1. Smaller melt zone.
All metal has a smaller melt zone because the cool side of the thermal barrier is way cooler due to the threads’ surface area being able to effectively dissipate heat to the cooling bar. You get better retraction and less or no oozing. There would also be huge benefits to this while dual extruding.
2. Higher temps for different materials.
Another benefit is that your printing temperatures won’t be limited by the ptfe liner which is usually only 240C, so you won’t be able to print nylon or polycarbonate or other higher-temp plastics should you have a need to in the future. There are other ingredients in the ptfe itself however, that slowly degrade at even lower temperatures than that, creating a health hazard. This degradation will also change the properties of the ptfe which is why you have to replace them all the time.
3. Exotic filaments (flexible/bronze/stainless/copper/wood)
If you’re not running all metal, you might have trouble printing exotic filaments, and many are abrasive and wear out your ptfe quickly.
4. Less maintenance.
You will constantly have to change the ptfe tube. The ptfe tube extends all the way inside the nozzle, so when replacing, it will be almost impossible to tighten the nozzle just the right amount so that it doesn’t push on the ptfe tube and bend it too much but still make a seal. When the ptfe tube bends from tightening there will be parts of the ptfe tube that won’t be touching the inside of the thermal barrier wall, creating areas in the hotend that have different temperatures. The result is some of the plastic will be at a liquid temperature and other parts will be cold and not print right or eventually jam.
Even if you install it properly by tightening it the perfect amount, and also cut the new ptfe tube perfectly and evenly, it is too hot inside the thermal barrier in the area where it is supposed to be cool, so you have a large transition zone and large melt zone. This is not good for retraction.
The thermal barrier tubes that work are internally stepped, and the step allows the bot to control the plastic meniscus more precisely, and never jam if installed properly. So instead of a huge hot mess inside the entire length of the thermal barrier it works as it should; with a cold zone and a hot zone. You also have to apply thermal paste to the cold side of the thermal barrier as well as where the cooling bar touches the heat sinks, but not in the hotend side of the thermal barrier (there is a heat break separating the hot and cold sides). Non-stepped threaded thermal barriers (one smooth diameter hole the entire length) don’t work and make solid nightmare jams.
This doesn’t mean that it won’t work right with the ptfe tube, as you can get some pretty nice prints, but it will still jam eventually. Some people get lucky and never get jams, but more people experience jams than not. For example, when I had a ptfe tube there was a moment in time where it printed perfectly and wouldn’t jam no matter what temperature or settings I used, and I was ecstatic but it eventually started jamming again. With the all metal set up it’s not going to jam; if you lower the temp during a print the plastic will just harden in the hotend and stop printing, but it won’t be a jam you can just increase the temperature and watch the plastic start flowing again.
