Problems with first dry-run

Problems with first dry-run

Postby SSmithDK » Sun Dec 07, 2014 9:44 pm

I've finally gotten around to re-string, re-calibrate and update the firmware on my GUS Simpson to get it running at last. Having done the calibration over three times with the same results for steps/mm values, I'm confident that it should be ok now. I have also - in this process - tightened the strings as much as possible without the motor skipping steps and run a script to move all three arms back and forth to work the string in a bit. I am however still having trouble when printing. I was trying to make my first dry-run, and I realized two major problems.

1. When the print starts, the nozzle runs down to about 10mm above the hotbed and then further down to around 3-4mm above the hot bed and then starts "printing" at that height.

2. The printer movements are not even in the z-axis. As the printer is working right around the middle of the hot-bed it looks just fine, but when it starts to move a bit out towards the edges, it starts to move upwards 2-3mm and then back down as it reaches the middle again.

Does anyone have any idea what the problem could be?

I made a small video where the problem seems quite obvious: https://www.youtube.com/watch?v=-Fd_rB0Z_UQ

Thanks in advance! :-)
Kind regards
Simon Smith
Stud. BEng Mechatronics,
University of Southern Denmark
SSmithDK
 
Posts: 5
Joined: Sat Jan 25, 2014 2:08 pm

Re: Problems with first dry-run

Postby imrahil » Sun Dec 07, 2014 10:03 pm

Did you convert gcode using segmentizer script?
https://github.com/NicholasSeward/Conce ... EPROCESSOR

or easier version - https://github.com/Fiacha/GUS_Simpson
imrahil
 
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Re: Problems with first dry-run

Postby SSmithDK » Sun Dec 07, 2014 10:09 pm

Yes, I have used the original segmentizer script to convert the gcode. It gives me my model hanging in the air, which should be right. I have also adjusted my sementizer script to contain my own calibration values and have added a fair amount (think 1 or 2 more than the script on github) with some points in the printing area.
Kind regards
Simon Smith
Stud. BEng Mechatronics,
University of Southern Denmark
SSmithDK
 
Posts: 5
Joined: Sat Jan 25, 2014 2:08 pm

Re: Problems with first dry-run

Postby timrwilliams » Mon Dec 08, 2014 12:25 pm

If you have reproducible bed Z0 values in 'segmentize' and GUS is making the right sort of plotting movements but in the air, Could that be a Z offset from the pre segmentize original Gcode. (Sorry if thats a bit obvious !)
You seem to be almost there.

Regards
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Re: Problems with first dry-run

Postby SSmithDK » Mon Dec 08, 2014 1:07 pm

Perhaps I should double check the Z0 values in segmentize one more time and add some more. I am having a bit of trouble getting very precise values due to hysteresis (I guess a combination of the spring and string tension).

The plotting movements are not quite precise in the air as it varies quite a lot in the z-direction for some reason. It is supposedly a flat surface, but the hot-end is moving 2-3mm up and down.

In the original model (before slicing) I have made sure to place the solid on the surface and center it to 0,0.
Kind regards
Simon Smith
Stud. BEng Mechatronics,
University of Southern Denmark
SSmithDK
 
Posts: 5
Joined: Sat Jan 25, 2014 2:08 pm


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