Resizing In Multiple Sizes

Discussion in 'RC Cars, Boats and Planes' started by Sputnikk, Oct 23, 2017.

  1. Sputnikk
    Sputnikk Member
    i have a lot of requests for my parts in different sizes... and I mean like 10 a day. I wanted to see if anyone has had a simple way to resize the updated files and be able to offer them in different sizes, rather than uploading a 1/125, 1/100, 1/96, 1/72, 1/48, and 1/24 separately. Seams like this should be a simple thing to have in the code so it was easier to keep all the files in one location.

    Anyone know how to do this? Or can I suggest to Shapeways that they have a way to duplicate and rescale?

  2. stonysmith
    stonysmith Well-Known Member Moderator
    When going from 1:125 to 1:24, that is a 500% increase in size.
    If you want to use the minimum wall thickness (to minmize cost and maximize detail) across the entire range, the model will have to be re-created in each size.
    Almost no automated software is going to be capable of re-engineering the wall thickness as the size goes up or down.

    You could try a parametric modeller like OpenSCAD, but an automated solution is far in the future.

    If you don't care about minimum wall thickness, then the simple "resize" option on the Models page will take care of your needs. Personally, I use Netfabb Basic to do my rescaling.
  3. MrNibbles
    MrNibbles Well-Known Member
    Going from large to small sizes can also cause design rule violations to happen, so any model that would need to be resized in such a system would probably need to start with a small model that gets enlarged.

    As Stony pointed out it's usually best to generate a new model, particularly if there's a large scaling factor involved, because of material use and cost issues. On the other hand I could envision a system that allows a small "tweak" scaling function valid for small scaling changes. For example base size plus 20% scaling capability set by an input variable on the product page. You'd still need more base models for a wider range of scales but at least you wouldn't need to generate a new one every time a customer contacts you with a request for a slightly different size.

    But then we also run into Shapeways logistical issues and room for confusion. First of all each uniquely generated size would need to be assigned a distinct product number, similar to what's done with customized products when text or images are added on the product page. That's not a big complication but it could still be confusing if different customers order slightly different scaled objects, for example the base model and one scaled up by a factor of 1.05. It makes it more likely that customers would get the wrong size model particularly if the product is wildly popular with multiple scaled orders per day.

    Pricing also becomes an issue. You might want or need to change your markup value using a formula, which might be different for different materials. The problem is compounded by the fact that different materials have different pricing formulas. Some base prices might be determined by material volume, some by surface area, some by "machine space," and other by a combination of these. So that might make it difficult to apply a markup value for a scaled part based on how you normally determine your markup value. Shapeways has this horrendously obtuse pricing framework that does not easily allow you to add a fixed or percentage markup value for a product design regardless of material let alone something more complex like scaled sizes. They would probably need to implement an alternate markup method to go along with scaled product option. Otherwise it's the same old rigmarole of needing to upload a different sized model and tediously setting markup values for each material.

    Another big problem is the success rate factor, particularly when something gets fabricated for years and then suddenly can't be fabricated with a decent success rate causing an automatic withdrawal from the store. Let's say your base model has successfully sold 50 models, someone orders another version at a scale factor of 1.1, and then this order can't be fabricated. What happens? Does Shapeways disable the entire product? Does Shapeways lower the range of scaling to an upper limit of +10% rather than the original +20%?

    While it is not an impossibility for Shapeways to implement this kind of thing there's a lot of internal inertia that makes it difficult. On the other hand there's a new CEO that might have a different vision for the platform and user/shop owner interfacing.
  4. barkingdigger
    barkingdigger Well-Known Member
    The other factor in re-scaling is the selection of detail. An engine block in 1:72 will be devoid of things like tiny bolts if they are below the minimum size threshold, or they might be rounded as simple blobs, but at say 1:24 they are more visible so you want them all to be proper hex heads, of the correct size. One model simply won't give you a "sliding scale" of infinite details.

    If the scale difference is small enough (1:64 to 1:48 is "close enough" in my opinion, as is 1:87 to 1:72, or 1:35 to 1:24) then you can design for the smaller scale and then simply scale the model up for the bigger one. As long as you keep the basic geometry, you can remodel the details and wall thickness to suit a new scale, creating several families of the same model at different sizes. But you still need to upload each one and create a new product at that scale.
  5. matalondaniel
    matalondaniel Member