How to force Cura to slice the platform slab

[mihan 0]

Hello,

 

I am new to 3D printing, therefore would appreciate any help how to force Cura to properly slice my model. As an architect I am modelling the structure in Revit, than exporting it into STL file and then slicing in Cura 13.04. I have 2 problems: first I can't force Cura to slice the platform slab with the walls. I can make separate model of the slab and separate model of the vertical walls, but not together... The STL is scaled in Cura to represent exact M 1:100 scale and here comes the second problem: the inner walls should be (after scaling) exactly 1,5 mm thick: how to configure Cura to print them as strong as possible? For better orientation I am attaching JPG for anybody willing to help me how to work this problem out. If there is need for STL or other files, I can post them too.

 

Thank you for any help in advance.

 

Mike

P.S. Would you, please, go here to look at the pictures:

http://umforum.ultimaker.com/index.php?/gallery/album/71-mikes-slab-problem/

 

[mgg942 0]

I'm new too, but I've done some design in OpenSCad and your first problem sounds as though the software is confused because the bottom of wall is merely touching the top of the slab, rather than projecting into it to make it a once piece solid.

To make the walls as strong a possible use 100% infill.

Mike.

 

[illuminarti 18]

Hi Mike -

Welcome to the forums, and to 3D printing!

Are you sure Cura hasn't sliced the base? I think the latest Cura doesn't necessarily show solid infill layers at the bottom of the print when showing all of it - it's a display efficiency optimization, I think. Use the slider on the right of the 3D view pane to step back to the first layers, and see if the base layers show up when just viewing the start of the print.

Currently Cura has a problem filling in small areas, such as the insides of small walls. For this print, I'd trying setting the wall width in Cura to 0.4mm - that will give a single pass along the perimeter of your object, and the slicer should then do a better job of correctly filing in the gaps. I'd be inclined to set a fairly high infill percent - at least 30% maybe more - in order to tie the walls together, and give a fairly well filled-in slab base that covers over easily. I'd also set the top/bottom thickness to 0.8mm or 1mm - to get 4 or even 5 (0.2mm) layers of solid plastic, so that any gaps in the infill have maximum chance to fill in correctly.

Personally, I wouldn't use a raft. I've never had much luck removing them. Assuming you're printing with PLA, I'd just cover the bed with the widest blue tape you can find, and wipe it down with isopropyl alcohol before you start printing. I'd try leaving the fan off for the whole print, or only start it on a high layer, after the base is printed. The challenge that you're going to have is that your print is likely to warp - the wide flat base is going to tend to curl up as it cools, pulling it off the print bed. Best case, this will leave the base of the print curved, worst case, the head will keep hitting the curling plastic and damage or detach the model. Using alcohol-wiped tape, and as little fan as possible will help to fix this.

(If you do this, you'll probably tear the tape when you take it off - in which case just sit the base of the model in a few mm of alcohol for 5-10mins when you're done, and the tape remains will slide right off.)

 

[mihan 0]

Hello Illuminarti, thank you for your knowledgeable reply: yes, the cca 130x130 mm model is warping up, so I will adjust the start of fan from (say) 10th layer up. You are probably right not to use the raft too. I tried to export various STL files from Revit and ALL gcode files from Cura 13.04 show NO slab in the bottom at all. I inspected it by the right hand slider to the Layer 1... Funny thing is that there, where no slab should appear, there is a slab in gcode and there where it should be, there is no slab at all... The walls are sitting correctly on the the slab in Revit model (0 mm) and they are joined with the slab too (in Revit) and the STL file shows the slab correctly too. But after slicing in Cura the slab is still missing. And the slab is 3mm thick in the model. I am little bit desperate about this condition... BTW if I export STL from Revit with just the slab, Cura will slice it correctly... Any ideas how to proceed would be much appreciated!

Hello mgg942, thanks for idea, but I can not join the walls and the slab into one solid before exporting the STL from Revit

software, because these two are separate families and I am searching the most logical way how to make correct 3D prints and maintain correct Revit model too... Anyway thanks!

Mike

 

[mihan 0]

Hello all, after inspecting the finished print I see that the height of the model is correct (including the thickness of the slab) and the walls are sitting on the slab, so Cura see the slab under the walls. But everywhere where the slab should be it is missing (there is a hole) and, on the other hand, there, where the slab should not be at all (no such thing in the STL file) there the slab is sliced by Cura. If anybody would be so kind to look into my STL and gcode files I would happily e-mail them for further inspection...

Thank you in advance,

Mike

 

[Daid 306]

For models like these I highly recommend the 13.05 beta version: software.ultimaker.com/Cura_closed_beta/

It will do a better job at the walls, and might solve the lower slab problem (But of that I'm not 100% sure)

 

[mihan 0]

Hello Daid, I would happily download the 13.05 beta if you can post the address from where...?

BTW I have downloaded and tried the Autodesk 3D Print Utility and I can confirm, that although it has some nice features, like automatically widening too thin walls, the end result is absolutely unreliable (low quality for architectural models, where you need sharp corners)...

Mike