Welcome! Log In Create A New Profile

Advanced

E3D to airbrush nozzle adapter

Posted by epicepee 
Re: E3D to airbrush nozzle adapter
March 24, 2017 02:17AM
Do you mean test the deltaprintr mini hotend? Get my nimble to me and I'll test it for you.


Simon.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters. Coming soon PT1000 cartridge sensors plug straight into duet boards.
Published:Inventions
Re: E3D to airbrush nozzle adapter
March 24, 2017 05:10AM
Quote
JamesK
Quote
realthor
I always believed that the flat on the nozzle is to cope with the imperfections of early 3d printers, it flats out the plastic that comes out and ensures better bonding with next layers, as they don't remain rounded.

Well, sort of yes and no. No to the first part, that's a common misconception, yes to the second part. It comes down to what shape are we trying to extrude and how do we get that. A round cross section extrudate would be bad, because there is minimal contact area and poor bonding



So to get better bonding we aim to extrude filament that is wider than it is high, something like



The tip of the nozzle provides a constrained space into which we can extrude the filament to get a variety of extrusion widths



The smallest width that can be extruded is limited by the bore of the nozzle - if you try and extrude less than that the system is under constrained, you can't guarantee where the filament will go and it will likely have intermittent contact the lower surface. In my simplistic view of the world, the largest width that you can extrude is determined by the diameter of the flat. If you try and extrude wider than the diameter of the flat the system is again under constrained. I'm not sure what that would look like, but given the viscosity of the plastics we use, I'm guessing it would look like this



So, my understanding (which I'm happy to have explained as to why I'm wrong) is that the nozzle bore sets the minimum extrusion width and the maximum rate of flow, while the maximum width is set by the diameter of the flat. A nozzle with a small flat looks like it should have a rather small range of usable extrusion widths, which seems like a disadvantage to me, as variable extrusion width is something that slicers can make use of to improve print quality. On the other hand, I don't yet see a disadvantage to having a large flat on the nozzle, so I'm interested in Srek's observations that the narrower tips have advantages in bridging and overhangs. I'm not disputing Srek's observations at all, just trying to understand them.

The drawings JamesK postet have one (in my oppinion) big mistake, the width of the outcoming filament should not be wider than the nozzle output size.
so for sure the filament output should flat (2nd picture) and not be round, but at least is should not be wider than the nozzle size.

Chri

Edited 1 time(s). Last edit at 03/24/2017 05:12AM by Chri.

[chrisu02.wordpress.com] Quadmax Intel Delid Tools
Re: E3D to airbrush nozzle adapter
March 24, 2017 05:21AM
Quote
Chri
the width of the outcoming filament should not be wider than the nozzle output size.
so for sure the filament output should flat (2nd picture) and not be round, but at least is should not be wider than the nozzle size.
Chri

That's an interesting suggestion Chri, what's the reasoning behind it? Clearly it 'can' be wider than the nozzle size as that is how 99% of the prints I make are done. The nozzle bore sets a minimum width for the extrudate (since if you try and extrude less than the nozzle bore it's undefined where the extrudate would be), so if it should also not be wider than the bore you're in fact saying that the only possible extrusion width is the size of the bore. Clearly extruding wider than the outer dimension of the flat face of the nozzle is a bad idea, but I don't immediately see what's wrong with the range of widths between bore size and flat size.

[edit: you can take the above argument too far of course. If you make a nozzle with a very wide flat and try and extrude at multiples of the bore width print quality goes down as the shape of the extrusion becomes less and less well defined. I've done some tests at 2x bore size and they show signs of poorly controlled flow. Up to about 1.5x bore seems very workable in my experience]

Edited 2 time(s). Last edit at 03/24/2017 05:25AM by JamesK.
Re: E3D to airbrush nozzle adapter
March 24, 2017 05:54AM
Quote
JamesK
Quote
Chri
the width of the outcoming filament should not be wider than the nozzle output size.
so for sure the filament output should flat (2nd picture) and not be round, but at least is should not be wider than the nozzle size.
Chri

That's an interesting suggestion Chri, what's the reasoning behind it? Clearly it 'can' be wider than the nozzle size as that is how 99% of the prints I make are done. The nozzle bore sets a minimum width for the extrudate (since if you try and extrude less than the nozzle bore it's undefined where the extrudate would be), so if it should also not be wider than the bore you're in fact saying that the only possible extrusion width is the size of the bore. Clearly extruding wider than the outer dimension of the flat face of the nozzle is a bad idea, but I don't immediately see what's wrong with the range of widths between bore size and flat size.

[edit: you can take the above argument too far of course. If you make a nozzle with a very wide flat and try and extrude at multiples of the bore width print quality goes down as the shape of the extrusion becomes less and less well defined. I've done some tests at 2x bore size and they show signs of poorly controlled flow. Up to about 1.5x bore seems very workable in my experience]

there are a couple of reasons:
* the pressure level of the outcoming filament rises this results in a more uncontrolled flow of the filament which is the main reason for not printing too wide sizes.
* it basicly lowers the print detail quality at X-Y as you have a wider surface (for sure helps to print faster grinning smiley)
* also overhangs will be uglier as the higher pressure will be more released to the open side than the other inner side where is also should go.
* the outside dimensions will be false as the filament will be more released to the open side, (= parts become larger, holes become smaller)
* due to the higher pressure the chance of the extruder gear loosing grip becomes higher.
* also due to the higher pressure you probably have more stringing
* when printing faster (and i`m known for printing fast grinning smiley ) all that issues become more worse.

for sure you can vary the filamentwitdh , also smaller, as the slicer then will make the line distance smaller.
for example my main nozzle is a 0,4 , but my print witdh`s variy from 0.35 to 0.5.
when using 0,35 there is not much issue maybe a little bit less stronger, and with 0.5mm there are already issues with overhangs, that why i use 0,5 mainly for plain mechanical structures like plates ect.

Last but not least it`s always a question of what quality requirements you have grinning smiley

Chri


[chrisu02.wordpress.com] Quadmax Intel Delid Tools
Re: E3D to airbrush nozzle adapter
March 24, 2017 06:10AM
Thanks Chri, that gives me lots to think about. It's interesting that you mention that most of the issues get worse at higher speeds - I have a heavy dual extruder print head, so I have to print pretty slowly. One of the things I've run into over and over again is that things I thought I understood to be 'true' only actually applied for the particular circumstances I was operating under at that point in time, and that the larger truth was more complicated!
Re: E3D to airbrush nozzle adapter
April 03, 2018 10:17AM
Is the Merlin available from a US seller? In fact is it still around? The website appears to be down.

Thanks!
Re: E3D to airbrush nozzle adapter
April 03, 2018 10:52AM
My website should be up and running.
Currently the best option to get the Merlin is from Protoworx in germany (they seem to have a bit of a web problem). Afaik RRD still has it available and does international delivery, they are just selling the stock they have though, while Protoworx is manufacturing new ones in germany and also offers a new modified version that should allow you to print even faster.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: E3D to airbrush nozzle adapter
April 03, 2018 10:57AM
Thanks so much Srek, was hoping I'd hear from you! I may just order one from RRD until the new model becomes available. Looks like a great unit! smiling smiley
Re: E3D to airbrush nozzle adapter
April 03, 2018 11:06AM
Oh, and right Srek, it was the Protoworx site being down to which I was referring. May I ask, which is your site?
Re: E3D to airbrush nozzle adapter
April 03, 2018 12:53PM
[merlin-hotend.de] is a referrer to the Merlin part of my main site [www.bonkers.de]


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: E3D to airbrush nozzle adapter
April 03, 2018 12:56PM
Ah yes Srek, that's the main site I've been pouring over, impressive work! I appreciate the lovely machining.

So is it the V3 which has not yet been released, or is there another on the way?

Edited 1 time(s). Last edit at 04/03/2018 12:57PM by papilio.
Re: E3D to airbrush nozzle adapter
April 03, 2018 01:06PM
Re: E3D to airbrush nozzle adapter
April 03, 2018 01:11PM
Quote
Srek
I'm talking about this one
[b.bonkers.de]

Okay thank you Srek, I'll be waiting! smiling smiley

Edited 1 time(s). Last edit at 04/03/2018 01:13PM by papilio.
Re: E3D to airbrush nozzle adapter
April 12, 2018 09:07AM
Calling out to Srek --

I've just come across your blog on running the Merlin with forced air cooling of the hotend. I too am using an aquarium air pump for part cooling, there's plenty of output remaining unused at the moment which would seem just the thing for keeping the hot end cool. I'm not quite able to tell from just the photos exactly how you've implemented the cooling around the hotend -- might you have some illustrations/CAD diagrams of the configuration shown, or could I ask for a bit of explanation pertaining to this aspect? Currently the only thing causing me a bit of indecision in ordering the Merlin is the temperature capability due to the PEEK element, cooling as you seem to be using may well be the solution to this. Thanks!
Re: E3D to airbrush nozzle adapter
April 12, 2018 04:16PM
Quote
Srek
I spent one year of my spare time developing and testing the Merlin hotend. I tend to become a bit defensive if someone claims a print is of good quality despite the hotend beeing used, especially when that person never used it himself. The Merlin has some shortcomings, a lack of print quality is not one of them.

Srek

I'm interested in making one of these, could you please outline what the shortcomings are?
Is it just slower print speed?

Edited 1 time(s). Last edit at 04/12/2018 04:24PM by briangilbert.

Co-creator of the Zesty Nimble, worlds lightest direct drive extruder.
[zesty.tech]
Re: E3D to airbrush nozzle adapter
April 18, 2018 02:17PM
Papilio: The air cooling is done via a channel through the base of my extruder, so the intake is at the top and parallel to the filament feed.
The air is guided close to the peek through a conicaly shaped chamber that is smallest at the lowest point of the PEEK element, where there is a small gap for the air to escape. This gap needs to be as even all around as possible and can be quite small (ca. 0.2-0.4 mm). With the air cooling i can print PC at 270+ C° without problems.

briangilbert: The Merlin requires a better fine tuning of the extruded material volume since it will scrap any excess material off, but this is an issue with every sharp tipped airbrush based nozzle.
Since it is a PEEK/PTFE based hotend it has lower temperature limits than an all metal hotend, but in reality this poses no problem since only very few materials require temperatures above what the Merlin can handle. I print ABS with an uncooled Merlin for >6 years now.
Speed is definitely not a shortcoming of the Merlin, in fact it can print faster than most.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: E3D to airbrush nozzle adapter
April 18, 2018 02:20PM
Thank you Srek, very helpful info to both my and Brian's requests. I'll be trying one out.
Re: E3D to airbrush nozzle adapter
April 18, 2018 04:13PM
thanks Srek


Co-creator of the Zesty Nimble, worlds lightest direct drive extruder.
[zesty.tech]
Sorry, only registered users may post in this forum.

Click here to login