Supports After Downscaling Issue

[BigMassiveClock 0]

I recently got into 3D printing and am trying to print out a multi-piece model. The original models are way larger then I would like mine to be (Almost full dimensions of printer bed). Using Cura I downscaled the entire model to 35% and foudn that some supports and the small connected details that they support which were there when the model was larger are now gone which has caused many blemishes when trying to print my models without the necessary supports. I realize that downscaling a model can ahve negative effects on the piece, however the model is still relatively large. Could it be an issue with my support settings? Any advice helps, thank you.

 

Below I have attached some screenshots. At 100% the detail is perfectly supported and modeled. At 50% the model is supported however you can see that the lines are not connected all the way along the piece and are seperated slightly. Finally, at 35% (size of interest), the model does not have supports, and prints two blops of filament in thin air that don't even resemble the small piece.

[GregValiant 1,248]

Let's say you've made your daughter a doll house and it is an exact 1/100 scale model of your own house right down to the fence around the yard.

You can paint the real fence around your yard with a 100mm brush.  You cannot use the same brush on the fence around your daughters doll house.  You would need to scale the brush down.

A ledge that was 1mm wide at 100% is now .35mm wide and maybe less than 1 nozzle / line width.  The only fix I've found is to scale the nozzle along with the part.  If your previews are with a .4 nozzle then switch to a .2 nozzle and .2 line width and you will get at least some of the detail back.  It's going to print a lot slower.  The alternative would be to go back into the model and scale certain features up so they don't disappear when the model is scaled down in Cura.

Other things to play with are Support Distance from the model, Z overrides XY, and maybe Adaptive Layers.

 

 And thank you for putting the "L" in your screen name.

[geert_2 557]

Yes, as GregValiant said: you can best adapt your model to the size it is going to be printed in. If you scale it down, everything below the nozzle-width falls away (unless you apply tricks). And other parts might fuse together because the gaps become too small. Or you might no longer be able to access certain areas with tools to remove supports, etc. So you have to adapt these in the design.

 

This is a bit similar to logo-design in a graphics editor: you need to redesign your logo for each size it is going to be printed in. If not, when scaling-up, the white spaces will seem too large, and the logo will visually seem to fall apart in separate pieces. It will look too crude and dumb. When scaling down, the opposite occurs: the white spaces will seem too small, and everything will seem to fuse together, and details and fine lines get lost. It becomes an unrecognisable blur or mess. Both hurt visually. Thus: when scaling up, you need to reduce white spacings, and need to refine the design and add details. When scaling down, you need to increase gaps and thicken lines and features, and make the model cruder by removing details that are too small. You need to take the printing method and viewing distance into account when redesigning the logo.

 

The same here in 3D-editing and printing, except that things fall apart or fuse together, and details are lost *physically*, not just visually.

 

[BigMassiveClock 0]

7 hours ago, GregValiant said:

Let's say you've made your daughter a doll house and it is an exact 1/100 scale model of your own house right down to the fence around the yard.

You can paint the real fence around your yard with a 100mm brush.  You cannot use the same brush on the fence around your daughters doll house.  You would need to scale the brush down.

A ledge that was 1mm wide at 100% is now .35mm wide and maybe less than 1 nozzle / line width.  The only fix I've found is to scale the nozzle along with the part.  If your previews are with a .4 nozzle then switch to a .2 nozzle and .2 line width and you will get at least some of the detail back.  It's going to print a lot slower.  The alternative would be to go back into the model and scale certain features up so they don't disappear when the model is scaled down in Cura.

Other things to play with are Support Distance from the model, Z overrides XY, and maybe Adaptive Layers.

 

 And thank you for putting the "L" in your screen name.

 

6 hours ago, geert_2 said:

Yes, as GregValiant said: you can best adapt your model to the size it is going to be printed in. If you scale it down, everything below the nozzle-width falls away (unless you apply tricks). And other parts might fuse together because the gaps become too small. Or you might no longer be able to access certain areas with tools to remove supports, etc. So you have to adapt these in the design.

 

This is a bit similar to logo-design in a graphics editor: you need to redesign your logo for each size it is going to be printed in. If not, when scaling-up, the white spaces will seem too large, and the logo will visually seem to fall apart in separate pieces. It will look too crude and dumb. When scaling down, the opposite occurs: the white spaces will seem too small, and everything will seem to fuse together, and details and fine lines get lost. It becomes an unrecognisable blur or mess. Both hurt visually. Thus: when scaling up, you need to reduce white spacings, and need to refine the design and add details. When scaling down, you need to increase gaps and thicken lines and features, and make the model cruder by removing details that are too small. You need to take the printing method and viewing distance into account when redesigning the logo.

 

The same here in 3D-editing and printing, except that things fall apart or fuse together, and details are lost *physically*, not just visually.

 

Thank you both, makes perfect sense now.