The metal bar is essential - the heated nozzle just burns through otherwise.
You might see two inserts eitherside of the injection point, I have two m3 bolts going thru the metal bar into the two inserts. Lines things up for me.
I have this set up quite close to my freezer. So my routine for this has been: inject, leave for 1 minute in insitu, remove to the freezer for 1 minute then crack open.
I have had the injector and been trying things for the past few months. Each project has slightly different routines and needs different nursing strategies! Leaving the mould in-situ for this one gives me a better surface finish.
I did start off trying to use HT resin in the hope I would be able to inject Nylon, but I found HT resin is quite delicate. Even showing it the vice on the injector cracked it.
To use HT would definitely require an outer metal frame.
My injector is from Travin (here in the UK). Good solid 1950’s style British engineering for approx £1500…