I mentioned a little while ago when I did the post for my Lack enclosure that I'd do something on All Metal Hotends.
First of all for those that don't know most of the cheaper 3 printers come with hotend that has a PTFE Bowden tube all the way down to the heat block and nozzle.
[Image courtesy of Kodak]
An all-metal Hotend extends the heat break up the cooling block so that the PTFE isn't in contact with the hottest part of the heater block.
[Image courtesy of Kodak]
Standard hotends aren't a really big problem but they do suffer from a couple of issues. Firstly if the PTFE tube isn't tight against the back of the nozzle you get a small molten plastic plug developing which can cause under extrusion and blocked nozzles. Secondly, if your printing some filaments that require higher temperatures like ABS or nylon the PTFE will degrade above 240 degC and start to give off some potentially dangerous gasses.
The all-metal design moves the PTFE well into the cold area of the hotend so no issues there but they can suffer from heat creep where the metal end slowly heats up and the plastic filament starts to melt before it reaches the nozzle then blocks the hotend.
The way to get around this is to tweak the settings and reduce the amount of retraction, pulling the plastic back between print paths, and increasing the hotend temperature by a few degC but unfortunately, it doesn't always work out as I found. and it doesn't take much to cause enough drag on the filament that the extruder starts to skip and you get under extrusion on the print.
There are a couple of designs and makes like MicroSwiss, Slice Engineering and E3D who make complete all-metal hotends and these tend to cost almost as much as a complete budget 3D printer. Some eBay clones are a fraction of the cost but the quality can be very poor and it's a bit more hit and miss. The other option is you can get spare parts that let you convert the standard hotend to all metal by replacing the heat-break section.
I have tried a couple of both complete hotends from eBay and heat-breaks in stainless steel and titanium without a lot of success even when the prints seemed to start ok after a few hours heat creep would set in the hot end would block and the print would be ruined so I always ended up going back to a standard Bowden setup but that's an issue because I wanted to start printing ABS.
Well, all that has changed thanks to Slice Engineering. I have always wanted to try one of their Mosquito or CopperHead hotends but at almost the cost of my complete printer I have been rather put off by these high-end Hotends. However recently they have started selling a CopperHead heat-break that will fit the Creality Mk10 hotend and at £30 I decided to give it one last try. Unlike standard heatbreaks which are all one piece and made of the same material, the CopperHead is bimetal and made up of 2 copper sections one the threads into the heat block and the other that slides into the cool block with a very thin wall stainless tube joining the two. The idea behind it is the copper bits are to provide good heat transfer at both the hot and cold ends and the very thin wall of the joining tube provides good heat separation.
When it arrived from the States was really impressed with the finish and quality. The only small fly in the ointment was the diameter of the cool block that was fractionally too large but nothing that a 5/16 drill couldn't fix 😀. I also got some Boron Nitrade paste that they recommend to help the heat transfer and there is enough here to last me a lifetime.
Once the cool end block was drilled out to fit the Copper Head heat-break it was a simple hotend swap and we were ready for some test prints and sofar so good. No problems at all with heat creep even on a print that was over a day-long and the print quality has been great on a variety of filaments.
So are there any down sides with the Copper head? the slight difference in the size was a bit of a pain, to be honest, and the tube for heat-break looks very thin so you need to be careful fitting the nozzles I guess it would be easy to damage it. But that's about it overall I'm really pleased to have an all-metal hotend that I can finally print with and use the ABS for making stronger pints.