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3D printing: some thoughts on all-metal hotends.

In the world of RepRap, all-metal hotends have been a big deal lately.

Do you really need one?

On the one hand, they promise the ability to print in amazing new and exotic, high temperature materials with seemingly unlimited posibilities.

They also serve to calm the nerves of those (myself included) who have had the unfortunate experience of looking over at your printer, only to discover that you have inadvertently gathered field data on the melting point of PEEK, PTFE, or some other polymer. Maybe you’ve been lucky enough to salvage the brass parts after the puddle of goo has finally cooled, maybe not.

So why have we been making hotends out of plastic anyway?  Couldn’t we use a metal tube and call it good?

Well, it turns out there are some problems with that approach, which are beyond the scope of this article, but suffice it to say that nearly all of them could be largely solved by using a PTFE (commonly known as Teflon) liner.  This keeps the filament pathway smooth, sealed and unobstructed, and provides a very low-friction pathway to allow filament to proceed, even if it is a little bit oversized or oddly shaped.

The problem still arises, though, that there is a crucial piece of the hotend that is temperature-limited:  PTFE generally has a maximum operating temperature of around 260 degrees C.

Enter the current generation of the all-metal hotend.

There are now a number of new and promising all-metal hotends on the market.  Most of them do a really good job printing in ABS.  A lot of them, though, are subject to mild to severe jamming when printing in PLA (some designs actually do a fantastic job of printing in PLA, but not many).  For some folks this is fine, but I find PLA to be way too useful to give up, unless I was getting something REALLY good in return.

Losing out on PLA is not the only price of admission, of course.  As I write this, an all-metal hotend will separate you from somewhere between 150% and 200% more of your hard-earned currency when compared with a PTFE lined hotend.

So, what exactly do you get for twice the cash and the potential loss of PLA?

Not long ago, I had a brand new, high-performing all-metal hotend in my hot little hand, and I wanted to see just what it could do.  So I went to one of my favorite filament suppliers, Makergeeks.com,  to see just what kinds of new, wonderful, and exotic materials were now available to me.   At that time, my experience had been limited to ABS, PLA, and a couple of rolls of Taulman Nylon.

Of course, what I found is the only current, common printing material that needs to be extruded significantly hotter than ABS is polycarbonate, which is usually extruded at around 300 degrees C.   It also generally costs more than twice as much as ABS or PLA.

I am currently waiting for a spool of PC to arrive, and I look forward to sharing my experience printing with it, but that’s for another post.

So, for up to twice the price, you get to print in polycarbonate.

Is that all?

Well, no.  The lack of a polymer liner does have some significant maintenance implications.  An all-metal hotend can be removed and dropped whole into a container of solvent for a deep cleaning, or even heated with a torch if need be.

There is also the possibility that an all-metal (or even a “mostly metal”) hotend can allow for faster printing.  The idea is that the metallic construction can withstand higher internal pressure, so the extruder can then stuff filament into the hotend more quickly, giving a higher rate of extrusion.  This, of course, assumes that the hotend is mounted in a printer which is otherwise mechanically capable of printing quickly enough.

So do you need an all-metal hotend?

If you see a need to print in polycarbonate, then yes, you do.

If not, you’ve got a decision to make.  If you’ve got a solid, robust printer that can move the carriage around very quickly, the notion of easy recovery from a disaster-level jam appeals to you, and the price doesn’t turn you off, then an all-metal hotend is well worth looking into.

15 comments to 3D printing: some thoughts on all-metal hotends.

  • Flag

    what hotend is better? e3d or aluhotend ?

    • I get that question a lot. Here is the answer: If you need an all-metal hotend, the E3D is the way to go. If you don’t, then save the extra cost and go for the Aluhotend.

  • Flag

    if you just want to print pla and abs… is there no difference between them (print quality, safety, speed,…)? or would you go for a complete other hotend?
    at the moment i have the magma hot end and i printed only abs. i ordered some pla and read about jams when you try to extrude it with the magma. so i want to go for a hotend for abs and pla. do you have any advice?

    • Now we’re talking! 🙂

      With PLA and ABS, my results from both of those hotends are actually very similar. Given the situation you are describing, I’d probably tip slightly in favor of the Aluhotend for the following reasons:

      1) The Aluhotend is shorter. The E3D’s greater length means that it consumes some of your Z-axis. If you’re using the auto bed-leveling, you’ll also need to mount a longer probe arm.

      2) The E3D cooling fan is quite loud. To be honest, it’s much more noticable on a printer that is fitted with bushings rather than bearings, but it’s definitely noticeable.

      3) The E3D is, depending on the exchange rate at the time and the place you order it, close to twice the cost of the Aluhotend.

      4) The Aluhotend will fit (possibly tightly) in the aluminum mounting plate that your Magma is in right now. The E3D will require a thicker mounting plate (there’s one on Thingiverse that works very well).

      Having said that, the E3D is, quite frankly, the best performing all-metal hotend I have used. It has not jammed on me once, and has required a surprisingly small amount of tuning and calibration to sing beautifully.

      Really, they are both very well designed and manufactired parts, and any complaints I have are extremely small (like fan noise). You won’t go wrong either way, it’s just a matter of looking at your needs and your budget, and deciding which is a better fit.

      Hope that helps!

  • Flag

    Thank you for so much detailed information! Yes i use auto bed-leveling (thank you for your instructions btw!!!!)
    i assume that on my current configuration (magma + bed leveling) its easier to install the aluhotend and because its cheaper i ordered the AluhotendV5 😀

  • Flag

    Hi!
    I just got my PLA. I tried to print it with my magma and it worked! No jams or other failures.
    Now i wait on my aluhotend to see the differences.

    • That’s great news! If you don’t mind my asking, at what temperature and speed were you printing? Have you had a chance to try some longer/larger prints? From what source did you get the PLA, and what color is it?

      You’re seeing success where other people haven’t, that’s very exciting!

  • Flag

    I know! I read about a impossible thing to get any extusion but on my printer it seemes to be no problem at all.
    My longest print today was 1h45m and tomorrow i will do a even longer print. I printed at 210°C and 50mm/s (I will try higher speeds).
    The parts are pretty nice (better than my ABS prints) and didnt warp.

    I have 1kg orange PLA and the filament rolls label says:

    Orange PLA 3mm
    N.W: 1.0KG
    Print Tem:190-220°C
    Batch No:2013-09-27

    I ordered it from RepRap Austria: http://www.reprap.cc/ for 25€

  • errehache

    First off thanks for all the help, you have been a great guide for me. I have the autobed setup because of your guides. I also recently bought the e3d. I have a quick question regarding the define temp. Their blog mentions that when using the semitec thermistor on should set the marlin software as:

    #define TEMP_SENSOR_(0,1,2) 5

    But how do I set on the marlin… do I subsitute or comment all theTEMP_SENSOR and leave the above #define or just change the first one?

    #define TEMP_SENSOR_0 5
    #define TEMP_SENSOR_1 0
    #define TEMP_SENSOR_2 0
    #define TEMP_SENSOR_BED 6

    Also, for the E3D, do you have a secondary fan to cool pla?

    Thanks again!

    • You just need to change the first one. The set of four #defines you have should work fine. As a side note, though, since you’ve got the bed sensor set as thermistor #6, make sure you’ve copied over the Makerfarm thermistortables.h.

  • TRS

    I wanted to let you know that I have been following your blog and it has helped guide me through the setup and operation of my Makerfarm Prusa. I just ordered an E3D hotend and was wondering what print speeds you had success with. Thanks!

    • Sorry for the late reply!

      I’ve been able to go up to about 100mm/s for perimeters with the i3 on a part that lent itelf to going fast (lots of long, smooth curves and very few retraction moves). I think the E3 can actually handle faster print speeds, but the design of the i3 is the limiting factor.

  • Greg

    Just out of curiosity do you use 3mm or 1.75mm filament?

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