First test print failure

Ok so started my first test print of a 30mm hollow box and it seemed to be going ok, the first layer wasn't great, a few gaps but the walls seemed to be doing really well, the sides were super smooth and appeared to be straight but then on about layer 70 of 100 the print head started raising too high and was visibly a mm or more above the print so just started getting strings. I have no idea what this means. Here is a picture. Any ideas

Did you set the motor current back to a normal value after initial commissioning? If T3P3 is still shipping motors with 1.68A current rating, then I suggest 1000mA for the towers. The extruder may not need as much.

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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].

is just one corner too low, or is that from the photo?

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dc42
Did you set the motor current back to a normal value after initial commissioning? If T3P3 is still shipping motors with 1.68A current rating, then I suggest 1000mA for the towers. The extruder may not need as much.

I left the extruder at 500 but I will increase it to 1000 and see how it goes. How would that cause this issue?

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voi9viper
is just one corner too low, or is that from the photo?

I am not sure, it seemed like one corner was ok and the rest were too high.

If this is your first first print then it can also just be some weird first run problem that you will never see again. Try to print it again and see if it does the same thing... If it does, then increase the hot-end temperature by 5 C.

Actually it looks like the cube is leaning outwards? What is the dimensions at bottom versus top?

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LarsK
Actually it looks like the cube is leaning outwards? What is the dimensions at bottom versus top?

Think that is just an optical illusion or the picture angle, the sides are all the same at just about 30.12 +-.02 all the way up.

ok second print succeeded and looks great but is not perfectly square, the sides are all 30.12 again but top to bottom it is 29.88 and the bottom is still a bit messy and thin and has a few tiny holes in it.





so how to I get it the right size and get the bottom printing better?

diagonal rod length affects X/Y size/scaling, but I think it's something else. The only thing that I know for sure that affects Z scale is steps-per-mm, and based on your results this seems most likely to me. This is easy to test without printing anything. Move the nozzle to x0, y0, z30. Measure the real height, move Z up at least 30 mm, the higher the better, but no higher then you can measure with the same instrument (calipers, ruler, tape measure, whatever) . Larger lengths give more accurate results , smoothing out any small errors in measuring. Ok, move the nozzle up, say 100mm, and measure the height. Subtract the first height. It's probably off by about 4 mm (just a guess here). Now do a little math:

(original steps-per-mm (using 80 as example ) * commanded_distance) / actual_distance, or (80 * 100) / 104 = 76.92 new steps_per_mm value.

I think that will fix all of your scaling issues. The same value is used for X,Y, and Z steppers.

Check your XY scaling with a much larger print, also check that the corners remain square. If the scaling is still slightly off but the corners are square, then you can correct the XY scaling, see [reprap.org].

Your Z steps/mm should not need to be adjusted, assuming they are correct for the geometry of your printer (I am guessing 20t pulleys, GT2 belt and 1.8deg motors, in which case 80 steps/mm).

If the bottom has holes in it, then most likely you are starting the print a little too high. Assuming you ran autocal or at least G30 before the print to get an accurate Z=0 height, try increasing the probe trigger height (Z parameter in the G31 command) by 0.05mm, which will reduce the starting nozzle height by 0.05mm.

btw after auto calibration, what deviation does it report?

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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].

Thanks guys, I check that stuff tonight when I get home. I'll post the deviation then also.

After auto calibration it says Calibrated 6 factors using 10 points, deviation before 1.113 after 0.122 then I did it again and it said Calibrated 6 factors using 10 points, deviation before 0.081 after 0.066 and the third time Calibrated 6 factors using 10 points, deviation before 0.057 after 0.056.

OK so I increased the probe trigger height from .95 to 1.0 but now it seems to not stick at all as if it is starting higher than before.

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MightyMouth
OK so I increased the probe trigger height from .95 to 1.0 but now it seems to not stick at all as if it is starting higher than before.

Try another 0.05mm then. Don't forget that you either need to reboot the Duet after changing config.g, or send the new G31 command directly so that it gets actioned immediately.

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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].

Ok thanks I didn't forget to reboot the Duet, I just didn't know I didn't have to