Part size problems / Edge Problems

[Ikarius]

Hey,

I've started to print mechanical parts with my Rostock and ran into some problems.
For calibration purposes I printed a 15 x 15 x 10 cube (Test 2 folder - link below) with a 5 mm hole right in the middle.
I am almost satisfied with the results, though I wish it was closer to 15.
The bigger problem is the hole in the middle, which is significantly smaller (4,5 mm) than intended.
I reran the whole process with a different part i created and got the same result - the hole diameter was smaller and the sides where slightly bigger. (see Test 1 folder)
I already did a few calibrations (rollierowland's manual calibration) and achieved an almost level bed.
I tried to search for a solution but found nothing that was of any use to me.

On a different (but maybe related note) if found that the edges of the cube where not smooth but had little holes - same on the opposite side (see outlines folder)
If one side was ok the opposite side was ok as well - same goes for the rough edges.

Any help or advice would be very much appreciated!

https://www.dropbox.com/sh/ci4alg4vbv6v ... geEla?dl=0

[IMBoring25]

This is a constant topic on any forum dealing with FDM/FFF 3D printers. Basically anything that's not perfect will make holes smaller than nominal, and there are a few factors that do so even if everything IS perfect. A summary of some of the factors involved is available in the Slic3r manual at http://manual.slic3r.org/troubleshootin ... ion-errors .

You can tolerate the undersize and fettle the holes manually, model the hole as a polygon with fewer sides sized by an inscribed circle (which won't make it round, but will reduce the undersize and probably give an improved fit at the contact points), use the XY size compensation function of your slicer, or make test pieces and determine how much to oversize the holes in your model.

[geneb]

How many times do I have to post this?

http://hydraraptor.blogspot.com/2011/02/polyholes.html

g.

[Ikarius]

This is a constant topic on any forum dealing with FDM/FFF 3D printers. Basically anything that's not perfect will make holes smaller than nominal, and there are a few factors that do so even if everything IS perfect. A summary of some of the factors involved is available in the Slic3r manual at http://manual.slic3r.org/troubleshootin ... ion-errors .

You can tolerate the undersize and fettle the holes manually, model the hole as a polygon with fewer sides sized by an inscribed circle (which won't make it round, but will reduce the undersize and probably give an improved fit at the contact points), use the XY size compensation function of your slicer, or make test pieces and determine how much to oversize the holes in your model.

I'm using MatterControl, unfortunately it doesn't have that feature. But thanks for the link it was interesting to read.

How many times do I have to post this?

http://hydraraptor.blogspot.com/2011/02/polyholes.html

g.

Until someone makes a sticky about this topic
I've searched for quite some time and didn't find a satisfying answer - maybe I just used the wrong search terms.
Thanks for the link anyway.

Did anyone take a look at the edge pictures?