Please help me choose a 3D printer

[curious aardvark]

And we'd also like to see some of these buuldings :-)

For pla I print at either 200 or 210. 210 is for when I'm printing at 65mm/s - about as much as the old girl can handle. The plywood frame on my creator does limit speed. I reckon I could probably hit 80/mms on the k-n-p. But as I'm usually using that for flexibles it almost never goes above 30 mm/s.

Yeah once you've got the hang of s3d - it's a very versatile bit of kit :-)

[Jeff B]

Town hall and firehouse fort hunter.jpgfirehouse_blend1.jpgfirehouse1.jpgfirehouse&quarter.jpg

[Jeff B]

My first time trying to post pics here and I'm not seeing a way to add text to the post...

Since you asked, CA, here's pics of the original firehouse that is the first building I modeled, the Blender model, and two pics of the print. The building is printed in 6 pieces - the walls, two roof pieces, the tower, the tower peak and the chimney. It's blue ABS - blue because that's the color that came with my machine. Roughly 5 hour print time for the walls.

So far I've had two issues with Simplify. First, with the roof pieces, the preview made it look like the shingles were all going to print as hollow outlines - but they printed fine. Secondly, when I tried to manually add supports to the tower (which was printed upside down), it wouldn't let me. I did get some sag in those bridged areas and had to trim them with a razor. Still don't know what the problem was with those supports.

My camera isn't too good at macros, but I hope you can see enough detail to know what I got.

Thanks for your interest, CA - I hope you guys will let me know what you think.

[curious aardvark]

Very cool :-)

I think I know why you couldn't add supports to the chimney.
By default it won't add supports to any gap smaller than 4mm.
You have to change the support pillar resolution to 1mm and it works.

s3dsupportresolution.jpg

Change that to 1mm and you should find that it generates support for even small areas.

@reprapsara - removed your post as jeff has already bought his printer and doesn't need a delta kit :-)

[Jeff B]

Thanks CA.

You got me curious, and I just reimported that tower model into Simplify. It displays weirdly, as if it has all kind of flipped normals, although it doesn't. It displays as if a number of faces are missing - yet Simplify had no problem slicing/printing it, it just wouldn't let me add supports.

I just tried the Repair>Flip Surface Orientation command, and that made the model display properly, and then I could manually add supports.

Bit odd - if Simplify thought the model had flipped normals, I'm surprised it would print at all. But if it happens again, at least I'll know what to do.

Thanks again!

[curious aardvark]

the issues are most likely due to the way blender exports stl files.
Maybe need an update version or a 3rd party add in to do a better job ?
That said the building look pretty good to me :-)

I've only ever designed in openscad, which only produces perfect solid models. So that's not something I have ever had an issue with.

The easiest way to check in s3d is to do a print preview. Often the model view and print preview look quite different. the print preview is the important one :-)

[Jeff B]

That tower is the only Blender model I've had any problems with. Simplify gave me a "very small, convert to millimeters?" message when I imported it. I think Simplify just had trouble parsing the small open supports. As I said, it printed without problems - looked fine in the print preview - it just wouldn't let me manually add supports onto what it was displaying as open faces.

I have learned to take advantage of the print preview more. When I zoom way in on it, I can see how Simplify averages things. For instance, on a vertical surface with 150 micron horizontal grooves and a 100 micron layer resolution - it takes every other groove and makes it 100 microns, every other groove 200 microns. Those kinds of arbitrary changes can be a problem with such fine detail - I'm glad I've learned how closely I can scrutinize the print preview.

The single biggest quality issue I cannot find a fix for is that the machine does not deal well with small vertical grooves on vertical surfaces. They come out rather dramatically rounded. You can see it on the big door of the firehouse, where the boards look more like bars. This happens even at pretty slow print speeds. I have wondered whether changing the acceleration rate in Sailfish might help that, but as I've said, I'm nervous about playing with Sailfish, and I wouldn't even know how to change the default values to something better.

Any thoughts on that?

I'll have to look into OpenCad (Openscad?) for the future, but I'm not changing horses now - I have too much time invested in Blender.

[curious aardvark]

look into getting a nozzle with smaller diameter hole.
There is only so much you can do with a 0.4 mm nozzle. Particularly on a tight right angle.
Probably wouldn't go any smaller than 0.2mm, but it would be worth trying a 0.3 as well.
There will always be a compromise between a round bead and a sharp right angle bend.

The other approach is to use a small file or folded piece of sand cloth/paper to just add in that sharp angle manually.

I guess it's a toss up between printing slower with a smaller nozzle, and how long it takes to finish with filing/sanding :-)

[Jeff B]

In thinking about it, I think you're right - I'm up against the limitations of the nozzle size. With a .4 nozzle, every right angle is going to have a radius of .2 That's not objectionable with details that protrude, but with small vertical grooves it becomes noticeable.
I did a second building with that same double door, and made the grooves slightly bigger and deeper, and the boards an even increment of .4, to see if it would help - it was worse. I suspect that the smaller and shallower the grooves the better, unless I reach a point where Simplify ignores them altogether.
At some point I may get a smaller nozzle, but I don't think I'll do that now.
The obvious answer is to avoid vertical grooves as much as possible, both in design and by printing parts flat.
But I will ask one more thing - I've been using "inside out" for the outer walls to help with overhangs. Do you think "outside in" might give better surface detail?
Thanks for your feedback. CA.
Oh, as far as sanding - too many small details piled on top of each other. For instance - to sand the boards on that double door, I'd have to sand off the door frame and hinges.

[curious aardvark]

outside in doesn't actually work for overhangs. think about it.
You have to build out gradually, so starting on an unsupported area won't work.

And don't think it won't do that, it will.

I did something recently that was a shaft with a hole at the top. Instead of bridging the gap and gradually creating the hole via the bridging - which is waht i thought it would do. It actually wanted to print the outline of the hole first - in thin air.