I’m not sure how the rest of you are bending outer stems, but here are a couple photos of how I do it. I have a 2x4 with a hole angled back that accepts the stem and compression strap clamped to the deck. The compression strap is actually a carpet strip made of aluminum with holes in it to accept screws. I bent the end over at 90 degrees and attach it to the top of the stem on the top end with a small screw or ring mail and a clamp holding the strap to the bottom end. The whole thing goes into the steamer. When it comes out of the steamer the end with the 90 goes in the hole in the 2x4. The bend is then started and screws similar to drywall screws are driven through the outer stem into the inner stem.