Prusa Nozzle Released

I have few problems now, but it jams from time to time, usually either on restart or at the 1 hour mark.

Black PLA 235°C. long fast retracts 3mm at 20 mm/s are the only method I found to control leaks (somewhat) and strings (very good). Bed at 65°C on first layer then 50°C.

this pic show on the left a filament that stripped and so jammed. the bulb length is > 15 mm.
on the right a normal filament of about 7 mm.

bulb is 3.14 on an original diameter of 3.01.

This on prusa v2 with 2! 40 mm fans with a lot of airflow. those fans are 20 mm thick and push a lot of air.

It is obviously an extrusion force problem caused by heat creeping in the barrel, but i cannot put temp higher as it is already very leaky

hobbed bolt stay cool

The printer is offline for a couple of days until I can convert it into an i3. Busy with shipping frame and rod kits, but that's a good problem to have.

My settings are almost identical to alj_rprp as I got them from this thread. I wonder if some of these heat issues are with i2 style X carriages where the plate mounts between the extruder and the carriage. Hobbed bolt is cool but the mounting plate is warm. I also had a stripped PLA issue just prior to jamming.

My prints are from black PLA from Makerfarm. I did have some distortion issues around the time it jammed but I thought they were due to extrusion stress but now that I look it's possible it could be heat related.as the consistency of the material is more brittle the closer to the hot end. The feel and flexibility of the material returns about 300 mm or so from the hot end. The bulb at the jam is 3.14 mm with the effected length of the material between 2.94 and 2.99 mm in diameter. The average and calibrated diameter is measured at 2.96. It's pretty close size wise but there is definitely a change in state of the material for the first 200 mm or so that isn't there in the raw material or with the previous J Head though I'm printing 45-50* C hotter with the Prusa Nozzle.

I see problems are only PLA related. As I use ABS will I have any problems?

ive tried 2 kinds of black ABS, and 1 kind of red red ABS. no matter what ive tried the filament slips and the hobbed bolt eats into it and you can hear the extruder clicking, missing steps. i spent most of the past weekends trying to get it working to no avail. ive also tried yellow and translucent green PLA. i must have over 100 .5mm thin wall calibration tests that messed up on the 1st or second layer. ive since switched back to the budaschnozzle and had quality back to back to back to back 2 hr prints. it seems there is wayyy to much friction in the prusa nozzle because it never jammed or slipped on retraction, only during extrusion. some of the plugs i was removing had a big amount of air bubbles near the tip, im thinking it sucked air into it during retraction. ive tried different temps, different tightnesses on the extruder spring, different filaments, and different retraction speeds and lengths. ive tried most everything i can think of, in hopes it wasn't the nozzle. the fact that the budaschnozzle produced quality prints makes me think the problem lies within the nozzle. i was extruding at 295C(the max is 300C) and it was till jamming.

What about adding a very small amount of oil to filament?
I have read that stratasys's ABS contains a bit of oil.
F.e. fire point of gun oil is about 400C
Someone on ultimaker forum wrote about successfull adding oil into bowden...

Kinda bummed that these promising new metal nozzles (the E3D and this) are being plagued with these issues. I guess it's all a necessary step in the evolution of all-metal hotends though, and will hopefully be worked out in time. If these issues don't get worked out soon enough, I may be forced to go with the reprappro hot ends.

thainfamousnate have you tried going hotter? It seems that SS doesn't conduct heat very well, maybe you need to go hotter then you expect.

@maddox

Welcome to the bleeding edge. Put on your big boy pants and buckle up, the ride is a bit bumpy.

Maddox: i've split my all metal hotend into the versions for this reason, where one is specifically for pla, and uses a ptfe liner to mitigate the increasing friction as the heat in the pla rises, however this has so far only been a relatively small problem statistically in 3mm hotends, and fairly rare in 1.75mm ,

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-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

Maddox, both hotends work very well with PLA, the Prusa is a bit hard to setup for it but it can be done.
In fact, once setup correctly, it prints a translucid filament that never worked reliably in my J-head clone.

The only drawback it the amount of leak due to high temps. And you need to be cautious on restarts, not letting the head stand still while being hot.

I had exactly 0 print problems with the E3D but it really needs the fan to be rigged to run continuously.

And both hotends give superior print quality.

It's a narrower window. I was able to solve the jam issue. Mechanically I wrapped the heater block in polyimide tape and start the fan when the hot end starts to heat. There is heat transfer up the filament. A print temp of 240*C seems to be my lowest possible. I slowed the speed and set the retraction to 1 mm @ 20 mm/sec and removed retract on layer change. The ooze is minimal, better than with the J Head. It does perform less reliably after a few runs, 20 mins or so. I haven't started anything long just yet. At this point I'd reckon it's down to heat control/ print speed ratio.

jzatopa, ive tried up 300C, the highest recommended temp for ABS. i dont think the thermistor is rated for much higher temps...

Maddox & JollyGrimReaper

Just to clear things up, the problems with jamming in some of the parts I shipped (E3D Nozzles) are absolutely a manufacturing defect, that is specifically confined to 1.75mm nozzles that were drilled with a single duff drill bit that wasn't replaced soon enough on the CNC. Paradoxically all the 3mm hotends have performed without issues.

Having an ultra-short thermal transition zone does absolutely get rid of jamming issues with PLA et al with no PTFE liner needed, no fancy print conditions or settings needed. See makerbot hotend designs for example. The only downside is that you then really need active cooling to maintain proper temperature gradients.

Sanjay

Sanjay: have you got your own cnc lathe or do you outsource?

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-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

SanjayM Wrote:
-------------------------------------------------------
> Having an ultra-short thermal transition zone does
> absolutely get rid of jamming issues with PLA et
> al with no PTFE liner needed, no fancy print
> conditions or settings needed. See makerbot hotend
> designs for example. The only downside is that you
> then really need active cooling to maintain proper
> temperature gradients.

What would you say quantifies as ultra short? A few mm?

I've implemented some mechanical changes as noted above and also mounted the nozzle to the bottom of the carriage to improve air flow. It works for longer periods of time but after about 30-40 mins the exact same issue happens. It's much as JGR says. Heat is traveling up the filament increasing the friction in the nozzle until it strips the filament at the hobb. Nearly 70 mm each time regardless of brand of PLA, retraction settings I've tried, speeds, temps. It does the same thing in the same place. About the only thing I've been able to control is the duration the machine can run and get a print without jamming. I've compared lengths of the jammed material to lengths that were taken out prior to the machine jamming and in every case it indicates that temperature through the material is a likely cause of increasing tension on the extruder. Prior to jamming the extruder starts dropping steps producing inconsistent material deposition sporadically throughout the print. A few layers later it will jam. If you stop the prints and start looking at the filament you can see the marks in the material from the hobbed bolt due to increased resistance. When an equal length taken from the same reference point (between the transition zone and the hobbed bolt) good extrusion shows no marks, jammed or about to jam extrusions start showing filament damager from the tension on the hobbed bolt. I'm not fluent enough in hot end design to say if this is an issue with the part, design or in my implementation and configuration but I do know that I can replicate the issue pretty much at will.

Like Crispy says, it's the bleeding edge and I'm willing to go that extra mile to check it out. I don't know at this point first time builders are going to be able to have the basic knowledge and experience to use all metal hot ends at this point.

Every other all metal hot end I can think of has a very short transition zone. I have never understood how this could work with such a long one. My experiments here: [hydraraptor.blogspot.co.uk] and here: [hydraraptor.blogspot.co.uk] show it doesn't work. The only difference with this one I can see is that it is polished inside. However polished stainless steel is nowhere near as slippery as PTFE and as far as I know that is the only material that has worked successfully with a long transition zone.

So the odd thing is why this works for some people, not why it doesn't. I would guess a small fan blowing on the barrel would help a lot.

---

[www.hydraraptor.blogspot.com]

nophead Wrote:
-------------------------------------------------------
> Every other all metal hot end I can think of has a
> very short transition zone. I have never
> understood how this could work with such a long
> one. My experiments here:
> [hydraraptor.blogspot.co.uk]
> -point.html and here:
> [hydraraptor.blogspot.co.uk]
> ntal-extruder.html show it doesn't work. The only
> difference with this one I can see is that it is
> polished inside. However polished stainless steel
> is nowhere near as slippery as PTFE and as far as
> I know that is the only material that has worked
> successfully with a long transition zone.
>
> So the odd thing is why this works for some
> people, not why it doesn't. I would guess a small
> fan blowing on the barrel would help a lot.

from all the testing i've done the pla itself is a huge factor in it, everything from color to whats in it ( eg pla is often "bulked" up with starch) there's just too many variables in just the filament let alone everything else going on around the hotend,

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

From what I've seen, PLA has hardly been the selling point of all-metal hot ends.

The selling point for these hot ends have been about how hot they can go and that they can extrude PEEK and Nylon.

Most of the hot ends being developed and sold can only be regarded as being at the experimental stage and not at the cutting edge or bleeding edge stage.

Did anybody ask for test history details to show that their hot end purchase was going to be fit for purpose?

I didn't, and my QU-BD all-metal hot end purchase was binned after a couple of hours of trying to make it work.

---

Blog - [airtripper.com]
Extrude Filament Force Sensor - [airtripper.com]

crispy1 Wrote:
-------------------------------------------------------
> @maddox
>
> Welcome to the bleeding edge. Put on your big boy
> pants and buckle up, the ride is a bit bumpy.


Thanks Chief I understand the nature of these things, and I have some things I'm working on myself as well, but with regards to the hotends, I was hoping that this would be one area where I could remain strictly a 'consumer' and not have to delve much into the troubleshooting and design analysis myself. I'm also willing to pay to not have to do that, but if I have to personally figure out what works and why, then I may as well save money and manufacture my own hotends (which is what I was hoping to avoid).


thejollygrimreaper Wrote:
-------------------------------------------------------
> Maddox: i've split my all metal hotend into the
> versions for this reason, where one is
> specifically for pla, and uses a ptfe liner to
> mitigate the increasing friction as the heat in
> the pla rises, however this has so far only been a
> relatively small problem statistically in 3mm
> hotends, and fairly rare in 1.75mm ,

How has the printing of PLA been in the 'LT' version hotends?


alj_rprp Wrote:
-------------------------------------------------------
> The only drawback it the amount of leak due to
> high temps. And you need to be cautious on
> restarts, not letting the head stand still while
> being hot.

Considering I'm going to be running 2 or 3 nozzles together (and consequently, because 2 of the 3 nozzles will be standing unused while the 3rd one prints, leaking while the other nozzles print is going to be a significant obstacle), so I think I just wrote off the Prusa nozzle for use in my personal case. I need a super sharp transition zone and probably a long retraction for the nozzles that are temporarily not in use, so the Prusa nozzle looks like it' might not be for me.



SanjayM Wrote:
-------------------------------------------------------
> Maddox & JollyGrimReaper
>
> Just to clear things up, the problems with jamming
> in some of the parts I shipped (E3D Nozzles) are
> absolutely a manufacturing defect, that is
> specifically confined to 1.75mm nozzles that were
> drilled with a single duff drill bit that wasn't
> replaced soon enough on the CNC.

I've been closely following your thread, and none of the people who had the jamming issues (hendo420, Polygonhell, extin) have received new parts and rectified the issue, so they haven't been able to verifiy whether or not it is 'absolutely' a manufacturing defect. I do, however, look forward to them getting their parts and verifying that the issues are indeed resolved with the newer batch.


> Having an ultra-short thermal transition zone does
> absolutely get rid of jamming issues with PLA et
> al with no PTFE liner needed, no fancy print
> conditions or settings needed. See makerbot hotend
> designs for example. The only downside is that you
> then really need active cooling to maintain proper
> temperature gradients.

Being able to maintain relatively steady-state temp gradients in the melt/transition zone seems to be pretty critical to a consistent performing all-metal hotend. For me personally, active cooling is no issue and a small price to pay for consistency/quality.


vegasloki Wrote:

> Heat is traveling up the filament
> increasing the friction in the nozzle until it
> strips the filament at the hobb. Nearly 70 mm
> each time regardless of brand of PLA, retraction
> settings I've tried, speeds, temps. It does the
> same thing in the same place. About the only
> thing I've been able to control is the duration
> the machine can run and get a print without
> jamming. I've compared lengths of the jammed
> material to lengths that were taken out prior to
> the machine jamming and in every case it indicates
> that temperature through the material is a likely
> cause of increasing tension on the extruder.

The visible transition in the filament is around 70mm in length at failure, or the hobbed bolt marks left a track that is 70mm long at failure? Just trying to make sure I understand what you're saying. If the plate and the top of the nozzle are warm/hot, maybe it could use some more cooling, perhaps via some extra fins like mrc proposed on page 4. Maybe you could find a way to actively cool the filament as well, like how the 'Mid air nozzles' of the Dimension SST 1200es blow air directly over the filament, as seen here in this pic:





nophead Wrote:
-------------------------------------------------------
> My experiments here:
> [hydraraptor.blogspot.co.uk]
> -point.html and here:
> [hydraraptor.blogspot.co.uk]
> ntal-extruder.html show it doesn't work.

Do you by chance have any blog posts/documentation regarding the conical taper that in the other thread you mentioned reduced your extrusion pressure by a factor of 3?



BTW Airtipper, this is a perfect use case for your extrusion force strain-gauge setup.

Edited 1 time(s). Last edit at 06/04/2013 08:35AM by maddox.

Here is where I added a taper: [hydraraptor.blogspot.co.uk]

And here is where I measured how much better it was: [hydraraptor.blogspot.co.uk]

Here is my final design: [hydraraptor.blogspot.co.uk]

It works very well with all the materials I put through it: ABS, PLA, PMMA, HDPE. The heat was removed by the Z carriage of Hydraraptor but a friend make one with a cylindrical vaned heatsink and a small fan like the E3D one and it worked fine with PLA.

The aluminium nozzle is not the best idea as the bore got bigger over time. My friend used copper, but that is very heavy and takes longer to heat.

The interesting thing about the Stratasys ones is they seem to have a very long melt chamber after a sharp transition.

---

[www.hydraraptor.blogspot.com]

maddox: my Aluhotend-1.75mm-LT's performed really well with with pla, and the Aluhotend-3mm-LT's have seen a lot of abuse by the people testing them and so far not one problem so those will be up for sale as soon as my ptfe tubing arrives,

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

thejollygrimreaper Wrote:
-------------------------------------------------------
> maddox: my Aluhotend-1.75mm-LT's performed
> really well with with pla, and the
> Aluhotend-3mm-LT's have seen a lot of abuse by the
> people testing them and so far not one problem so
> those will be up for sale as soon as my ptfe
> tubing arrives,

may I ask you to comment message about Magma issues in Aluminatus thread? [forums.reprap.org]

karabas Wrote:
-------------------------------------------------------
> thejollygrimreaper Wrote:
> --------------------------------------------------
> -----
> > maddox: my Aluhotend-1.75mm-LT's performed
> > really well with with pla, and the
> > Aluhotend-3mm-LT's have seen a lot of abuse by
> the
> > people testing them and so far not one problem
> so
> > those will be up for sale as soon as my ptfe
> > tubing arrives,
>
> may I ask you to comment message about Magma
> issues in Aluminatus thread?
> [forums.reprap.org]
the number of people who have experienced issues with the magma are relatively tiny compared to how many of them are out there in the wild ,even with the defect ,

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

nophead Wrote:
-------------------------------------------------------
> Here is my final design:
> [hydraraptor.blogspot.co.uk]
> omise-extruder.html

That last blog post was back in '09, and you were having clogging issues. What was the problem and resolution with that? What hotend do you use on your personal printer(s) now?

> The interesting thing about the Stratasys ones is
> they seem to have a very long melt chamber after a
> sharp transition.

I found that interesting as well. And they use stainless steel tubing as well in that long transition, no PTFE.

maddox Wrote:
-------------------------------------------------------
> That last blog post was back in '09, and you were
> having clogging issues. What was the problem and
> resolution with that?

I think it was just some particle blocking it. I tightened it more to stop it leaking and it was reliable after that as long as the filament was not too small. The pipe I used to make it had an internal diameter of 3.6mm, which is too big for 3mm filament that is actually only 2.85 +/-0.1mm. It worked fine with 3mm filament that is 3.0 +/- 0.1mm, A smaller bore solves that. The filament I get now is all 2.85mm so I would use a 3mm bore.

I haven't used any cheap filament cut with starch though.

>What hotend do you use on your personal printer(s) now?

I use J-Heads because they are smaller, lighter and don't need a fan. I have an E3D one I have yet to try for higher temperature plastics.


> I found that interesting as well. And they use
> stainless steel tubing as well in that long
> transition, no PTFE.

Yes but the transition happens at the entrance I think, so all the stainless is at the melt temperature, so friction is not an issue. They used to have a PEEK disk at the entrance. Not sure if the version above does.

---

[www.hydraraptor.blogspot.com]

maddox Wrote:
-------------------------------------------------------

> The visible transition in the filament is around
> 70mm in length at failure, or the hobbed bolt
> marks left a track that is 70mm long at failure?

The marks get deeper leading to the hobbed bolt where the material is stripped by the bolt. Based on the bulbous nature at the point 70 mm down from the hobbed bolt I'm thinking that's where the jam is as that builb and the hob marks are the primary differences between a successful extrusion and a jam.

@Airtripper

I agree that the primary benefit of an all metal hot end is for material that requires a hotter temp. I would disagree that this isn't cutting edge tech. I would argue that alpha/beta/early adopters/experimental are indeed on the cutting edge. Much as your filament tension feedback mechanism. (great idea and implementation) Like many other machine tools (which is basicaly what a Reprap is) there are different components and sometimes different machine technologies that need to be employed for a certain material or result. This appears to me to be one of those points in the life cycle of Reprap where for optimal results it may be best to use different extrusion technologies for a given result.

I've accepted that PLA likely isn't the best choice for this part and that other than flexibility to print hotter it offer no benefit for using PLA and in fact for some adds more issues than it solves. Perhaps the next step along with the design of different extrusion tools is the capability to more easily change tooling in the machine. Some are doing this now but it doesn't seem to be popular outside a small group of users.

vegasloki Wrote:
-------------------------------------------------------
> maddox Wrote:
> --------------------------------------------------
> -----
>
> > The visible transition in the filament is
> around
> > 70mm in length at failure, or the hobbed bolt
> > marks left a track that is 70mm long at
> failure?
>
> The marks get deeper leading to the hobbed bolt
> where the material is stripped by the bolt. Based
> on the bulbous nature at the point 70 mm down from
> the hobbed bolt I'm thinking that's where the jam
> is as that builb and the hob marks are the primary
> differences between a successful extrusion and a
> jam.

That bulb you say was my nightmare when extruding PLA with my Budaschnozzle 1.2

The matter is that PLA begins to expand when it reaches certain temperature, before melting. In my case, it happens just in the PTFE barrier, and unless I cool it with a fan, extrusion and retraction gets impossible eventually.

It's a matter of time too. That expansion doesn't happen instantaneously, it happens slowly, and if you print fast enough, and don't leave the filament still and heated for a long time, you wouldn't even notice.

Anyway, it gets solved with a good cooling system. When I get my prusanozzle, I'm planning to make a carriage with the prusanozzle(s) raised and inside a cooled case, so the cool air impacts directly on the tubing. (Also, the fan will be needed to prevent the carriage from melting).

elgambitero Wrote:
-------------------------------------------------------
> Anyway, it gets solved with a good cooling system.
> When I get my prusanozzle, I'm planning to make a
> carriage with the prusanozzle(s) raised and inside
> a cooled case, so the cool air impacts directly on
> the tubing. (Also, the fan will be needed to
> prevent the carriage from melting).


Even with two fans it won't cool PLA enough on the test i2 so that it can print reliably over time. At this time I don't believe this is the best choice for lower temp material. My priority is to print and at this point the Prusa Nozzle isn't reliable with PLA in applications where other parts perform better with less trial and error.

At this point I'll try some ABS through it and see how that works though I'll likely sel it in the end. I don't regret buying it though at this point it's more trouble than it's worth.

would anyone be interested in a used .4 prusa nozzle?

thainfamousnate Wrote:
-------------------------------------------------------
> would anyone be interested in a used .4 prusa
> nozzle?


How much