Hi all, I’m back with another likely noob question. I went to adjust my flushing volumes as someone suggested that was the cause of a problem I am having. I am just printing with one filament and the support material is being used as an interface for the supports. Apparently by default studio auto calculates, but it just shows zeros including the multiplier. If I increase the multiplier it will increased the flushing amounts but it still is auto calculated. Same even if I disabled auto calc. Not finding much on the wiki to explain all of this.
Normally you should keep the multiplier at 1 and then make your own adjustments after auto-calculating. It is usually best to make the support material flush more than the auto-calculation because the auto value is too low and some support material will mix with your PLA and make it weaker.
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Yah for some reason it defaulted to 0 and the autocalculat preference seems to do nothing. If I set it to 1 It approximately doubles the flush volume from support to primary filament. I’m not sure if that is enough or if it could be actually lowered. I have so many questions about this as this is my first experience with an AMS, as all printers I’ve played with were single extruder with no material system. Are the flushing volumes in mm as in with the setting below it will flush 420mm of support material. If so then my confusion is even worse because according to my model it changes filament 26 time so the waste should be much higher. I’m also confused as to why it is 26 times when it only has a few layers of support for the interface layers. I also don’t know if I need a prime tower in this scenario.
If it is changing 26 times, it will be flushing the support material 13 times.
The default value for flushing support material is too low, it mixes in with the PLA and can cause layer separation issues and weakness after switching from support to PLA.
I usually make the support 600 to 700 which might be more than I need. I haven’t experimented to see what is the lowest that works, so I choose a value that I know will be more than enough.
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My numbers don’t add up and I’m not sure why it changes 26 times. Would you use a prime tower in this situation ?
I always use the prime tower with multi color or material printing
alright I said F it and just set flush to 800 for both and did the prime tower. Hopefully it turns out ok.
I replied to your other post here, with some images to illustrate:
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It’s not just a support filament issue, I had this on a couple of my multi-colour model profiles when I performed test prints.
I noticed because my white base model with black elements was white until it hit the first black element and then everything turned a very dark grey that should have been white.
I assumed I screwed up somehow and then it happened on another different model’s profile.
This was a couple of days ago. It hasn’t happened again although, I have been looking in the flushing volumes far more than I usually would.
I increase flushing for support material and whenever it is transferring from a dark color to white or another light color.
I wish there was a way to make it remember my flushing choices. Sometimes I forget to change them
Mine all went to zeros as the OP said theirs had, but, was unrelated to support material, my case was all PLA, just different colours.
I think your comment was referring to mine.
Yes, I was agreeing with you that it also should be increased when going from dark to light colors. I actually increase any color if it is transitioning to white.
Did the same thing happen to you where the multiplier was set to zero? Mine has always defaulted to 1. I guess I better remember to check next time I do a print in case it is some bug setting it to zero.
I struggled with this for a while and found the Bambu defaults and ways less than acceptable.
My first few prints with all defaults came out acceptable enough to not worry until I checked the amount of poop created.
Then I just did not bother with dedicated support material as I have no big issues printing them with the material used for the model.
With so many support filament related topics lately I gave it another shot…
YES, you do need a lot more flushing volume if using different filament types.
Yes again if you use the same material but a very different colour.
And another yes if you actually need a CLEAN model with no residue mixed in from the support material.
As I prefer calibration over trail and error anyway I tried this for the support issue.
Here’s what I found useful and working - try at your own if you want:
Create a small and simple model with many filament changes.
It really helps if you use filaments of different colour.
White PLA or PETG with white supports makes things very hard to judge…
For my little test I used light green PLA and translucent red PETG for the models and just the Bambu support filament for PLA for both models.
Yes, I just ignored all obvious as I only wanted work and worry about the flushing volumes 
I started with just 10 and of course this resulted in a total mess.
Then I worked my way up until the model was free from ‘unwanted’ white remains.
Did the same for the support material of course.
I noted the volumes resulting in no visible discolouration.
Then I added 20 to the volume to work my way down again.
Meaning I noted the volume that resulted in me spotting colour problems again.
I averaged the volumes and added 5 to be on the safe side.
I know, it sounds like overkill…
But if you have ONE preferred support material and honed that in, than you only need to the same ONCE per new filament.
And wasting a bit of time and filament ONCE is, IMHO, much better than wasting a few good and big models in a row…
Just saying…
Is the “support material” used to print the entire support structure?
If so, that is unnecessary and more expensive. Only the support interface layer has to be printed with “support material”. The rest of the support structure can be printed with the same PLA or PETG that the part is printed with.
A lot of good information.
However, the original post was about how flushing works or how to improve it.
The problem was about Bambu Studio resetting all flush volumes to zeros without the designer knowing or even entering the flushing volumes window.
A bug experienced by a few of us.