Maybe this has been posted before, but I was unaware of this.
I have been assembling my quadcopter and as advised have used red loctite # 271 to lock the metal nuts and the prop mounts.
I have used it all up and bought some blue loctite #243 and have used it on some of the nylon nuts last night and have just noticed today that it has eaten away the part of the nylon bolt inside the nut and the nylon nuts are soft and easily split in two with my thumb nail.
I must hold my hands up and admit that I didn't realise that threadlock could do this to plastic, but thought I would bring it to everybodys attention.
Martinp
Comments
That is because despite what you may hear , nylon is usually self lubricating:- that means a form of lubricant is expelled from inside the material as part of a continual chemical process.
Just few weeks ago I did a test on a M2 nylon bolt and nut with Loctite 243 (aka Blue Loctite) to check if that was useful.(and yes, I know that nylon is already a locker, but I wanted to know if I could enhance the the thread locking properties)
After a few hours (3-4h?) the bolts I tried to unbolt it and both seems ok, but I noticed no locking properties which surprised me.
I will try to make a second more scientific experiment next time.
It should not be able to attack nylon 9 or nylon 66, it sounds like there is something else mixed in with the nylon (maybe PC, ABS), if the nuts are from a China supplier then that would explain it, the nightmare of my life was bloody Chinese plastic suppliers and their fiddles.
Get a nut and drop it in some nail varnish thinner.
check out this guide
http://catalog.gpi.net/Asset/Chemical-Compatibility-Ver-6.pdf
Thanks all, as I said I was unaware that it could attack plastic in that way.
@Chris, the various grades of locktite come in different colours, red, blue and green I believe, you're supposed to select the correct grade according to components that you are locking and what their duty is.
@Ellison, I was simply taking on board the general advice of the forum that vibration is a problem and nuts can undo themselves.
@Jesse, you're correct I had to use the cooker to release two of the spinners (after I had removed the spinners from the motor shafts)
@Sgt Ric, I'll follow your advice in the future and only use it in metal to metal from, and I'll use blue or green and avoid red I think.
Major fail.
Now I only use it for metal to metal!
The locktite does not dissolve the plastic, but will cause it to become extremely brittle and crack easily. This does not happen with all plastics however, I have a feeling polyethylene would be ok with it. In RC Helicopters the rule is that locktite is used for metal to metal, and CA (superglue) is used for metal to plastic connections. I always use one or the other when assembling any model, and clean the threads first with alcohol to remove any oil before assembly.
Blue helps to keep my motors attached to their mounts. Blue can be loosened, Red is considered a permanent lock, Purple is very easily loosened.
Locktight reacts with metal interference and catalyz'es faster.
As well as heat, acetone or fingernail polish remover will remove a locktight connection.
Locktite is only for metal-to-metal contact.
"Blue" locktite is a "general purpose" locktite and it's colored blue.
"Red" locktite is stronger and typically requires a heat source to undue. It's colored red.
If you use locknut then don't use Loctite!
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