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Having a great time with my Orion. Prints are looking great. I'm having a problem with incorrect sizing, however. My prints are coming out .25mm smaller than designed. I caliper a tube to fit inside a 3d printed object, but the hole created when calipered is always smaller and the tube will not fit.

I've printed out test cubes to measure layer width. When I print with .55 width, it calipers at .55. That seems to be working fine(I'll get a micrometer soon so I can be for sure). I'm not great with editing firmware yet, but this seems like something I can't fix with slic3r settings. The height and width of the actual cube are off by .25mm.

I've worked around it by adding to design, but I know this is the incorrect fix.

I do have to say that .25mm is a crazy small amount to be talking about. Crazy that within a month I start to worry about fractions of a millimeter! impressive technology.

Adds to my last question: If I add more perimeter, that DOES add it to the inside of the model, correct? Opposed to adding "thickness"?

DELTA_DIAGONAL_ROD can change you're X/Y scaling, and you can fine tune that value to whatever accuracy you want, when aiming for less reasonable levels of accuracy you are likely to end up hitting a few different limiting factors.

That doesn't speak for why you're Z height would be off. I'm forgetting off the top of my head what it is that would do that, but I'm thinking it's something like steps per mm.

I wouldn't go changing any firmware values just yet without more input because this seems to be multi-variable fix.

As for the slicer parameters, that is generally correct although each slicer can behave differently and may have options that determine it's priorities. I know I wouldn't try to predict what any slicer would do if you told it to build a .7mm wall with .3mm wide traces.

There's actually an understood phenomenon with holes in 3D printed parts in all 3D printers, but I can't find the reference right now.

[edit - FOUND IT! http://hydraraptor.blogspot.com/2011/02/polyholes.html ]


g.

Yep, geneb found the link


The best thing to do is to scale up your ID hole in your model

John

I've found that .5mm bigger does the trick very well - so for a 5mm hole, I make it 5.5mm.

That link makes a-lot of sense for what I've experienced. I didn't go into as deeply as nophead, I just compared two prints from an OpenSCAD piece with $fn of 720 to one of 32 and the smoother high polygon print ended up being worse, which got turned into a mental do-not-do and I hadn't thought about it more than that. Thanks for that gene