Loctite - how strong is it?

[Jim_gsxr1000]

there is air in the bottle, its enriched, around 24% and once you open the bottle atmospheric oxygen gets in, you typically need to drop to around 3% to allow curing (Critical Lower Saturation Limit) as for the pressure you need around 2x10^5PA to activate it not a lot of force really

 

[PhillipM]

I'd be using a little 2k methacrylate tbh.

 

[Julian_P]

Why doesn't the screw cap on the bottle of Loctite glue itself on permanently?

Julian

 

[gerrymoore]

PhillipM...can you elaborate?? Gerry

 

[MattF]

Thanks for the replies....I realise that a keyway or pinning is best but I cant pin it 'cos the bearing is in the way and have no facilities to do a keyway.

You can drill in from the end of the shaft too, to secure the two. Similar to a keyway, but you could just drill a hole which encompasses the shaft and flange then tap the hole and screw a locking screw down there. A photo of your setup would help, so that people can see what's permissible to suggest.

Regarding Loctite or the ilk, as much as I've heard it gets used for no manner of stuff which handles more stress than you're likely going to be putting on yours, I wouldn't, but that's just personal choice. It should work fine, however.

 

[gerrymoore]

Here are pics of the sprocket and hub...first is the sprocket with welded freewheel...next is the hub with thread...then both attached and finally a pic of the whole wheel.

As you can see, there is not much room for drilling and tapping.....

 

[Jim_gsxr1000]

It dosent Glue its self on as there isnt enough pressure there and its a single thered

 

[MattF]

Is that shaft hollow all way through? If so, I'd just pop a length of steel rod through, with a large disc/washer at either end and then drill a hole through the rod at 90 degrees, one at either end, with a split pin securing the rod and washers in place, up against the bearing faces. Worst you can get then is a wheel working slightly loose, but it can't come off. It can't go past the large retaining disc/washer, and you won't have to heat the hell out of the shaft to get the Loctite to part company if you need to remove the wheel at a later date.

 

[gerrymoore]

Hi Matt...no can do, the hole right through is for the axle which the wheel bearings run on....can't pin the wheel to this. I'm not concerned with the wheel coming off, just need to secure the sprocket to the wheel......

 

[MattF]

Hi Matt...no can do, the hole right through is for the axle which the wheel bearings run on....can't pin the wheel to this. I'm not concerned with the wheel coming off, just need to secure the sprocket to the wheel......

I really should pay more attention to what I'm looking at. With it being an imperfect setup, and if you haven't enough meat to drill out for a securing pin or screw, then a chemical solution like the Loctite is about your lot. It should do the job, and it's not going to be a world ending catastrophe if it doesn't work, so give it shot.

 

[PhillipM]

Why doesn't the screw cap on the bottle of Loctite glue itself on permanently?

Julian

Because the plastic they use for the bottles is breathable, it lets air through, they also tend to catalyse on metals and not plastics, so the curing rate even with no air there would be very slow.

I don't think it's anything to do with pressure, loctite will cure even on a loose bolt thats just been wound half in. The only threadlockers I've seen that needed slight pressure are the tape type..

 

[Sean]

funny mine had. had to crack the bottle with a pair of pliers before applying it to the tread of the crank bolt doing a timing belt at the WE.

 

[Jim_gsxr1000]

Its pressure and Absence of oxygen, it can go off with either or, some on a thread will go off even if its not tight, your right it does perform better on ferrous metals but will work on a lot of other materials that is what I was referring to when I spoke about Vander walls forces

 

[hotrodder]

FWIW add me to the list of people that's had the cap get loctited to the bottle and also had the stuff 'go off' and no longer set... in the later case it was eons beyond it's date and the story i've been told regarding that was something along the lines of the military or some other huge customer asked them/insisted it was given a shelf life/expiry date

It's strength/set up time can be improved on active metals like ally and stainless by using their specific primers/activators but even then falls short of the shear strength obtainable on carbon steel
The colours don't mean much in the grand scheme of things... there are 'red' flavours that are more than double the breakaway torque of other 'red' flavours for example and while retaining compounds are generally green so are some of thread lockers that have similar strength to 'blue' but are capillary versions

Dunno how much torque each electric motor is capable of producing but (based on leccy bikes i've experienced) i would have thought it'd be less than a human i.e. i'm pretty sure a person sprinting would undo a loctited sprocket that's being used 'backwards' not so sure about an electric bike and even if it's a particularly powerful one it'd be smoother than a human which should help?
Having said that there's loads of room to pin the sprocket isn't there?


Only drawn one but two or three small dowels would be ideal?

 

[Robotstar5]

The pic above reminded me of how we secured some bushes at work, drill and tap for a small grubscrew where marked?, you could even threadlock the grubscrew

 

[Shox Dr]

FWIW add me to the list of people that's had the cap get loctited to the bottle and also had the stuff 'go off' and no longer set... in the later case it was eons beyond it's date and the story i've been told regarding that was something along the lines of the military or some other huge customer asked them/insisted it was given a shelf life/expiry date

(pic)
Only drawn one but two or three small dowels would be ideal?

Good idea HR.

In the mid 80s I had a Boulder Defiant MTB. It had an Evolution size Headset 1.125 and I couldn't stop it from coming loose so I Used 648 Bearing Retainer * along with activator.

Great until I came to service the bearings. Like hell could I undo the locknut, even with heat, I ended up literally peeling it off the steertube
It was only after speaking to my Brother in law, I found out one of it's uses: Cylinder head bolts on Chieftain Tanks, no wonder I couldn't get it off

I've had a lot of mine a long time, and have found some of them losing their strength, but if used with the activator, it has so far done what it was used for.

Locitite and their ilk are really just glues. As I understand it there are only a few types of glue:

Anaerobic
Aerobic
Chemical
And super glue that I think goes off in the presence of water vapour, and that's why breathing makes it cure faster, but I could be wrong diddly wrong, there.

*military spec (not freely available to the general public)




*not available to the general public

 

[MattF]

The pic above reminded me of how we secured some bushes at work, drill and tap for a small grubscrew where marked?

It's a time honoured and simple method which works very well. An effective way of keying something to a shaft without broaching, and also locks both items together, preventing movement both along and around the shaft, if you use a grubscrew. I've got some kit here knocking on a century old which uses the method, so it's definitely stood the test of time well enough.

 

[gerrymoore]

Thank you to everyone who has replied to my original post...I think a lot has been learned ....and not just by me!

I will have a go at drilling a small hole and tapping for a small grubscrew...I haven't got a small grubscrew but presume they are readily available from my local Small Grubscrew Centre (old python joke!!)

I'm waiting on some electronics from China before I can carry on with the Segway build but I'll report back on progress and the 'sprocket fix'.

regards Gerry

 

[Chook]

Clean it up really well with priming fluid and apply enough Loctite 660 "Quick metal", winding it on and off to make sure the threads are fully covered. Nip it up tight.

There is no way it will come loose without heat, if it was squeaky clean for good adhesion before the Loctite was applied.

 

[MattF]

Btw, you don't necessarily need to use a grubscrew. With an application like that where it's not going to risk fouling anything, a set screw or small bolt would be fine too. Doesn't matter whether a head is protruding or not, but just make sure your screw/bolt is short enough so that the shoulder of the head sits flush with the flange once tightened up.