JB Weld question

[Cogsy]

I've just bought some JB Weld, I've never used it before and I don't know how good it works.

What I'm hoping to do is glue some 1" x 2" ali blocks together, so I can machine the water hoppers for my hit and miss engines, as I don't have any suitable stock to use 1 piece. I intend to seal the inside of the hopper, so the ali won't corrode, and the outside will be painted so the join shouldn't be visible, but will the JB Weld hold the pieces together while I do the machining?

Thanks for the help.

 

[Ramon]

Hi Al,

As a keen advocate of JB weld I'd like to say a cautious yes. I have used it to hold exhaust systems for glow motors together and it has stood up to the heat in that situation without fixings or indeed failure. The Waller engine I built had the steam chest bonded to the cylinder but was retained by two small 8BA capheads but withstood the subsequent machining forces. It is extremely tough stuff once fully cured but I would say that if you had any minor doubts then try to introduce a couple of small fasteners that can be sunk below the machining level and filled in with JBW after. BTW if you smear JBW all over the machined surfaces after assembly and then rub it down with emery it it makes for not only a good painting surface but will give a better impression that the surface underneath is cast if that is what you intend.

Do let it cure really well - a couple of days in a warm atmosphere for the maximum strength

Hope that's of use - Ramon

 

[canadianhorsepower]

I've just bought some JB Weld, I've never used it before and I don't know how good it works.

What I'm hoping to do is glue some 1" x 2" ali blocks together, so I can machine the water hoppers for my hit and miss engines, as I don't have any suitable stock to use 1 piece. I intend to seal the inside of the hopper, so the ali won't corrode, and the outside will be painted so the join shouldn't be visible, but will the JB Weld hold the pieces together while I do the machining?

Thanks for the help.

Hi Al,
Ive used jb weld many many time before. even use this stuff as a casting on the outside of
hgot saws to add stransfer port and no problem but that thin layer is not a good idea it will peel off.
your surface must be ruff (many punch with a prick puntch) it should like a wood file. after about 2hrs
you can use wax paper and a pieace of metal to applu pressure and make it look better.
as for sealing the inside (not a joke) clean it with acetone and apply a thin layer of clear nail polish.
If you dont want to paint to outside use DEVCON Aluminium and you wont tell the difference

 

[Jasonb]

I've also used it to bond valve blocks to cylinders and on my Bensom build subsequently machined the port face with a 40mm indexable endmill taking 0.025" deep cuts and it stayed put. That had no other fixings but that had quite a large surface area.

To be safe I would rough out as much as possible befor joining, introduce some dowels or small fixings as Ramon suggests and when machining hold the parts in such a way as they are clamped together.

J

 

[portlandron]

I have used Super Glue to hold parts together for machining or to attach a part to a block to be held in a chuck for machining. After machining heating the parts will allow you to break the joint. The joint needs to be clean smooth and flat to hold.
Epoxies, like JB Weld, don't hold very good when dealing with a thin application of epoxy.