In my experience the issue is more commonly because the heat break is not threaded into the block far enough to begin with. What then happens is the nozzle bottoms out on the block before making contact with the heat break. You should think of the block as more of a coupler, and want the heat break and nozzle to press into each other within the block.
That is true, without a doubt. What I am saying is in addition to that.
Aluminum will expand more than brass when heated. There will be a gap created between the nozzle and the heat break when heat is applied. The block is a coupler, yes, but it is also a shrink fitting by default.
In my experience the issue is more commonly because the heat break is not threaded into the block far enough to begin with. What then happens is the nozzle bottoms out on the block before making contact with the heat break. You should think of the block as more of a coupler, and want the heat break and nozzle to press into each other within the block.
That is true, without a doubt. What I am saying is in addition to that.
Aluminum will expand more than brass when heated. There will be a gap created between the nozzle and the heat break when heat is applied. The block is a coupler, yes, but it is also a shrink fitting by default.
Thermal expansion is fun. ;)