Dura-Gem is in the news
Originally shared by Fabbaloo
Could A Sapphire Nozzle Should Fix Those Abrasive 3D Printing Issues? http://fabb.lu/1McXlw0 #3DPrinting
Am I the only one who thinks a Sapphire nozzle is fixing a problem that barely exists?
I have been using similar nozzles, but with a bit more refined design, for half a year now. They were originally made for a scientific project printing extremely abrasive stuff, and I am now having a first batch manufactured for potential sales.
My version has an improved geometry of the jewel which actually improves printing quality compared to all other nozzles I have tested so far.
Since the scientific article about this project is not published yet, I had to keep things a bit secret, but you can see a photo of one of the prototypes here: https://ultimaker.com/en/community/view/11141-nickel-plating-nozzles-for-carbon-filled-filaments-updated?page=2
@Nathan_Walkner I don’t believe for one second that @Proto-pasta carbon fiber PLA has the same layer shear properties as standard virgin PLA. I’ve used it extensively, and while the carbon fiber obviously doesn’t create a true composite material in any fashion, the layer adhesion is much stronger than other similar and lesser materials. The small fibers do in fact barb into the layer below, especially when printing a touch hot. If I saw actual repeatable data that clearly evidenced otherwise, I would reconsider, until then my anecdotal evidences are enough to convince me.
Using gem stones in high wear applications is common in industry. For me, it’s Ruby and not Sapphire, but the effect is the same. There is a cost/benifit for everything. For some people, there will be a very real advantage. For most hobbysts, no real advantage, just an expensive bragging check box.
@Nathan_Walkner show me something verifiable. I use many filled filaments, including the carbon fiber XT, and the @Proto-pasta PLA is the only one (cheaper too) that actually seems to have increased layer adhesion. Maybe there is no cross-linking, that I can’t verify, but I do know from general usage, it absolutely has better shear strength than standard PLA, and other CF filaments.
This is why I need more awesome measuring tools, I’d love to have a nice unit to actually conduct a shear strength analysis with. Until that’s performed, we are just speculating anyway.
We have done comparisons between for example protopasta carbon PLA, Colorfabb XT-CF20 and unfilled version of the same plastic.
I don´t believe the flexural or tensile strength increases when adding the carbon fibers.
The flexural modulus however appeared to be higher in our tests, although filled plastics seems to suffer more from creeping that unfilled ones, which made the test results a bit unpredictable.
In short words, carbon fiber plastics appears to be more stiff, meaning the bend less under a certain load. The maximum load they can handle is probably not higher than for the unfilled one though.
When it comes to reasons to print these kind of abrasive materials, you can think of other stuff than carbon fiber to put in plastic that will give it certain very interesting properties.
@Nathan_Walkner I’m not a material scientist, I’m guessing the same applies to you. Perhaps if you haven’t printed with it you should try. I didn’t believe it could change the PLA properties so significantly either, but I’m telling you that it absolutely does.
Flexural modulus is not shear strength, I was under the impression you knew that.
Still no data, just pomp and heresay.
You’re right, sorry.
So, we printed my nozzle torque wrench in different materials: https://www.youmagine.com/designs/nozzle-torque-wrench
And then compare the torque, since that should mainly depend on the flexural modulus.
I should not paste the data file since the article is not published yet, but we ended up with roughly 0.3 Nm for ABS and XT and 0.5 Nm for PLA.
XT-CF20 gave about 0.6 Nm and Protopasta carbon fiber PLA about 0.8 Nm
As I said though, the carbon fiber plastics seems to creep when kept under load for some time, so it was a bit difficult to test them properly.
why a gem? I had quotes made for ceramic and silicon carbide nozzles, will probably be much cheaper and almost as good, or lets say you will never need a new one. I have destroyed brass nozzles in 1 day running on CF and other abrasive filaments. Now I have stainless steel, works just fine too.
@marc_kerger Gemstones are common in industrial applications. If the volumes were high enough ruby could be used for an import nozzle about the same price as a stainless nozzle. It’s a pretty niche product but for abrasive materials it could be a better choice than some metals.
Regarding my nozzles, I can not discuss the details, what I have tested and not and so on, for obvious reasons.
The stainless nozzles I used so far suffer from low thermal conductivity and are not that much harder than brass.
The best budget option right now I would say is the hardened E3D nozzle: http://e3d-online.com/is-carbon-killing-your-nozzle
But the one I tested prints quite bad actually. If you need to print lots of abrasive stuff and can live with ugly overhangs it is a good option though.
@Nathan_Walkner , @Chris_Burger . The addition of the carbon fiber particles does on fact improve layer to layer adhesion, tensile modulud, and flexural modulus. The act of crosslinking simply determines whether a plastic is thermoser or thermoplastic. These plastics are clearly thermoplastics. The ‘barbing’ between layers is what actually improves the layer to layer adhesion. As with any fiber reinforced plastic, the added fibers give the plastics surface area to bond to. I know this because 1. I’m a mechanical engineer, 2. My company has done tensile testing on all axes on cf filled abs dogbones on an MTS universal testing machine. I cannot share the results, but I will say that there is an improvement on strength, but it is heavily reliant on build orientation. as for flexural modulus, this is a parameter that is calculated based on a material’s tensile vs compressive modulus (don’t want to go into the boring guts of this). As an initial guess, you can generally just use your tensile modulus, but increasing the tensile should always increase your flexural. Hope this clears things up on that.
Thermal Conductivity
stainless steel 24
brass 125
sapphire 25
ruby 40
diamond 1000 - 3320
Maybe we should be looking at industrial diamond nozzles for better thermal transfer which may allow higher print speeds.
@Eric_Moy great info, thanks. Wish I could see the numbers 
@Daniel_Kruger The issue with diamond is that it’s an order of magnitude more expensive as well. In many cases where a tool (for example waterjet) is using a ruby nozzle the diamond costs are 10x plus in most cases, sometimes more. I’m not familiar enough with cubic zirconia to know if it would have some of those same properites at a reduced cost.
Some glow materials are abrasive. The metal embedded filaments probably do to. About the data, if it conflicts with your current belief, would you change your belief or find a way to deny the new data?