Questions about the new Bambu ObXidian HF Hotend

Bambu Filament and Accesories Accesories
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I am looking to purchase the new 0.4mm ObXidian form the Bambu store tomorrow when it is released to benefit from the discount but I do have some questions that I am unsure about and hoping anyone out there can help me so that I can decide what to do (sorry in advance for all the questions).

  1. I understand that the ObXidian allows for faster flow rate which in turn should mean faster print times. Realistically, how much of an increase in speed time am I likely to gain from the standard Bambu hot end? I’m mainly using PETG HF and PLA Matte at the moment.

  2. I previously purchased the Bambu 0.6mm and 0.2mm complete hot end kit when I purchased my P1S, is it necessary (or best practice) to purchase the complete ObXidian kit or can I purchase the hot end and connect swap out of my Bambu 0.4mm or even use a new fan from my other purchases?

  3. I upgraded my P1S with the hardened steel gear extruder, is that going to be an issue when using the ObXidian?

  4. Apart from E3D offering a 0.6mm version, is there any difference between the E3D 0.4mm version and the Bambu version?

  5. Similar to last question, E3D have ObXidian profiles on their website but I also see that Bambu have shared official Bambu tuned profiles halfway down the Bambu ObXidian store page. Does anyone know if they are the same profiles or different?

  6. Finally, for those who have the ObXidian, what’s the verdict, yay or nay? Worth getting the 0.4mm or should I hop over to E3D and get the 0.6mm for even faster print times?

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1.) I typically used flow rates around 20 mm³/s for most filaments on the Bambu 0,4mm hotend. When doing max flow tests in Orca, some filaments didn’t show any defects up to 45 mm³/s (i think e.g. PETG HF) and I didn’t bother to try any faster. Some showed first defects around 40mm³/s ( I think PLA Matte). I just set max flow to 35mm³/s for all filaments and call it a day. And that is at temperatures reduced by 10°C as recommended by E3D.

It is not that easy to put that increase into effect though: parameters you can change are speeds, line width and layer height.
I haven’t tried to increase speeds to 500 yet. No idea what’s the impact on quality.
A larger layer height will affect overhangs and layer visibility apparently.
increased line width allows you to reduce nr of walls for the same wall thickness. E.g. it is no problem at all to print 0,6mm line width with a 0,4mm nozzle or even wider. That renders the 0,6mm nozzle quite pointless in my opinion. It could cost resolution of fine details though. You could also leave outside walls at default line width and only increase inner walls, top/bottom, etc.

Anyway, print times reduce only for bigger parts. Amall parts are mostly limited by accelerations and layer times and won’t benefit much.

I’m mostly printing at default settings though. The Obxidian nozzle still pays off with more consistent extrusion and much better layer adhesion also at fast speeds (for the materials I tested in the range of +30% at 300mm/s).
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With that information you could check print time improvements by slicing your preferred parts with adjusted settings as suggested above.

2.) I purchased the bare hotend and used the parts from my completely unused 0,8mm bambu hotend. Assembly is a bit fiddly but very doable.

3.) hardened extruder certainly is no disadvantage.

4.) I don’t know for sure but I would be very surprised if there was a difference.

5.) Bo idea. I created my own profiles, because I missed them apparently.

6.) I wrote my opinion on 0,6mm in 1.) :wink: Only consideration would be filament thst is heavily filled with particles, e.g. wood.
I’m happy with the Obxidian and won’t go back. It has two disadvantages though:
a) needs higher purge volumes for clean filament swaps. sometimes, when I print something in white after a black part, the first layer is still a bit contaminated.
b) I have more poop spill on the build plate.

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Thank you, really helpful, especially the print times on larger vs smaller parts. I’m actually thinking of buying the A1 Mini for dedicated small parts only and keeping my P1S for larger almost full size bed prints.

Sounds like you’ve convinced me to settle on the 0.4mm and I’ll probably just get the hot end only and use other existing parts. The purge volume and spillage is probably something I can compromise on if it means shaving off a good time from larger prints.

I guess I will have to start tinkering with the settings to see what trade off I can get between print quality and speed.

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