3D Printing Forum

Supposedly extremely good... Perhaps something for @Anders to look at

According to their kickstarter:

* Outstanding nozzle material properties: energy efficient / ensure high quality printing results
* Calibration efforts are more stable (constant layer thickness even during extreme long print-runs as well as during high temperature print processes)
* No extreme tempering effect. (Hardened Steel nozzles suffer a strong tempering effect caused by heat, which makes the steel softer.)
* Our flattened nozzle tip doesn't scratch glas beds unlike diamond / sapphire nozzles or not flattened nozzle tips.
* Another positive aspect is that there is no need for long lasting researches because it is anyway a reliable quality standard in the plastic extrusion industries and this lowered the developing cost of the 3D Printer nozzle and it grants a fast production after the crowdfunding campaign became successful.
* It has no tungsten nozzle tip in a steel or brass body instead our nozzle is completely made of a premium tungsten alloy which makes it more reliable and grants better thermal conductivity
Made of a premium tungsten alloy which is generally used in the plastics industry or for aerospace applications

Most of the stuff they say is bad about gem tipped nozzles is solved in Anders design tough

But only 1.75mm nozzles

Oh God, that's a lot of misconceptions concentrated in one single campaign there

I am not going to go through all of the points, but here are some comments:

In short words, one can make a tungsten nozzle, but it will not necessarily be better (harder) than a hardened steel nozzle.
When people refer to tungsten as very hard, they normally refer to tungsten carbide, which is a very different story than a tungsten alloy.
The reason why not to go for tungsten is basically that it is hard to machine (when making tiny holes) and expensive, while not extraordinarily hard as an end product.
Hardened steel is clever since you can drill that tiny hole before hardening, which makes manufacturing way much easier.

The tempering thing is interesting though, I actually did not think of that, although their statement that hardened steel gets much softer than tungsten by tempering seems wrong at the printing temperatures most people use (?)

The thermal expansion issues they refer to are valid if you are operating an industrial extruder with a 3 meter long screw, but will not have any measurable effect on a 3D-printer nozzle.

An industrial extruder will face quite different wear issues compared to a 3D-printer nozzle, so relying on that tungsten alloy as a well known material in plastics extrusion industry is not necessarily the best argument.

The scratching glass bed thing another misconception.
First of all, you need to have a flat shoulder at the tip for manufacturing reasons, and for printing quality reasons, so all nozzles will have that feature.
Secondly, borosilicate glass has a hardness of about 6-7 (Mohs) while ruby/sapphire is about 9 and tungsten about 7.5. So if scratching the glass plate would be an issue, tungsten will not solve that problem.

Anyway, for my boron carbide project, tungsten would not be hard enough anyway, so that is another reason I did not go down that route

EDIT: It would be interesting to know if they actually printed large amounts of carbon fiber plastics, it seems like they had a very short testing period and I am not entirely sure that tungsten will handle CF better than hardened steel (?)

Anders Olsson wrote:The tempering thing is interesting though, I actually did not think of that, although their statement that hardened steel gets much softer than tungsten by tempering seems wrong at the printing temperatures most people use (?)

I had not thought about it either before, but it actually is kind of true... if the nozle was hardened steel it would get softer than it initially were at quite normal 3d printing temperatures, but it still would be quite a lot harder than it was before hardening.

Here is a tempering color list (copied from https://en.wikipedia.org/wiki/Tempering_(metallurgy) )
Faint-yellow – 176 °C (349 °F) – engravers, razors, scrapers
Light-straw – 205 °C (401 °F) – rock drills, reamers, metal-cutting saws
Dark-straw – 226 °C (439 °F) – scribers, planer blades
Brown – 260 °C (500 °F) – taps, dies, drill bits, hammers, cold chisels
Purple – 282 °C (540 °F) – surgical tools, punches, stone carving tools
Dark blue – 310 °C (590 °F) – screwdrivers, wrenches
Light blue – 337 °C (639 °F) – springs, wood-cutting saws
Grey-blue – 371 °C (700 °F) and higher – structural steel

As you can see our temperatures are very much in the range of tempering temperatures.

Yes, I had a look at another page: http://www.threeplanes.net/toolsteel.html
It seems the change in hardness is marginal though: Here is another source that includes tempering time: http://www.jmst.org/fileup/PDF/2004454.pdf So it tempering should only have marginal effect on the hardness/wear resistance, even if kept hot for ~27 hours as in the last figure.
In other words, I would not use this as a sales argument for tungsten nozzles.
Interesting subject though, I would never have thought about this if it was not for the tungsten nozzle

This is odd.
I was thinking, how do they cut threads and drill that conical hole if the material is harder than hardened steel as they claim?
They say they use laser to drill the small hole (I would say EDM is more likely), but a laser would not machine the rest of the nozzle.

A guy actually asked about the type of tungsten alloy in the kickstarter comments, and got this reply:

Hi Craig thank your interest in the alloy. Right now we don't want to publish the alloy combination. Please consider it took as a lot of time & effort and cost us a lot of money to find the suitable alloy combination for 3D Printing and it would be absolutely demotivating for us to see from tomorrow on copies of our nozzle with our alloy combination on ebay. I can tell you such information only after a successful crowdfunding campaign by a private message and not here in the comments. I hope you can understand this.

So I started looking into tungsten alloys, and machinable grades usually have a hardness of 25-35 on the HRC-scale: http://www.tungsten.com/products/tungsten-alloy/
Now, that is much softer even than the tempered hardened steel, and just slightly better than stainless 304

That of course explains the machining, but I am getting seriously confused about this campaign now.
Tungsten alloys appears not possible to harden the same way as steel can be hardened, and chemical processes to improve hardness does not appear to be easy too.

So, what am I missing here, any comments/ideas?