Problems creating small models. what size to design at? SketchUp

SketchUp 3D Printing
1

I had opened this question in the main Sketchup forum, but following a suggestion I have copied it to 3D printing, as it relates to adjusting the size of a sketchup model so it will print to the correct scale size;

I am designing models, currently mainly road vehicles for
3d printing, for T scale models railways (1/450 scale). These models are
small - in this scale a short wheelbase Land Rover scales out to just
8mm in length. (some that I did managed to design and print - http://www.shapeways.com/shops/t450 )

Herein lies my problem - I am not sure what size to use to initially create my designs.

At first I tried using the actual size of the final model, but that failed because the circle tool does not work at those sizes.

Then I tried at either 1000x (this being convenient as I could just
convert mm values to m), or at full size of the actual vehicle. When
doing this I set the measurement and angle accuracy to the maximum
first. The problem with this was when I then used the scale tool to
reduce the size of the model to 0.001 or 0.00222 for the actual 3d print
size the models do not always scale smoothly and can often end up with
holes where some of the faces just dissappear completely. I have tried
scaling the model as is, and also converting to a component first, but
either way can get the problem.

I would be grateful for any advice from anyone who has experienced
this problem, so that I can create my small scale models with curves on
the bodywork as required.

2

modelling using meters for mm is a very good approach, but still need to keep an eye on tiny triangles that may result from intersecting curves with curves, i.e. a rivet on a tubeā€¦

for scaling after modelling, I normally use the ā€˜Tape Measure Toolā€™, i.e. use it on the wheelbase, and type 5.44mm and it will ask if you want the whole model scaled to thatā€¦

john

3

This seems odd, as scaling isnā€™t supposed to trigger the cleanups that can merge nearby vertices and thereby lose edges and faces. Did you do some other editing after the scale down? Can you post an example file in which this happened?

4

Has anyone been able to find an answer to neil_machin first questions? We need an answer as well.

5

I also use the method John posted. Model at 1000x scale, then use the Tape Measure tool to scale the model back down to the correct size.

6

There is no absolute rule by which to assure that a particular scaling will avoid the small faces problem, it depends on each modelā€™s details. Particularly if you intersect, solid tools, or followme complicated shapes, you can generate remarkably tiny geometry. You just have to try a particular factor and see whether it catches all of the issues. Yes, there can be confusing ā€œwhat size is that now?ā€ questions depending on what you choose.

7
  1. Make the tiny model a component.
  2. Make copy of tiny component and place it off to the side.
  3. Scale up copy
  4. Do the editing in the over-sized copy.
2 Likes
8

I am designing models, currently mainly road vehicles for 3d printing, for T scale models railways (1/450 scale). These models are small - in this scale a short wheelbase Land Rover scales out to just 8mm in length. (some that I did managed to design and print - http://www.shapeways.com/shops/t450 )

Herein lies my problem - I am not sure what size to use to initially create my designs.

At first I tried using the actual size of the final model, but that failed because the circle tool does not work at those sizes.

Then I tried at either 1000x (this being convenient as I could just convert mm values to m), or at full size of the actual vehicle. When doing this I set the measurement and angle accuracy to the maximum first. The problem with this was when I then used the scale tool to reduce the size of the model to 0.001 or 0.00222 for the actual 3d print size the models do not always scale smoothly and can often end up with holes where some of the faces just dissappear completely. I have tried scaling the model as is, and also converting to a component first, but either way can get the problem.

I would be grateful for any advice from anyone who has experienced this problem, so that I can create my small scale models with curves on the bodywork as required.

9

I recommend asking this in the 3D Printing category. 3D Printing - SketchUp Community
Most modelers wonā€™t have encountered this issue, but I imagine those who have done 3D Printing will have, and it might be easier to attract their attention if posted in the 3D Printing topic category.
Sorry, I wish I knew the answer myself, but I havenā€™t done 3D Printing yet.
Also, adding a screenshot always gets you more replies!

10

answered on other threadā€¦

11

Build your models at real world size and then scale them down when finished.
Keep it simple; refrain from creating complex geometry.
That is, modeling 24-segment circles and 12-segment arcs is pointless when reduced to 1/450 scale.

12

Do what Geo says, it has the side advantage that you could put the models in 3D Warehouse, for anyone who needs the real world vehicle. Do the 1/450 scale in the 3D printer software.

13

I manufacture model railroad items and have a Form 2 3D printer.
I use Sketchup Pro and design in 1:1, Real World, scale then scale down to the particular scale I want to print it. Most of the time there is little that has to be changed when doing the scaling.

2 Likes
14

Iā€™ve done that, too. Itā€™s a whole lot easier to work in the full size dimensions. No need to calculate all the dimensions down to their scale size. You can also make models for different scales quite easily, then. Make sure when you scale down your components and groups that you adjust their scale for the smaller size.