How Much Heat Will JB Weld Tolerate?

[John Stiles]

I have bonded magnets into electric motor cans, and in the directions it said to bake[in the oven] the can after gluing in the mags. I've had pretty good results doing this; and just wondering if a broken aluminum muffler(Fox ) can be repaired this way, and take the exhaust heat?

[Ted Winterman]

John,
     I have used JB weld on 5 or 6 different mufflers from Fox 35's to Supertiger 46-60's without any problems. JB will take the temps.

                                                 Ted     

[Alan Hahn]

John,
I am not sure what directions you are referring to. Be aware that you can demagnetize neodymium rare earth magnets (if that is what you have) if you heat them to too high a temperature.

If these were the motor instructions, then I assume they gave you the correct temperature (heat the oven up, then turn off because every time the oven turns on to bring the temperature back up, you can get heat spikes from the radiation of the coils --if electric).

When I glued in my magnets using JB weld, I put the can with just glued magnets in my drill press, and then used a heat gun to warm the outside of the can as I spun it. This was more to allow the JB Weld to flow a little than to cure it. Also I kept my hand nearby to sense how hot I was getting the can. I could easily touch the can after I turned off the drill press. My particular Neodymiun magnets claim they can be heated up to over 200C, but I  am still not willing to test that. Most Neodymium magnets are lower in their temperature ratings.

[Brett Buck]

I have bonded magnets into electric motor cans, and in the directions it said to bake[in the oven] the can after gluing in the mags. I've had pretty good results doing this; and just wondering if a broken aluminum muffler(Fox ) can be repaired this way, and take the exhaust heat?

 

   It depends. I wouldn't count on it to have much structural strength at temperature, so I wouldn't us it on the lugs or anything with much load on it. Plugging up holes, maybe holding the halves together, might be OK. Given that it's Fox, I would just get a replacement rather than trying to fix it. They can have you one in a few days.

     Brett

[Bill Hodges]

I have used it to repair cracks in the exhaust manifold on a Cat D-6.  Lasted until we traded in the tractor which was at least 3 or 4 years. 

Bill Hodges

[Lauri Malila]

 Hi.

 It's better to start with about 60C, that way the stuff (and other epoxies too) does not start boiling and end result looks nicer. 60C is enough for normal use and about doubles the strenght of the glue joint, compared to curing in room temperature.
 If you need more heat resistance, you can slowly raise the temperature up to about 100 degrees (C) as the resin gets harder. L

[John Stiles]

Thanks for the info, y'all; I don't do the electric engines anymore...I got accused of cheating with the modified magnets...and I left them in a 300 degree electric oven for 1 hour to "heat cure" but I also learned to use a soldering torch to release those same magnets. It's a simple crack, and I'd order a new muffler, but I don't particularly like the style. I had heard that heat actually made slow cure JB Weld get harder....just wondered if these nitro engines get that hot.

[Tom Rounds]

Thanks Bill,
I think we took that D 6 in on trade and the exhaust manifold fell off right after we unloaded off the truck.  (Just Kidding) If it would have been a Deere it wouldn't have cracked.
Tom

[Bill Hodges]

Tom:

Actually, that old D-6 was traded in on a JD 750.  Can't ever recall having a manifold problem with a JD.  The old INT TD-9's & 11's were guaranteed to bust manifolds and throw tracks.

Hope to see you in Cocoa on Sunday.

For the uninitiated, the picture is a JD 550G enclosed cab crawler with a FESCO two disc fireline plow behind it.  This is the main piece of wildland firefighting equipment in Florida. 

Bill

[Alan Hahn]

Thanks for the info, y'all; I don't do the electric engines anymore...I got accused of cheating with the modified magnets...and I left them in a 300 degree electric oven for 1 hour to "heat cure" but I also learned to use a soldering torch to release those same magnets. It's a simple crack, and I'd order a new muffler, but I don't particularly like the style. I had heard that heat actually made slow cure JB Weld get harder....just wondered if these nitro engines get that hot.

Sorry John,
I just read the first part about the magnets, and not the last part about the muffler! Whoops

[RC Storick]

I have bonded magnets into electric motor cans, and in the directions it said to bake[in the oven] the can after gluing in the mags. I've had pretty good results doing this; and just wondering if a broken aluminum muffler(Fox ) can be repaired this way, and take the exhaust heat?

It will hold.

[john e. holliday]

On my Brodak .40 I broke part of the bolt lug off the case when lthe Olympic went in.  I cleaned the engine real good and tried to J-B Weld it.  It held for a couple of flights.  I determined not enough threads in the case, really the machine screw was no long enough.  Cleaned every thing up again and J-B Welded some longer machine screws in place.  They were long enought that once the weld set up I cut the heads off(allen head bolts/screws).  Made sure all was still good and proceded to use the nuts to hold the muffler on.  It is a Adimisin Muffler from Brodaks.  With my ball driver I have no trouble installing the engine or removing it.  The muffler is attached to the engine and is going into its third airplane.  Have fun,  DOC Holliday