Problem with all metal J-head V6 hotend

Just bought an all-metal V6 hotend (pictured), but cannot get it to print before it jams. Printing 1.75mm PLA into a 0.4mm extruder. I have the fan turned on constantly (Indeed, it would not extrude at all without the fan on. My guess is that the cooling fins got too hot and heated the PLA which made it soft and impossible to feed the filament). I was able to have some small success after turning the fan on, and could hand feed filament seemingly without a problem. However, when I bolt the extruder and assembly back together, I cannot get it to extrude for more than a few minutes before it jams. I disassemble it every time, but cannot find a consistent problem. I drill out the old plastic, clean it, and it will work again temporarily. Has anyone else had this issue or experience with this type of extruder? Thinking about going to another extruder with PTFE tube. I have had another extruder hooked up to this assembly and have had consistent extrusion, albeit poor prints (I didn't realize it was a 3mm extruder, and I am using 1.75 filament). Any advice greatly appreciated.

Well you answered your question the key here is it is made for 3 mm not 1.75 so either try some 3 mm filament or get the 1.75 version perhaps you can adapt it with a PTFE tube to make the barrel smaller I know they make both sizes best bet is to contact the actual makers of this hotend for a fix. The main purpose for all metal was to run hotter material like nylon whose temp would melt PTFE and to increase print speed.Feel free to correct me if wrong

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rwt

Hi Roger,
Possibly not clear in my original post, but I have had a 3mm extruder working, though not well, with the 1.75mm filament I am using. The current V6 extruder that I am using and trying to get working is indeed a 1.75mm extruder.

Scott