Flow Rate Tuning

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sinned6915
Posts: 55
Joined: 28 Nov 2017, 10:06

Flow Rate Tuning

Post by sinned6915 »

Which of the parameters does the flow rate tuning wizard tweak? Where would we use the flow tweak setting for?

Starting with the bottom as the fastest flow rate, say 10, then at the top, the slowest say 0.1.

After the calibration cube is printed, then what value are we trying to nail down?

I am worried that I will constrain myself too much by tightening up the window too much.

Thanks

Dennis
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crpalmer
Posts: 3
Joined: 14 Nov 2017, 06:12

Re: Flow Rate Tuning

Post by crpalmer »

You are tuning both the min and max values. For PLA, you may be able to use the full 10 - 0.1 range but if you print with, for example, TPU then the window will be much smaller and pretty obvious from the cube (it will have obvious visual problems).
sinned6915
Posts: 55
Joined: 28 Nov 2017, 10:06

Re: Flow Rate Tuning

Post by sinned6915 »

I have made a few of these cubes now and all of them look awful, but I think that is part of point. I dont feel that I am makeing any headway.

There are pronounced vertical ripples at the corners that blend into diagonals on the flats. I tried to take a pic and note the top and bottom with the Flow variables as I understand them.

It definitely looks better towards the top, but not what I would consider acceptable by any means. Like the top 4mm or so.

Re-reading your post I wonder if I am not using the right values- the Wizard shows the range of 10-1, but you said 10-0.1. Did I misunderstand the values?

And the walls of the calib cube are thin- 0.36 to 0.38 mm instead of 0.4. Outside dims are short too => 24.74mm instead of 25mm. I did measure the filament to be 1.72 and I changed that in the Matl tab. Style Inset variable is still 0.

The reason I I am on this adventure is new brand/roll of PLA where I have been printing PETG mostly. And I changed my heater cartridge out. All of the sudden, now the ID''s are tight.

Am I missing something fundamental?

Dennis
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sinned6915
Posts: 55
Joined: 28 Nov 2017, 10:06

Re: Flow Rate Tuning

Post by sinned6915 »

Can someone post a picture or two of their flowrate calibration cubes for comparison?

It would be nice to have something to compare to.
frozen.rabbit
Posts: 132
Joined: 17 Nov 2014, 09:20

Re: Flow Rate Tuning

Post by frozen.rabbit »

Min 0.0001, Max 200, never adjusted. Flow Tweak 0.97 (adjusted for different materials)

As to my understanding from using KS for a long time, Min/Max values are how fast or slow the extruder can push filament, relative to print speed. well before Wizards.

Max/Min isn't for adjusting flow rate in that way, it affects print speeds more than flow rate.

Flow Tweak has a direct influence of how much material is being deposited, adjust that instead.
sinned6915
Posts: 55
Joined: 28 Nov 2017, 10:06

Re: Flow Rate Tuning

Post by sinned6915 »

frozen.rabbit-

what kind of extruder are you using and what kind of calibration did you do for the extruder?

it seems that all this business comes down to the drive end of the extruder. I am trying to understand the context that you use the tweak setting.

thanks

sinneD
frozen.rabbit
Posts: 132
Joined: 17 Nov 2014, 09:20

Re: Flow Rate Tuning

Post by frozen.rabbit »

I'm on a Wade's style extruder, 9:1 geared. This difference would only affect your E-steps/mm in your firmware.

I just print 20x20mm calibration cubes, and adjust the flow tweak up and down til I get a smooth, solid top surface. Flow Tweak 0.95, 0.96, 1.01 etc.

I never adjust Max/Min.

Try a cube at 0.0001 and 200 max/min and see how it works. The setting you are using are definitely changing the ripple pattern as it prints.
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pjr
Posts: 692
Joined: 05 May 2015, 10:27
Location: Kamnik, Slovenia

Re: Flow Rate Tuning

Post by pjr »

I think it's fair to say that the minimum flow rate is dictated by the extruder steps, the maximum by extruder melt volume and the cool by the fan capability

All these values do is to limit the print speed to those maximum and minimum limits and in accordance with extrusion width and height.

As an example, the extruder on the Mk2/S + MMU uses 140 steps/mm and therefore a minimum of maybe 35 steps/second (0.6mm^3/s) is not unreasonable. Likewise an E3D V6 can melt around 11.5 mm^3/s, so I tend to set a limit of 10mm^3.

As frozen.rabit says, the flow tweak is the main method used to calibrate the extruder. It is also possible to tweak with filament diameter (my preferred method) or to change the E-steps within firmware (something which needed to be done with the Prusa Mk1 & Mk2 and the brass filament drive pulleys).

Peter
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