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Hi all,
I have have been having random head-crashes of my kossel mini between 2 - 4 hours into prints. I have been able to isolate it to one stepper motor that has now eventually failed, but was reading up in the doku when I came across paragraph to ground stepper :

"Note: it is highly recommended that the stepper motor casings be grounded, especially in belt-driven printers. Otherwise, motion of the belts causes static charge to build up, which eventually arcs over to the windings. If the motors are screwed to a metal frame, grounding the frame is sufficient."

There was anorther post on here to suggest to do it by attaching ground to frame which in turn is attached to the stepper through metal vertex of the kossel. My question is if I can ground it to mains ground as seen in quick illustration as attached.

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Hi all,
I have been quite happy running my duet wifi on my homebuild kossel mini for a few months now (just casually running it during weekends here and there, so no pro by all means)

I am perhaps running a few fw versions behind at:

Firmware Name: RepRapFirmware for Duet WiFi
Firmware Electronics: Duet WiFi 1.0
Firmware Version: 1.20beta8+1 (2017-11-18)
WiFi Server Version: 1.20b9
Web Interface Version: 1.19.3

Generally I am very happy with dimentional accuracy of my print for practical stuff, but I have been having start/end blob issues to my moves and I have started to experiment with pressure advance settings as I would like to print a few more aestetic figures and not just my current mounting brackets and hooks

However, I am not having much luck with my current troubleshooting, so I thought I would post my settings here for you to critique if anyone have the time to look through.

Some background, .. Firstly, my printer is a mini kossel with a capricorn bowden. I have a e3d v6 hotend and a duetwifi + smarteffector setup (calibrating to 0.007 which I am quite happy ). I am on 24V.

From config (sorry about my obvious comments, but I am quite new to this..)

M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation

M92 X100 Y100 Z100 E815 ; Set steps per mm (Extruder steps mm) 837 corrected from wiki > 815 (5.02.2018)
;For 256microstepp from 100 -> 1600

M566 X1200 Y1200 Z1200 E1200 ; Set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z18000 E1200 ; Set maximum speeds (mm/min)
M201 X1000 Y1000 Z1000 E1000 ; Set accelerations (mm/s^2)
M906 X1300 Y1300 Z1300 E900 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

G21 ; Work in millimetres
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves

I am uploading a couple of pictures for reference.
The blobs come at both start and end of move. For the benchy they are at the same spots for the different settings I have tried for the pressure advance:
M572 D0 S0.05 and up, but when I go over 0.2 my extruder seems to start grinding away at my filament. I did not try lower.

I used S3D and have following settings:
and

Clearly the devil is in the relationship between my retraction, speed and jerk, however... after a good while of blind guessing and reading through posts, I am still not getting it right. Simply I am not "getting" it

I am sure some of you could instantly spot my err and I would be very grateful to any pointers to further try out.

On a more positive sidenote:
I had a small session about 3d printing and coding to 50 young boys in a school here in Dublin today. It is very cool to see them inspired by this technology and the kossel makes for a very interesting object to watch as it makes wonderful movements. Next month I will be showing the minikossel on a stand at Dublin Maker 2018, so if anyone is in town, do hook up for a light chat and a Guinness

Here is a picture of it in action, but only showing without the kids So much fun.

Pps: New forum looks/works great!

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Installed 2.02 today. Download and install of .zip was insanely easy. No issues here on a kossel mini with smarteffector. Homing et.al. worked as expected.

Thanks again for your hard work @dc42

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Not used here and works well without. Printer sits next to my computer and I can also connect on mobile device like tablet or phone if required.

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@deckingman @Phaedrux Thank you both for reply and insights. I will have to tinker around a bit with your input. I am considering also a zesty-nimble for the smarteffector. I see it mentioned on the forum and it has its own adapter published on thingiverse, but am a bit conserned if calibration will work well for it.

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@jpwheless To run script, would I just copy it into new textfile, rename as .gcode and run? Would this work I realise post is a while ago and also wondered if you have considered change to script since in regards to the latest updates?

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Thanks for quick reply @dc42 . I was aware of ground loops and have been connecting to the Duet with laptop powered by battery alone which was suggested a safe option. I also think the new doku is very very good, so thank you very much for this

I updated the drawing as suggested and will wire up the rest of printer again shortly. I have also updated my steppers to 0.9 17HM19-2004S as suggested earlier in your blogpost. Practically my kossel mini came together by reading your blog, so thank you so much again

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Hi all,
I have have been having random head-crashes of my kossel mini between 2 - 4 hours into prints. I have been able to isolate it to one stepper motor that has now eventually failed, but was reading up in the doku when I came across paragraph to ground stepper :

"Note: it is highly recommended that the stepper motor casings be grounded, especially in belt-driven printers. Otherwise, motion of the belts causes static charge to build up, which eventually arcs over to the windings. If the motors are screwed to a metal frame, grounding the frame is sufficient."

There was anorther post on here to suggest to do it by attaching ground to frame which in turn is attached to the stepper through metal vertex of the kossel. My question is if I can ground it to mains ground as seen in quick illustration as attached.

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Thank you all for great suggestions. Sorry for late reply, but was on short holiday I will give it a try later on today. I use S3D, but was wondering if there a way to adjust the settings "live" while printing?

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