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PLA shrinking


jcosmo

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Posted · PLA shrinking

Ive been doing calibration on my printer and finding that I seem to be getting shrinkage in the x and y directions.

Its very uniform, such that the 20mm boxes come out at 19mm quite consistently. At first I thought it might be slipping somewhere in the drive mechanisms, but I noticed that whe I printed a hollow box that the base is accurately 20mm square, and the. The layers above "step in" to 19mm square. The box itself is very consistent above that point, indicating to me that the accuracy of the printer probably isn't the problem.

Any hints?

Does PLa shrink in this fashion? I'd read ABS was more prone to shrinking than PLA.

Is it likely that the is a mechanical problem somewhere in the printer instead?

Rather rushed photo

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    Posted · PLA shrinking

    A better photo:

    http://www.flickr.com/photos/jasoncosmo ... otostream/

    I attached the gcode file & cura profile.

    Interestingly I just ran off four of Daid's UM feet and whilst they don't exhibit the 'elephant foot', they are all 29x29x20 rather than 30x30x20.

    http://www.flickr.com/photos/jasoncosmo ... otostream/

     

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    Posted · PLA shrinking

    Observing the print process as closely as possible I think that the printing is being done at the 19mm box size, but that the foot was printed larger, so probably not a shrinking problem but a problem in the size it's attempting to print to.

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    Posted · PLA shrinking
    Observing the print process as closely as possible I think that the printing is being done at the 19mm box size, but that the foot was printed larger, so probably not a shrinking problem but a problem in the size it's attempting to print to.

    Hi

    I couldn't see anything wrong in the GCode

    Things to check

    Steps per unit for x and Y. Default is 78.74

    Do a 100mm X 100mm square to see if the error is proportional, that is about 3% out (should be 3mm out), or if it is still out by 1mm

    Let us know how you go

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    Posted · PLA shrinking

    FYI,

    I've printed a "tube" of 118 mm inner diameter (should fit OVER something that we measured as), and it came out 116. About 2% error.

    Then I printed an L shape with 100 mm between the surfaces (on the same side). That measured up as 99.8. only 0.2% error. It might be that it's overflowing my edges.

    The L-shape comes out bent: The PLA shrinks a bit.

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    Posted · PLA shrinking

    I've had to take the hot end apart and remove plug - first time I've had to do that so took a while.

    The X & Y steps per unit are as described.

    I'll go over the machine and check all the belts and pulleys, install the belt tensioners I printed a while back, and then see how it comes out.

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    Posted · PLA shrinking
    Interestingly I just ran off four of Daid's UM feet and whilst they don't exhibit the 'elephant foot', they are all 29x29x20 rather than 30x30x20.

    http://www.flickr.com/photos/jasoncosmo ... otostream/

     

    The tipped corners are rounded off. Mine are also 29x29mm.
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