In the morning I mixed up some 30 minute zpoxy and installed the motor mount in my Loc Lil Ditter. An hour later, the epoxy that was left in the mixing cup was hard and the motor mount was securely installed. Later in the day I mixed up more epoxy for a fillet for the top centering ring inside the body tube. Twelve hours later, the epoxy never hardened. The next day I mixed up a test batch and it hardened after an hour and a half. I was able to remove the uncured epoxy using dowels, sticks, rags, paper towels and alcohol. What could I have done wrong when I mixed the epoxy for the CR fillet? I have been using epoxy for mid and HP rockets for 15 years. Technique: When using a dowel or stick to apply epoxy down a body tube, I roll up some paper from my printer to make a tube that I insert into the body tube. This prevents me from dripping epoxy inside the tube. Plus the white paper reflects light which makes it easier to see what you are doing down the body tube.