Horizontal holes
I just realized that holes on the horizontal plane are coming out very strange:
Now you might say, that's simply due to the process, overhang and all. But the bottom looks exactly the same, and prints a straight 2mm (on the outside part) where the hole should be at least one layer deeper. I've also not found any options in Slic3r that seem to affect this at all. I spent the last hour trying to figure this out, and things like "don't support bridges" or manipulating layer and extrusion size have no effect on how this feature is sliced. What gives?
Re: Horizontal holes
This is unfortunately due to the processing of the tangential angle in Slic3r.
You can only get cleaner holes if you construct your model as follows.
Depending on the hole size and your needs angles from 120° to 160° will work very well. (In my experience)
Re: Horizontal holes
[...] and prints a straight 2mm (on the outside part) where the hole should be at least one layer deeper.
Specifically, the hole should be less than one full layer deeper. I think what you're seeing is due to layer height, and the slicer needing to round off at an even layer height at some point. Looks like it rounds in favor of a full layer line.
A quick test would be to print the same hole with a lower layer height and compare.
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Re: Horizontal holes
Interesting technique. Thanks for sharing. Wouldn't the best angle depend on the layer height used for printing? The coarser the layer height, the greater the size of "point" at top and bottom of the hole needed?
Depending on the hole size and your needs angles from 120° to 160° will work very well. (In my experience)
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He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
Re: Horizontal holes
Interesting technique. Thanks for sharing. Wouldn't the best angle depend on the layer height used for printing? The coarser the layer height, the greater the size of "point" at top and bottom of the hole needed?
Depending on the hole size and your needs angles from 120° to 160° will work very well. (In my experience)
I didn't test different layer heights. But my test series was made of 5mm holes at 0.2mm layer height. In contrast to the round hole, even the 160° corner angled has kept its dimensions. This corner adds only 0,039mm to the hole height. I have no clue what Slic3r does there. Maybe it doesn't cut angular holes because there is no point where the tangential angle to the xy plain is 0°.
Re: Horizontal holes
MK3 printed parts holes are also not perfectly round, see https://github.com/prusa3d/Original-Prusa-i3/blob/MK2/Printed-Parts/scad/x-end.scad#L79
Re: Horizontal holes
Interesting technique. Thanks for sharing. Wouldn't the best angle depend on the layer height used for printing? The coarser the layer height, the greater the size of "point" at top and bottom of the hole needed?
Depending on the hole size and your needs angles from 120° to 160° will work very well. (In my experience)
I didn't test different layer heights. But my test series was made of 5mm holes at 0.2mm layer height. In contrast to the round hole, even the 160° corner angled has kept its dimensions. This corner adds only 0,039mm to the hole height. I have no clue what Slic3r does there. Maybe it doesn't cut angular holes because there is no point where the tangential angle to the xy plain is 0°.
I might be talking out of the hole where I sit, but maybe the important constraint shouldn't be the angle between the tangential lines, rather the distance between the intersection of the tangential lines and the desired circle. It seems to me that if that distance was equal to (or slightly larger than) the printed layer height, it would enforce rounding a gap in the offending layer. At least in the bottom of the hole. On large enough holes, that might actually not work on the top of the hole as that would approach 90° overhangs as what would normally be a bridge gets a small gap in the middle.
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Re: Horizontal holes
I found my old test object:
The picture on the right side proofs the fit of a 5mm shaft without post-processing.
Re: Horizontal holes
I might be talking out of the hole where I sit, but maybe the important constraint shouldn't be the angle between the tangential lines, rather the distance between the intersection of the tangential lines and the desired circle. It seems to me that if that distance was equal to (or slightly larger than) the printed layer height, it would enforce rounding a gap in the offending layer.
That sounds like a damn good approach. This would make the construction independent of the hole size. Maybe half the usual layer height (0.1mm) would be a good starting point for tests.
I will test it soon.
Re: Horizontal holes
I tested the constant distance approach, different layer heights, different hole sizes, and positions.
Let me tell you my latest theory:
After slicing the model into layers, Slic3r will check if there is an uninterrupted path between the left and the right side of your hole. Even it is connected by a single/incremental point (the hole ends exactly on a layer change). If this is the case it creates a bridge. If not then walls.
If we want a clean hole we have to add geometry to interrupt this path. Form and angles don't matter and the maximal needed distance is one layer height.
I think I'll use this approach in the future for small holes (because faster to construct):
Big holes will need support or still my old one.
RE: Horizontal holes
This is unfortunately due to the processing of the tangential angle in Slic3r.
You can only get cleaner holes if you construct your model as follows.
Depending on the hole size and your needs angles from 120° to 160° will work very well. (In my experience)
Hi,
any quick tipp how to create this in fusion360?
RE: Horizontal holes
I´ve created two construction lines, but dont know how to extrude the material between them. Any ideas?
RE: Horizontal holes
any quick tipp how to create this in fusion360?
I've prepared a demo project for you. You can open it on your machine and look for all the constraints I used. Use the front view with visible sketch to get an overview.
I added different solutions for different hole sizes and as a bonus solution to use fillets on the bottom side.
RE: Horizontal holes
any quick tipp how to create this in fusion360?
I've prepared a demo project for you. You can open it on your machine and look for all the constraints I used. Use the front view with visible sketch to get an overview.
I added different solutions for different hole sizes and as a bonus solution to use fillets on the bottom side.
wow, many thanks! Vielen Dank 🙂
I´ll take a closer look at that.
RE: Horizontal holes
Why not just make an ellipse in Fusion 360 with a layer height extra in Z direction - will that work?
5mm hole sample with layer height 0.2mm.
Have a look at my models on Printables.com 😉