Scaling problem with slicer software

[fred_dot_u]

Both of the cubes are 1/10th the "real" size. Instead of 25.4 mm, both are 2.54 mm. Something is amiss in the software, I believe.

[TFilbert]

That's so strange. I've made 3d parts before, exported a dxf file and had stuff laser cut out of steel and the shop who received the dxf had no problem at all with scaling being off by a factor of 10.

I'll ask a co-worker who has a lot more experience with autodesk inventor.

[TFilbert]

Alright...How about this file? --I found an "options" button in the pop up window to save the export stp file. In the options, the units were set to centimeters. I changed that to millimeters

[fred_dot_u]

that one is 2.54 cm / 25.4 mm / one inch!!!

[TFilbert]

So weird, but glad I figured it out. Looks like I can do my modeling in inches, change the units in document settings to mm, then make sure that the units of the stl file is set to mm.

[fred_dot_u]

STL files are unit-less, usually interpreted by slicers and the like as millimeters. What you did in the last file resolved the confusion.

[TFilbert]

Printed my cube last night. Overall, I'm pretty happy with how it turned out. I used minimal fill inside the cube. X and Y axis was within .005 of nominal, one was higher, the other was lower. Z axis was off by about .040"

[curious aardvark]

dxf files are NOT solid 3d models.
they are 2 dimensional vector graphics.

So most likely using a different conversion algorithm to a proper 3d model.

you can usually 'fix' z-axis issues by making sure that the print layer height is an actual factor of the actual height of the model.

I use 0.25mm layer height a lot if I'm making something that uses whole MM.

If the model height is not divisible exactly by the layer height then the slicer has to fudge one or more of the layers to try and get the correct height.

It does depend on how critical a few hundredths of a mm are to the design.

It's also worth bearing in mind for x& y as well.

[TFilbert]

Thanks. I am aware of what .dxf files are for. I did not say I was trying to 3d print a .dxf I said that I have exported .dxf files from the same software to have things laser cut out of steel plate, and that there were no scaling problems with those parts. But thanks for your input, especially about the filament sizing and how it can affect the finished dimensions/tolerances of the printed part. That is something I had not considered yet. (That the printer can only print a whole filament diameter, and has to + or - a layer if the dimensions of the part are not a whole factor of the filament diameter)

[fred_dot_u]

Not a multiple of filament diameter, a multiple of layer height. I have both 2.85 mm and 1.75 mm filament printers, but use 0.20 mm layer heights, rarely 0.10 mm layer heights. Those are the numbers for managing a "clean" slice.