brass extruder nozzles stupidity or business

[smile]

Why the extruder is from brass and not plated with some oxidation resistant metal?

While I do know that copper and brass are two very good heat transfer metals, they both oxidize from heat. Given the temperatures and small nozzle that must maintain precission why the extruders are not plated like modern soldering iron tips, and why the nozzle (the hole itself) is not made from another metal?

Like water jet nozzles are made from precious minerals, you could make it from stainless steel 316L and put it in electroplated brass nozzle shell.

[doraemon]

Don't know why brass was chosen, but it could be any of the reasons below:

- Matching thermal characteristics for heater block it's pressed into
- Ease of machining to size
- Resistance to corrosive elements that are expected
- High heat conductivity
- Ready availability in supply base
- Aesthetics

It might even be something not listed; it's hard to say if something is a stupid decision without knowing all the design constraints. This is something that often comes up at work, when an outsider will assume the designer is incompetent for not designing something a certain way, but upon further review, it was the best compromise given the constraints and relative weights of said constraints.

[DrewPetitclerc]

It might even be something not listed; it's hard to say if something is a stupid decision without knowing all the design constraints. This is something that often comes up at work, when an outsider will assume the designer is incompetent for not designing something a certain way, but upon further review, it was the best compromise given the constraints and relative weights of said constraints.

I so agree with the Doraemon on this one observation that I'm compelled to stand an cheer (in my head),

I love when an engineer speaks truths.

Regards
Drew

[smile]

I'm, not saying brass is bad, but why not coat it? Why leave nozzle hole itself brass when stronger metal would ensure better long term reliability with the same machining cost?

They do make syringe needles cheap, stainless and small size you know....

[roller]

There's been many nozzle experiments in the reprap project ... stainless, aluminium, teflon coated, anodised ... you name it it's been tried. At the end of the day brass has proven best ... cheap, accurate and sufficiently durable and most importantly reliable ... many other alternatives have generated "issues". Considering I have nozzles 3 years old that have had kilometres of filament through them and they still fine and I have some other "experimental" nozzles that were just a pain, I don't see the point of chasing other materials unless there is some other significant revolution that demands it.

The big issues in hotends has always been maintaining stable temperature at the heat chamber and tip while avoiding the conduction of heat up the injected filament. Especially doing it on a budget.

[JuliaDee]

it's hard to say if something is a stupid decision without knowing all the design constraints. This is something that often comes up at work, when an outsider will assume the designer is incompetent for not designing something a certain way, but upon further review, it was the best compromise given the constraints and relative weights of said constraints.

I agree with doraemon (and Drew) on this, and would just add that my overall opinion of the Up/pp3dp/Delta Micro engineering team after using the product for more than 18 months is quite high, and I've found it's best to give them the benefit of the doubt rather than jumping to the conclusion that something could be done better or smarter. Yes, they've made some compromises here and there for cost reasons, but in general it's all pretty darned clever and well thought-out, and reflects the expertise the company gained over the years of producing the Tiertime industrial printer line.

julia

[doraemon]

I'm, not saying brass is bad, but why not coat it? Why leave nozzle hole itself brass when stronger metal would ensure better long term reliability with the same machining cost?

They do make syringe needles cheap, stainless and small size you know....

Could be the given dimensions they need is non-standard, which will significantly drive up cost. I recently was looking into a press-fit pin design for a component, but needed one feature changed. As soon as it was no longer a standard, off-the-shelf pin the price went up 100X, effectively killing my design.

Alternately, as roller mentioned, it's probably already been tried and found lacking for some reason. I'd guess it could be related to friction or heat, especially if plastic filament is abrasive. I remember being surprised the first time a machinist told me that he keeps separate end mills for working on plastic due to its higher abrasiveness compared to cutting aluminum or steel.

Of course, ideally we'd have the chance to talk to the designers and find out the "real" reason why, rather than just sit her and speculate.

[roller]

I think that machinist meant there is extra friction with plastic so the endmills get hot, melting the plastic and at best ruining the finish though more usually gluing the endmill to the work and snapping it. So you need far fewer flutes and lower RPMs for plastic. They are actually not too wearing on endmills.

[josejuako]

Can be built in a more serious brass with carbon my question?. Bushings , some electric motors have high resistance to friction and are maker of brass with more resistance than our nozzles. The difficulty of this issue from my experience with nozzles UP is to make the hole in machining I think they should be injected or stamped. Just ideas to share with you.


J

[mb20music]

Why the extruder is from brass and not plated with some oxidation resistant metal?

Like this ?

http://www.ebay.com/itm/HIGH-LUBRICITY- ... 1626449%26

[roller]

Why the extruder is from brass and not plated with some oxidation resistant metal?

Like this ?

http://www.ebay.com/itm/HIGH-LUBRICITY- ... 1626449%26

Mostly hype. Spray your nozzle with silicon spray (from memory) before you use and you have the same thing.

[mr6k]

Smile,
Soldering iron tips are plated as the solder flux is highly corrosive, ABS is not Also the soldering iron long life tips are made of iron which will not "whet" with solder, so they need a coating. Stainless Steel is a very bad heat conductor.

With the small hole and tolerance of the nozzle any plating would be difficult to control the final thickness, let alone ensuring the plating liquid flowed uniformly through such a hole during plating. Most likley any attempt at plating would leave the actual nozzle hole starved of plating.

As roller points out brass seems to be the proven high heat conductive good wear resistance, easy to manufacture material of choice, plus I don't think it oxidizes significantly at the used temperatures, at least not with the materials going through it, which it is designed for.

Smile, I know you may feel emotional about these subjects, but using the term "stupid", rather than a less emotional term is, in my opinion, rather rude.

cheers

Peter

[wackojacko]

I printed with1.75mm solder and it corroded the nozzle hole size and made it bigger.

[Lawrence]

Hi Bruce
When you used the solder filament, did it successfully produce a model. A photo wood be good.
Did the solder have flux in it? If yes, then the flux would have been corrosive.
If you did produce a model, and the flux was the corrosive agent, then all that is needed is a filament with similar metal properties but without the flux, and the Up! has become a metal extruding 3D printer. All it then would need is for some enterprising company yo produce and supply the filament. That would be pretty exciting.

[jason simpson]

Hi All. This is my first post here. I am about to test some silversteel, ceramic and some toolsteel nozzles. Have just finished testing 316SS and will let you all know. Interested in how the ceramic ones go.
I am doing the tests on my other printer not on my Up Plus2.

[ming]

Most of my design tasks starts with requirements then costs.

As for the nozzle in this case cost I believe is the main factor
Material selection, conductive and durable many material will meet this req. but cost prevails.
The nozzle again I'm assuming without knowledge of the creator, comes from a raw hex stock 6mm. There are limited materials available in raw hex stock form. Round will be cheaper but will be more machining time. And drilling the small nozzle tip is not easy if you use a hard material and the standard drills are not very long for that size. Brass does not need to be anodized or plated to prevent corrosion, one less step ($). Tooling is cheaper ($). Machining time is less ($)

If I were to make the tip in production
Long hex stock on an auto feed lathe with live tooling and transfer chuck
Feed . Chamfer the tip . Drill set depth of the tip .
Transfer chuck holds part . Feeds material . Cut threads . Cutoff part
Drill or Counterbore backside (depending on machine, the first step could be in parallel while this is performing
All this can be done in one minute maybe even 30 seconds per complete part.

If you try with plating or anodizing or anything that adds time for secondary or third operations your cost is not even in the same factor as a one step machine and ready to sell part. I'm not expert in plating and for such a small tip. How consistent is the hole is and do you need to re drill or finish the orrifice?

[Fred]

Would Liquid Tin (used for tin plating home etched PCBs) work on a brass nozzle? And would it be worthwhile. The typical plating on a pCB is only a few microns so maybe wouldn't last long anyway.

[roller]

Hi All. This is my first post here. I am about to test some silversteel, ceramic and some toolsteel nozzles. Have just finished testing 316SS and will let you all know. Interested in how the ceramic ones go.
I am doing the tests on my other printer not on my Up Plus2.

I think you are missing the purpose of the nozzle being Brass ... it's a good thermal conductor. The nozzle provides the melt chamber with it's heat by conducting it in form the heater block which in turn acts as thermal mass/battery.... an insulator simply wont transfer sufficient energy to keep the pool in the chamber in it's liquid state as printing progresses - you may not even be able to get enough heat in to start a print within greatly modding the temp upwards at the heater block but overall this will produce greater instability in temps at the melt chamber. That rules out the ceramic.

As for the steel options ... steel is generally much poorer than brass but it might be worth looking up the thermal conductivity before you bother. If it's similar or better it's worth a go.

[Chris botha]

hmmm thread got me thinking of sourcing bismuth in 1.7mm wire.. we use heaps of it at the factory in thailand for cold metal mould.. anyone know if its been used succefully in priters?

[caesar]

I thought about bismuth too but it has a very small transition gap from solid to liquid and the printer needs it smooshy rather than running.
Maybe mix it with some poly-(plastic) to widen the transition temp and make it work in a printer?