> trying to epoxy but may be too cold in garage. what is the corect temp
> range for proper cure? i had 2 scarfs come apart partially.

If and only if it is metered and mixed properly, ambient temperature governs the speed of the reaction. You could put it in a freezer for a year and it wouldn't gel, but once you take it out and warm it up it will continue to cure, unlike polyesters and most other catalyzed reactions. Manufacturers' specifications are usually given for 77 degrees F. 18 degrees cooler will double the reaction time for the same thermal mass, and 18 degrees warmer will halve it. The gel time given is for a fairly large mass though, frequently 500 grams. The cure reaction is exothermic, that is it generates its own heat. So, the larger the mass, the more heat is generated, and the faster it gels. Spread that same mass over a large area however, and it can give up its heat to air, wood, or whatever it contacts, and it stays cooler, taking longer to gel. In a scarf joint, the glue line is very thin, and so takes longer to cure. It's just a matter of leaving the piece clamped longer.

Make sure you have the correct ratio of resin to hardener, and complete mixing. Make a mixing tool with 4 screws sticking out of a piece of dowel, and chuck it up in a variable speed drill. Mix at low speed for 2 minutes, scraping the sides of the container twice during that period. Incomplete metering and mixing will cause the problem you describe far more commonly than low ambient temperature. Try it again and see if that doesn't fix it.