#Brutal variation in flow at external perimeter

1 messages · Page 1 of 1 (latest)

median glade
#

Hi, how are you? I'm having problems with flow variation on the outer walls when I activate scarf sean. As you can see in the photos, the variations are so high that they leave marks with color changes in the print, which frankly look very bad. This doesn't happen when I use normal stitching. Is there any way to limit this flow variation without having to reduce the speed of the outer perimeter so much?
Thank you in advance for your help.

image.png image.png
harsh belfry
#

the scarf seams naturally have flow variation as it ramps flow from 0 at the beginning of the line, and then back down to 0 at the end of the line

median glade
#

I understand, but does the variation have to be so great? Can't it be limited?

elfin lark
#

By tuning your scarf seam settings.

median glade
#

I performed the configurations found on most websites: external perimeter 0.6mm, correctly adjusting the advance K, lower external perimeter speed of 100mm/s, but nothing related to flow variation or similar that could solve this problem.

#

Are you referring to a specific one?

harsh belfry
#

Scarf seam has settings. A shorter seam length will induce flow variation over a smaller space

median glade
#

Are you referring to the seam separation value?

harsh belfry
#

no, ths scarf joint length

#

you appear to have it set to quite a large value

median glade
#

Now I understand, but what are the normal values?

harsh belfry
#

20mm length I think

#

you can load in a default profile for something to compare

median glade
#

I'm using the default value of 20 mm and I'm getting those flow variations.

harsh belfry
#

do you have 'scarf around entire wall' enabled?

median glade
#

yess

harsh belfry
#

there's your issue

median glade
#

I tried disabling it, but the seam is still visible even when I disable it.\

#

It's as if I've deactivated the scarf sean

harsh belfry
#

you do have to tune scarf seam if you want good results

median glade
#

I don't think we're understanding each other, but thanks anyway.

harsh belfry
#

none of the profiles have scarf seam actually tuned

#

it's more of an experimental feature

#

so if you want flawless seams, you'll have to do a bunch of testing to figure out the best settings for your machine/profile

median glade
#

I understand, but none of the parameters they touch involve anything that changes the flow variation on the outer wall, so they don't solve anything. The seam itself does disappear, but at the cost of other problems.

harsh belfry
#

really? making the seam not cover the whole wall loop ought to minimize the flow variation from the seam to the 20mm where it's located

#

if there's still massive widespread flow variation, that would seem to indicate some other setting issue

velvet cargo
#

i think i would set all the speeds for all the features to the same volumectric rate to try to minimise the hotend preasure build up

median glade
median glade
velvet cargo
elfin lark
median glade
# velvet cargo you can limit the volumectric flow here

Now I understand. The real problem is that the perimeters that cause problems are those with the lowest volumetric flow. In other words, if I wanted a uniform or nearly uniform extrusion, I'd have to drastically reduce the volumetric flow to around 5 mm³/s to see any effect. And that would turn an 11-hour print into one that takes 1 day and 10 hours

elfin lark
#

There will always be a trade-off somewhere.
A great saying for proper mindset:
"Good...fast...cheap...you only get to pick 2."

median glade
#

Hahaha, frankly, I think it's a really bad mistake. I still think there must be a way to fix it. Thanks anyway for your advice.

velvet cargo