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Author Topic: Servo removal  (Read 30 times)

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Online Deerslayer

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Servo removal
« on: March 06, 2020, 06:43:32 AM »
There are a lot of ARFs in our collective hands, predominantly constructed of some sort of foam.

Many of these owners will sooner or later need or want to remove a servo or perhaps a receiver or even some weights (I have done all of this). We find that sometimes the things are stuck in place as if someone's life depended upon them staying come hell or high water. Very nasty!

Sometimes  the only way you can get the thing out is to start cutting, gouging and prying, possibly making a major mess of the foam.

If you are lucky, you can use a solvent to break the mechanical bond between the servo and the foam. The Flitetest guys put me on to this a long time ago.
The usual solvent is ordinary isopropol alcohol from the medicine cabinet. It will not damage plastic or foam or paint of any kind that I have encountered.

Soak the joint area, either by dripping the alcohol around it or using a small paint brush, kept soaked. Try to start prying the glue away from either the servo or the foam or perhaps both, at one or more places. An Exacto knife, dental pick (my preferred method) or such may work best. Once you start to lift even the tiniest edge, keep soaking that area. You should find that it gets easier to pry more of the joint apart, especially if you pause frequently.

Be careful. Some plastics, particularly the cases of our beloved HXT and Turnigy type servos, are easily cracked and broken. Not a big concern if you just intend to junk it.

Unfortunately, some factories and even some modellers like to slap their adhesive all around a servo, including underneath it. This makes removal particularly difficult. With some luck, you can break the bond around the visible part of the servo and pour lots of solvent into the gap. You may need to wait a few seconds or a couple of minutes for it to take effect.

The principle involved id that the alcohol is very low viscosity and density, as well as being quite volatile. This means that it will "wick" into microsopic spaces, and vaporize, expanding that space. 

When you have extracted the object, you can use more solvent to clean it up. I have servos that have been removed, the gear train replaced, reassembled and they are indistinguishable from brand new ones.

When the time comes to re-install the servo, push it part way in, apply just a bit of hot glue at a couple of places, preferably at or under the tabs, and then fully seat it. It should be solid as a rock, yet you can extract it easily, if necessary, using this solvent technique.

I was stumped while trying to remove a defective servo from my (Joysway) Hobby King Skipper. Alcohol did  not work. The crap they cemented this thing in with seems like what is used on high end double-sided tape, i.e., it remains extremely sticky and terrible to get off of anything - including fingers!
In my desperation, I noticed a little bottle of something called Un-Cure I had bought many dog years ago but did not recall ever using. It came from the local hobby shop, sold as a CA debonder.  So, I dribbled some onto a piece of scrap foam to ensure that it didn't just dissolve the object. Then, I used the same technique as described above. Voila! It worked. I will find out for sure, when I find a suitable replacement servo, that there is  no residue which would defeat the new hot glue bond. I have no idea what chemical this stuff is, but at least I have a clean removal and ten whole working fingers.
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Offline ganguy

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Re: Servo removal
« Reply #1 on: March 06, 2020, 07:57:14 AM »
To avoid removal problems, when installing new servos, I embed small pieces of wood in the foam and use the mounting screws that come with the servo. I'm hard on servos and this makes replacement an easy field-fix.
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"