Questions about replacement nozzles

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BaltimoreBully
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Questions about replacement nozzles

Post by BaltimoreBully » Wed Mar 18, 2015 4:11 pm

When my nozzle was jammed with hips about a week ago and it didn't seem like I was going to get it unclogged, I ordered some new nozzles. I did a google search for .35mm hexagon hotend and what came up was the Maker Farm site. But all they had was .4 mm and .3 mm nozzles for 3 mm filament. I ordered them anyway in the .3 mm size. I ended up getting my nozzle cleaned out and got the printer printing again. The Maker Farm nozzles came in the mail today and I figured they could just serve as backups if I get another jam and need to soak my nozzle. My questions are, are the .3 mm nozzles a direct replacement for the .35 mm or would I have to recalibrate my extruder if I used one? Would I see much of a difference in print quality if I use the .3 mm nozzles? Is there any advantage or disadvantage to using a smaller nozzle than stock? These nozzles look exactly like the one that came with my Taz 5 and that's part of the confusion. They even have the same 3 engraved on the side. Thanks in advance for any info.
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mhackney
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Re: Questions about replacement nozzles

Post by mhackney » Wed Mar 18, 2015 7:01 pm

I've observed a lot of confusion/misunderstanding on extrusion calibration here. I'll answer your nozzle question in a minute but let me set the record straight re extruder calibration.

Extruder calibration has nothing to do with the hotend or nozzle. Extruder calibration is simply determining the number of steps required to push 1mm of raw filament throught the extruder. It does depend on how many steps per revolution the stepper uses (all 1.8* steppers are 200 steps per revolution), any gearing down in the drive train, and the effective diameter of the cobbed bolt/gear. Remember, it is the steps per mm to move the incoming raw filament, not the amount that comes out of the nozzle. I think this confuses a lot of people. Once you've calibrated your extruder, you can swap hot ends, nozzles, without recalibrating. In fact, you can even move the extruder to a completely different printer and it will not need to be recalibrated. There is a very minor effect due to filament diameter but even the difference between 1.75mm and 3mm filament is negligible.

Now, on to your question...

You certainly can use a .3mm nozzle. You don't need to recalibrate your extruder but you do need to change some slicing configurations. These differ from slicer to slicer but they are all similar and something like "extrusion width". Set that to .3mm. You will likely need to change your layer height too. A good rule of thumb is layer height is between 50% and 75% of nozzle diameter.

A .3mm nozzle will give a bit better print quality if you change the layer height but at the expense of longer times to print. Even if you don't change the layer height print time will increase with some improvement in bottom and top surface quality.
Sublime Layers - my blog on Musings and Experiments in 3D Printing Technology and Art

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BaltimoreBully
Posts: 47
Joined: Sun Feb 22, 2015 10:43 am

Re: Questions about replacement nozzles

Post by BaltimoreBully » Wed Mar 18, 2015 7:59 pm

Thanks Mike. I'm glad that you had the answer, I didn't want to specifically ask you, because you field a lot of questions. You seem to be becoming our resident guru. Also thanks for the clarity on extruder calibration. You're right I did have it confused as to what exactly it did. I'm willing to have a little longer print times in exchange for a bit better quality, specifically in the top layer. I have printed out your 75 mm disk no less than 30 times in the last two days. I think I have pretty much nailed getting a quality first layer. But I haven't worked out all of the issues with getting good top layers yet. I have been printing things at .2 mm layer height. So if I do change the nozzle to the .3 mm, I can change the settings in Cura to 1.5 and see if that changes my results any. Thanks again for the good info.

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mhackney
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Re: Questions about replacement nozzles

Post by mhackney » Wed Mar 18, 2015 8:18 pm

Glad to help, I know it was confusing when I first started too.

The top layer is the toughest to get really nice. The one tip I can offer is to keep the nozzle tip polished so it smooths over the filament as it lays it down.
Sublime Layers - my blog on Musings and Experiments in 3D Printing Technology and Art

Start here:
A Strategy for Obtaining Great Prints

Strategies for Resolving Print Artifacts

The Eclectic Angler

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