OK, so I did search, or try to, on past threads, really can't find an answer. I've successfully made my first 3d model of a 'starter' project via sketchup to try this out; have the .skp file pretty much done and I'm happy with it. I'm hoping I didn't make a fatal error to start with to make the entire model in feet and fractional inches. OK, so I know I have to do some kind of process to scale it down 1:160 using some kind of software from somewhere; what do you use to do that step? I'm also seeing there is a plugin from Sketchup now, but does it work for the scaling? Can it do the feet and fractional inches to decimal inches or what is the best way to do this? Then I have to go through some kind of process to check the model for polygon closure and change the file format to .STL, one step, or two, or what here? I've looked at the Shapeways instructions, still not very clear, and looked through a lot of threads and it seems like a moving target. I've seen so many good works from members here I figure this is the best place to ask. I'm a greenhorn at this stuff for now, and the model is pretty simple, I'm hoping to get a recommendation on both tool and process here.
I believe you can scale down what you have in Sketchup. Using the scale button, when you have the object selected, just type in 1/160. That should do it.
Personally, I have used at least five different methods for generating a 'Shapeways happy' .stl from Sketchup files (as you mentioned there are many, many different ways to do it). That said, the process that I discovered first (and which I generally use) is: 1) Starting with the model that you've made (in real world, 1:1, feet and inches), in Sketchup: File>Export>3D Model (save the file as a COLLADA ".dae" file) 2) Using 'Meshlab' (a free 3D mesh processing program); File>Import Mesh (the .dae you just created); then File>Export Mesh As (a .stl, as selected from the drop down box). 3) Using 'Netfabb Basic' (a free mesh editor and repairer); do everything described here: https://www.shapeways.com/tutorials/how_to_use_meshlab_and_netfabb under "Fixing inverted normals, bed edges and holes" 4) Finally, using the netfabb "scale tool," I readjust the model to the desired size. Note, as you've probably noticed, I typically do not worry about the scale of the part until I have finished all of the .stl conversion steps (and hole removal, etc.); for whatever reason, units invariably tend to get lost/changed/messed up when you move through different software packages and file types. By default Netfabb works in metric, so chances are whatever .stl you imported will not be the size that you wanted. If you are brave you can try to figure out what changed along the way (perhaps netfabb assumed that your 'inches' were actually 'cm' for example) but ultimately it shouldn't matter. If you just want to fix it: go into Sketchup and figure out one of your boundary dimensions (ie. the length/width/height of the box drawn around all of your parts, as you have placed them in space). On one of my boxcar files, the maximum length is 42' 5" (covering the outermost ends of the roof walk). Now, using Google (cause I'm lazy) I convert that number to metric (in my case, 42' 5" = 12928.6 mm). Now divide that number by 160 (in my case the result is 80.80mm). Now look at the "Information" dialog box in Netfabb (with your repaired model open) and see what it has decided that particular outer dimension should be. In my case, it reads the overall length of the part as 509.0 mm, which is way to big (to be fair, it actually lists the width of the part at 509.0 mm, but since the length it lists is shorter than 509, and I'd measured the longest dimension in Sketchup, I know that 509.0 mm is the number that I am looking for). To find the appropriate scale factor to re-size the part to N-Scale, divide the desired length (80.80 mm) by the netfabb length (509.0 mm). In my case I get a scale factor of "0.15875." Scale the model by this value and you have an appropriately sized part, in N-scale, in mm! Now upload this part to Shapeways and select "mm" as your desired unit. Do this a few times and you will probably notice that you are always getting the same scale factor (and you should if you are using the same .stl conversion process each time). Once you have that number nailed down you don't have to bother doing the math again, just write down the appropriate conversion and use it from then on out! The nice thing about scaling at the end is you don't have to worry about what happens to the units anywhere in the process; if you know what measurements you started with (in mm, or feet, or barleycorns) and what you want to end up in (mm) you can quickly find the scaling factor that suits your needs. Anyway, enough ramblings - that's my general procedure. I'm sure there are much more efficient ways of doing the .stl conversion in particular (like one of several sketchup plugins) but I use Meshlab just because I already have it on my computer. Hope that helps!
Hi Randgust First - Install one of the .stl converters into sketchup. Download and install netfabb studio. Best way is to answer is your question is by how my work flow goes. Get your drawing / plan, invariably this is in feet and inches, work out a scale so when you draw your model it is in real life size [there are a couple of quirks in Sketchup that limit your drawing [mainly circles] if you draw the item as 1:160]. whilst you lot over there have not really embraced the metric system I would use millimetres to draw your model it will make things so much easier. Start your drawing, after you have completed a stage, i.e. drawn a basic body shape, export the model to a .stl file, open this in netfabb, if there are errors you will get a cross, I click the repair icon and it shows where the errors are, I go back to Sketchup and fix them, recheck in netfabb, once fixed create a copy by "saving a copy as" that way when you move to the next stage if all goes pear shaped you can easily start again. When your model is complete and no errors use the scale tool in netfabb and scale to 0.00625. Save this as "part" - "export part" - xxxxxx.stl file. Your file is now ready to upload to Shapeways. Do not use Sketchup scale tool as this can do some funny things. Reasons for working in millimtres There are no fractions to work with. It keeps all your workflow in the same units. If your finished model is to be printed in FUD then there is no point in drawing anything smaller [i.e. a bolt] then 16mm in real life as this is below what the printer can print. [16mm scaled to N scale is 0.1mm] All your wall thickness to be no less than 128mm [Shapeways will not print less than this] in fact they will now not print to what their specification sheet says, they have made the minimums greater. Netfabb has an automatic repair tool - this works but it can make changes that you may not want so I prefer to make sure the model is correct and not allow software to think it is doing the right thing. By learning how to repair as you draw more you will know where the potential errors can creep in and you will not make them. Hope this helps, any more help or advice please ask or pm me.
