3D Printing techniques. - Large bore J-Head.

How it came to be.

I ended up clogging my nozzle and figured I would heat it up and dig out most of the plastic before soaking in acetone. I used a 1.55mm drill bit to dig out the gunk. Unfortunately I got a bit overzealous and by hand ended up enlarging the orifice of the nozzle to said size.

Lemons into lemonade. J-Head into Huge J-Head.

I then ordered a replacement head made out of all metal and as of this writing I am still waiting for delivery. What can I do? I still need to print parts. I tried to print with it, with predictable disastrous results. However there seemed to be some glimpses of it sticking properly.

Trial and failure.

Success!!! Sucks less!

Results.

After Thought & Techniques

Printing with such an oversized nozzle is a weird balance of large and fine. To explain this, its like trying to paint with a water hose. Not exactly accurate, but if done properly you can achieve "good enough" results and much much faster prints.

The formula that works for me.

  • Temperature 235-240c (pushing the limits of the j-head)
  • Undersize configuration in Cura (I set mine to 1.45mm nozzle)
  • Layer thickness does not matter as long as your nozzle does not cool too quickly. (I have used anywhere from .3mm to .8mm and will be trying 1mm at some point)

The things I have observed.

  • The nozzle is wildly fluctuating in temp. Best to set temperature higher than lower.
  • My nozzle clogs shut at anything approaching 210c, keep it at 220+ range and be happy.
  • Printer speed becomes critical and changing mm/s setting does not impact the printer the same way it did with a finer nozzle.
  • This is a viable option to print large parts with reasonable accuracy.
  • Infill should be on the higher end of the spectrum.
  • Do not make the wall thickness less than 2x the nozzle width if you want to maintain tolerance. As of this writing the sweet spot seems to be 4mm walls with a 1.5mm shell.

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Bruno M.

Engineer, Tinkerer, Technologist, Maker.

New York

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