Proper shape fotr extruder tip?

I have seen three shapes used for extruder tips: pointed (QU-BD), Flat (Solidoodle), Round (home made from crown nut). Is there any consensus as to which is best? If the end is flattened how wide should it be?

I'm getting some surface roughness (like 180 grit sandpaper) using ABS @210 with a .35 hole on flat top surfaces and was wondering if my tip shape had anything to do with it.

Roger

You'll probably get a lot of different answers to that one! Personally, I don't think your problem is caused by the nozzle shape, but printing ABS at 210C seems rather too low.

Edited 2 time(s). Last edit at 06/17/2014 07:02AM by waitaki.

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Waitaki 3D Printer

Depends on your hotend, really. I could print PLA on my old one at 162C, but with my E3D v5 I print, at the lowest, 240C. For ABS I print 270C.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

@MrDoctorDIV i highly believe your print temps are not actual temps. If I ran at 270C I'd have a puddle of liquid ABS. Have you ever checked with a IR thermometer? As well, if someone may try to print at the temps you are posting, there are alot of hot-ends out there that would melt down at 270C.

What's your temp reading when you power on the hot end at room temp?

Edited 3 time(s). Last edit at 06/17/2014 08:38PM by Dirty Steve.

I really think that tip geometry DOES matter. So does tip roughness.

Remember that the extrudate is not only put in place by the nozzle, it should ideally be squezed by 30-40% of its diameter by the tip in order to produce the optimum shape of extrudate and better layer adhesion.
(Thats how we achieve layer heights < nozzle diameter)...
So, yes it does matter. Take a look at E3D´s nozzles, I think they are shaped like this for a reason.

The outer tip shape can have a huge influence on the surface quality, but it shouldn't.
The problem is the amount of material. If you extrude a little to much a flat tip will iron the surface and it will still look good. A sharp tipped nozzle will graze the surface and move through the excess material. If you calibrate correctly you can get perfect finish surfaces with sharp tipped nozzles.
In general i found that sharp tipped nozzles are better for bridges.

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