Need an opinion - which is better? Left or right sock? The only difference is how it surrounds the tip. The left sample is tearing up a bit, but that’s probably because it was printed in cheap flexible material on a polyjet printer. My concern is that for newbies who are new to 3D printing, don’t take good care to keep their tips clean (we see this a lot with gunky tips) and therefore, my concern is that the left sock will tear off or get pulled off more easily than the right one because the silicone sock is closer to the tip. Opinions?
@Whosa_whatsis watcha think?
I like the one on the right cleaner lines
@Alex_Krause What do you mean by cleaner lines?
Looks more refined the radius is nice and crisp. And doesn’t look as if it’s stretched over the nozzle. But at the end of the day I would take the one that preforms the best over the one with more aesthetic appeal
It’s more important for the one on the left to fit snugly and not slip down. Also, the one on the right is probably easier to clean if it does get messy. For my purposes, I’d prefer the one on the right, but I’m not a typical case.
They both fit snugly. The only difference is that the one on the left, the hole is a bit smaller so that it wraps around tighter. Whereas the one on the right, it’s simply a perfect fit and doesn’t stretch around the brass tip. The E3D socks stretch around the nozzle on the other hand, but that’s to conform to different sizes I think.
My only concern is that because this is 1mm thick silicone, it will rip more easily if stretch like it’s currently happening on the left one.
Btw @Whosa_whatsis the only reason the one on the right looks like it slipped down is because the heat break is shorter. It has an older heat beak design.
Is insulating / blocking air from the heat break a good thing or a bad thing? does it make a difference? I would rather have the one on the right, since it is less likely to snag.
You don’t want tension on the silicone. It loses tensile strength and can start to tear when it gets hot. An air gap between the silicone and the heater also makes it a more effective insulator. You also have an exposed heater and your sensor in the nozzle, so the surface of the silicone will actually get hotter than your temperature setpoint if it’s touching.
Right one it is. Will have several thousand socks in a month 
I would consider the one under tension might be less likely to get caught on something. If under less tension, I would expect that any forces acting upon the silicone would impart more deformation than if the silicone is already under some tension of its own. Thing is, I can’t be for sure. The only way to know for sure is to test it.
As far as looks go, I prefer the one on the left. After watching a christmas tree print this week that had the little strands of filament go out to mid air and loop back – I realized how much heat was actually injected into the small little strand as it looped back around. This was with an uninsulated nozzle, and I’d really like to try again with an insulated one to see if it comes out a little fuller than when it first got printed.
@ThantiK Yeah the left one is better, but since the sock is so thin (1mm wall thickness), it will get pulled down if the hole in the silicone is smaller than the nozzle. My concern is newbies don’t take this into consideration, and won’t pay attention to push it down onto the nozzle so it expands around it.
If the objective is to keep nozzles clean, wouldn’t the exposed nozzle be subject to collecting plastic anyway? The E3D nozzle sock covers all of the nozzle save a tiny bit of the tip.
The one on the left looks like it wasn’t manufactured to spec in my opinion. Obviously it was but if I was a consumer and saw that the hole didn’t perfectly fit my nozzle I would consider it a manufacturing side problem rather than a design element
the right one. All what @Whosa_whatsis said. + Don’t tear it. If the nozzle gets dirty, you are overextruding. I don’t like the e3d-cover, imho it is a bad design.
I would try to cover the metallic contact as well: the reason is it can be easy to fumble around the hot-end with a metallic accessory (let’s say a small plier or tongs). A short is very easy to happen in those cases. Covering the contact would help to prevent such a situation…
@Michael_Memeteau Given the design, I think it’s probably more likely to be an allen wrench slipping while trying to reach that set screw. Hopefully, people will be smart enough not to do that while the heater is on, but I recently lost the little bit of faith I had left in the intelligence of the general public.
Initially we designed it to use a set screw but we assemble them without a set screw now.