Im looking to buy a all metal hotend for my printer. The v6 looks like a good option. However i can see no clear answer to whether or not the 1.75 bowden version has the ptfe passing all the way through the heatsink. If it does, is it still safe to print at high temperatures quoted? Or are the quoted figures for the 3mm version without the ptfe passing through? Thank you.
I have no connection with e3d other than being a customer, so this is NOT a response from e3d The highest temperature I've personally printed with is 285, and I've used both a 3mm and a few 1.75mm v6's. I now use 1.75mm exclusively. The PTFE liner is inside the heatsink, which should always be cool enough to touch - if it gets hot then there is something wrong. To quote from the description "The PTFE filament guide inside the V6 HotEnd is never subjected to high temperatures, so there is no risk of damage through overheating." My understanding and belief is that the figures quoted apply to all v6 variants. Hopefully someone from e3d will confirm Hope that helps John
I go to 285C on a regular basis. The Teflon liner only goes about 32 mm into the heatsink where it butts against the heatbreak. If you want to really bulletproof the system you can replace the stainless heatbreak with a titanium one. E3D used a stainless heatbreak because stainless steels are generally poor thermal conductors compared to other steels. It helps keep heat in the hot-end and reduces the amount of leaked heat the heatsink has to dissipate. Your common titanium alloys are ever poorer thermal conductors. I don't know what E3D makes their heatbreaks from, but a quick comparison of two of the most common alloys shows my point. At room temperature, 304 stainless (aka A2 SS) has a thermal conductivity of 16 W/(mK) while Grade 5 titanium (Ti-6Al-4V) is just 6.8 W/(mK). Values will change as the heatbreak warms up.
The PTFE goes to the top of the heatbreak inside the heatsink. At this point, the heatbreak is cold enough not to affect the PTFE. This is designed to reduce the friction on the filament. We regularly go over 400°C without any issues, you just need to make sure you change your thermistor and block if you go above 300°C, and replace them with a PT100 and a copper block.