Kenmtb

Hi
I need to reattach a servo on my foam carbon cub ss. Looks like they use a light weight brittle white epoxy. I would like to buy the same stuff but I can not google a part number.

Some forums mentioned using electronic save silicon or tub calking but I am not sure which one to buy. A part number or the full name of the product would be a huge help.

I would like to avoid having to buy a hot glue gun.
Thanks
Ken

Stormrider51

I asked the same question some time back and nobody seemed to know what the glue was. I was told at my LHS that it is a type of silicon but they weren't sure. I finally bought a hot glue gun that switches between high and low temperatures. If I remember correctly it cost something like $12. It turned out to be money well spent. It has allowed me to do everything from minor repairs to pretty much rebuilding one of my foamies. Be sure to use the low temp setting on foam.

John

Kenmtb

Thanks for the advice. It is hard to believe that no one sells the stuff they build the planes with :/
As a noob, I do not know all of the ramifications of using non oem adhesives. Will hot glue add
excessive weight? Will it hold up as well for servos after a mishap? Can hot glue be removed without
tearing out the foam?
Thanks

Stormrider51

I use two types of glue, foam safe CA and low-temp hot. Both have advantages for certain situations. The CA is great when you need to bond two surfaces with minimal physical bulk in the joint. Joining two halves of a wing during a build are a good example. You need a firm bond but also need to maintain the close fit and alignment between the two halves. Extra mass would throw things out of kilter. Other situations either need a filler or a little extra mass doesn't matter. That's where hot glue comes in. I broke the lower wing on my Parkzone Albatros D-Va right where it joins the fuselage when a gust of wind flipped it on take off. There were some bits of foam missing. I ran a bead of low temp hot glue along the break and fitted the wing back together. This left me with small visible gaps where foam was missing. I went back and filled those areas with more glue. That wing is still flying today. That same plane had a casting defect from the factory in that the rear of the fuselage where the tail surfaces attach was cocked enough that I had to make considerable rudder trim to maintain a straight flight. The accident described previously broke the fuse just in front of the tail surfaces. I took advantage of that by using hot glue to build up the crack on one side so that it straightened the tail. In another situation, I bought a Parkzone ultra micro P-51D and the aileron throw was much to small to initiate a good roll rate. I split the fuse and saw that the bellcrank that activates the ailerons sits on a pylon and the pylon itself was rocking forward and back with servo inputs. The part of the throw of the servo was being absorbed by the rocking of the pylon. I added a puddle of hot glue all around the pylon and the problem was solved. No more rocking and the ailerons had plenty of roll authority.

You asked about removing hot glue without also removing foam. Can you remove any glue from foam without damaging the surface(s) it is bonded to? As for weight, just don't use more than the repair calls for and I think you will be fine.

And if you discover what that white rubbery glue they use is, please let me know!

John

Kenmtb

Thanks for the super detailed reply. The original servo glue was white and kind of brittle. It splits away from the foam easily with
a screwdriver with minimal foam damage. Someone on youtube mentioned adding "microballon" compound to glue or something. The rubbery white stuff that holds motors and wires in place is a mystery also. Some claim it is a form of calking. My hobby shop recommended trying automotive silicon. I hear you have to stay away from silicon that uses acids to cure. Ill have to go to autozone and see what they have.

You would think that oem servo adhesive would be well documented and people would not have to guess about what the manufactures used

bikerbc

Super Phatic works great on foam for repairs where no gap filling is required .. It will also join balsa or plastic etc to foam ..

AMA 74894

My Feedback: (1)

there are literally hundreds of factories in china pumping out styrofoam arfs... if you were lucky enough to find a brand name for the adhesives they use it would likely be in Mandarin
I use an adhesive called Foam Tac by Beacon adhesives, readily available online. for foamies I have not found a better adhesive, it is VERY similar to the white stuff.
(BTW, you should be able to use lighter fluid, or 'Goo Gone' to dissolve the old glue and to dissolve Foam Tac... test on a scrap piece first to make sure the goo gone does not melt the foam...)

Kenmtb

Good info to know. Wish there was a sticky listing all of the adhesives and glues that people are using.
For some reason googling does not come up with much.

amc72

My Feedback: (2)

This is the reply from horizon support I received last week for a repair on a FW190.

We would recommend a silicone based adhesive such as RTV silicon.

Kenmtb

RTV- have to be careful from what I read. If it cures with acid then it can be corrosive to electronics.
BTW I kind of gave up looking for the original. The microbubble/epoxy approach would be near $20 so I said the
heck with it and use foam glue and kicker

I applied the glue conservatively to the corners of the servo only. Hopefully it will still be removable if necessary.

JohnBuckner

My Feedback: (1)

If you want to use any old RTV any Walmart or hardware store varfiety then fine, Use it if what you are talking about are servos? Sure some varietys may be corrosive to electronics so what? So don,t go potting open circuit boards in the stuff. just mounting a servo in a case of course works fine.

As far as finding out what kind of adhesive was used by a factory would be fruitless. In most cases even the importers will have no idea or a choice in the matter unless you are one of the biggest importers. The actual factorys will use what ever is the very cheapest for them in their actual location at the time of production.

John

Rodney

John, it is not the RTV itself that causes the corrosion, it is the fumes as it cures. It is very insidouse and can get into the electronics if there is any gap in the seals etc. I speak from experience and tests made in the aircraft industry. Do not use it around any electronics before it has cured else you are almost guaranteed to have some corrosion. After a week or so of curing, it is quite safe around electonics. Now, they make an electical grade of RTV that is safe to use but it is quite expensive.

Kenmtb

DOH-
Why can't hobby shops just sell some simple flexy servo goop for noobs. I really like the stuff the manufacture used cause it cuts away really easily and held things in place nice. Will bathroom caulk work? Heard that from another forum.

JohnBuckner

My Feedback: (1)

I don,t doubt what you are reporting however I have had some foamys that include my 1975 Cox Founier that my wife gave me for my birthday that year, because I also owned at that time the full scale version. Anyway The original servos are still stuck to the sides of the foam compartment and that airplane still flies with that RTV still stuck on the side of those servos to this day and there have been a number of newer ones that I have done in the same way with no problems although Glow will always be my preferred power system. Go figure

I would speculate that its all got to do with simple moderation that works for me its not necessary to pot the servo in the stuff.

John

AMA 74894

My Feedback: (1)

Bathroom caulking will work, but test it on the foam first to make sure it won't dissolve the foam (obviously test in a spot that's OK to potentially have a little melt hole in it )

OR: what I mentioned earlier
http://www.beaconadhesives.com/cgfoam.html
foam tac. stuff is very very good for foam. (and is removable without harming the foam or the servo)

Kenmtb

Looks like some good stuff. That will probably work just about anywhere