Problem with arcs on second print of stand after moving Ormerod

Yesterday I printed a stand for a tablet and all went well (thing: [www.thingiverse.com]). I had to rotate this STL in blender to print from the logical base up to the two longer prongs. I rotated with Blender and then sliced using the standard Ormerod 0.5 settings. That print took the 2 hours and went rather well.

Then I decided to move the Ormerod. This was only a 0.5 meter movement with a 180 degree rotation (I had the electronics box facing me before). After the move I did the manual bed levelling and got much the same numbers. As expected, the small movement didn't really change the print bed positioning much.

After that, and again a few times this morning I tried to print another stand. Things start out well, as seen in the first screenshot:

However, once the first layer is set down the arcs no longer produce a smooth result, but put down a more straight lined version inside the original arc as seen in: .

I realize that the kapton tape looks a little grungey on the shots, the PLA seems to stick reasonably well to it. The first layer doesn't seem to move unless the print head catches on some plastic that is on it.

Any hints as to what to try to tune are greatly appreciated.

If you moved it, chances are you need to redo the bed levelling / z homing. Even though the first layer stays in place on the bed, it might be that the head is too high and the second layer won't stick to the first. That arc consisting of straight lines looks like it could have "fallen off" and been dragged inside the corner.

Also, you should check the gcode file in something like gcode.ws to make sure that is not broken, but that doesn't look like something Slic3r would be mistaken about.

Looks like the Z is a little too high for the 1st layer. The outer perimeter and the inner fill should be joined. It also would cause bad adhesion like you're seeing on the sharp corners.

It could be due to Y belt slippage. Are you using Matt's Y belt clamps, or something similar?

The lines are coming out straight because the filament is printing above the bed, so it has nothing to stick to. As the filament cools it shrinks and gets pulled into straight lines.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Your photo is definitely showing poor first layer adhesion is the problem. Either the Z height is too high, bad bed levelling or the kapton surface needs de-greasing and cleaning.

Dave
(#106)

Yes the nozzle seems to be too high, infill should reach perimeters



you could try this:

use a slice of 0.1mm paper (A4 80gr. laser an inkjet paper = 0.1mm)

lower the nozzle on paper until you feel a very slight resistance when you move the paper, to make small adjustments, grab and turn the gear wheel on the z-motor/threaded rod, this will enable you to make fine adjustments in 0.016mm steps, (if you find the motor to hard to turn, lower the current with command M906 Z200)

zero the nozzle at 0.1mm (send G92 Z0.1)

Erik

It seems that I was much to familiar with setting the Z=0 (or 0.1) base parameter from the other side of the machine. Having the print nozzel that much closer to my head which was on a flat angle to the nozzel before.

Using the method directly above by @ormerod168 I am now printing another stand, well past the danger zone of the second layer. So I managed to setup the Z home 7 times in a reasonably repeatable way to be too high without using the paper.

For the record, some things which were suggested that didn't change things for me in this case: when I moved the Omerod I used a USB extension cable, which was possibly the issue. Moving the controlling Linux machine closer and removing that extension didn't change things. Printing from SD card (instead of streaming from pronterface over US didn't change things. And by didn't change things, I mean that the print was repeatably failing in the same way at the same time.

The first layer does not look good to me - it should not look so 'elevated'.

I would lower the Z home, and also look at increasing a new slic3r print setting: in Advanced -> Extrusion width -> try an increased "First layer".

As a Z test, its worth running a print of 4 * 2 layer cylinders of approx 15 mm OD and 5mm ID, spaced sufficiently apart (eg 100 to 150mm square) and confirm that all are nicely squished onto the bed, with no gaps between threads.