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I need help with finding what properties or designs I need to look for. I know that I will need these characteristics to work with the material of my choice:

  • Can reach 300 °C or up
  • Can handle nozzle size larger than 1 mm
  • Can be used with polycarbonate filament

I plan to use it in a custom RAMPS 1.4 3D printer running the Marlin firmware, in case this changes something.

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  • $\begingroup$ Welcome to the Stack! please take the tour. While the Stack as a Q&A site handles various ways to deal with problems, it is not a recommendation platform, and indeed, recommendations are something we don't deal with at all. $\endgroup$
    – Trish
    Sep 2 '18 at 8:19
  • $\begingroup$ A suitable question would be if a specific hotend would suit your application, or something related to the technology (such as thermistor type). This is a little bit too subjective/open to attracting spam posts. $\endgroup$ Sep 2 '18 at 9:31
  • $\begingroup$ Rephrased question slightly, in an attempt to (hopefully) remove the fishing/shopping vibe. $\endgroup$
    – Greenonline
    Sep 3 '18 at 6:43
  • $\begingroup$ With the rework of Greenonline and mine it is a technical question. $\endgroup$
    – Trish
    Sep 3 '18 at 11:20
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Handling a 1mm nozzle implies a desire to reduce the overall print time (otherwise why use a large nozzle), so you will need to consider not only the maximum operating temperature but also the rate at which plastic can be melted. (See also this question and one on overheating to compensate)

Using 1.75mm filament is a good start, this has a better surface area to volume ratio, but you're likely to see issues with both the heater cartridge power (so a 40W heater is probably going to help), but also the size of the melt zone and the thermal mass of the heater block.

As you need to push a reasonably large amount of heat from the cartridge to the filament, it is important to minimise the thermal resistance - so using a steel nozzle would be a disadvantage here (but since polycarbonate is abrasive, you will need to consider wear resistance as part of your trade-offs). You can get longer nozzles and larger heat blocks designed to work better in high flow applications.

Also remember that your extruder needs to work 6 times faster to achieve the same linear speed compared to a 0.4mm nozzle (with at least as much pressure), so this also might need to be upgraded (or driven a little harder).

If you can however tolerate a somewhat slower print speed, you might not need to reach 300°C to print PC.

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  • $\begingroup$ On a side note: PC is a very abrasive material, he might want to look for a very tough nozzle, probably even with a trigonal Di-aluminium-tri-oxide crystal - the red variety of Corundum is available as far as I reckon. $\endgroup$
    – Trish
    Sep 3 '18 at 11:19
  • $\begingroup$ I guessed that part of the question might have some significance - thanks. $\endgroup$ Sep 3 '18 at 11:21
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    $\begingroup$ @SeanHoulihane Using a large nozzle does not imply printing faster in terms of mm/sec of the head movement. Actually you should reduce the printing speed, like you already explained, the throughput of the filament is way larger which may not be kept in pace by the heater cartridge. However, the overall print may be printed faster as the layer thickness will also be larger and generally less perimeters are needed. $\endgroup$
    – 0scar
    Sep 3 '18 at 11:31
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By interpreting your question as "Can most hotends print polycarbonate at 300°C+?", and taking into consideration the answers to Can cheap hotend parts sourced from China actually produce good prints?1, then it would seem to be safe to assume2 that most hotends can, given a few adjustments or considerations:

  • Use of a PT1003 or thermocouple, en lieu of a thermistor
  • Use of PTFE tubing

Taken directly from E3D's V6 product info:

The V6 can comfortably reach 285°C with the supplied thermistor. By swapping a thermistor for a thermocouple (may require additional electronics) or PT100 you can reach over 400°C. This not only allows you to print extremely high temperature materials like Polycarbonate and Nylons but also eliminates HotEnd meltdown failures associated with PEEK/PTFE designs. The PTFE filament guide inside the V6 HotEnd is never subjected to high temperatures, so there is no risk of damage through overheating.


Footnotes

1 The materials used by cheaper clones of the higher quality, more expensive, branded hotends are probably the same as those used in the branded hotends, and indeed are probably produced using the same pirated patterns/molds/casts, but with less care and quality involved. They can even be produced in the same factory, but are items that have failed the QA tests, and as such are not deemed to be brandable.

2 Although, to paraphrase a quote from a movie: Assumptions can be considered to be the mother of all disasters.

3 A Pt100 or Pt1000 is a Platinum RTD (Resistance Temperature Detector) with a resistance of 100 ohms at 0°C which changes with temperature. From this manufacturer's website:

A Pt100 or Pt1000 is a Platinum RTD (Resistance Temperature Detector) with a resistance of 100 ohms at 0°C which changes with temperature. They are suitable for applications in the temperature range of -200°C to 600°C but are more commonly used in the range -50°C to +250°C. These temperature sensors are reliable and can offer a higher degree of accuracy.

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    $\begingroup$ I think this is misleading with regard to the PTFE. The design of the V6 has PTFE as a guide up to the middle of the cold side, not extending through the throat. This means that the PTFE does not need to be 'good', it simply isn't stressed. $\endgroup$ Sep 3 '18 at 10:13
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    $\begingroup$ Also, a 300°C at 1mm diameter might demand a different (stronger) Heater block - Volcano style or even a double-heater-cartridge design might be interesting. $\endgroup$
    – Trish
    Sep 3 '18 at 11:13

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