This was a new one.
I’d just replaced nozzle and wasn’t surprised to find nozzle leaking. Have had that happen before. Haven’t had heat break leak before.
Completely filled in the silicone sleeve and encased the wires and thermistor. Fortunately didn’t do any damage to any other parts.
-S
Oof. Sorry to see that.
It’s been sometime since I’ve reassembled hotends and I previously did it cold, but I’ve seen recommendations it’s better to do it hot (to account for thermal expansion). Would you mind sharing if you assembled it hot or cold?
I took off the old nozzle when hot. I’ve tried to do them when cold but haven’t been able to get them to budge. Threaded nozzle when cold and then tried to finish tightening when hot.
I don’t really like doing them when they’re in the head. Feel like I’m putting a lot of torque on it and the hot end usually starts to turn but I can’t get it tight enough if it’s cold. I’m not sure if there was some filament in the way that kept it from getting a good seal. Is there something I should be doing to clean the seat before I install the nozzle?
-S
On the spare hot end I received, there’s a 45° bevel cut at the mouth of the threads on both sides of the heater body. On the nozzle side, there are six little gaps at each of the flats that can leak material. This is defective-as-manufactured. I’m guessing the bevel is there for deburring, but it’s the wrong way to deburr when the tolerances are so close.
As a correction for this defect, I’d recommend a washer made out of brass shim stock. You want something that can deform into the bevel recess. This is a crush washer whose lifetime is one tightening. When you take off the nozzle, replace the washer. There might be other ways to fix this, but this seems reasonably expedient.
Making washers is a bit tricky. The center hole should be punched to 5 mm. Then you want a 0.5 mm nick in the interior diameter so that the washer will rotate onto and past the threads. Punching the hole can be done with a small length of 5 mm drill wire ground flat on one end and a 5 mm hole into something moderately hard like, say, oak or maple or aluminum. You might be get an adequate result punching with the drill bit itself. The outside is far less critical and could be cut by hand or punched out with a circle punch as is used in leatherwork.
