My homemade e3d hotend is printing fine. But I retraction is a problem, I have notised that I cant pull out the fillament without first extruding 3-5mm. And theres a blob at the end of the fillament when it comes out. Any ideas?
My e3d is also homemade and I’ve got the same effect. I suppose it’s a tiny gap between the thermal break and the heat sink.
That blob is representative of a good pull. It should mean you cleaned the nozzle as well. The gap between heatbreak and heatsink is non critical however if there is a gap in the heater block between nozzle and heatbreak that will cause retraction problems. The end of the heatbreak should be turned on the lathe so that the end is perpendicular to the sides. Do not chamfer the inner edge of the heatbreak. Do chamfer the inner edge of the nozzle. If the heatbreak were chamfered it would cause an obstacle that would hinder retraction
I don’t know how closely you’ve followed the drawings so can’t tell for sure. Also unsure which version and diameter too. Post pictures and more info and I might be able to help. Looks like a direct (mendel90).
Problem is probably in the surface finish inside the heatbreak or thermal management of the heatbreak. Check your cooling. Get rid of burrs or blemishes inside of the heatbreak.
Chamfers are probably not relevant, particularly the ones between nozzle and heatbreak as the plastic is fully a fluid at that point. (Or at least or should be.). Getting the surfaces between the heatbreak and noozle that butt against each other flat and perpendicular is important for sealing, but not that big a deal with retraction. Do chamfer the entrance and exit of the heatbreak and the entrance to the nozzle. Getting things concentric is key.
Check your nozzle orifice length. This has a huge impact on retraction behaviour.
the blob is normal, it comes from the end pushing into the heated tip, and pulling on partially molten plastic.
Thx for the help all! I do have chamfers, maby I should remove them. My e3d is direkt drive (mendel90 correct Sanjay!) and its close to a v5, but with bigger cooling fins. The nozzle is a real e3d 0.4mm.
I only mentioned the chamfers because of issues with the metal magma and the fix that worked for me and many people who used the Trinity labs hotend. Also try seasoning it with kanola oil
BTW what type of filament? Pla by chance?
Ok D Rob thx for the help! Yes thats pla.
It’s quite normal, I have exactly the same on Replicator 2s always have to load for a moment before I unload if the hot-end is cold.
Yeah all metal and pla has been a real challenge for many. Abs will be a piece of cake for you. Reduce retraction speed and distance in your firmware. Then do a cold pull. Take the end of your filament trim it. Then dip it in canola oil. Heat the hot end to 190c push it in and extruded several inches. Cool to around 120c and do a cold pull. Heat to around 220c and sit a few minutes let the oil bake out. Repeat cycle. Best to pla temp and extrude to air until clean. Pla is a starch sugar base plastic. Think caramel in a pot. it tried to sick to pores oy abraded areas in the heatbreak. this causes retraction issues which leads to jams and stripped filament. Season a cast iron to prevent sticking. Same with the hotend.
Also this design requires a heatsink fan.