Help on choosing the right hot end - j-head vs. magma

I'm going to order a prusa i3 from makerfarm as my first 3D printer. There are several options for the hotend and I'm not sure yet what I should order. The j-head seems to be a very good piece, many reprapers are using it and report good things about it. So I thought I'll go with this one, but then I heard about the new magma, which Colin recommended me as a beginner and I absolutely believe him, that this would be a good choice, but I still have some concerns.

The PROs to choose magma in my eyes would be:
+ faster printing
+ able to print more materials due to the higher temperature
+ Colins recommondation for it

CONs:
- doesn't print PLA
- it seems that quite a lot of users have problems with it

The point of not being able to print PLA looks like a bigger drawback to me, as I think it is a easy material to start with, biodegradable and doesn't produce too much smoke (smell). Or am I completely wrong? Do you think I won't miss PLA?
On the other hand I would like to be able to try out other materials at higher temperatures too and not only PLA and ABS...

Do you have some experiences with these? What would you recommend me?
And what about getting both hotends? Are they "easily" interchangeable?

If I'll go for the j-head would you rather suggest the 0.35 or 0.50mm nozzle? At the moment I would buy the 0.50mm.

I'm really looking forward to hearing some suggestions and then to build my first 3D printer!
Thx

J-head 0.5mm nozzle for 1.75mm filament.

Would be my choice. Especially as a beginner, if you mess up, it doesn't cost you a fortune and the J-head is very commonly available.

When you think you have learned a thing or two, maybe go for an all-metal hotend, but in my opinion, the J-head is a great start and I regret that I only got one after a year. It's rock solid, even if it means you can't go to superhigh temperatures.

Ok thanks for the quick reply!

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Ohmarinus
J-head 0.5mm nozzle for 1.75mm filament.

isn't the 0.5mm nozzle for the 3mm filament? or both?

Sounds like a reasonable argumentation to start with a rock solid hotend which is commonly available and then upgrade if necessary... I just wonder why Colin recommended me the magma.

If you are located in Europe (honestly, I don't know how much shipping would be to the rest of the world, though), you could go for the E3D hotend instead of the Magma. It's also an all-metal construction and many people including me have been printing about every material without problems, so it combines the best of both worlds with the downside that it is heavy and rather long compared to the petite Jhead. The team behind it is also posting a lot of updates and new developments in the forum.
Another European alternative might be the Ceramic Chess Hotend by 2Engineers. Practically, this is a Jhead nozzle/heater block mounted to a ceramic replacement for the plastic body. With this, you can reach temperatures up to 260°C (maximum operating temperature for the PTFE tube inside), so you can print most materials (probably >90%) with it. Size and weight should be similar to the original Jhead.

I wonder about the support for the Magma hotend because the developer behind it, Trinitylabs, practically folded. Maybe it is now produced by other manufacturers.

ya know,

I've just been reading up on some of the problems people have been having with All Metal Hotends and jaming, and I was trying to figure out why the J-Head has been so awesome with no problems.

The Thermal Expansion of PTFE Liner is ~ 100 (x10-6/K) with a conductivity of 0.25 (W/m-K)
The Thermal Expansion of PEEK is ~ 47 (x10-6/K) with a conductivity of 0.25 (W/m-K)

The designers of the these new Hot Ends have picked Stainless Steel due to the fact that it's conductivity is ~ 18.

So Stainless doesn't conduct heat nor heat up well at all. 18 compared to 0.25

But I think they failed to take into account that stainless steel also only expands at ~16 (x10-6/K)

So not only does these stainless tubes not absorb heat, but they also don't expand at all. Double Whammy.

So no wonder PLA (that expands like a mo-fo) jams in these Hot-Ends. The stainless barrels aren't expanding enough to allow the 'warm' PLA to travel through.

The reason PTFE liners work so well is because they expand with the PLA at close to a similar rate.

Stainless Steel is a terrible choice.

EDIT: Researching some more there really isn't a good material choice. If it's a thermally non-conductive material, it usually means it won't expand much either. So the only way I could see a all metal Hot-End working well is if the stainless portion is short, and over-sized.

Edited 2 time(s). Last edit at 01/22/2014 10:08AM by ShadowRam.

Thank you all for the information! I guess, I'll take the J-head to start and then I'll see what's next...

@uGen: I just bookmarked these two alternatives! Might absolutely be woth to have a look at as an alternative! And generally I prefer european based companies due to the cheaper shipping and environmental sustainability.

@ShadowRam: wow thank you very much for your detailed explanation! It's always nice to understand the reasons behind an opinion rather then only know what is "good or not so good"!

So I guess the 0.5mm nozzle for 3mm filament should be fine! What would be the advantage of the 0.35mm nozzle? If there really is one...

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ShadowRam
So no wonder PLA (that expands like a mo-fo) jams in these Hot-Ends. The stainless barrels aren't expanding enough to allow the 'warm' PLA to travel through.

As a non-engineer, it would seem to me that stainless barrel would be the more ideal solution then the worse one. If the tollerance of the inner diameter of the barrel is more consistant, then its easier to design around. If you presume that the diameter essentially remains a fixed size across a reasonable range of temperature then you know what that cavity size is. And if your extruder advances X amount of filament into the hot end, then X amount of filament is then extruded out. Where if the inner material is PTFE the thermal expansion is greater, giving a larger variance of the cavity size. Larger variance in cavity size leads to a larger variance in the amount of material extruded leading to inconsistances in print quality.

If the diameter of the bore in the barrel is such that the material expands and jambs, then it would seem to me that the bore diameter is incorrect for that sized filament, not that the material is improper for that use.

Ideally any design that has rapid thermal expansion, you want all the materials to be close/match in their expansion.
So they expand together, and don't loosen up, stress other materials, or create gaps.

But you are correct, that if you want to maintain a dimension over a range of temperatures, this is a good thing.

But PLA (which is what we are working with) does not maintain it's dimension over time.

It will heat up over time up the barrel.

And also with retractions, you are pulling hot (swelled) PLA into the transition barrel and it will get stuck there if the stainless is staying at it's diameter and not expanding with the PLA like PTFE does.

The solution 'could' be to open up the diameter of the stainless.

But you might run into the problem of 'backflow' like when trying to feed a 1.75mm filament into a 3mm hotend.

Hobbit85,

I purchased an 8" I3 kit from Makerfarm (my first 3d printer) just before Christmas. I went for the Magma hotend. I knew that I wouldn't be able to print PLA, but I've seen good reviews about it printing ABS and other materials. I have read many reports of j-heads being destroyed for a variety of reasons, including beginners construction errors. I figured that for the extra few dollars, the magma gave me extra capabilities that I would want later, and I probably couldn't kill it. It's cheaper to buy a hotend that can do PLA later (Aluhotend ~$50, J-Head ~$60, etc.) than to get the J-Head with the kit and buy an all metal later . In my case I also grabbed an E3D v5, which has excellent reviews printing PLA, at the same time from Filastruder.com. Just my two cents.


Regards,

John

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Hobbit85
Ok thanks for the quick reply!

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Ohmarinus
J-head 0.5mm nozzle for 1.75mm filament.

isn't the 0.5mm nozzle for the 3mm filament? or both?

Sounds like a reasonable argumentation to start with a rock solid hotend which is commonly available and then upgrade if necessary... I just wonder why Colin recommended me the magma.

To get a better understanding of the J-head, I gladly redirect you to it's wiki:
[reprap.org]

There you can see the MK5 has, under the title "1.75mm Conversion" a list of requirements for the brass nozzle piece.
3mm needs an opening in the barrel of 3.5mm and a 1.75mm filament needs a 2mm opening in the barrel.

You could, as an alternative, insert a piece of PTFE, however this is not recommended because then the PLA will expland too much and cause a solid block of filament in the hotend when it cools down, this block would then be 3.5mm wide and you will not be able to get that out anymore because the next time you heat up the hotend, if will probably backflow or settle and harden.

So thats why I bought a 2nd J-head for my 1.75mm conversion, and it's almost done. Now going to the gym and then I'll wrap up the electronics.

Just look on youtube for the J-head, I can recommend it to any beginner. If you damage it, you can just buy replacement parts for a small figure, as opposed to the full-metal ones that will be harder to replace only certain parts of.

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ShadowRam
ya know,

I've just been reading up on some of the problems people have been having with All Metal Hotends and jaming, and I was trying to figure out why the J-Head has been so awesome with no problems.

The Thermal Expansion of PTFE Liner is ~ 100 (x10-6/K) with a conductivity of 0.25 (W/m-K)
The Thermal Expansion of PEEK is ~ 47 (x10-6/K) with a conductivity of 0.25 (W/m-K)

The designers of the these new Hot Ends have picked Stainless Steel due to the fact that it's conductivity is ~ 18.

So Stainless doesn't conduct heat nor heat up well at all. 18 compared to 0.25

But I think they failed to take into account that stainless steel also only expands at ~16 (x10-6/K)

So not only does these stainless tubes not absorb heat, but they also don't expand at all. Double Whammy.

So no wonder PLA (that expands like a mo-fo) jams in these Hot-Ends. The stainless barrels aren't expanding enough to allow the 'warm' PLA to travel through.

The reason PTFE liners work so well is because they expand with the PLA at close to a similar rate.

Stainless Steel is a terrible choice.

EDIT: Researching some more there really isn't a good material choice. If it's a thermally non-conductive material, it usually means it won't expand much either. So the only way I could see a all metal Hot-End working well is if the stainless portion is short, and over-sized.

I've run quite a bit of PLA, ABS and PC through my E3D with no problems (besides the PC having too much moisture). I've even switched from ABS to PLA midprint to get a dual color print...materials are different because I wanted those colors and those were the materials I had the color in.

I sell the original J-Head in my store because it just works. Stay away from anything by trinitylabs. All metal hotends are improving but they are more finicky to get printing right if you want to use a range of materials.

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I currently print only with PLA using the E3D. I have had jheads as well and never had any issue with any of them, other that the cheap ebay ones.

Oh, btw I got the J-head from reprapworld, works fine. I've heard the Danish seller doesn't have such good ones though, but I haven't tried them and apparently he does have a really good MK8 drive gear for a direct drive extruder.

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tjb1
I've run quite a bit of PLA, ABS and PC through my E3D with no problems (besides the PC having too much moisture). I've even switched from ABS to PLA midprint to get a dual color print...materials are different because I wanted those colors and those were the materials I had the color in.

The E3D one does seem to be less prone to problem compared to the others.

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ShadowRam
So Stainless doesn't conduct heat nor heat up well at all. 18 compared to 0.25

But I think they failed to take into account that stainless steel also only expands at ~16 (x10-6/K)

So not only does these stainless tubes not absorb heat, but they also don't expand at all. Double Whammy.

I get the sense that you have no idea what those numbers mean. 18 means it's a far better conductor of heat than PEEK at .25, about 72 times better in fact. It's just low for a metal. That goes the same for "absorbing" heat. You are correct that its thermal conductivity makes it less desirable than PEEK, but for exactly the opposite reason from what you've stated.

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ShadowRam
So no wonder PLA (that expands like a mo-fo) jams in these Hot-Ends. The stainless barrels aren't expanding enough to allow the 'warm' PLA to travel through.

The reason PTFE liners work so well is because they expand with the PLA at close to a similar rate.

No...just no. You're talking about expansion from a PEEK tube on the order of 0.5-1% over a stainless tube at typical hot end temperatures, which is below typical tolerances in filament diameter, and far below the clearance designed into the tube already. The reason PTFE liners work so well is because of their incredibly low coefficient of friction along with low thermal conductivity. If a stainless barrel is jamming consistently it needs better cooling.

My vote:
start of with an "official" j-head. You should be able to find it in a variety of sizes. I've found 0/5/0.4/0.35/0.3/0.2mm.

To start off with generic printing go for a 0.5mm or 0.4mm
If your focus will be small/detailed stuff then start with a 0.4mm or 0.35mm and then consider smaller once things are good and you've burnt through some plastic.

I just put a new JHead MKV from hotends.com on my Makerfarm 8" i3. It works great, just make sure you get the right groove mount for it if you decide to get an MK V from hotends.com. The Makerfarm Jhead is an MK IV, whereas the Jhead coming from hotends.com is an MK V. The MK IV groovemount isn't compatible with an MK V Jhead. The correct groovemount is available from makerfarm for $7, so just make sure you get that if you want to go to an MK V Jhead.

As far as the all-metal hotend goes, I know someone locally that didn't have much luck with his. I think he ended up getting and E3D. IMHO you should just go with the Jhead. It might not have the versatility of the all-metal hotends, but if you're just starting out I think it's better to go with tried-and-true.

Hi everyone,

thank you very much for all the advice! Really apreciate it!
I just ordered the kit with the jhead... if i need a all metal hotend later, I'll get it then...

can't wait until the kit arrives!

I've used the jhead for a few years. I think it's a good hotend, and the price is right. It's not how I would design a PTFE hotend, but it gets the job done and has very rarely created headaches for me. Really the only complaint that I have with it is that it can leak slightly over time at the PEEK/brass connection. I think you can tighten everything up, but I worry about cracking the PEEK. It's not really that bad, so I just deal with it.

I know all-metal is all the rage right now, but I personally like PTFE as the material that carries the filament up to the melt zone. If you're printing with "the usual" materials like 99% of reprap users, then it works great. I'd be willing to try an E3D hotend since it gets good reviews and it's not excessively expensive. I don't believe that it would necessarily be better than a jhead, but it seems like a quality part.

Just a sidenote, I found the reprapworld 3mm/0.5mm J-head much easier to work with than the 1.75mm/0.5mm J-head. Somehow cooling is much harder than with the 3mm version. Got it to work now, and works great, but just prepare to really 'need' a good fan shield pointed on the J-head PEEK.

Crap, So I just ordered my Makerfarm i3 8" with the .35mm J-Head hotend...and Im a noob to 3d printing...Did I just screw myself??

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Robdizz
Crap, So I just ordered my Makerfarm i3 8" with the .35mm J-Head hotend...and Im a noob to 3d printing...Did I just screw myself??

You'll be fine. The 0.5mm nozzle is more forgiving, but you should be ok with the 0.35mm nozzle. Are you using 1.75mm or 3mm filament?

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