I've been working on a number of small parts and that trick has made a huge differences in getting clean results. What I've done is draw the set up for making the part, make it a component, then copy it. Scale it up, finish building the part in the larger version, save the file, and then delete the larger component. It's worked every time so far.

Hi Slarti, Certain "things" in SketchUp are stored inside the model even if they are deleted from model space (or are not otherwise used in the model). Component, Materials, Styles and (empty) Layers. In each of the browsers of the above (under "In model" where applies), on the right, there is a small, blue icon that triggers a flyout menu. There you can find the "Purge" command. Note that as long as an unpurged component has a material, you cannot purge that material for instance. An alternative is Window > Model info > Statistics - and at the bottom, there is also a Purge button that purges all 4 kinds together. I guess your dae import came in as a component and is still among your "In Model" components.