1 Topic by supraflyer

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Topic: microscopic holes at layer change question

I have some very small holes in the abs structure. The attached photo shows the issue at magnification ~100X.
I would appreciate any critical thinking on this issue. I think it would preclude using the cylinders as pressure vessels.
Thanks in advance

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2 Reply by op7ical (edited by op7ical 2013-04-28 19:31:49)

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Re: microscopic holes at layer change question

It is very hard to say what we are looking at in that photo.  Could you zoom out a bit?

Generally, the best way to seal a part is to use many solid layers for top+bottom fill, and to use many perimeters.  Maybe 4 or 5 solid layers would be good.  Also, make sure that your flow is calibrated - and maybe even over-extruded a bit, since this will help fill in gaps.

3 Reply by IanJohnson

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Re: microscopic holes at layer change question

Because the print is made from oval shaped threads, any change of direction will have a rounded corner.  Those points are where the outer perimeter turns to the inside or comes back out again.  Also any starting point will have a rounded edge as well.  The holes are where two rounded corners meet.  A little more extrusion will cause them to squish together more, but there will always be a little gap of some kind.  It doesn't go all the way through, it's just on the surface.

If you are making something that needs to hold pressure, I would recommend vapor smoothing it.  That will cause the outer surface to melt and flow together, sealing up any tiny gaps.

4 Reply by ysb (edited by ysb 2013-04-28 22:07:22)

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Re: microscopic holes at layer change question

the last version version of slicer (1.1+) can correct this problem (i think it's 'seam hiding' and 'jitter' in style tab)

Find all my 3D printable models here
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5 Reply by nlancaster

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Re: microscopic holes at layer change question

ysb,

I think you mean kisslicer.

6 Reply by supraflyer

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Re: microscopic holes at layer change question

So, all this help is most appreciated. I tried the vapor surface repair and it works very well. I would like to try to get the layer change marks to go away completely.
Is there some existing code that could be used to vary the first few layers and last few to make the layers on a slant.

first layer thickness  .15 mm at zero degrees, .22mm at 90 degrees and .3mm at 180 degrees , 22 mm at 270 degrees and so on for two layers until the size was .30 at zero and .60 at 180 deg. This I think would allow the layer change to be continuous instead of
jumping around and twisting the molten plastic.

Thanks in advance