This is a fully reversible modification to the Creality hot end that eliminates the known issue of the PTFE tube slipping in the Bowden fitting allowing a small gap to form between the end of the tube and the back of the nozzle. This is the most common cause of partial or under extrusion.
This mod takes a short length of your stock PTFE tube and traps it in the heat break so it is impossible for the gap to form. Nozzle changes can be done exactly as before, and by using higher performance tubing allows the stock hotend to reliably print at higher temperatures.
Due to the low temperatures at the top of the heatsink, PLA is perfectly adequate for the spacer.
Image 1: Shows everything you will need. The stock hotend with the Bowden fitting removed. A piece of PTFE tube. The spacer.
Image 2: Push the tube into the hotend, right down to the nozzle. Mark the top of the heatsink on the tube. Note that the end of the tube contacting the nozzle must be flat and square for an effective seal to be produced.
Image 3: Use the threaded potion of the Bowden fitting to gauge a further mark towards the nozzle end of the tube. Cut the tube at this new mark using a sharp knife.
Image 4: Fit the spacer over the freshly cut end of the tube.
Image 5: Insert the tube and spacer into the hotend.
Image 6: Screw the fitting into the top of the heatsink finger tight only. Any tighter and you could deform the tube causing it to pinch the filament. For peace of mind you could use a drop of Loctite on the fitting threads, but initial testing indicates that this may not be necessary.
Fit the hotend and attach the Bowden as usual.
This is a prototype modification, and while it does work I would appreciate any feedback or reports of any long term issues.
Please note, if has been brought to my attention that there may well be a number of different heat sink designs from Creality out there, and that some may have insufficient distance from the top of the heat break to fit the spacer and be able to screw the fitting in sufficiently. You should be able to get the fitting screwed into the heat sink a good 5mm. Any less is likely to cause issues.
Please also take a look at the work of Luke Hatfield, who has developed something similar. Choice is good!