Let me put some context. I want to use my 350 to print Carbon Reinforced PETG, in order to do that I have to be able to reach around 260 Degrees, a bit more if I have to use a hardened steel nozzle to manage the wear.
As you may know, PTFE starts to degrade and generate toxic fumes around 240-260 degrees. In the Snapmaker 2, we have a PTFE lined hotend, that means that there is a PTFE tube that gets up to the nozzle, thus I needed an all-metal hotend to avoid the problems of PTFE degradation.
In terms of nozzles, the Snapmaker 2 supports MK8 nozzles which are very common and easy to find in various types: brass, steel, hardened steel, titanium and copper plated. I’ve found one that looks especially interesting as it’s a copper-plated nozzle that can support carbon fibre , so I’m going to use this one as it improves thermal performance respect to brass and it’s close to hardened steel in terms of wear resistance, awesome
Now the tough part, the heatbreak. The heatbreak on the Snapmaker 2 is a custom one, but after taking some measurements, I realized it has an M6 thread for the nozzle and a non-threaded 6 mm type on the heatsink side. This is also a size supported on the MK8 heatbreaks, but quite difficult to find. I’ve been able to find some steel heatbreaks which can be compatible ( titanium would be better but could not find the available in all metal ). I’ve ordered them and this how they look like besides the standard SnapMaker 2 heatbreak:
Mechanically speaking, they fit nicely and are fully compatible. The screw in the Snapmaker 2 heatblock and in the heatsink. This is how it looks with the copper-plated nozzle and the Snapmaker 2 heatblock:
And this is how it compares to the stock hotend:
And the final picture inside the Printhead
The great question here is: how does it perform?
In order to test it, I’ve done some measurements, just changing the heatbreak ( so keeping the brass nozzle in both cases). I’ve attached 4 thermocouples to the hotend: 1 to the heatblock, 1 to the nozzle, 1 to the exterior of the heatbreak and one inside the heatbreak. I’ve also done the testing outside the printhead, so the works possible conditions. Then I’ve used
- M104 S100 - Set Temp at 100 Deg C
- M105 - Read Temp from FW (This has variability as the thermistor can move around between tests, that’s why I also measure directly the temperature in the heat block and nozzle)
and wait 5 min after reaching the target temperature. The results are:
- FW Temp: 100 Deg C
- Heatblock: 108 Deg C
- Nozzle: 105 Deg C
- Heatbreak: Inside 62 Deg C / Outside 53 Deg C
so we have a delta T between heatblock and inside the heatbreak around 46 deg.
- FW Temp: 100 Deg C
- Heatblock: 102 Deg C
- Nozzle: 102 Deg C
- Heatbreak: Inside 66 Deg C / Outside 54 Deg C
so we have a delta T between heatblock and inside the heatbreak around 36 deg, which is 10 Deg C worse than with PTFE, but comparable. In order to minimize the heat-creep, I would suggest to use a very good thermal paste on the heatbreak and heatsink interface. A very good one that hols up to 350 Deg C is Thermal Grizzly Kryonaut..
As soon as I can setup again my 350, I’ll try to do some testing and report back.
@Atom, I hope this is inline on what you were looking for