JB weld question...

A while back… I suggested using the wonderful J.B. weld as a perminant solution, and The team thought that it wasn’t the best Idea, because we thought that it was more of a “fix it” product than a production product.I was just wondering weather or not anybody on this forum has any experience with the stuff and if your results were good. I have used it before… and it held allright, plus the user reviews all seem to be astounding… But if you’ve had any bad experiences with it, please post them here :slight_smile:

Thanx in advance

epoxy is stronger than the resin used in fiberglass construction (boat hulls, car bodies…)

it is definately a production quality material, and JB weld is one of the best epoxy products on the market.

the storys about it are true. I fixed a leak in the oil pan (small hole on the side) on my Fiero, and it lasted 3 years at least (I sold the car)

Funny, I used JB Weld for the same purpose, reinforcing the hole with a screw. Held up great.

JB Weld is a fairly good adhesive and an excellent filler. It has a lot of compressive strength, moderate shear, and poor tensile strength. It adheres well under poor conditions (heat, oil, chemicals) but isn’t as good underwater. I knew a fellow who repaired a crackled engine block with it, that’s where I first heard of it (over 20 years ago!!)

There are far stronger adhesives, like the clear stuff in a doiuble-tube syringe from Radio Shack (and others), but these are poor fillers. I recommend buying a small package and playing with it, you;'ll learn what it can and cannot do.

Hope that helps.


I’ve seen a FIRST robot with its drive gearboxes held together by a similar product (it was titanium-filled, instead of steel-filled like J.B. Weld). It worked…but wasn’t pretty.* I’d advise against that particular application.

When using it, watch out for the fact that it slumps as it dries, so it can be tricky to apply precisely to oddly-shaped surfaces. (I’ve also used a Devcon-brand aluminum-filled epoxy that is of a thicker consistency, which is more easily applied to complex shapes.) Also, though it’s stronger than fibreglass resin, if you’re using significant quantities of it as a structural reinforcement, it should itself be reinforced with something like a fibreglass mesh.

*The team was 919, Harbord C.I., in 2002.

What Tristan said - I recently was suprized to learn that while epoxy is curing at first it gets more runny, then it gets thicker as it hardens.