Both Devcon and JB Weld are very good products for most general repairs.
There are times, though, that I've had to bring out the "big gun".
I've had excellent service using Pig Putty on a couple of pretty darn critical applications.
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PIG® Concrete Repair Putty
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Sets rock hard and looks like concrete, too!
PIG® Concrete Repair Putty Pre-measured, 2-part epoxy-eliminates the guesswork when mixing. Working time of 4 minutes-cures in 60 minutes. Can be drilled, sanded, sawed, carved, stained or painted.
Additional Specifications
dielectric strength : 300 volts/mil (11.7 kv/mm) @ 0.125" (3.2 mm)
shelf life : Min 24 months at 75 F (24 C)
work life, minutes : 4-7
hardness (shore D) : 75-85
compression strength : 12,000 psi (83 mPa)
temp continuous : 250 F (121 C)
temp intermittent : 300 F (149 C)
shrinkage : Less than 1% <HR></BLOCKQUOTE>
I've used it to shim a couple of machinery shafts, repair a bearing seat for a high-temp oil pump. I can't forget patching the crankcase of a racing motorcycle when the chain snapped and smacked a hole into the case near the countershaft sprocket. The bike survived two more 6 hour endurance races, as well as a 12 hour. Only when a rider augered in but good did the bike be parted out.
Also, I actually repaired the nose of the crankshaft and keyway when the crank sprocket went "Tango Uniform". 63,000 miles so far, and you'd never known that the engine almost suffered a catastrophic failure.