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Loctite and Plastic Caution !!

dpope49

Heliman

Luverne, Alabama

Maybe a Word of Caution !

I have read a lot of posts concerning the use of Loctite for bearing retention etc. on plastic parts. Hence, I have been a little hesitant about making this post as it seems none of you folks have had any trouble with this practice and I hope that you don't.
I would, however, like to share an experience:

Last year I was involved pretty heavily in 1/5 scale on road cars. Having some trouble with bearing retention I used blue loctite to retain wheel bearings and differential bearings within their plastic carriers.
About 3 months later at a race when traveling around 50mph both rear wheels and a couple of diff gears flung themselves around the track.
After inspection I found that everywhere I had used the loctite the plastic had crystalized, stressed cracked, and finally failed in a violent shattering (almost like car glass does when broken).

The next day I called loctite after looking at their spec sheet and list of chemicals used in the compound.
I was told that all loctite threadlockers and retaining compounds contain Dimethacrylate Ester (that didn't tell me nothin') but the guy I spoke with said that this chemical will react with plastic to the results that I experienced. He said this is why the instructions say that it is for use on metal to metal contact. He indicated that the rate of progression is different with varying plastic compounds but warned that this crystalization possibility exists with most known plastic compositions and there is no way to predict if or when the failure may occur.

There is a loctite made specifically for plastic to metal or plastic to plastic. (# 425

http://tds.loctite.com/tds5/docs/425-EN.pdf
Looks like it's mostly super glue.

The clutch bearings on my heli (plastic clutch bell) were spinning in the race. I just used a touch of the 425 on opposing sides. It works fine and is pretty easy to remove the bearing when needed. No harder to remove than with the blue loctite and I don't worry about stress failures.

08-27-2004 Over year old.
HobbyHomee

Heliman

Beale AFB California

Hey cool deal I did not know this. Makes sense. but ill be sure not to use it on plastic anymore.

08-27-2004 Over year old.
Stretched

Senior Heliman

Mobile, Alabama

That is good to know!

Thanks for sharing.

08-27-2004 Over year old.
pva

Veteran

New Zealand

Hi
This comes up every now and then. Alternative is to use the Tamiya threadlocker, which is safe for plastic.
Ciao

08-27-2004 Over year old.
Galifrey

rrProfessor

Bristol

I use CA for plastic to metal locking...

bearings or screws.. apply with a toothpick for bearings... you dont want it in the races

Don't Email me as I wont reply - PM Only (spam countermeasures)

08-27-2004 Over year old.
davehour

Elite Veteran

Guayama, Puerto Rico 00785

Thanks for the info!

08-27-2004 Over year old.
Alu-swashplate

Senior Heliman

Germany

hi

hmm damn...ive secured the bearings in my rappy 50 chassis with blue threadlock....only mainrotorshaft bearings, and only a light small spot.....and now ?

08-27-2004 Over year old.
z11355

rrMaster

New England

honestly, you'lll probably crash and ruin those
bearings way before any loctite damage.

Or take the bearings out now and clean the area.

08-27-2004 Over year old.
Raptor Rulezzz

Key Veteran

Rockanje, Zuid-Holland - The Netherlands

Blue loctite doesn`t attack the raptor frames... believe me

Dunnow about other plastic`s though, but the raptor frame is blue loctite proof

Cheers,

Rich



Proud Member of Team QuickUK, Team Duralite & Sponsored by V-blades & 4rc.nl

08-27-2004 Over year old.
Alu-swashplate

Senior Heliman

Germany

hi

ok thats good news

08-27-2004 Over year old.
dlflyer

Senior Heliman

Flushing, Michigan

Thanks for the post. I had posted a question on this same subject. (Locktite vs Expoy) . You have given information we all can use. Thank You

08-27-2004 Over year old.
4cyclic

Key Veteran

Montreal, Can. and northern Vermont

Rich is right here.
I've used blue loctite on plastic parts for last 30 years and never experienced problems. I think most plastic parts in helis are immune.

J.L.

08-28-2004 Over year old.
Phranque

Senior Heliman

Wherever you go, there you are.

Even CA can be a bit too good. If you have to take something apart, some of the plastic can come out with the screw. White glue (Elmer's or generic) works great as a threadlocker for plastic.

Flying a heli is like seeing the Matrix, it is a mind bending experience.

08-28-2004 Over year old.
GMPheli

Elite Veteran

W. Bridgewater, MA USA

I have used the plastic safe blue 425 loctite for some time now and I like it. It holds about the same as regular blue. It can be hard to find though.

08-28-2004 Over year old.
Brett

Veteran

Chicago Burbs

In a car the bearings may have got hot in which case locktight will act like lubricant allowing the bearing slip creating more heat. That should be only reason for a failure in plastic I would think.

08-30-2004 Over year old.
w.pasman

Elite Veteran

Netherlands

I also never had problems with blue loctite on the black plastic on the raptor. The white frame spacers seem OK with loctite too.

08-30-2004 Over year old.
HOMEPAGE  
Pipeous

Veteran

Surrey, BC, Canada

I had the same happen to a servo case on an off road rc. the screws threaded into an aluminum case. the locktite on the screws got on the servo case and it shattered around the mounting holes. I thought it was just the locktite and traxxas servos.

hmm I was thinking of doing the blade grip mod on my evo. guess I will try the 425, but maybe it is time to bling out instead.

08-30-2004 Over year old.
HOMEPAGE  
NewHeli

Key Veteran

Pittsburgh, Pennsylvania, USA

I use blue locktite in my blade grips to hold the bearings...I hope that plastic is immune!

NewHeli

Nathaniel Rice
Team HeliWholesaler/Miniature Aircraft
Team YS Engines

08-30-2004 Over year old.
iskoos

Key Veteran

Orlando, FL

I have never heard plastic to metal or plastic to plastic locktite. Is it labeled as #425 on the plastic bottle?

08-30-2004 Over year old.
dpope49

Heliman

Luverne, Alabama

White Bottle with Blue Label.

See link for picture: Put 425 in the product search field.

http://www.loctite.com/int_henkel/l...eid=19&layout=3

I get mine at a specialty bolt and fastener company but there are a lot of sources on the web. Google search for loctite 425.

08-31-2004 Over year old.
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Loctite and Plastic Caution !!

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