Small blobs since changing to E3D hot end

Can anyone who is getting good print quality from an E3D v6 on a delta or other machine with a long Bowden tube share their settings?

I recently replaced the Jhead hot end on my delta by an E3D v6. Now my standard Escher Lizard test print comes out with lots of small blobs on it:



The print on the left was done using the Jhead, the one on the right using the E3D. So far I have tried:

- Reducing the retraction from 6mm (as used on the Jhead) to 2mm (the maximum recommended by E3D)
- Reducing temperature to 180C after the first layer
- Increasing temperature to 205C

What else should I try? I currently have retraction speed set to 45mm/sec and extruder acceleration set to 1000mm/sec^2. I am using slic3r 1.2.6. Print speed is 50mm/sec for perimeters, 100mm/sec for infill. The same test print also comes out well on my Ormerod, which has a Bowden-fed RepRapPro hot end, although I have to use slower print speeds on that machine.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Did you try lowering infill speed? Might be too much preasure left in the tube becouse of too high speed. Having long bowden tube will increase the lag bowden suffers from.

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Quote
dc42
Can anyone who is getting good print quality from an E3D v6 on a delta or other machine with a long Bowden tube share their settings?

I recently replaced the Jhead hot end on my delta by an E3D v6. Now my standard Escher Lizard test print comes out with lots of small blobs on it:

2015-06-20%2020.13.51.jpg

The print on the left was done using the Jhead, the one on the right using the E3D. So far I have tried:

- Reducing the retraction from 6mm (as used on the Jhead) to 2mm (the maximum recommended by E3D)
- Reducing temperature to 180C after the first layer
- Increasing temperature to 205C

What else should I try? I currently have retraction speed set to 45mm/sec and extruder acceleration set to 1000mm/sec^2. I am using slic3r 1.2.6. Print speed is 50mm/sec for perimeters, 100mm/sec for infill. The same test print also comes out well on my Ormerod, which has a Bowden-fed RepRapPro hot end, although I have to use slower print speeds on that machine.

I suggest you reread the E3D page . . . 2mm is for standard extruders . . . for Bowden, they suggest starting at 5mm:

"Excessively long retractions will cause issues by dragging soft filament into cold areas, because of the PTFE liner however Lite6 can cope with quite aggressive retractions without sticking. For direct extrusion systems you should use anywhere from 0.5mm-2.0mm, for bowden systems you might want to go up to 6mm. Retraction beyond 8mm should never be necessary. A good starting point for direct systems is 1mm, and 5mm for bowden setups."

(Just noted that is for the Lite, and not base v6 . . . . would have thought they would be the same, but I guess the liner in the Lite makes it mlre tolerant . . .)

- Tim

Edited 3 time(s). Last edit at 06/21/2015 02:01PM by tadawson.

Quote
tadawson
I suggest you reread the E3D page . . . 2mm is for standard extruders . . . for Bowden, they suggest starting at 5mm:

"Excessively long retractions will cause issues by dragging soft filament into cold areas, because of the PTFE liner however Lite6 can cope with quite aggressive retractions without sticking. For direct extrusion systems you should use anywhere from 0.5mm-2.0mm, for bowden systems you might want to go up to 6mm. Retraction beyond 8mm should never be necessary. A good starting point for direct systems is 1mm, and 5mm for bowden setups."

(Just noted that is for the Lite, and not base v6 . . . . would have thought they would be the same, but I guess the liner in the Lite makes it mlre tolerant . . .)

- Tim

Yes, that's for the Lite. For the standard E3Dv6, they say this:

"Excessively long retractions will cause issues by dragging soft filament into cold areas. E3D-v6 hotends need less retraction than most hotends. For direct extrusion systems you should use anywhere from 0.5mm-1.0mm, for bowden systems you might want to go up to 2mm. Retraction beyond 2mm is likely to cause issues."

2mm does sound rather short for a Bowden extruder. Perhaps Bowden systems are better off using the Lite version?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

With the E3D v5, a long Bowden tube, and a geared stepper motor extruder, I'm running 6.0mm retraction @ 100mm/sec (acceleration adjusted in firmware).

Are you sure that some of the blobs are not being caused by wet filament?????

Quote
vreihen
With the E3D v5, a long Bowden tube, and a geared stepper motor extruder, I'm running 6.0mm retraction @ 100mm/sec (acceleration adjusted in firmware).

Are you sure that some of the blobs are not being caused by wet filament?????

Thanks, I'll try 6mm again despite E3D's warning, and increase the retraction speed and acceleration. I'll also try a different roll of filament.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I upgraded to a wades extruder on my x- carrier to get rid of the retraction problems and blobs caused by the bowden system.
Sure they are optimised for fast print speeds but only if you can print in a continous line as soon as you have different islands to print you get these nasty blobs.
Most of them I could compensate for on my old bowden system with a quite simple test:
Extrude some filament, mark the position of the filament and then open the extruder to release the pressure on the filament - the distance the filament comes back out is the minimum retraction you need to get the pressure off the nozzle.
Add about 2mm on top of that and you should be almost free of blobs, adding a wipe in the slicer reduces it further.
If there are still too many blobs increase the retraction by 1mm each test until blob free.
Keep in mind that long retractions should be performed at low extruder speeds (30mm/s or so) to prevent chewing and filament dust collecting on the hobbed bolt.

Is this PLA? What brand? I've seen recommendations as high as 220 for some variants of PLA, and the relatively short melt zone of the v6 means it should probably run towards the high end to keep nozzle pressure down, especially when running fast.

Are you using the same speed for normal and external perimeters? If you're not, that can exacerbate issues with nozzle pressure.

I would also second the comment that slower retraction might not hurt. 30mm/s is actually what I'm using for the moment.

Quote
IMBoring25
Is this PLA? What brand? I've seen recommendations as high as 220 for some variants of PLA, and the relatively short melt zone of the v6 means it should probably run towards the high end to keep nozzle pressure down, especially when running fast.

Are you using the same speed for normal and external perimeters? If you're not, that can exacerbate issues with nozzle pressure.

I would also second the comment that slower retraction might not hurt. 30mm/s is actually what I'm using for the moment.

It's PLA filament by eSun. It extrudes well on my Ormerod at 195C first layer, 180C or 185C remaining layers.

I use a slower speed for external perimeters. The speeds I use are the same as the ones that gave good prints with the Jhead.

@vreihen, you suggested that it might be a problem with the filament having picked up water, so I did a few tests:

- I tried a black filament from a different supplier, and it printed well - no blobs.

- I tried a light blue eSun filament. The blobs were there, more drawn out than with the white filament.

- I tried the original white filament in my Ormerod again. The print was near perfect, no blobs.

Edited 1 time(s). Last edit at 06/26/2015 06:25PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I solved this problem by increasing retraction to 8mm.

Edited 1 time(s). Last edit at 08/09/2015 03:30AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I have been using and e3d v6 since day one , 8mm retraction seems like a lot ! at most 4.5 or even 3.5 should do the trick! at what speed did you set the retraction to ?? That plays a lot! and I also think you might be printing to hot. Don't forget every roll is deferent and e steps calibration should be done for each roll or simpler still reducing the flow rate in your slicer.

Edited 1 time(s). Last edit at 08/11/2015 01:11PM by Tibuck.

Quote
Tibuck
I have been using and e3d v6 since day one , 8mm retraction seems like a lot ! at most 4.5 or even 3.5 should do the trick! at what speed did you set the retraction to ?? That plays a lot! and I also think you might be printing to hot. Don't forget every roll is deferent and e steps calibration should be done for each roll or simpler still reducing the flow rate in your slicer.

I am using 100 mm/min retraction speed and 1000 mm/sec^2 acceleration.. The Bowden tube is 650mm long, not counting the part inside the E3Dv6.

Edited 1 time(s). Last edit at 08/11/2015 02:44PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].