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Cycleman
(@cycleman)
Trusted Member
Topic starter answered:
RE: overhang issue?!

@diem

I am learingin fusion 360...two weeks now and I understand what you saying. You have a right. This is very important.

in the bench boat as you say the blue one in slicer is where there isn't support and it prints in the air. As you see in my boat the door in the half height to the top there is drooping while in the slicer the blue is only to the top. 

so isn't a problem?!

Posted : 28/04/2021 6:52 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: overhang issue?!

@cycleman

The benchy is deliberately difficult to print.  Yours is quite good for a first try.  Your printer is ready for general printing.  When you have some experience you may wish to tune your printer for extra precision for a special project. It is then that you will need to worry about the finest details.

For now, print, learn and enjoy.

Cheerio,

Posted : 29/04/2021 1:11 am
Cycleman
(@cycleman)
Trusted Member
Topic starter answered:
RE: overhang issue?!

@diem

thanx again!!!!

on last question. I do the extruction perimeter with micrometer. I have 0.9 and I get 0.39 average. but with the math of prusa I get 1.15

Extrusion multiplier = (Extrusion width (0.45) / Average measured wall thickness).

so extrusion multiplier=0.45/0.39... is 1.15. I put it and I get overextrusion

I find this  https://guides.bear-lab.com/Guide/Extrusion+multiplier+and+filament+diameter/8 and I get 1.02 that seems right. I didn't try it.

And last I find https://teachingtechyt.github.io/calibration.html#flow and in the middle have a calculator have I get 0.92.

any idea?

 

Posted : 29/04/2021 7:44 am
Diem
 Diem
(@diem)
Illustrious Member
RE: overhang issue?!

What are you trying to do?

I suggest you reinstate the default profiles and print with them for a while.

When you are used to the standard output and have fine-tuned your first layer and you have everything running well you can begin to tweak settings and compare them to previous prints.

Cheerio,

Posted : 29/04/2021 3:08 pm
Cycleman liked
Cycleman
(@cycleman)
Trusted Member
Topic starter answered:
RE: overhang issue?!

ok thanx for the advice Diem.

Posted : 29/04/2021 3:45 pm
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(@)
Illustrious Member
RE: overhang issue?!

Anywhere build up isn't well supported, you can get droop. Overhangs is one of those places. Yes, it can be reduced by adjusting print speed, cooling flow, and other factors. All the adjustments are there: and kudos to Prusa for giving us access.  The professional way is to use support material: usually soluble support material on a multi-extruder printer or even a single extruder with MMU. 

On the other hand, if you expect cast quality from FDM printing, well, you need to reset your expectations.

Bridging is a curse of FDM, but you should know the Prusa MK3 does a really good job of it. Yes, it could be better, but making it better costs money, time, and investment into understand the process. One area where Prusa could help, is a better print fan shroud - there are several after market versions that "appear" to do better than the stock 95% shroud - and Prusa could find a good airflow engineer to make something that is well designed and hits that 98% mark - but hasn't because what they have works "well enough" for most. And those that want that extra 3% can design something or make their own off the web.

That said - a better shroud only helps certain printing conditions - the one that always gets me is the directional nature of an overhang. So I plan a print based on the knowledge airflow matters -- but it's taken me a few years to learn why.

 

Posted : 29/04/2021 6:06 pm
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