Going to call out bad design choices, specifically around simple nozzles.
Working my way down the learning curve. Ordered a set of various nozzle sizes, as all my printing in the last year has been with 0.4mm nozzles.Specifically, wanted to experiment with larger (0.8mm) nozzles.
The set ordered:
The good news, the M6 threads match. The odd news, the hexagonal face is 7mm instead of 8mm. Bothersome - the “shoulder” around the orifice is narrower.
On very little basis, I propose a standard for nozzles. For 1.75mm filament, an M6 thread on the nozzle seems sufficient.
We need a standardized shoulder around the orifice to have predictable characteristics. I suspect we need a shoulder roughly of the size of the orifice. The shoulder forces the vertical dimension of the extruded plastic, and transfers thermal energy.
I recommend an 8mm hexagonal outer face for nozzles, as this allows for substantial shoulders on larger nozzles, while keeping the same vertical dimension.
In the reviews of the DeltaPrintr Mini, noted the recess on each nozzle face for a thermistor. Only logical the thermistor placement should be as close as possible to the point where plastic is extruded.
To be clear, I think the family of E3D inspired hot-ends are excellent if you are satisfied with slow, stately, majestic rates of extrusion. The large thermal mass evens and somewhat mitigates changes from varying rates of extrusion. Placing the thermistor embedded in the thermal mass, opposite the zone where plastic heats, means the over-taxed 8-bit controller will less bothered by varying rates of extrusion. (Never-mind the temperature variations in the extruded plastic.)
But if you want performance, you want to better know the actual temperature, in the instant. That means measuring at the closest point. That means allowing for a thermistor in the nozzle.
So … as standard, an M6 thread, an 8mm outer hexagon, a shoulder equal to the orifice, a fixed vertical distance between mount and nozzle-end, and allowance for a thermistor in the nozzle. Outfits meeting (or not) the community standard should be named (or shamed).
Substantial arguments welcomed.