That’s funny, but true… 
…
Same problem with my 0.2, it takes forever then makes the first layer look disgusting. I don’t really understand what’s the problem
Same issue here, happens with a .2 nozzle, not with a .4 nozzle. Did not care to wait for it to finish given the increasing size of the blob…
Same issue here. 0.4 nozzle, latest firmware.
Same here, latest firmware, 0.2 mm nozzle, runs for over 6 min and makes a couple of blobs that grow over the nozzle, I had to remove them by hand.
Works fine with 0.4mm though.
Could it be that the printer is set to run a certain volume (mm3) filament during the calibration, and through the 0.2 nozzle it just takes so much longer?
I have been having print failures one after another with first layer failures and continual purging sine the last firmware update of my A1-Mini. I found this piece of advice curious and it’s the only thing I have not tried for the last week. I just want to report back here that I did the factory reset and machine setup like it’s a new machine. After this I did a print without bed-leveling or flow calibration and the first layer was too far from the bed and I cancelled the print. I then reprinted the same file with bed-leveling only (no calibration) and this was perfect. I have not tested flow calibration yet and I expected bed-leveling to have no impact since I just ran the machine setup after factory reset.
I will do one more with calibration and let you know what happens.
For now it seems that a factory reset has helped.
Thank you,
Stephen
For those still having trouble with the dynamic flow calibration running for several minutes, you can try to comment out one section in the start g-code which doesn´t totally solve the problem but makes it much better.
I will post the complete section to be sure you comment out the correct lines, because they look very similar…
By the way, I found this somewhere in another forum and it was the official response from the Bambu Lab Support…
;===== auto extrude cali start =========================
M975 S1
;G392 S1
G90
M83
T1000
G1 X-48.2 Y0 Z10 F10000
M400
M1002 set_filament_type:UNKNOWN
M412 S1 ; ===turn on filament runout detection===
M400 P10
M620.3 W1; === turn on filament tangle detection===
M400 S2
M1002 set_filament_type:{filament_type[initial_no_support_extruder]}
;M1002 set_flag extrude_cali_flag=1
M1002 judge_flag extrude_cali_flag
M622 J1
M1002 gcode_claim_action : 8
M109 S{nozzle_temperature[initial_extruder]}
G1 E10 F{outer_wall_volumetric_speed/2.4*60}
M983 F{outer_wall_volumetric_speed/2.4} A0.3 H[nozzle_diameter]; cali dynamic extrusion compensation
M106 P1 S255
M400 S5
G1 X-28.5 F18000
G1 X-48.2 F3000
G1 X-28.5 F18000 ;wipe and shake
G1 X-48.2 F3000
G1 X-28.5 F12000 ;wipe and shake
G1 X-48.2 F3000
M400
M106 P1 S0
M1002 judge_last_extrude_cali_success
M622 J0
M983 F{outer_wall_volumetric_speed/2.4} A0.3 H[nozzle_diameter]; cali dynamic extrusion compensation
M106 P1 S255
M400 S5
G1 X-28.5 F18000
G1 X-48.2 F3000
G1 X-28.5 F18000 ;wipe and shake
G1 X-48.2 F3000
G1 X-28.5 F12000 ;wipe and shake
M400
M106 P1 S0
M623
G1 X-48.2 F3000
;M400
;M984 A0.1 E1 S1 F{outer_wall_volumetric_speed/2.4} H[nozzle_diameter]
;M106 P1 S178
;M400 S7
;G1 X-28.5 F18000
;G1 X-48.2 F3000
;G1 X-28.5 F18000 ;wipe and shake
;G1 X-48.2 F3000
;G1 X-28.5 F12000 ;wipe and shake
;G1 X-48.2 F3000
M400
M106 P1 S0
M623 ; end of "draw extrinsic para cali paint"
;G392 S0
;===== auto extrude cali end ========================
New owner here. 1.03 FW.
Facing this issue.
Mine doesn’t take forever, but sometimes it takes awhile and i get worried the ball of filament gets too big!.
UPDATE. 1.03.01 supposedly has an update for flow calibration k value issue.
Not sure if this helps, will report back if the flow calibration still takes forever.
New 1.03.01 FW → Still having flow dynamic calibration running forever. Doesn’t seem to have solve the problem.
Hi there! 
I’ve been printing for quite a while and have used many machines. I just wanted to give you my experience with nearly all the other brands of printers before you jump ship on Bambu.
I’m glad I started with a friend’s Creality and got to see how many problems the older cheap machines had and how many hours of tinkering it took to get just an acceptable print.
I then got my own AnkerMake m5c and I love that printer so much, it was the perfect blend of tinkering and problem-free performance. I racked up 3,000 print hours in 7 months with nary an issue and ZERO replacement parts, save for the POM wheels that most older style machines use.
The Bambu A1 Mini I have is one of the best products I’ve ever purchased. I can’t believe how good it is being from a brand new company. It’s astonishing how they single-handedly jumped to the top of the market segment. Any issues you are having, I promise you it’s not an indication of the company or its products.
Sorry for the wall of text, but I just wanted to save you the trouble of going with another brand. If you want maximum printing and minimum maintenance and fixing, you will not find a better set of machines for even double or triple the price. Even $5k and up machines don’t have the effortless smart performance I’ve had with Bambu. I honestly wanted to hate them at first, I couldn’t imagine them being as good as people say, but wow was I wrong.
I literally cannot wait to get a P1S or X1C, and of course AMS to go with whichever one I get. Most likely P1S at this point.
Happy printing! 
Are you only running the dynamic flow calibration for each new filament you are using? I usually just run it on the start of a new roll and then turn it off in “Handy” I do the bed leveling at the start of the day of printing, but then also turn that off for the rest of my prints. Lastly, I loved using timelapse, but realized that many of the smaller prints don’t look all that great in timelapse, so I often turn that off as well for most things.
Hey guys had this problem on 1.03, just updated to latest and about to test.
Specifically my issue was with the calibration running forever with TPU and never clearing to the point where the blob was big enough to wrap around the nozzle and silicon sock and start getting on the housing… at which point I cancelled the print.
That process also resulted in a TPU clog so my thinking is it may have been a partial jam / clog at first resulting in an in ability to build up the appropriate pressure… or it could just be a bug that resulted in the clog after.
Swapped nozzles since sometimes (in my experience) TPU clogs are hard to fully eliminate and I want to KNOW it’s not a clog inducing the issue. Since you guys are having those issues and apparently not all running TPU I assume this is not the case but am controlling for it anyway.
My read on the 1.03.1 update was that the K-factor fix was related to those who wanted to do their own flow rate calibration AND THEN have it properly saved to their machine (which wasn’t working). I’m behind on dev docs so not sure what else has happened with this issue post 1.03.1.
Will report back.
so i want to follow up on this post about TPU specifically. IF you use TPU on the A1 Mini, and you don’t have it on a frictionless roller, you will have this issue. it is slightly stretching the filament when it pulls it in and causing the pressure to build up weirdly and can/will cause it to not ever finish, or take forever. what I would do is EITHER unravel a good bit and babysit it the first time it runs, then turn off the calibration, or print and buy a couple bearings and make a frictionless roller for it. Doing this removed all of this issue for me with TPU. i tried both examples btw.
yes, i think 1.03.1 fixed things for normal filaments (PLA / PETG), but for TPU it still runs forever.
Could you share a link to how you do frictionless roller mod? I’m keen on that.
Thanks
There are a lot of options, I am new to the forums and can’t reply with links apparently but search makerworld for A1 extended bearing spool holder and you will find a really good example.
The big thing is printing a roller and using actual bearings(not printed ones preferably) so the spool can spin freely. You can find more like this and pick the one you want to try on makerworld or printables. 
I had no experience of 1.02 firmware. My A1 mini upgraded to 1.03 on the first day I started it. But since flow dynamic calibration took so long to run on certain nozzle or filament, I no longer use it and use manual K value only.
From manual calibration, I found K factor of same SUNLU PLA on 0.2mm nozzle is 0.3 while 0.4mm nozzle is just 0.02. And for Geeetech TPU on 0.4mm nozzle is 0.35.
Assuming the flow dynamic calibration started off from 0 with small increment steps, it would take much longer to get to 0.3 vs 0.02. I think this is why it took so long.
I have the same issue with PETG… really annoying. I shut of flow calibraton but since then I also haven’t been able to finish a single print. The parts get stuck on the nozzle and are pulled of the bed 
but very nice quality up to that point…)
Still occurring here too, no change after firmware update.