1
$\begingroup$

I have an Ender 3, currently in stock Bowden extruder configuration.

I want to be able to print nylon and TPU, both of which require temperature too high for the tolerance of the PTFE Bowden tube (as well as the issues with the flexible filament in the tube).

Therefore, I've considered converting my printer to direct drive. However, the conversions I've seen, both DIY/print the parts type and commercial, seem to include a short length of the same PTFE tube between the extruder (now mounted on the hot end carriage) and the actual hot end. This same material ought to have the same temperature limit (about 250 C) as it would have in a Bowden configuration -- and for nylon, at the least, this is a problem, since the PTFE would start to soften from contact with the heat break.

Am I missing something in these conversions, or is the PTFE's glass transition not the limiting factor in printing hotter with a direct drive conversion?

$\endgroup$
3
  • $\begingroup$ TPU does not need more than 250°C, which is ok with stock hotend. No need of all metal hotend. Nylon, depending on the brand and blend, also can be printed at 250°C just fine. What you need is an enclosed chamber for it! $\endgroup$
    – FarO
    Jun 9 at 21:42
  • $\begingroup$ @FarO Please elaborate -- perhaps in an answer, not a comment, since this sounds like a frame challenge. What's an "enclosed chamber" in this context? $\endgroup$
    – Zeiss Ikon
    Jun 9 at 23:47
  • $\begingroup$ @FarO Oh, it just came to me -- you're talking about a printer enclosure, to prevent premature cooling of the part as it prints (presumably to limit warping). $\endgroup$
    – Zeiss Ikon
    Jun 10 at 0:09
2
$\begingroup$

Direct Drive v.s. Bowden has no relation to the maximum print temperature. What determines the maximum print temperature is the design of the hotend itself. There are "all-metal" designs, where the PTFE tube (Bowden or not) stops in the cold zone and the heatbreak and all other components that get hot are fully made of metal. Other hotend designs have the PTFE tube run all the way down into the hot zone and this limits the maximum printing temperature. It has nothing to do with whether the hotend is Bowden or not.

$\endgroup$
5
  • $\begingroup$ So, do I need a direct drive extruder for nylon and TPU, or do I need an all metal hot end, or both? $\endgroup$
    – Zeiss Ikon
    Jun 9 at 23:49
  • $\begingroup$ @ZeissIkon: For TPU you absolutely don't need an allmetal hotend (print temperatures are in the same range as PLA or slightly higher) and you don't need a direct drive, but it helps a lot; with a bowden you'll be stuck going really, really slow. For nylon, some variants can be printed at low enough temperature not to need an all-metal hotend, but you'll be limited to those. Bowden vs direct drive should not matter for nylon any more than it does for other non-flex materials. (Direct drive is always better, but not essential.) $\endgroup$ Jun 10 at 1:50
  • $\begingroup$ Direct drive may not be needed for 98A or 95A TPU, but anything floppier than that will either require ridiculously slow print speeds or a direct drive. I printed nylon on a 60 cm Bowden drive and it works. $\endgroup$
    – FarO
    Jun 10 at 7:17
  • 1
    $\begingroup$ So I need direct drive to print very soft TPU (for things like gaskets) at reasonable speed, but for nylon not specifically formulated to minimize print temperature, I need an all metal hot end, not direct drive. Looks like I get to spend some money before printing nylon. $\endgroup$
    – Zeiss Ikon
    Jun 10 at 11:06
  • 1
    $\begingroup$ @ZeissIkon Exactly. However Polymaker Copa, Fillamentum Nylon FX256 and Formfutura STYX-12 Nylon will print easily at 250 °C, or even less. Copa is tested by Polymaker when printed at 240 °C, for example (see datasheet). $\endgroup$
    – FarO
    Jun 10 at 14:44
1
$\begingroup$

Bowden tubes extending to the nozzle to make a seal will damage the Teflon (PTFE) tube if exceeding 250°C for an extended time. An all-metal hotend for a Bowden would have either the nozzle sealed against the heatbreak or an integrated nozzle and heatbreak. Then the Bowden tube would attach with a minimum gape with either the heatbreak or heatsink.

Note: The heater block needs to be at the maximum operating temperature When making a seal between the nozzle and heatbreak.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.