I am pulling my hair out on this one.  I found a great design for landing skids for it is about 1mm too big on all sides.  This may have been by design but I prefer it to be flush to the frame.

If I try to simply resize the design in Cura from the 26mm wide to 24mm wide scaled to proportions, the screw holes get too small and misaligned.

I tried importing the STL into Sketchup which is what I'm comfortable using knowing full well it would just be a puke of messed up geometry, I figure I'd try to clean it up as much as I can (wow it was a mess), use the offset tool on the outline and it all in 1mm.  It was a mess.  I even tried fixing the model in Trinckle but still comes out messed up in Cura.

I know there are some easy 3d programs out there now but I don't think they can actually shave off 1mm from a curvy edge like the offset tool can?

Scratch that ... I just went brute force method and imported into Sketchup where I was able to use the offset tool to shave 1mm off the silhouette. The price was steep though that is one helluva jumble of geometry I had to go through. Despite all that work I still had to run it through Trinckle to fix errors I just could not find. But I did get a lucky good fix from Trinckle ... printing now.  

I didn't see your post. Otherwise I would have suggested you use TinkerCAD to do what you wanted. Here is a video that I think Snow posted illustrating how easy it is to "remix" parts.

Thanks voodoo. I'd tried that but its capabilities are too rudimentary ... don't get me wrong, it's a great free program.  But I needed to keep the complex silhouette and shave off from there.  This program only allows you to shave off in a box or circle and that is it.

It turned out that my brute force approach was still not enough.  I had to practically start from scratch.  But the hardest part was getting the sillouhette and I was able to do that.  And from there were was just your run of the mill Sketchup problem soilving exercise.  It was a phenomenal pain the ass all for shaving off 1mm around the sillouhette, widening the screw hole recesses, and reducing the base thickness.  But I'm the type to plow even harder when I get pushed back lol so annoying.      

Maybe I'm missing something, but the way I would have done it (in TinkerCAD) is to import the STL, scale the whole thing down by 1mm (width and length only), fill in the original holes, and then make new holes to the right size/position.

I'm not familiar with TinkerCAD but if it works like any other scaling, the holes would not only get smaller but they would get repositioned from the scaling algorithm. I needed to have everything other than the outside stay exactly the same. Put another way, I just needed to "shave" 1mm off the outer edge - I didn't even care about keeping the integrity of the contour shape on top.

If that free program in AndyRC's video allowed you to pick an entire side then cut off a specified amount, that would have been golden. But I suspect from a modeling perspective that is way more complicated to automate than it sounds for anything other than a square or circle.

(06-Sep-2020, 11:39 PM)the.ronin Wrote: If that free program in AndyRC's video allowed you to pick an entire side then cut off a specified amount, that would have been golden.  But I suspect from a modeling perspective that is way more complicated to automate than it sounds for anything other than a square or circle.

I pretty much use TinkerCAD for all my designs because I'm lazy and can't be bothered spending the time to learn more complex design programs when TinkerCAD has so far been able to do everything I've needed. To simply shave 1mm off the the outside of a shaped STL file in TinkerCAD, I would use the following technique which should take less than 10 minutes:-

1. Import the STL file.
   
2. Make two more clones of the object (clone A and clone B). Both are solid objects at this point.
   
3. Extrude clone A up by 1cm.
   
4. Extrude clone B up by 2cm and set it to be a hole.
   
5. Resize clone B (hole) to be 1mm less in both width and length.
   
6. Position clone B (hole) over cone A (solid) and centre it.
   
7. Group clone A and B together. A shaped hole will now have been eroded out of centre of clone A leaving you with a "tube" in the shape and size of the original with a 1mm thick wall.
   
8. Set the shaped tube to be a hole.
   
9. Position the shaped tube over the the original and centre it.
   
10. Group the shaped tube with the original. Because the tube is a hole it will erode 1mm off the outside of the original.
    

Job done

Hmmm thank you Snow. I think I need to take a closer look then at TinkerCAD. Sketchup is ridiculously picky about open manifolds so it would be nice to have something less particular like TinkerCAD. It took my a good hour and several iterations to get my landing skids close to right.

That's why I like TinkerCAD so much, especially for remixing and modifying existing designs. On the other hand, trying to create a landing skid from scratch would have been far more effort than just an hour. Still do-able, but with all those angles it wouldn't be as quick as using proper CAD software by someone who is well versed with using it.

Post a ZIP of the STL files and if I get some time I'll see if the technique I specified in post #7 actually works in reality.