Insufficient flow at start of each layer

[Andrew Moore]

Hi,

I am having a problem with the flow of ABS at the start of each layer as shown in the attached picture.

Jitter is set at 0degrees in the above prints to more clearly show the behaviour.

Once the flow starts the print quality is very good and the measured extrusion width matches that set in KISSlicer.

I have managed to "fix" the issue by either:

- modifying the flow settings, this results in measured extrusion width > set extrusion width, or

- priming a small amount at the start of the layer, this results in blobs and zits on the print

I've systematically experimented with varying filaments, print temperatures, extrusion widths and flow rates but can't seem to get rid of this behaviour without adversley affecting measured extrusion width.

Is tweaking flow rate, and living with the larger extrusion width, the correct way to handle this situation or is there something else I should be trying?

Any assistance greatly appreciated.

Thanks.

[Peter Gregory]

This looks like a suck / prime issue.
You can use CubeItMod post processor to change the suck/prime values.
You can also change the flow separately for solid, perimeter and infill.

[Andrew Moore]

Hi Peter,

Thanks for the response.

This looks like a suck / prime issue.
You can use CubeItMod post processor to change the suck/prime values.
You can also change the flow separately for solid, perimeter and infill.

I'm not using a Cube printer (Replicator 1 clone) so not sure if I can use CubeItMod? Or is it a more generic tool?

My current workflow is KISSlicer -> gpx.

I have played with the prime, suck and wipe values extensively. I does fix the problem but the values required for the fix leave blobs/zits at the start of each layer. Similarly, tweaking the flow rate fixes it but then increases the extrusion width. I actually have to tweak the flow *down* a bit (~0.97) to get spot on extrusion widths. This obviously makes the behaviour I am seeing even worse.

Cheers

[toranarod]

I have had the same problem.   Is your printer as cubeX?   

[Peter Gregory]

CubeItMod is written for the CubeX

However, the source code could be modified to work with other printers.

There is logic specific to the Cubex to group gcode values together for setting suck / prime settings for short & long lines.

Also special code to handle the "starting puddle" problem.

The rest of it is generic to any printer.

It speeds up or slows down the movement to decrease / increase flow for fill / perimeter / solids.

The .au file included with CubeItMod contains the source code.

[Bart]

Hello Andrew,
I use the rep1 with gpx as well,  with better results.
Do you use the M101/M103 commands on the printer tab?  That could result in double prime and suck when set so in the Sailfish firmware.

Did you measure your filament ok.? Because normally I leave the flow tweak to 1.  Only adjusting the filament diameter with 0.01mm steps (increasing is resulting in less extrusion)
What settings do you use for suck and prime and on what speed?
Bart
>
> Op 28 mei 2014 13:31 schreef "Andrew Moore" <deane....@gmail.com>:

>
>> Hi,
>>
>> I am having a problem with the flow of ABS at the start of each layer as shown in the attached picture.
>>

>> Jitter is set at 0degrees in the above prints to more clearly show the behaviour.
>>
>> Once the flow starts the print quality is very good and the measured extrusion width matches that set in KISSlicer.
>>
>> I have managed to "fix" the issue by either:
>> - modifying the flow settings, this results in measured extrusion width > set extrusion width, or
>> - priming a small amount at the start of the layer, this results in blobs and zits on the print
>>
>> I've systematically experimented with varying filaments, print temperatures, extrusion widths and flow rates but can't seem to get rid of this behaviour without adversley affecting measured extrusion width.
>>
>> Is tweaking flow rate, and living with the larger extrusion width, the correct way to handle this situation or is there something else I should be trying?
>>
>> Any assistance greatly appreciated.
>>
>> Thanks.
>>
>>
>>

>> --
>> You received this message because you are subscribed to the Google Groups "Kisslicer Refugee Camp" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to kisslicer-refugee...@googlegroups.com.
>> To post to this group, send email to kisslicer-r...@googlegroups.com.
>> Visit this group at http://groups.google.com/group/kisslicer-refugee-camp.
>> To view this discussion on the web visit https://groups.google.com/d/msgid/kisslicer-refugee-camp/6cbc7f3e-7c70-4253-8608-5a0449f2507e%40googlegroups.com.
>> For more options, visit https://groups.google.com/d/optout.

[hugues]

Usualy I've this problem with printing at 0.05 layer height. To fix this, I setup a nozzle diameter higher than the real. So for a nozzle of 0.5 I setup an extrusion width of 0.51 or 0.52.
Hope it's help.

[hugues]

Forget to say that my flow tweak is setup to 1 when doing this

[Andrew Moore]

Hi Bart,

Do you use the M101/M103 commands on the printer tab?  That could result in double prime and suck when set so in the Sailfish firmware.

Yes, I am using the M101/3 commands. I have set the "deprime (steps)" values to 0 in Sailfish however.

Did you measure your filament ok.? Because normally I leave the flow tweak to 1.  Only adjusting the filament diameter with 0.01mm steps (increasing is resulting in less extrusion)

I have measured the filament but have used up a lot of the rolls since then. I'll re-measure and see if it's changed at all.

What settings do you use for suck and prime and on what speed?

 I was using pretty small values. A prime of 0.7 would pretty much fix the issue but started to leave blobs. Using suck didn't really make any difference. Speed was 15mm/s. I didn't really play with this value at all.

Thanks.

[Andrew Moore]

Hi hugues,

I have a 0.4mm nozzle and have tried extrusion widths up to 0.42mm but no higher. This hasn't really made any difference.

Is your measured extrusion width the same as the one you set in KISSlicer?

Thanks.

[hugues]

Yes I've the same values between the measured one and the KS setting. Maybe you can try 0.45 Max in the extrusion width value.

Did you try other extrusion speed or temperature ?

[Sergey Afonin]

I had the same issue. I defined it as wrong pressue inside extruder (hot end). Flow becomes to stable after extruding some portion and drops down after M101/103 command. I solved this issue increasing the extruder temperature a bit.Filament is not more pressed inside extruder and flow is more stable.
I use RapMan 3.1DH

пятница, 30 мая 2014 г., 11:39:03 UTC+4 пользователь hugues написал:

[funBart]

Hey all, about the Replicator1 dual I updated my settings and short guide in this post: https://groups.google.com/d/msg/kisslicer-refugee-camp/Qp4GkDmtJL4/91s5x0IxW1QJ

I don't understand the discussion about the nozzle and in KS defined path width regarding this problem. I had this kind of trouble as well in the past because of two reasons:

firmware issues (Sailfish regarding the acceleration settings)

• it's possible because of way off settings of the JKN Advance (K and K2) under the Machine / Acceleration (Misc) tab that this blobs / meager extrusions occur. I had it when playing with it.
• I suggest you set them (if not already) to the default values. I have set all to the "fine Quality" default, tweaked my 2nd extruder offset and set both extruders deprime to 0 (as I only use slicer based suck and prime)
• Screens of my firmware settings:

settings in the slicer

• to be sure: turn Mark path Start/Stop to none
• I assume there is no fancy Gcode added in the Gcode "select / deselect extruder" tab to do extra prime or suck
• under style: all widths to nozzle diameter. So 0.4mm  Kisslicer uses this width values only to plot / offset the center of the paths on each layer. Changing that values has nothing to do with the problems shown.
• Be sure destring / Wipe is checked on the style tab.
• The only thing I'm always very very neurotic about is the accurate filament diameter on the Material tab, as tweaking it ok is making a difference of night and day with your print. Measure it on different spots in different directions, print a test cube and adjust with max 0.01mm steps. Write that measurement on the spool. Leave the flow Tweak alone to 1, as it's only needed with specific prints / materials.
• I have tested Prime and Suck intensely, Not only with Kisslicer, but with a special made generator as well (by Ddstarkey), and I had great results with both Suck and Prime set to 0.5mm. Sometimes a little adjusted to 0.45mm or 0.55mm. Not more. And certainly not only Prime or suck set. 
•  I don't use Wipe a lot, because of excessive extra motions with difficult prints.
• There has a lot said about the speed of Destringing of an extruder: some say it has to be done slow (10mm/s) others 80mm/s or faster. I have good results at 30mm/s
• About the temperature: when setting it high: a lot of oozing can occur when inactive or traveling. I set it to the lowest temperature possible with the chosen speed. In general that's 220 degrees @ 100mm/s with PLA (transparant PLA 210 with me). ABS on 230 degrees.

I can imagine every machine has it's own characteristics, but with this settings I have great results and certainly not the problems shown.

Bart

[Andrew Moore]

Hi Bart,

Thanks for the awesome post!

 
All of this makes sense. I have done some of the things you have suggested, but not all.

I'll try your suggestions from top-to-bottom and report back.

Cheers

 

[Andrew Moore]

Hi Bart,

As you can see, your suggestions have helped immensely. Thank you very much!

There are some artefacts in the corners (they appear exaggerated in the photos) and the corners are quite rounded. Is that likely to be printer mechanics or something I can tweak in the slicer?

Thanks again for your help.

Cheers