Pressure advance tuning

Gear

Hello! I've been trying to tune pressure advance (pa) for a bit now and basically did M572 D0 S0.05 every 20 layers (with the little gcode bar at the top) and see if there is any difference. though the problem is is that I don't see any differences between the 10 settings from S0.05-> 0.2
I'm printing this model at 100mm/s with a 60cm capricorn xs bowden driven by a bondtech bmg and a genuine e3d v6.

I made a little test model
angle one

angle two

angle three

Phaedrux

Have you seen this?

https://duet3d.dozuki.com/Wiki/Pressure_advance

What is your extruder jerk and acceleration set to?

Personally I find it easier to tune pressure advance by looking at the solid infill ends.

Gear

yes I used that, but couldn't really see a difference.

M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X80.00 Y80.00 Z1600.00 E415.00 ; Set steps per mm
M566 X600.00 Y600.00 Z12.00 E1200.00 ; Set maximum instantaneous speed changes (mm/min)
M203 X7500.00 Y7500.00 Z300.00 E3600.00 ; Set maximum speeds (mm/min)
M201 X1000.00 Y1000.00 Z20.00 E3000.00 ; Set accelerations (mm/s^2)
M906 X1600.00 Y1600.00 Z1200.00 E300.00 I30 ; Set motor currents (mA) and motor idle factor in per cent

might have to do solid infill and see how it fares.

dc42

You should not need to do solid infill. The effect of pressure advance should be readily visible on the sharp vertical edges of a cube. It will be less visible (or perhaps not applied at all) or curved edges, which I think is what you have in your model.

deckingman

Here is what works for me (and I've done an awful lot of work on this but nobody takes much notice).

My own test results lead me to the conclusion that the effect of pressure inside the hot end becomes more apparent over time and with speed. That is to say, the longer you force filament into the hot end for, the more the pressure builds up. Therefore the effect becomes more apparent and easier to spot when you do long moves at speed.

So what works for me to print a cube, as large as will fit on the bed and use a high percentage infill. Start slow to get a nice smooth first layer. Then whack the speed up to the highest practical value that the machine is capable of while still giving good quality results. Solid infill works best for me because you can usually tune the pressure advance over a single layer. Lower infill percentage means less lines so less time to tune it. If you need to do it over multiple layers, then you need to slow the printer down and lay down a few more solid layers to get smooth surface. Otherwise any roughness from the previous layer will adversely affect the next layer.

Towards the end of a long high speed move, the carriage decelerates but because of the pressure build up in the hot end, the rate of extrusion does not slow down at the same rate. So we get over extrusion and the end of a move - the longer and faster that move, the more noticeable it is. So simply observe the beginnings and ends of those long infill lines. Even better is to use a finger tip rather than an eyeball. The over extrusion tends to feel rougher than it looks. Increase pressure advance until the ends of the long infill lines look and feel as smooth as the perimeters.

On my machine at least, once the optimum value has been found at the highest practical speed, then this value will also work for all lower speeds.

That's what works for me anyway.............

SputnikOC3d

and this is tested ... per filament type and for each nozzle diam ... correct ?

And that you deckingman ... and all

deckingman

@sputnikoc3d said in Pressure advance tuning:

and this is tested ... per filament type and for each nozzle diam ... correct ?

And that you deckingman ... and all

For the first line of the above - yes. I have found that anything which affects the viscosity of the filament will affect the pressure and thus will need a different pressure advance setting. That includes temperature as well as filament type. In general, a higher temperature makes the filament less viscous (more "runny") so slightly lower pressure advance is needed.

Nozzle diameter has a huge effect. For example, I need to use 0.4 to 0.5 pressure advance on my machine using a Diamond 3 colour with 0.5mm nozzle but with a 0.9mm nozzle, I need no pressure advance at all (which is quite logical when you think about it).

For the second line of the above - "And that you decking man ... and all" I have no idea what that means.

Gear

@dc42 picture model as you can see all the corners are sharp as a knife.

dc42

@gear said in Pressure advance tuning:

@dc42 picture model as you can see all the corners are sharp as a knife.

The corners look deliberately rounded to me, but it's hard to be sure from the photos. What is the nozzle size?

Gear

@dc42 @deckingman i'm running an 0.4 nozzle, I tried deckingman his method with petg and this is the result I got on

M572 D0 S0.2

S 0.2