How I tuned my retraction with flex3drive in case it helps anyone else. April 24, 2016 04:04AM |
Registered: 8 years ago Posts: 3,525 |
Re: How I tuned my retraction with flex3drive in case it helps anyone else. April 24, 2016 11:25AM |
Registered: 9 years ago Posts: 425 |
Quote
DjDemonD
So I'd been having a lot of problems with bad retraction using flex3drive on my corexy. No problems with extrusion it was printing really well, but stringing was bad.
Having been through the flex3drive thread [forums.reprap.org] the recommended speed for retraction was just 10mm/s. This seemed crazily low but I tried it and still got no improvement.
When I watched the motor it didn't seem to be retracting at all. Despite the fact that on other printers I've used really high speeds such as 100 mm/s and got good retraction. I appreciate the extruder motor can't really move that fast but using this high setting seems to generate the fastest retraction possible.
So a bit of testing. I used pronterface to command extrusion of 1.8mm at a speed of 600 mm/min (10 mm/s), these are the recommended settings for this extruder. Nothing happened - motor stalled. So I reduced this speed value down by 100 mm/min and tried it again,and again. I tried both extrude and reverse each time. By doing this I could see what my motor with the mechanical load it has, can achieve. It was managing 300 mm/min reliably. I tried this setting which is just 5 mm/s in slic3r. But printing with this setting is slow, there's a noticeable time delay with each retract and the print quality seems to suffer with the long waits at each retraction.
So I went back and adjusted the motor current up, vref on A4988 driver was 1.0v. Now I could get 500 mm/min (8 mm/s) but with a very noisy motor (i am using 1/4 stepping to keep the extruder steps/mm given the 40:1 gearing to a sensible level - 760 on my setup). Not happy with this I switched to 1/8 stepping, 1520 steps/mm. Much quieter and was able to easily get to 600 mm/min (10 mm/s) for a short extrude/retract. Why I seemed to be able to get better performance on 1/8th stepping compared to 1/4 is something I am sure someone will elaborate on.
I am using this retraction test object [www.thingiverse.com]. Knowing I can reliably retract at 10mm/s, I reduced the amount down to 1mm retraction. And got a perfect retraction test object.
I appreciate this might be standard procedure or obvious to many reading this, or maybe not, but I hope this helps anyone trying to get this to work and not really understanding why it isn't working. Previously I had just set a high retraction speed and adjusted the amount of retraction to tune it and this worked on every extruder/motor combination I've tried so far, but here testing the motors capabilities and trying different micro stepping settings and motor currents was well worth the effort.
I should say I'm using ramps 1.4, marlin 1.1.0 rc3 and a 40mm 1.8 deg stepper.
Re: How I tuned my retraction with flex3drive in case it helps anyone else. April 24, 2016 06:57PM |
Registered: 8 years ago Posts: 3,525 |
Re: How I tuned my retraction with flex3drive in case it helps anyone else. April 25, 2016 05:28AM |
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Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 04:15AM |
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Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 04:21AM |
Registered: 8 years ago Posts: 3,525 |
Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 06:56AM |
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Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 11:29AM |
Registered: 8 years ago Posts: 3,525 |
Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 12:37PM |
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Re: How I tuned my retraction with flex3drive in case it helps anyone else. November 27, 2016 02:36PM |
Registered: 9 years ago Posts: 425 |
Re: How I tuned my retraction with flex3drive in case it helps anyone else. April 16, 2017 10:41AM |
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Re: How I tuned my retraction with flex3drive in case it helps anyone else. April 16, 2017 11:57AM |
Registered: 9 years ago Posts: 425 |