Subtract Procedure Help

Newbe Question.
I have 4 (12x5) C channels arranged parallel to each other & perpendicular I have a 2x2x1/4 angle running through them.
I need to break the angle at each channel.
What is the best way to achieve this?



  • It is possible to select all C's and cut out the L profile by
    a boolean subtraction.
    I think the question what is best is how will it be done in reality ?
    Which runs through.

    And it depends on BIM/LOD or not.
    For generated 2D plans it may not even matter if they intersect (?)

  • Yes most views will not matter if the angle is one piece.
    If I subtract the channel from the angle the channel is deleted from the drawing.
    Do I have a setting wrong?

  • I don’t know if that works as intended.
    But it looks like in newest V18s the cutting solids stay,
    which I think is much better.

    Maybe it is cheaper to weld many Ls in beteen than
    Having cut outs in all Cs ?

  • I'll give it another try later. I'm busy with another project.
    Picture of the all aluminum platform I'm working on.
    The red channel is dropped 2.25" for the grate and the angle catches the grate as it hits the main frame.

  • Here is the DWG
    BC Pro 18.2.14

  • Michael Mayer
    edited July 2018

    Well, I have not much clue about how steel (or Aluminium)
    construction is better done in reality,
    if it is better to bolt, weld, glue or something, or better cut in
    pieces instead of cutting outs or drill, how much space for
    tolerances required and such .... It's up to you.

    (The details are here often discussed or dictated by an engineer or
    even the company who finally builds it)

    But I can say for Boolean Subtraction,
    no matter if cutting elements currently get lost or not (copy ?),
    (it annoyed me in previous versions and I did not find a setting
    or option to keep the cutting element)
    you can select multiple elements before starting the Subtraction
    and then select one or more elements to cut at a time.
    Like cutting 500 C profiles by a single L profile in one go.
    Which I think is great and much better than doing it one by one.

  • Charles wrote:

    I need to break the angle at each channel.

    Hover the angle profile, select the SUBTRACT tool from the Quad Model tab, select the 4 channels as subtractors, right click to complete.

    The DELOBJ system variable controls whether source entities used to create other entities are retained or deleted.
    In the Settings dialog, click on the dropdown control to see an overview of the possibilities.

  • Thanks, Hans for pointing the way.

    Found this did the trick for me. Unchecking this kept the subtracting object in the drawing.
    The DELETETOOL system variable controls whether the subtracted entities (tools) are deleted or retained.

  • @Charles Alan Butler said:
    The DELETETOOL system variable controls whether the subtracted entities (tools) are deleted or retained.

    Thanks a lot !

    And when I watch Shape, keeping is even default setting.
    Don't know why I had to suffer previously :)

  • Yes lots of option and hard to know which one does what.
    We spend a lot of time figuring this out. But it's great when the software works with us.
    I don't do enough 3D work to keep current.

    I'm finding the SLICE is sometimes better than SUBTRACT. Still learning.

  • I never managed Slice to work for me.
    I always expect to draw a cutting line by my cursor.
    I would have to read deep in help files first.

    But I am able to use Split, in a 3D View at least.

    For settings I tend to always search for wrong terms or arrow key myself
    through 1000 entries.
    And when I read the tips below I always tumble over Setting descriptions
    like "the value is stored as a bitcode using the sum of the values of ..."

  • For me the slice needs lines I can pick to define the cutting plane.
    See the picture. I select the top railing on the left to slice.
    Then pick points 1, 2, 3 Enter
    The 45 deg slice is made. Then I can extrude the other top rail into the sliced on to get a 45 deg miter joint.

    I never used split before.

  • You made me ambitious.
    I looked at the help file and now understand the Slice Tool.
    I think it is quite complicated to use but powerful.
    It really does work in a way as I had expected.
    (Define plane by input, not just existing objects)

    I can get it to work - like Split Tool - by selecting a face.
    But here on Mac, only in very rare cases, the Prompt Menu
    shows the correct options for that Tool.
    (I have seen it only one time so far)
    For me Prompt Menu mostly shows selection options only.
    I can not entity-select>Quad>Slice.
    I can only Ribbon>Slice>Select>Enter=>Slice options

    Or I get the create Block Option Window very frequent.

  • How about generating a boundary from the face of the solid and use that for subtraction?

    You might like to play with BricsCAD Shape as it gives access to the BIM modelling tools not available with BricsCAD Pro, which I assume you might be using. If you do this type of work a lot, then Platinum + BIM module would pay for itself quickly.

    Design take, Why not place the grating on top of the support beams? This simplifies construction and removes the top of supporting beams from being a slip hazard.

    Few comments on the model:

    Global Material
    Looks like your file (template) originated from AutoCAD. There is a bug in BricsCAD in relation to the global material. Models created in AutoCAD don't display that well as a consequence. You can fix by opening a BricsCAD native template and copy and paste the global material. After this it will display nicely in BricsCAD. However, on return to AutoCAD it will looked washed out.

    When I subtracted from the equal angle I found a sliver of the solid remained. This is because the red PFC isn't quite touching the outside support beam. You can't pick this up using DISTANCE on the model as the units are set to Architectural. Switching to decimal showed that there is a 0.00006" gap. Minute, but enough to affect your model!

    Jason Bourhill
    CAD Concepts

  • Thanks for taking the time to share.
    The video was very helpful.

    The drawing is many generations old as I reuse dwg files for this client.
    The dwg is sort of like a template file and not sure where & when the materials came into the drawing.
    Thanks for the heads up, I'll get some fresh drawing files for the next on.

    The bulk of my work is architectural but I need to be more disciplined when switching to mechanical drawings.

    The original design had the grate on top but the client (fabricator) wants the grate under the main channels.
    He will build the platform in two sections & the stair separate.
    Then assemble on site. I thought it is a lot of cutting to get the grate under the channels but that is how they want it.

    Thanks again Jason, your input is always welcome.

  • Michael Mayer
    edited July 2018

    @Jason Bourhill said:
    How about generating a boundary from the face of the solid and use that for subtraction?

    Jason Bourhill
    CAD Concepts

    If the geometry would be clean and flush, I would stay with Boolean Subtraction.

    • Select all Ls
    • Start Subtraction
    • Select all Cs
    • Enter

    I think everything needed should be included in the Pro Version (?)
    That should help for the Grate too.
    There would be a few nice direct Modeling Tools in BIM Version or Shape that
    should make modeling such things easier.
    Like Connect with nearest and such things.

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