Hi all,
I have searched for this issue in existing posts but I do not see it.
If I am not looking in the correct place, please let me know.
I have recently replaced the entire hot end on my P1S.
Since doing that I have completed the flow dynamics and flow rate calibration, but had (not great) results.
I then printed this manual flow rate cube
but I am getting strange results.
It would appear that the flow rate is acceptable to start, but as the printer moves across the part, it begins to [under extrude]?
I would first verify that the bed is properly trammed parallel to nozzle travel. Flow rate may be OK, but if the bed is not “level” the filament is not equally squished.
A printed wrench improves grip on the skinny knobs and makes precise adjustments much easier.
The wiki says " Please make sure that the nozzle is just touching the printing surface . The nozzle should not push against the printing surface , and there should be no gap between the nozzle and the bed .
That “just touching” point can be hard to judge exactly. Some use a feeler gauge, but this also requires some judgement of friction drag as you pull the gauge through the gap. I use a small flashlight behind the nozzle, put my eye at the level of the bed and watch for the very distinct point when the nozzle tip touches, cutting off the light shining through the gap. YRMV
Thank you; I have done this, and I believe that has resolved THAT issue.
However, I am still struggling with flow rate / calibration (or am I??) I’ve been looking at this so long I’m not sure what is real anymore.
I think that 0 and 5 show clear under-extrusion, whereas 15 shows over extrusion; but I still don’t feel 10 is a particularly good finish.
Am I overthinking?
The Bambu test patches sort of work for the calibration job.
But one has to be able to properly judge them, after which it can still be a hit and miss game.
I usually create two profiles for the main filaments, one for Vase mode, one for normal prints.
Vase mode calibration is dead simple, just adjust the flow ratio until the set wall thickness matches the reality.
For the normal calibration I do some small cubes of 2 to 3mm height.
Starting with the default 0.98 I print just two wall loops, no infill, no top layers.
0.42 + 0.45 = 0.87.
It that’s not a match I adjust accordingly.
E.g.: I measure just 0.82 for those two walls> 0.98 (Flow ratio) divided by the measured thickness of 0.82 gives us 1.195 and that we multiply with the value we need.
1.195 multiplied by 0.87 gives a flow ratio of 1.04 - rounded…
That gets me in the ballpark for the top layers and to get them right it is just minor adjustments to the found value.
15 and 5 are definitely not right. Using the Studio procedure, 10 should be your choice before performing the second calibration pass. The second pass will start with a flow correction based on the 10 coupon and then reduce the flow in smaller steps to fine tune the flow.
Thanks Ikraus; I appreciate the nod to 10 as the right place to start - thank you.
So that brings me on to these;
To the naked eye, 5&6 are starting to look under-extruded, and there’s an obvious fault with 3, but I’m discounting that for the sake of this exercise;
The trouble I am having is understanding what I am looking for; the calibration prompt says object that is seamless and has the best smoothness; does this mean in the middle of the tile, or am I looking at the end loops as well? (because none of the ends look great here)
I would have to say the best is 4; then (strangely) I’d say 2. [so should I choose 3, and assume the print error is causing the rest of the imperfections, or is that not how this works?]
Once again, not sure whether I’m putting far too much thought into this and I should just choose one and print some blocks as User_302… suggests.
In both rounds you look for the same thing(s).
You want the patch that has the best looking top surface.
Means no gaps between the infill lines and no saw teeth building up where infill meets the wall.
Don’t go by eye unless you trust your nickel plated eyesight.
Prefer a good and clean magnifying glass and check the top layer against a good light source.
Check in the infill direction and 90 degrees to it.
Where to draw the line…
If the first round goes from bad over half decent to bad again you still go for the best looking one.
But if the previous number already shows clear gaps between the infill lines you might want to look closer and if in doubt use the next higher number.
I go for the smoothest center. I feel that if I get the center correct, pressure advance calibration will take care of the edges.
It can be very difficult to choose. Good light, and a magnifying glass help. Or taking a picture and zooming in close can also. I’ve even applied an auto detailing tip - wrap a finger in a piece of plastic grocery bag and rub it across the surface. The bag somehow magnifies the feel of a rough or dirty surface.
