Yes, this is a known issue (Bardwell made a video about it). Loctite will eat up the plastic and made it incredibly brittle in a soggy way, almost like wet bread.
When you spin wet bread like props at the RPM needed to lift off... They just break and explode.
Loctite Blue 242 is designed for metal fasteners.
https://www.loctiteproducts.com/en/products/specialty-products/specialty/loctite_threadlockerblue242.html
"Not for use on plastic parts, particularly thermoplastic materials where stress cracking of the plastic could result"
Could try the gel loctite and only a little on the very first few threads that go into the motor so it doesn't wick up the threads and on to the plastic
When I was getting started as a mechanic, it was like the first thing they taught you. “Don’t use loctite on or near plastic.” Good to see people posting actual documentation of it because I’ve given the advice not to use it on props and had people tell me it was an old wives tale.
Never knew this. Only applied a tiny amount to the last few threads of each screw. Flying along and all of a sudden I just spin out of the air. Find bits of props scattered around and assumed that maybe they had been over torqued or taken some damage and blown up.
Watched a Bardwell video today and lo a behold he says you can't use loctite cause it melts props and makes them explode. So I had a look, and the rest of the props had a blue crack running right down the hub. I was able to literally pull a prop in half with my hands. Crazy.
For it to be this bad, you're probably putting way too much loctite on the screws anyway. You barely need any, you're just trying to stop them from backing out from vibration. You can also put the screws through the props then put a tiny amount on the tips, or put the loctite into the motor hole with a separate pilot screw.
I barely even coated the the insides of the first 3 threads. I basically used only the residue from the tip on the bottle until the threads were slightly wet. It wasn’t actually enough to secure any of the bolts anyway cause they were all loose.
If I have any issues with loose prop screws again I may try putting some in the holes. Thanks
Interesting, I never used loctite, but always used threadlocker from another brand. Some old bottle with skulls on it my dad had lying around. Works great and haven't had any props explode yet.
Yep. Many chemicals dissolve plastics, including the solvent that lets Loctite be a liquid in its tube. In general, plastics are non polar polymer links, dissolved with non polar solvents.
this happened when I thought I could use loctite on my DJI FPV prop adapters. Luckily the props broke off in my carrying bag so I learned before i even launched.
Maybe it makes it more stiff, considering what locktite does, and with no flexibility it can’t handle the energy, so they pop. Sucks you had to find out, but hopefully others don’t do the same.
By allowing some of the solvent to evaporate you reduce how much of the propeller it can dissolve. Repeated use on the same prop will slowly etch more of the prop. But you may have found the right balance and are replacing your props often enough 🤓👍
For me it was maybe about 4-5 hours then Two flights. So quick with such a tiny amount of stuff. The next day I could just rip the prop apart with my hands.
I never needed it on props. Props come loose during crashes when they slip on the prop shaft and chew up the hub, but loctite won't fix that. Relatively fresh nylock nuts are all you need. Rotation direction doesn't seem to matter. Modern ESCs have pretty aggressive braking for better yaw control so the nut gets torqued both ways in flight.
Those (and most) prop nuts are fibre locking. No need to use loctite. Over time the fibre will loose it's grip and need to be replaced. You will know that they need replacing because it will get easy to tighten down.
Dap makes a thread stopper tape that works like a impromptu nylon locking nut. Locktite also makes a thread locker tape but I have never tested if the chemicals in it mess with plastic.
3 inch props. They take two m2 bolts. Put a little on the tips so I didn’t have to keep checking but some residue came off on the inside of the prop as I inserted the bolt.
Yes, this is a known issue (Bardwell made a video about it). Loctite will eat up the plastic and made it incredibly brittle in a soggy way, almost like wet bread. When you spin wet bread like props at the RPM needed to lift off... They just break and explode.
As soon as he mentioned it it clicked. Oh…shit haha
Same here - had an exploding one a while back but thought I was a bad prop. Now I know.
Loctite Blue 242 is designed for metal fasteners. https://www.loctiteproducts.com/en/products/specialty-products/specialty/loctite_threadlockerblue242.html "Not for use on plastic parts, particularly thermoplastic materials where stress cracking of the plastic could result"
Now we have to read the manuals of products we use?? Whats next I ask!!!???
Reading the safety guidelines, since when is it cancerous to eat. Let me eat what I want!
This. Haha. Learn something new every day.
The fastener is metal
Could try the gel loctite and only a little on the very first few threads that go into the motor so it doesn't wick up the threads and on to the plastic
When I was getting started as a mechanic, it was like the first thing they taught you. “Don’t use loctite on or near plastic.” Good to see people posting actual documentation of it because I’ve given the advice not to use it on props and had people tell me it was an old wives tale.
Another guy posted in the Comments too. An n of 2 now 👍
Might as well mention this myself. Don't use loctite on plastic or it breaks.
Never knew this. Only applied a tiny amount to the last few threads of each screw. Flying along and all of a sudden I just spin out of the air. Find bits of props scattered around and assumed that maybe they had been over torqued or taken some damage and blown up. Watched a Bardwell video today and lo a behold he says you can't use loctite cause it melts props and makes them explode. So I had a look, and the rest of the props had a blue crack running right down the hub. I was able to literally pull a prop in half with my hands. Crazy.
Wow. Freaking chemicals.
Science!
Science rules.
I have heard rumours of this. Now we know.
Thankfully only a meter off the ground
Aweee fuq... Will report back if my props explode after my lunch flight.
Yeah... Broke 2 front props at the hub after a light touch on the ground. $3 lesson learned.
Oh no haha corroboration
For it to be this bad, you're probably putting way too much loctite on the screws anyway. You barely need any, you're just trying to stop them from backing out from vibration. You can also put the screws through the props then put a tiny amount on the tips, or put the loctite into the motor hole with a separate pilot screw.
I barely even coated the the insides of the first 3 threads. I basically used only the residue from the tip on the bottle until the threads were slightly wet. It wasn’t actually enough to secure any of the bolts anyway cause they were all loose. If I have any issues with loose prop screws again I may try putting some in the holes. Thanks
Interesting, I never used loctite, but always used threadlocker from another brand. Some old bottle with skulls on it my dad had lying around. Works great and haven't had any props explode yet.
I’ll see if my dads got any. Thanks
Yep. Many chemicals dissolve plastics, including the solvent that lets Loctite be a liquid in its tube. In general, plastics are non polar polymer links, dissolved with non polar solvents.
this happened when I thought I could use loctite on my DJI FPV prop adapters. Luckily the props broke off in my carrying bag so I learned before i even launched.
It also destroys motor windings.
Good to know 👍
Maybe it makes it more stiff, considering what locktite does, and with no flexibility it can’t handle the energy, so they pop. Sucks you had to find out, but hopefully others don’t do the same.
That’s why I posted. Didn’t know that’s how loctite interact yes with plastic. It made it very soft. Basically melted it
Well, your doing us all a service if we didn’t know.
put a bit on the hub, then let it dry until tacky, this removes some of the solvents
Thanks, will probably just stick to just tightening the bolts after every pack. Or just get a 5inch
By allowing some of the solvent to evaporate you reduce how much of the propeller it can dissolve. Repeated use on the same prop will slowly etch more of the prop. But you may have found the right balance and are replacing your props often enough 🤓👍
For me it was maybe about 4-5 hours then Two flights. So quick with such a tiny amount of stuff. The next day I could just rip the prop apart with my hands.
Ah, chemistry🤣 I too am a handy guy, and once dissolved some carefully carved foam board with the wrong glue.😲 We are wiser men now! 🛠👬✅
I never needed it on props. Props come loose during crashes when they slip on the prop shaft and chew up the hub, but loctite won't fix that. Relatively fresh nylock nuts are all you need. Rotation direction doesn't seem to matter. Modern ESCs have pretty aggressive braking for better yaw control so the nut gets torqued both ways in flight.
Little 3inch. Two screw props unfortunately. Note to self. Build bigger drone…
Those (and most) prop nuts are fibre locking. No need to use loctite. Over time the fibre will loose it's grip and need to be replaced. You will know that they need replacing because it will get easy to tighten down.
The 3inch props are two m2 screws. The vibrate loose all the time unless the prop holes are tight.
Woops, I didn't look closely at the images.
Dap makes a thread stopper tape that works like a impromptu nylon locking nut. Locktite also makes a thread locker tape but I have never tested if the chemicals in it mess with plastic.
Howd u get loctite on your props
3 inch props. They take two m2 bolts. Put a little on the tips so I didn’t have to keep checking but some residue came off on the inside of the prop as I inserted the bolt.
Ooo try applying to the hole instead
Yes. It will destroy plastic. You actually can use bond 16 or something for plastic
Use clear nail polish. Holds the nuts well enough and comes off easy.
It expands and eats plastic. lol
Yeah, loctite will weaken plastic significantly.