E3D V6 problem in Prusa MK3s
I have had my Prusa MK3 for years and upgraded it to a MK3S and it has performed flawlessly.
Recently I change the nozzle and subsequently had leakage problems. On searching the forum I see that many other people have had the same problem and many have hit the nail on the head as to what caused this.
The problem is that when tightening the nozzle against the thermal break while holding the thermal block with a spanner the heat sink turns before the nozzle tightens sufficiently against the heat break. What happens is that continually tightening the nozzle moves the heat block down untill the nozzle tightens against the heat block instead of the heat break. The actual tension that the nozzle has against the heatbreak is just the friction that the heatsink has clamped to the extruder body. Ideally the heatsink should have a flat side and the extruder body have the corresponding flat to stop the heatsink from rotating.
I carefully removed the hotend from the extruder and placed the the heatsink part into a vice. While heating the block with a hotair gun to make sure any residual filament in the thread was molten I screwed the block onto the heatbreak until only the heatbreak neck was visible and then tightened the nozzle to 2.5NM ( not 3 as was suggested in the manual) while holding the thermal block with a spanner. This promply stripped the thread in the thermal block at the thermal break end! When trying to remove the nozzle from the block it was so tight I could not remove it with a ring spanner and had to use the torque wrench to remove it. My torque wrench is a small one which can accurately set the low value required. It would seem that the suggested torque is way too high. The only reason people don't strip the thread is that the torque is actually limited by the heatsink to extruder body friction.
To overcome the lack of friction between the body and the heatsink I will have a go at gluing with superglue some 120 grit wet and dry arount half the heatsing neck. I will let you know how this went.
RE: E3D V6 problem in Prusa MK3s
Good luck. I feel for you. I used to hate changing the nozzle on my MK3S for that exact reason. As careful as I was, I always seemed to end up with slight leakage. If you ever get an MK4 I recommend tossing all of your old nozzles and only using the Nextruder nozzles that combine the nozzle and heatbreak. Nozzle changes are done at room temperature in a minute or two and there is no chance for leakage.
RE: E3D V6 problem in Prusa MK3s
It seems that integrated nozzle, heat break and heatsink are the way to go as I see other brands now doing that also.
Cheers
RE: E3D V6 problem in Prusa MK3s
I had upgraded my MK3S+ with a Revo6 hotend (because I hated the process for nozzle changes on the MK3xx) shortly before the MK4 was released. I was so happy with the print quality and the simplicity of the nozzle changes now that I did see no need to buy an upgrade to one of the Nextruder variants. If you are happy with the print quality, bed calibration and speed of your MK3S, a Revo6 is a much less expensive upgrade that eliminates the awkward process with the nozzle changes. The change is really without any tools there.
I bought a separate MK4, but I am still using my MK3S+ with the Revo6 and see nothing wrong with it.
RE: E3D V6 problem in Prusa MK3s
Hi, thanks for the information on the Revo6. I was not aware of this. It looks like a good solution for the MK3.
Cheers
RE: E3D V6 problem in Prusa MK3s
I have got a new heat block and after having removed the hotend from the extruder I used superglue to glue a 5mm strip of 120 grit wet and dry sandpaper to the neck of the hotend heatsink. I then fitted the new heat block to the heatsink and screwed the nozzle to the heatblock (cold) until it was firm and the sandpaper was to the front of the extruder with the heat block in its correct position. I also made sure that there was sufficient gap between the heatblock and the nozzle rim. After reinstalling the hotend I heated the hotend to 280deg C I held the heatblock with a wrench ( I made a custom one out of 3mm steel plate) and firmly tightened the nozzle with a 6 inch ring spanner. I folded up a small piece of paper and stuck it into the heatsink fins to ensure that it did not rotate. It seems that the sandpaper gave sufficient grip to ensure the heatsink did not rotate with a firm tightening of the nozzle.
I have since used the printer and have no filament ooze. It would seem that firm tightening of the nozzle is all that is require to ensure a leak free hotend. On no account should a torque wrench be used with the recommend 3NM of torque.
RE: E3D V6 problem in Prusa MK3s
Revo is the way to go.