Sandstone question. Would this work/print?

Discussion in 'My Work In Progress' started by Zenchuck, Mar 11, 2013.

  1. Zenchuck
    Zenchuck Member
    [​IMG]

    This is a detail in a project I am currently working on. It is a knob that is supposed to rotate. I have carefully made the clearances at .9 mm and the center cylinder is 3 mm diameter. My question is regarding the height of the knob itself. I am new to printing in general and I know that min. width is specified is 2 mm but in this case is it still considered a "wall"?

    Thanks for any insight into this.

    ~Andrew
     
  2. Youknowwho4eva
    Youknowwho4eva Shapeways Employee Community Team
    The general rule for walls vs details is, if it sticks out farther than it is wide, it's a wall. If it's wider or equal to how tall it is, it's a detail.
     
  3. Zenchuck
    Zenchuck Member
    Okay, thanks for the tip. I heightened them a bit.

    My second question is about the auto boolean features at Shapeways.

    -How far do objects need to intersect? For example, if you had 2 cubes that were placed exactly next to each other in 3d with 0 space between would the object print as a single solid object?

    thanks,

    Andrew
     
  4. Youknowwho4eva
    Youknowwho4eva Shapeways Employee Community Team
    Having items face to face causes issues. The checking software will automatically delete one of the overlapping faces. Then you have a face in the center that the software tries to make sense of, usually wreaking havoc on your model. Best is to have them overlap if you're relying on the upload software to join your model.
     
  5. stop4stuff
    stop4stuff Well-Known Member
    Last edited: Mar 13, 2013
  6. Zenchuck
    Zenchuck Member
    I will try the Netfabb product.

    This is great to get answers to some of these questions.

    My final question is about making objects fit together similar to lego blocks - basically a friction fit. I understand the .9mm clearance for objects that are printed next to each other, but if I was trying to lock two objects together wouldn't a .9 mm gap on all sides be loose? should I be designing tighter than that? If anyone has tried this with success I would like to know the design that was used. This project is in sandstone to take advantage of the full color printing.

    ~Andrew
     
  7. Youknowwho4eva
    Youknowwho4eva Shapeways Employee Community Team
    I've seen friction fit items in the detail materials. The problem with using the other materials is the accuracy of the prints. Sandstone is listed as having medium accuracy... I don't know what that means. But I don't think a friction fit item could be guaranteed to work every print with sandstone.
     
  8. stop4stuff
    stop4stuff Well-Known Member
    LEGO stud fit is made oversize - +0.05mm stud, -0.05mm socket iirc - because the material is ABS and has some give. FCS is gypsum based and has no give. The print accuracy won't get anywhere near a tolerance fit either/

    Paul

     
  9. Zenchuck
    Zenchuck Member
    Ahh, it seams like all my clever ideas are going out the window. Thinking about friction fitting items has made me think more about my initial design of the knobs and other items to have them spin. I realize now that the items will be too loose as well. I'm going to start again and make this one big monolith.

    [​IMG]