Looking for 1.75mm nozzle with 1.85mm input diameter

I like to print with a nozzle (M6 threaded) with an output diameter of 0.3mm. All the nozzles I have, have an input diameter of 2.00mm. Some manufacturers or sellers have full specifications (CAD) and state 2.0mm for the input diameter while most other manufacturers or sellers just state the thread and the output diameter without any CAD drawing.

Do you know a manufacturer or seller, who offers input diameters smaller than 2.00mm? I think 1.85mm would be ideal. Output can be 0.3mm or 0.4mm.

Background: I have printing issues which I relate to dynamic under-extrusion. The area difference between 2.00mm and 1.75mm is +31%. When printing fast (i.e. infill, 80mm/s), the filament is pushed though the output nozzle quickly and hardly expands in width. But when after fast printing slow printing occurs (i.e. perimeter, 30mm/s) the filament in the 10mm long nozzle has time to expand and instead of being fully extruded it partially melts and expands inside the 10mm long nozzle which leads to under-extrusion. If I select same printing speed for all features, the issues disappear. To test my hypothesis I need a nozzle without a massive over-clearance (+0.25mm) of the input diameter.

Edited 1 time(s). Last edit at 10/22/2018 07:44AM by lukie80.

The Merlin Hotend comes with an input diameter of 1.8mm. you can use 0.2, 0.3 and 0.5 mm nozzles with it.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Thanks for your information. I have nozzles with a M6 thread (e3d, ultimaker) so I'll have to find an M6 to M1.7 adapter with an inner diameter of 1.8mm or get the whole marlin hotend and adapt my extruder around it..

I made a heatbreak drilled to 1.8mm instead of 2 but often experienced blocking due to retraction and gave up.
A M6 M1.75 adapter ?, you will need to make one. M1.7 taps break easily

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Quote
MKSA
I made a heatbreak drilled to 1.8mm instead of 2 but often experienced blocking due to retraction and gave up.
A M6 M1.75 adapter ?, you will need to make one. M1.7 taps break easily

Thanks for the tip. I assume 1.8mm in the nozzle should be OK, because filament will melt on contact. Indeed, I was not aware how small the airbrush nozzles are. The adapter would have to have an external M6 thread and an internal M1.7 thread.

Keep in mind the M1.7 needs a 1.35 (nominal diam minus pitch) hole.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Usually the thread for the M1.7 threaded nozzles are cut slightly under diameter to ensure a tight fit. Threads that were done to specs can lead to the tip becoming unwound and dropping out.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]