Changing hot end tips  

RE: Changing hot end tips

The main limitation to keep in mind is the maximum volumetric rate that your hotend can handle. This will vary depending on the heating capacity of the hotend, the nozzle mounted and the specific filament and settings being used to print. In general, a safe value for a Mk3 with an E3D V6 hotend with a 0.4mm nozzle mounted and printing PLA is around 11.5mm^3/s. This maximum flow rate -- referred to as Maximum volumetric speed (MVS) in PrusaSlicer (in Filament and Print Settings) -- is based on Layer Height X Extrusion Width X Speed. Exceed this rate and you may experience extruder clicks and jams. 

At smaller layer heights or narrower extrusion widths, you can move faster. Conversely, at larger layer heights and wider extrusion widths, you'll want to slow down. Fortunately for us, PrusaSlicer will do the calculation based on the MVS values we enter. The more restrictive of the value entered under filament or print settings will apply. If you set a good MVS value, PrusaSlicer will move at speeds up to those you specifically set, but will apply a throttle when and only if needed to stay within the specified MVS.

Things that can affect your rates:

• Extruder speed limit (only for very high speeds).
• Hotend type (Mk3 is E3D V6).
• Heatbreak and heater block composition (e.g. aluminum or copper).
• Nozzle size and composition (e.g. size, brass, steel or copper).
• Filament type and composition. (e.g. PLA, PETG, filled).
• Print temperatures.

If you want to calibrate your maximum extrusion rates, I have notes on the procedure I use here. I've got more notes on changing nozzles on the Mk3 here that might also be helpful.