Btw, I used the Orca Slicer for my test, not the Bambu Studio. I am not sure it makes a difference, but worth a try.
Iāve never used Orca, but I am going to d/l and give a try today. Oh, and @Thrawn, thanks a bunch for taking a deeper dive into this /w me. I appreciate your responses and advice.
Hmmm (he says, thoughtfully stroking his beardā¦) thatās ā¦ odd.
Perhaps do a manual pause on one layer then later the built in Pause?
I didnāt deep read all the posts, but did you do a full set of filament profile calibrations in OrcaSlicer?
Also - on that subject, I have found different color of filament from the same brand can have dramatically different profiles, never mind across brands, thatās bigger.
Hereās a long post I did as a PSA on OrcaSlicer vs Bambu Studio if you are interested:
https://forum.bambulab.com/t/psa-up-your-game-studio-softfever-orcaslicer-arachne
For sure, I donāt doubt that. Iām more wondering if the slicer is changing something that you didnāt change when you do the filament change.
There has to be some variation thatās occurring to cause that, no?
Can you try one going half speed and see what happens?
Iām using bambu studio, and no, Iām using the generic PLA profile. I am yet unsure how to perform filament profile calibrations - Iām am still pretty new to all of this.
What I can say is that I can slice a calibration cube and print it in green fine. I can then unload green and load grey and print another grey cube just fine. Then add the pause command at layer 51, click slice plate, and send the print with the grey still loaded. At layer 51 it pauses and the extruder moves over the chute. I unload the grey and load the green, extrude until I see green, then hit resume on the printer. The printer homes and then begins printing again in green, but with this problem occurring. Independently running as a mono-color, both colors complete the cube fine without issue using the same slicer settings. Iām not adusting anything else in the slicer except for the manual pause which requires a reslice before printing.
Yes, thatās a good call, Iāll run one on silent today and see what happens. I will also try adding a manual pause but without changing filament to see if adding the command or pausing alone is doing something. Iām currently printing a couple corner panels so it may be a couple hours. 
Oh jeez, this is awesome. I commented to Thrawn that Iād try Orca today, and if I wasnāt already convinced to give it a try, your post did the trick. Iām going to take a look at it as soon as my current print finishes.
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Can you also try printing two on the same plate but pausing one and not changing filament and completing the other in a single color?
Your welcome, thatās why I wrote it. This 3D printing can be complex. 
If you read the link to OrcaSlicer Calibrations page I posted youāll see he gives great Step-by-Step directions of how to calibrate for each filament.
Generally you have to do that only once as long as youāre using quality filament because most have good consistency from batch to batch now.
BTW - something I didnāt get at first is on this forum you can reply to multiple people with one post. You just highlight the sentence or thought and click the little āQuoteā button. It inserts their comment. Wash rinse and repeat. Easier than posting 3 times to three people. 
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@Thrawn @Matt @ThanksForAsking
So, I think I figured it out:
C is the control
1 is representative of my initial attempt
2 is the same as the initial attempt with quality filament
3 is my first attempt with Orca Slicer instead of Studio
4 when I realized what was happeningā¦
So, the first color isnāt warping during the print, it isnāt until the second color is added and printing begins that the new color deforms the original. Part cooling turns off with the pause command and the extruder moves back to the trash chute. Once the new filament is added, I click resume and printing resumes. However, part cooling does not instantly turn back on. It prints several (varying amount of??) layers before cooling turns back on. Sometimes it turns back on quickly, sometimes it does not. You can see the layer line in 1, 2, & 3 when the cooling kicks back on and the print āautocorrectsā its size. In print 4, I reloaded the filament and immediately restarted the fans upon printing using the Handy app.
As an aside, I did attempt this
M400 U1
G28 X Y
M106 P2 S100
to try to immediately start the fans after homing, but this didnāt work. I just jacked the M106 command from somewhere in the initialization gcode that was commented āturn on the big fanā so I have no idea if that is even right.
Here is a closer look at 3 and 4:
There is a tiny bit of a lip on the new color in block 4, but I am happy enough with this result. There is a little droop in the over hang on the X, but it isnāt very noticeable on the print when holding it. Not sure if I still maybe have a slight cooling issue going onā¦ regardless, I think the cause of the deformation is figured out.
Anyone know what might be going on with the fan situation, or any suggestions on better code to add to start the fans after a pause like that?
Also, thanks so much for all of the support, I feel kinda bad for not noticing the fan behavior earlier.
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Great detective work!
Not at all, we all learn from each other here. Sometimes youāre asking the Q and sometimes youāll explain to some other poor chap whoās stumped.
Donāt feel bad, the fix is always obvious in retrospect, eh? Besides, you did a stellar job in tracking this down, glad you got a handle on it! And learned a bunch in the process.
You might put this in as a Bug Report, it seems an easy enough fix to get in the Firmware.
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P2 is for the big auxillary fan on the left side of the printer.
P3 would be the chamber fan for X1C
Try:
M106 S255 (without the Px value)
that should be the part cooling fan on the toolhead.
The speed ranges from 0 to 255 for 0% to 100%
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Iāll give it a test, thanks!
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Hey, thanks for this. I printed a test piece today and had, for the first time, what I would consider a successful multi color print. I introduced the fan startup code after the xy home, and all was well!
M400 U1
G28 X Y
M106 S255
Thanks again!
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