Master Builders!

I've been building some practice frames and after getting the front triangle all brazed up I noticed that the HT angle changed. The first one changed by 0.7 degrees from 72* to 72.7*. The second changed from 72* to 72.5*. Both frames had extremely tight miters and the alignment was spot on after tacking as well. I've not encountered this before in any of my previous frames to date and I'm racking my brain trying to figure out how this happened. My current thought is that either I'm not using enough heat, and because of this I'm spending too much time brazing the HT/DT joint, or, I'm using too much heat.

I start at the DT/HT joint and braze 90* around the joint, then move to the opposite 90 diagonally across, then the third 90, and finally the last.

I've timed myself and I'm sitting around 5 minutes per joint, but due to the extra bronze on the underside of the DT/HT, I'm at about 8 minutes at this joint. That needs to come down no doubt.

What exactly could be happening to cause that much movement?

Any and all thoughts and advice is welcomed.

Thanks.

Brandon