larger or smaller prints then asked

[stevendeman]

hello,

i have another problem.
i have a step file that i convert in an STL file with two different drawing software one with NX en one with IDEAS.(same step file)
when i print these files i get a diffrent size of print, the print with STL file from NX is to big and the one with IDEAS is to small (see picture)
i print with leapfrog printer and PLA material.
i thought it was the shrink but that is not the problem is think.

someone any ideas

thanks

[soofle616]

No picture was attached. When you import the .stl into your slicer program does the model appear larger or smaller depending on which file you load? If so then the issue is in the conversion to STL. If not then it's more than likely a problem with your slicer. I realize that's not terribly helpful but you haven't given us a ton of info to go off of.

[stevendeman]

sorry, i have leapfrog printer, work with simplify 3D.
when i load the two STL files i see the difference in size immidiately.
i try to print a thin wall cilinder outher diameter 75mm, wall thikness 1.5mm.
STL file converted with NX is outher diameter 78mm
STL file converted with IDEAS is outher diameter 73mm

so both aren't the correct size that i want

thanks

[soofle616]

If you're seeing it in your slicer then the issue is in the conversion to .stl

I haven't ever worked with NX and my experience with IDEAS dates back better than 10 years ago (and never with converting files to stl) so I really can't help you any more than that. But it's a safe bet that the conversion is the problem and not the slicer or the printer. As a work around to get your print to come out properly, since you know the difference in OD between what you want and what you're getting it would be an easy thing to adjust the scaling within S3D to get what you want. Either use the NX file at 96% or the IDEAS file at 103%

[stevendeman]

Hello,

thank you for replie, i have converted the same file with autodesk inventor and when i import that file into S3D i get. the same output as the IDEAS file.
what i dont know is the measurements of that file it's possible that the output STL has the correct diamensions but when i print it the material shrinks

thank you

[curious aardvark]

check that your wall thickness is a sensible multiplier of your extrusion width and layer height.

ie: if you want 1.5mm wall thickness you need to be using an extrusion width that fits within that. so 2 (inner and outer = 4 layers) layers at 0.4 is 1.6 which enlarges the print slightly.
So better option would be one wall layer and 100% infill.

Likewise if you print something 0.8mm thick (like my sling pouches) then you need to use 0.2mm layer for 4 layers. Or use several processes to get the right height in simplify3d.

None of it's complicated - but you do need to take basic aritmetic into account when you design something for printing.

Also abs tends to shrink about 1% of the overall size, so I usually enlarge the print by 1% on the slicer bed for abs and that usually sorts it.
Pla usually prints the size I wanted - unless I got the maths wrong :-)

so just check the numbers :-)

[soofle616]

aardvark makes some good points but given the difference in size I'm still going to say it's a scaling issue and not material shrinkage or wall thickness problems. We're talking differences in OD of 3-4% in both directions. ABS shrinks about 1% so for a nominal OD of 75mm one could reasonably expect an ABS part to end up being slight over 74mm after it's cooled. So I suppose with measurement errors 73 isn't out of the realm of possibility. On the other hand the second print is oversized by 3mm which is definitely not a function of material shrinkage. While it could be partially due to wall thicknesses there would have to be something seriously wrong with the slicer settings to get that result.

Ultimately you've already stated that you can visually see the difference in size when you bring the files into your slicer. If you can see the difference there then the problem is your stl files. Everything that happens after that point may or may not help or hinder you getting the prints you want but the problem exists right from the start. Solve that problem first before you go looking for other issues. If you can't solve that problem then the simple solution is what I mentioned before, simply scale the model in your slicer to get the size you need.