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Compensation for blob start point on outer perimiter

Posted: Sat Oct 27, 2018 4:16 am
by martin1454
So you know know it works with the Z-blob on corners - You can try to calibrate some negative retaction, coasting, wipe, etc, but it will always be a bit bigger than the outline -
comp.png
How about a parameter where you can compensate for the blob size? Like if the blob is 0,3mm larger than outline, then start 0,3mm towards infill instead, and then quickly turn out to the perimiter?

Would this be possible?

Re: Compensation for blob start point on outer perimiter

Posted: Mon Oct 29, 2018 11:08 am
by S3D-Jake
Thanks for your feedback! I'll be monitoring this thread to gauge user interest.

Re: Compensation for blob start point on outer perimiter

Posted: Tue Oct 30, 2018 1:38 am
by SweHogelid
martin1454 wrote:
Sat Oct 27, 2018 4:16 am
How about a parameter where you can compensate for the blob size? Like if the blob is 0,3mm larger than outline, then start 0,3mm towards infill instead, and then quickly turn out to the perimiter?
That sounds like a really good idea! Same would be nice to both start and end of perimeter, in the end it maybe it would be possible to move nozzle a tiny bit inwards before it retracts and moves on. The most common problem I have with blobs is at the end of perimeter, but sometimes at the start as well.

Re: Compensation for blob start point on outer perimiter

Posted: Tue Oct 30, 2018 6:06 am
by dkightley
How about a parameter where you can compensate for the blob size?
My only issue about this suggestion is "What would be changed by such an option?"

Negative retraction, coasting, wipe, etc...these are all actual changes to something.....the amount of filament pushed into the print head at a particular point in the print process, mainly.....but Compensate for blob size? All of the ooze control parameters have some form of effect on blob size.

A user guide that explains what the existing parameters do both in terms of cause and effect is probably what is needed. An understanding of what changing each parameter actually does and when...and why you would want this change to happen at that point on your printer....is all that's needed. And of course a small amount of patience to "tune" the slicer to your own personal printer and the materials you use.

Re: Compensation for blob start point on outer perimiter

Posted: Tue Oct 30, 2018 7:23 am
by martin1454
dkightley wrote:
Tue Oct 30, 2018 6:06 am
How about a parameter where you can compensate for the blob size?
My only issue about this suggestion is "What would be changed by such an option?"
The start/ stop point would be changed - pulled a bit towards infill -
see this bad example for the idea:
Untitled.png
Untitled.png (4.43 KiB) Viewed 836 times

Re: Compensation for blob start point on outer perimiter

Posted: Tue Oct 30, 2018 11:34 am
by SweHogelid
dkightley wrote:
Tue Oct 30, 2018 6:06 am
How about a parameter where you can compensate for the blob size?
My only issue about this suggestion is "What would be changed by such an option?"
I'm not very good at explaining this in English so please bare with me.
I almost exclusively print perimeter from inside and outwards. The way I think about this request is that the printhead could make a small move inwards (over already printed area) before retracting.
The reason for this is that the only explanation I have for the blobs with my printer is that the main board isn't quick enough, "pausing" the printhead a fraction of a second before retracting and thus leaving a blob.

I have made many many attempts with coasting and negative starts and dussins of other changes but never really found anything that works. On my former printer, a Velleman 8400 I just ramped up retraction speed and distance and had next to none blobs. Now with my Ultimaker 2+ I find it impossible to get same results regarding blobs.

Re: Compensation for blob start point on outer perimiter

Posted: Tue Oct 30, 2018 12:16 pm
by SweHogelid
@martin1454
Sorry for hijacking your thread, I now realize we have different ideas but want the same thing of course.
I rest my case and will make my own thread when I have thought this through a little more.

Re: Compensation for blob start point on outer perimiter

Posted: Wed Oct 31, 2018 5:42 am
by martin1454
SweHogelid wrote:
Tue Oct 30, 2018 12:16 pm
@martin1454
Sorry for hijacking your thread, I now realize we have different ideas but want the same thing of course.
I rest my case and will make my own thread when I have thought this through a little more.
No problem - looking foward to your idea - any idea that helps :D