. I really enjoy this glider but it doesn't get the same workout a competition pilot would give it. So, it seems the logical thing to do is leave the frames alone and find two decent servos to replace what I have been using. MKS makes one that is about the same size as the KST that would work. If money were no object....

Your help is greatly appreciated in clarifying my thoughts about this problem. Larry
LWeller is offline Find More Posts by LWeller
Reply With Quote
Old Apr 30, 2016, 02:53 PM
LWeller is offline
Find More Posts by LWeller
Registered User
Holland, Michigan
Joined Dec 2006
542 Posts
This is a P.S. to my post above,

I spent several hours on the Internet today researching information on the ideas I read about here. I mention that so you don't assume I had all these answers before you posted your help. The Hobbyking servos I hadn't mentioned in the beginning because I'm really dissapointed to learn they share metal and plastic gears, besides not fitting my needs. I am still whipping myself for buying them. I will find a use somewhere .
LWeller is offline Find More Posts by LWeller
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! How to remove wing servo which is epoxied? John Kim The Builders Workshop 17 Feb 02, 2016 05:04 AM
Help! Removing a servo tray SLoViper Beginner Training Area (Fuel) 7 Apr 26, 2014 04:29 PM
Discussion How to remove epoxied servos from composite wings cbr998 Slope 14 Aug 09, 2012 02:03 PM
Help! How Do I Remove Hot-Glued Servo From Foam Wing? nolebotic Foamies (Kits) 10 Dec 27, 2009 11:40 AM
Will this servo fit in this tray? sinkhole Radios 2 Sep 08, 2004 08:52 AM