Hi everyone, My name is Chuck and I live in Austin, Texas. I am a software engineer during the day and a mad entrepreneur by night. I have been doing embedded software development for about 20 years. My question(s) is(are) a little vague at this point. I am designing a largish corexy printer. I am tired of fiddling with my little (cheap Chinese) Prusa i3 clone. I want to build a printer that will deliver consistent professional quality without having to mess around with it all of the time. (welded aluminum frame) I am thinking about a 400mm cube of build volume with the gantry moving for the Z axis, rather than the bed. The Z height will be set by adjusting the homing switch. That makes sense to me because even though the Z will be heavier, the weight will be predictable and that seems better. The build volume should be scaleable to around 600mm, simply by changing the length of a few key parts. I will probably use a Smoothyboard for the electronics and an external MOSFET or SSRs for the hot end. I am planning to develop a controller that looks more like a CNC with external motor drivers. I also want to print fast. As fast as is practical. So, my question is (finally) what print head should I be looking at? I am thinking of a bowden configuration more than direct to lighten the gantry. What print speeds are even possible? Should I expect really dramatic improvements in speed? What about 3mm filament? Does that help speed with a .4mm nozzle? Or is it more for a larger nozzle? I have a lot more questions, but I guess I should stop there. Any observations or advise would be much appreciated.