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Drawings from stl files

_Ðave__Ðave_ Member, Developers Posts: 712 ✭✭✭✭
An Issue that I've been trying to find a solution for and hoping that Onshape will provide a solution is that after I perform one operation in my cam software I can verify and create an stl file of that operation from the initial stock.
 This operation may not be finish as per the drawing or original solid model. What I would like to do at this point is create a process drawing of the stl with dimensions for that operation. Therefore my question is that is this something that others would be interested in and will the upcoming drawings in Onshape be capable of dimensioning stl files.

Best Answer


  • michael3424michael3424 Member Posts: 673 ✭✭✭✭
    I'd be moderately interested in this, but only for dimensioning STL files downloaded online, so for me it would be pretty far down the priority list.

  • kevin_quigleykevin_quigley Member Posts: 306 ✭✭✭
    Bit pointless if you ask me. A bounding box command and box edit as in Rhino would be far more relevant for mesh handling. 
  • _Ðave__Ðave_ Member, Developers Posts: 712 ✭✭✭✭
    Kevin Quigley Thanks, I don't understand what you mean by a bounding box command and I'm not familiar with Rhino could you please elaborate. I'm trying to make manufacturing process drawings for a CNC machine Shop and wish to avoid having to recreate models at the different stages of the process. My Cam software will create an stl file of the part at the different stages of the process but i can not dimension a stl in Solidworks. Converting stl to step would also solve my problem. I've seen that spaceclaim will do a very nice job of making drawings from step files and was hoping for the same functionality from the upcoming Onshape drawings.

  • burhopburhop Member Posts: 22 ✭✭
    Dave, the problem with STL is that it is just a faceted format.  For example, if you were to zoom in on a circle, you would really see a polygon. This is fine for CAM and additive manufacturing because the "error" is smaller than the accuracy of the machine.

    However, mechanical CAD software and most CAD formats (like STEP) use precise representations. A circle is a circle and a circular cutout (hole) is perfectly round.  You can easily go from a precise format to an imprecise format but not the other way. Converting from STL to STEP is generally not possible (except in some special cases).

    Spaceclaim and others have done a good job at bringing both precise and "faceted" formats together so that you can do some things like dimensions.  I expect folks like Onshape and others are thinking about this too. I'd kind of like it too given the 3D printing I'm doing.
  • _Ðave__Ðave_ Member, Developers Posts: 712 ✭✭✭✭
    @Burhop Thanks for the insight on the details of stl files. Converting to step appears to be quite an effort. but just dimensioning from the corners of the triangles should be relatively simple and that would be all that I need.
  • kevin_quigleykevin_quigley Member Posts: 306 ✭✭✭
    Bounding box is a command used in a lot of applications that either creates a box or gives back the dimensions of a box that encloses the shape you have selected. Ideal for checking the overall dimensions of something (as in x,y,z).

    Box Edit in Rhino5 (and equivalent commands in FormZ and Modo for example) let you select an object and resize the xyz size and location just by typing in the values. This is extremely useful.
  • kevin_quigleykevin_quigley Member Posts: 306 ✭✭✭
    Converting from STL to STEP is easily done, but what the STep file is, is simply an exact replica of the stl triangles, so it is of limited use. The problem with applying dimensions to trianulated mesh parts is the snaps tend to be very hard to work with. Hence why overall bounding box tools work better.
  • burhopburhop Member Posts: 22 ✭✭
    edited May 2015
    You (meaning CAD developers) can do useful things with the faceted geometry, like looking for sharp angles that often correlate to the edges, deriving circles when you find 30 side polygons, etc. That makes dimensioning easier.  Its just a matter of priorities from the CAD developers.

    On going from STL to STEP, I should have been more clear. You are not going to get CAD friendly BREPs like Kevin Quigley  pointed out.

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