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Great start but now poor finish. With kit buit MK3S  

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Nigel
(@nigel)
Honorable Member
Great start but now poor finish. With kit buit MK3S

My prints at first with supplied Prusa Filament were great. Now I am getting the issues others mention. Salmon finish and some poor upper layering. I am running my Prusa via a Raspberry Pi Mk3 with the latest Octoprint.

Nigel
Life is keeping interested and excited by knowledge and new things....
Posted : 06/06/2019 3:02 am
Casey liked
Nigel
(@nigel)
Honorable Member
Topic starter answered:
RE: Great start but now poor finish. With kit buit MK3S

Adjusting the bondtech gearing with the idler tension makes a huge difference. It boils down to a few turns of the screw bolt. This needs addressing.

Nigel
Life is keeping interested and excited by knowledge and new things....
Posted : 06/06/2019 3:05 am
Casey liked
JMcK
 JMcK
(@jmck)
Reputable Member
RE: Great start but now poor finish. With kit buit MK3S

There are a fair number of issues that routinely pop-up that are caused by the extruder idler being too tight or too loose. But the tension is entirely subjective. What is needed is an objective measurement.

They would need to add some sort of tension measuring to the idler. They probably couldn't/wouldn't add a dedicated sensor, but I wonder if there's a way to measure the tension via the driver chip like is done with X and Y... It would probably involve running it up and down a couple times. It would be tricky to do with filament in there, but maybe inaccurate without filament. It would be really cool though if idler tension was measured as part of the filament load process...

When someone asks you if you're a god, you say, "YES!"...
Posted : 06/06/2019 9:53 am
Casey liked
GregB
(@gregb)
Trusted Member
RE: Great start but now poor finish. With kit buit MK3S

"They would need to add some sort of tension measuring to the idler. They probably couldn't/wouldn't add a dedicated sensor, but I wonder if there's a way to measure the tension via the driver chip like is done with X and Y... It would probably involve running it up and down a couple times. It would be tricky to do with filament in there, but maybe inaccurate without filament. It would be really cool though if idler tension was measured as part of the filament load process..."

 

That would have helped me diagnose the problem when my Bondtech gear screw fell out.

Posted : 06/06/2019 4:48 pm
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(@)
Illustrious Member
RE: Great start but now poor finish. With kit buit MK3S

Most of us just count turns after the screw engages the spring.  Tighten screw until spring contact, then two turns (MK3 formula),  and four turns for the MK3S (only one spring).  The spring is fairly linear... but you might find 3 turns is adequate (Mk3S).

Posted : 06/06/2019 5:43 pm
bobstro
(@bobstro)
Illustrious Member
RE: Great start but now poor finish. With kit buit MK3S

I generally tighten the screws until roughly 1mm protrudes with no filament loaded. If something seems off, I'll adjust with the filament loaded, going by feel to loosen or tighten. This is something that would very hard to quantify due to the difference between filaments and materials I think. 90% of the time, my initial "~1mm" provides good results and it's not something I spend time worrying about.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 06/06/2019 6:59 pm
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