JB Weld...

[Loony661]

Disclaimer: I don’t expect much out of this, but it was on the shelf and I have the time..

So I discovered a little problem with my MS460 yesterday while looking it over after an impact it received.. I found the upper AV mount broken, and worse, an ear from the case also broken.. The ol’ desperation fixer - JB Weld - was in a faded box, bought years ago, on my shelf. I figured, “Why not?”.

 

[Loony661]

The break was clean, dry, and naturally rough from the cast magnesium, so I gave it a shot.. My plan is to gently drill the excess from the threaded hole, and chase the threads..

Have any of you had success with JB Weld on chainsaw repairs like this? I figure it’s just going to break again, especially given the nature of the break through the mounting hole, but if it works, I win!

 

[jacob j.]

I've not made a repair like that on a case with JB Weld but I'd be interested to see if it holds.

I have made non-structural repairs on saw cases with JB Weld (usually filling a hole) which works ok.

 

[JugHead27]

I'd run it

 

[quattro.pilot]

nothing ventured, nothing gained.... you got nothing to loose. JB Weld can surprise a guy some times

 

[Loony661]

So I just drilled out the excess JB from the threaded hole with a bit that was 1 size smaller than the recommended tap drill size. Then I had to clean the threads out. My chaser set only goes down to 6mm - not going to work on this 4mm thread. So I got creative:

I took the original bolt and cut a channel into it with my cut-off wheel at an angle that would put some positive angle onto the threads, and also force the chips down and away from the threads... It worked very smoothly! So far, so good.

 

[Wonkydonkey]

Disclaimer: I don’t expect much out of this, but it was on the shelf and I have the time..

So I discovered a little problem with my MS460 yesterday while looking it over after an impact it received.. I found the upper AV mount broken, and worse, an ear from the case also broken.. The ol’ desperation fixer - JB Weld - was in a faded box, bought years ago, on my shelf. I figured, “Why not?”.
View attachment 328386 View attachment 328387
View attachment 328388

If that was me in your shoes, I’d try and fashion up a tie strap to tie into the av mount and the rest of the casing and tapping a new thread lower where I’ve marked in red . You'd have to have it on top of the av thou. it would help make it last longer

 

[Duce]

Too much stress and vibration, that's why it broke to begin with, worth a try. Good luck!

 

[Stevetheboatguy]

This is the chit.........





Jb has it's place. But I'm sold on this stuff. It just doesn't give up. Most times it's stronger than the original part.


Steven

 

[Stump Shot]

If you could drill and tap for a small diameter screw on one side or the other or both might make it more permanent. In other words go straight down through the broken part on either side of the screw mount hole.

 

[slackinoff]

I think it will hold as is. You have a nice clean break, plus the grain of the magnesium is perfect for allowing the jbweld to grip. Let it cure inside the house for 24h. Cold garage wont cut it.

The only time I have had JB weld not work was when exhaust heat weakened it. And it still lasted for a good while in that extreme heat. (exhaust stud). Threaded insert finally fixed that issue for good.

 

[Loony661]

Too much stress and vibration, that's why it broke to begin with, worth a try. Good luck!

It broke because the saw was impacted by a tree..

 

[Loony661]

If that was me in your shoes, I’d try and fashion up a tie strap to tie into the av mount and the rest of the casing and tapping a new thread lower where I’ve marked in red . You'd have to have it on top of the av thou. it would help make it last longer
View attachment 328407

Great idea!

 

[Loony661]

If you could drill and tap for a small diameter screw on one side or the other or both might make it more permanent. In other words go straight down through the broken part on either side of the screw mount hole.

I don’t think there’s enough meat on either side to do that, but great idea!

 

[Stump Shot]

I don’t think there’s enough meat on either side to do that, but great idea!

Even a tiny roll pin may help, if it's possible.

 

[Loony661]

Even a tiny roll pin may help, if it's possible.

I was just thinking about that too...

 

[redtractor]

This is the chit.........


View attachment 328419


Jb has it's place. But I'm sold on this stuff. It just doesn't give up. Most times it's stronger than the original part.


Steven

Does this stuff mix in the nozzle, causing it to harden making the tube a a one time use?

 

[Stevetheboatguy]

Does this stuff mix in the nozzle, causing it to harden making the tube a a one time use?

Yes and no. Yes it uses a mix nozzle, but they are replaceable. And if you only need a small quantity. Just spluge some out minus the nozzle and mix it like jb or any other.

I believe that they also sell it in smaller packages now.


Steven

 

[Loony661]

Update: the JB Weld did not hold for long under the abuse of everyday logging. That being said, it lasted longer than I expected. I ended up just applying Loctite to the 1 remaining bolt for that AV mount and ran it that way a while. Well now that failed finally. Looks like I’ll need a crankcase half if anyone has one they would part with? I looked at the FarmerTec replacement case, and the price is right, but I’d like to explore replacing with OEM at this time. I need the Mag side crankcase half for an MS 460 Magnum if anyone has one? Let me know, thanks gents!

 

[jacob j.]

I think I have a case half - I'll look this weekend.

It is tough though to mix and match Stihl case halves because of differences in the deck heights.