E3D V4 All metal hotend

[mhackney]

I can't dance!

[mhackney]

I'm doing a series of experiments on a part that I can make "retract jam" consistently. Turns out that retract speed has a bigger influence than distance (but they work hand in hand). I had been retracting at 50mm/s but slowing that down to 25 mm/s makes a BIG difference, no retract jamming and no stringing, etc. Back when I started with direct drive extruders, conventional wisdom was to retract quickly - snap the filament away from the part. This may be a problem for these new hot ends with small melt zones. It's worth doing a few experiments on your own:

Code: Select all

retract speed   retract length
15mm/s          1, 2, 4mm
25mm/s          1, 2, 4mm
35mm/s          1, 2, 4mm
45mm/s          1, 2, 4mm

and see what works best.

[McSlappy]

I have wondered this very thing! Thanks for experimenting - as soon as I get my e3d replacement I'll put these numbers in!
I bet your reel prints are a perfect stress test for any hot-end

Just an update on the e3d. I contacted Sanjay and let him know my troubleshooting wasn't successful, he was very helpful and prompt - shipped out my new e3d and trusted me to return mine to him.

If you ever have issues with their products, they'll sort it out. I love their service!

[cyrus104]

Mhackney, this is great info as I'm still working to tune my E3D-v5. Are you doing all these tests with ABS?

Thanks

[mhackney]

I'm using mostly PLA, it tends to exhibit this "hydraulic plugging" whereas I've never experienced it with ABS. I do print a lot of ABS though and the E3D is superb for it as well.

[mhackney]

Well Ok! I've done enough experimenting now to feel comfortable in the following statement:

High retract SPEEDS has a negative effect when printing PLA with E3D and Kraken hot ends (and JHeads and SeeMeCNC's too as I learned last year). You can maintain a large retraction length (4mm or so) and slow down the retraction speed to 25mm/s or less and not have any problems with skipped extruder steps or filament starving. Speed the retract up, and you will start to have occasional starvation and hear skipped steps for more "complex" parts (i.e. those that have lots of detail requiring retract). The E3D and Kraken appear to be a little more sensitive to this probably due to their much smaller melt zones than other hot ends. Simply slowing down the retract SPEED eliminates problems and you still get beautiful prints with no stringing in PLA.

[Eaglezsoar]

Well Ok! I've done enough experimenting now to feel comfortable in the following statement:

High retract SPEEDS has a negative effect when printing PLA with E3D and Kraken hot ends (and JHeads and SeeMeCNC's too as I learned last year). You can maintain a large retraction length (4mm or so) and slow down the retraction speed to 25mm/s or less and not have any problems with skipped extruder steps or filament starving. Speed the retract up, and you will start to have occasional starvation and hear skipped steps for more "complex" parts (i.e. those that have lots of detail requiring retract). The E3D and Kraken appear to be a little more sensitive to this probably due to their much smaller melt zones than other hot ends. Simply slowing down the retract SPEED eliminates problems and you still get beautiful prints with no stringing in PLA.

What did determine to be the best retract length?

[mhackney]

For my Kraken and E3D I am running 3mm and 25mm/s now. I was running 4mm and 55mm/s. That high retract was causing problems.

[Polygonhell]

It's kind of a crapshoot setting retracts on the rostock bowden, next time your printing watch the bowden tube at the fittings during the retract, I'd bet there is a good 2mm of motion before any plastic starts to be pulled back.
I did a bunch of tests on retraction length and speed, and there was never any benefit over 40mm/s which I think is what I'm running currently. The overall time of retraction is in some ways more important than the actual speed though.

FWIW I couldn't print PLA reliably in either of my two E3D hotends even with retraction disabled and I really tried, both print ABS and Nylon flawlessly, so I'd assume there is some manufacturing variance and I'm unlucky enough to have 2 bad ones, or there is some environmental factor. My final solution was to use a JHead for PLA, it takes perhaps 5 minutes to swap out which is nothing compared the print time.
I just ordered a Kraken, and out of interest a 3rd E3D, so it'll be interesting to see if it does the same thing here.

[mhackney]

I agree with your Polygonhell, the PTC fittings need to be stabilized. I'm running the E3D PTC fittings at both ends and there is NO movement there because of the way they are designed. They are great. On my old H-1 and H-1.1 and the Steves Extruder, a short fast retraction was desirable. A "snap" to stop the PLA flow. I got used to a fast retraction and "assumed" that was good for a Bowden too - maybe even more so. You know what they say when you assume - you make an "ass" out of "u" and "me".

I have PLA printing better than I've ever printed PLA with both the E3D and Kraken now. I love these hot ends. Do you have a rev5 E3D? There were some PLA issues with the v4 model.

[Polygonhell]

I have a V4 and a V5 they behave identically. I was an early adopter, I think I started this thread, Sanjay sent me the second one when I had issues with the first, I have no issue with E3D or Sanjay they did everything they could to make me happy, and I really like the way it prints ABS.
However I do think it's important to note there is clearly some variation in these things.
I tried plastic from 3 different suppliers, every temperature in 5 degree increments from 165 to 265, no retraction etc etc etc.
I could occasionally get prints in PLA out of it, but it would almost always jam during the print, it's mostly documented on my blog. In the end I decided why fight it to get prints when my Jhead produces virtually perfect PLA prints.

As I say, it could be environmental, I ordered a 3rd one, just out of interest, along with a kraken, I'm interested to see if the 3rd one is any different.

[rampeh]

mhackney, You mentioned that there were issues with PLA with the v4 E3Ds. I believe my E3D is a v4 and i've always had issues with stringing and PLA since it tends to jam when i crank up the retraction.

Do you (or anybody else reading) know what changed between v4 and v5? Is there a lip / geometry issue that causes jamming with PLA that could be fixed with some sanding, or is it something I can't fix?

[bvandiepenbos]

yes, I would agree from my experience slow retract speeds can work better than fast sometimes. I always assumed it is the longer time that helps not so much the speed.
I have not tried going as slow as 25 mm, I am going to give it a shot.

Something else I have done to create a longer time for retract is to use crazy high "Z" lifts... like 15 mm. Looks wild hoping up and down but it can help.


One feature I think could be helpful in the slicer software would be a 'dwell' feature to provide a way to pause before and after retract.
All my engraving machines have a dwell setting to give the cutter time to get to full depth before moving in X & Y, also delay to allow cutter to pull out before moving.

[mhackney]

I do not know what the difference between V4 and V5 are, send E3D an email and ask. They may have an upgrade path.

Brian, I always assumed that the retract took advantage of the thixotropic properties of the molten plastic. Basically, if you remember SillyPutty, if you pull on it slowly it stretches but if you pull quickly, it snaps cleanly. This is an extreme example and "real world" materials like PLA and ABS have different thixotropic behaviors. But there are downsides to this if the material is constrained the way it is in a hot end.

I agree that a longer Z lift is also a good area to explore. This has the effect of putting the "snap" outside of the hot end where it can do no harm with respect to "hydraulic plugging". Coming from the Cartesian world, I hadn't explored that since Z moves are pitifully slow on a Cartesian printer but blindingly fast on a delta.

[cyrus104]

What have you guys found to be the best E3D / MAX settings for T-Glase? I'm having a heck of a time on the retraction and getting it to lay down properly with a .4mm E3D (I know it should be bigger for the full T-Glase effect).

[lordbinky]

Keep your non-Newtonian behavior to yourself!

[McSlappy]

Keep your non-Newtonian behavior to yourself!

Ha ha

I have rewed excitement to do my own retract speed / length / z lift tests now. I wish I still had my old head to test Only a little more and I'll have a shiny new one to apply this knowledge to.

[mhackney]

I wish I still had my old head

- You lost your head?

[bvandiepenbos]

I do not know what the difference between V4 and V5 are, send E3D an email and ask. They may have an upgrade path.

Brian, I always assumed that the retract took advantage of the thixotropic properties of the molten plastic. Basically, if you remember SillyPutty, if you pull on it slowly it stretches but if you pull quickly, it snaps cleanly. This is an extreme example and "real world" materials like PLA and ABS have different thixotropic behaviors. But there are downsides to this if the material is constrained the way it is in a hot end.

I agree that a longer Z lift is also a good area to explore. This has the effect of putting the "snap" outside of the hot end where it can do no harm with respect to "hydraulic plugging". Coming from the Cartesian world, I hadn't explored that since Z moves are pitifully slow on a Cartesian printer but blindingly fast on a delta.

Michael, thanks I learned a new word and material property. Interesting. thanks for sharing your knowledge.
now, if I can only remember that word for the next family scrabble game, heheheheh

[Eaglezsoar]

Michael, thanks I learned a new word and material property. Interesting. thanks for sharing your knowledge.
now, if I can only remember that word for the next family scrabble game, heheheheh

He's a walking and talking encyclopedia and dictionary mixed into one! (smart too!)

[mhackney]

Just don't ask me about sports! My mind is filled with science and engineering stuff.

Another great party word - with a demonstration - is triboluminescence! Basically, light is produced when chemical bonds in a substance break. The demo is great - get a pack of official Wint-o-green Lifesavers and go in a dark room - really dark. Then put one in your mouth and chew it (the 1st break is best) with your mouth open. You will see the sparks. It freaks people out!

[Eaglezsoar]

Just don't ask me about sports! My mind is filled with science and engineering stuff.

Another great party word - with a demonstration - is triboluminescence! Basically, light is produced when chemical bonds in a substance break. The demo is great - get a pack of official Wint-o-green Lifesavers and go in a dark room - really dark. Then put one in your mouth and chew it (the 1st break is best) with your mouth open. You will see the sparks. It freaks people out!

Where do you come up with this stuff, I had to admit that one made me chuckle.
The funny part is that it is factual but not to many people come up with stuff like that.

[McSlappy]

I wish I still had my old head

- You lost your head?

Well my e3d is being replaced as we speak... And yes I did almost lose my head while troubleshooting

[Polygonhell]

FWIW I got my kraken in the mail and a 3rd E3D that I ordered at the same time (I really wanted to know if it was just me or I was incredibly unlucky), I haven't done extensive testing, but after 1 print, it sure seems like this one is a lot better behaved with PLA than the last two.

The kraken is going to require rewriring my Max, certainly not looking forwards to that.

[McSlappy]

Interesting... Perhaps there was a group of e3d's that were unfriendly to PLA...