Is there any reason I shouldn't assemble my dual with hardened nozzles? I have them. I will likely print in some abrasive stuff frequently, and if they perform as well as the brass ones, then seems easier to just put them in now, than switch later.
I recall Sanjay saying something about the brass nozzles transferring heat to the filament more efficiently.
That's correct. Use brass unless you print abrasive materials. If abrasive use hardened unless you can't tolerate lead. Use stainless steel. Heat conduction is best on brass -> faster melting -> higher speeds.
@Alex9779 , I just want to confirm what I understand. You are saying that when we gonna print Abrasive materials it is better/best use the hardened nozzle, while printing other than that use the brass nozzle ? Now I am curious how easy we change the nozzle if we often mix printing between Abrasive materials and not.
That's what Sanjay said in the the Q&A session and that's what sound most reasonable for me too, yes...
Richrap says that he is preparing a blog post on hardened nozzles. He's testing them with different materials at the moment to try to prove that you can print "everything" with them. However in his G+ post on the wooden statue, he does imply that it's not straightforward and you will see that he has bandaged up the nozzle with Kapton in order to do what he does!
I am pretty sure the hardened is also lead free, so if you need lead free you can use hardened or stainless. Stainless doesn't hold up to abrasive materials, I think Sanjay had said they had a large order for stainless which is why they carry that as well as hardened. Stainless and hardened are the same price on E3D's website.
I remember Sanjay said there are people ordering a lot of stainless but he does not know what they are doing. And I am pretty sure he said that if you can't tolerate lead then you have to go stainless. A while ago stainless was suited for abrasive filled filaments but then the hardened came up... Maybe @Sanjay can clarify please?
Your typical stainless is harder than brass, but it's still much softer than properly hardened steel. I seem to remember Sanjay mentioning that the hardening process leaves a residue that makes hardened nozzles unsuitable to whoever is buying stainless.
It likely wouldn't be possible/sensible to use hardened for food grade stuff and I think some people are buying stainless for applications where they could/should use hardened but just haven't noticed that the hardened is available. By my reckoning the hardened has worse thermal transfer properties than the Brass but it's slightly better than the stainless. I still maintain though that a true universal nozzle would be tungsten (or potentially nitride hardened aluminium if you want something easier to make)
I feel like the heat transfer difference between steel and brass wouldn't make too much a difference in this application, maybe just a slight increase in temperature for the steel, but nothing major, steel is still a very good heat conductor.
Steel has less than a third of the thermal conductivity of Brass, Stainless is about half that of Steel. Aluminium beats all 3 which is why they made the head block and heatsink out of aluminium rather than the whole thing out of Brass. But Aluminium is too soft (without case hardening) to make a nozzle. It does make a difference, at higher extrusion speeds with the worse conductivity you get a thermal gradient between the heatblock and the nozzle (and thus the filament temp) and it requires more and more force to extrude, but you can't just raise the hotend temp to compensate for the gradient as it would cook the filament material as soon as it stopped moving or during a retraction. Quality drops through belt slop aside I think this actually tends to be the final speed limit on most FDM printers,
Henry, had you considered the Volcano assembly, as this has the thermal inertia to handle large throughputs. The only limiting factor is the lack of a good range of smaller nozzle sizes but this may be due to the physics of the device. Richard Horne has had real success using Volcano on the BB. Mike
I did @mike01hu but then decided (still not sure if it was right) to go with the dual.It's not the throughput, but rather the abrasiveness. I am working on a medical filament with Microna2 mixed in (a calcium carbonate powder) and I imagine it's like extruding limestone. I mean sure the ancient Egyptians manage to build the pyramids with bronze tools, but pretty sure they weren't trying to maintain 0.4mm precision!
Hard nozzles are available for Volcano although I suspect you would be wanting stainless steel to meet health criteria. The additional thermal capacity of Volcano will work to cancel out the lack of thermal transfer with stainless steel nozzles. I believe that thicker layers and higher print speed are preferable but my experience of this is zero. Again, you might want to open a dialogue with Richard Horne as his experience is extensive.
This isn't going in the body, it's for experimental and educational uses (I am working to develop different filaments that can simulate different tissue types for imaging and surgical training models); Actually just ordered my Filastruder (thank @elmoret for the advice). since you don't want to know the giant pile of OSHA violations I probably racked up in the lab with this first proof of concept which I hand mixed the additives in by hand with a test-tube spatula and attempted not to burn the lab/self... Note: really, really don't try this at home. Even worse, I sliced up the spare filament I had on hand with a scissors (thank god for eye protection)... But while it literally looked like a pile of poo it actually worked in the experiment...
@Henry feldman Just to carry on with the Volcano saga, have a look at Richard Horne's latest post on G+ where he has dropped a few hints and tips. Mike
At this point I'll be happy when any filament comes out of the nozzle! Almost done with the build, but looked at the clock last night, and realized I was due at the hospital in 6.5 hours...
Forgive me if this is considered spam, but I saw these tungsten nozzles and thought of us https://www.kickstarter.com/projects/61825400/3d-printer-tungsten-premium-nozzle-0