Toothbrush Head Stand

    From FreeCAD Documentation
    Freecad.svg Tutorial
    Topic
    Modeling
    Level
    Beginner
    Time to complete
    1 hour
    Authors
    EmmanuelG
    FreeCAD version
    0.16 or greater
    Example files
    Thingiverse 2403310
    See also
    None

    A daily-life problem

    Electric toothbrushes rarely come with a head stand, while in a family you will often see multiple heads used with one body. Many people facing a common problem lead us to a variety of solutions, as you can see on Thingiverse (200-800 projects are related to that). Here is the first answer and how to design it.

    This tutorial will take you through the steps needed to model the part shown in the image below using basic tools from the Part Design Workbench (many of the tools and capabilities are not covered).

    TBHS-model.png

    First idea : a plate

    • From the start-page, select Workbench PartDesign.svg Part Design, or create a new document and select the Part Design workbench.
    TBHS-0.png

    Create a sketch

    • Click on Sketcher NewSketch.svg New sketch. Either from the contextual task menu at the left, or the toolbar above or from the Part Design menu at the top.
    TBHS-1.JPG

    A dialog prompts you to choose the sketch orientation and provide an offset.

    • We will pick the XY Plane as shown in the image above (that orientation correspond to the common build plate of most 3D printers), then click OK.
    TBHS-2.JPG

    You now are facing the XY plane from above, and have access to the drawing tools.

    • Click on Sketcher CreateRectangle.svg Rectangle.
    • Click to place a first point.
    • Click to place the opposite corner.
    • Press ESC or click the right mouse button to stop using the tool.
    TBHS-3.JPG

    You now have a floating rectangle of unspecified dimensions.

    • Click on a line of the rectangle, you now have access to the constraint tools at the right of the toolbar (depending of the size of your screen you may need to drag them to the left in order to see them all)
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 80mm, click OK.
    • Repeat with the other side of the rectangle, also 80mm.
    TBHS-4.JPG

    You now have a floating square.

    • Click on the lower left point of the square.
    • Click on the origin of the XY plane (at the intersection of the two thick lines).
    • Click on Constraint PointOnPoint.svg Coincident.
    TBHS-5.JPG

    You now have a totally constrained sketch, as you are told by the solver on the left and the change of color. It is a good practice to always have a totally constrained sketch.

    An under-constrained sketch can leave room for unwanted change, if you modify something later on.

    On the opposite, an over-constrained sketch is also not good. In that case the solver warn you of redundant constraints and you should remove some of them.

    • To leave the sketch, click either on the "Close" button on the left, or the Sketcher LeaveSketch.png icon in the toolbar, or press ESC.
    TBHS-6.JPG

    You now only see the square, and the contextual task menu on the left show you more options than before.

    Create a pad

    • Click on View-axometric.svg Axonometric among the standard views, to better see what will happen.
    • Click on PartDesign Pad.svg Pad.
    • Enter 4mm and click OK.
    TBHS-7.JPG

    Your sketch is now in volume !

    Create a sketch on it

    • Select the upper face
    TBHS-8.JPG

    The color of the face change and you have more options in the contextual task menu.

    • Click on Sketcher NewSketch.svg New sketch. As a face was selected it will not ask you to choose a plane.
    TBHS-9.JPG
    • Click on Sketcher Circle.svg Circle, click to place the center, move the pointer and click to define the radius.
    • Draw 4 circles on the pad (of any size)
    • Press ESC or click the right mouse button to stop using the tool.
    TBHS-10.JPG
    TBHS-11.JPG

    Now the circles share the same radius.

    • Click on Sketcher External.svg External geometry.
    • Click on the four sides of the square, it add lines, color magenta.
    TBHS-12.JPG

    Theses lines will serve as reference to position the circles.

    • Click on Constraint Length.png Distance.
    • Click on a center of a circle.
    • Click on a magenta line.
    • Set distance (20mm from each side).
    TBHS-13.JPG
    • Click on a circle
    • Click on Sketcher ConstrainRadius.svg Radius and set it at 1,5mm.
    TBHS-14.JPG
    • To leave the sketch, click either on the "Close" button on the left, or the Sketcher LeaveSketch.png icon in the toolbar, or press ESC.
    TBHS-15.JPG

    Create a pad

    • Click on View-axometric.svg Axonometric among the standard views, to better see what will happen.
    • Click on PartDesign Pad.svg Pad.
    • Enter 25mm and click OK.
    TBHS-16.JPG

    You have the basic shape, it just need final touches.

    Rounding the corners

    • Holding CTRL click on the vertical edge at each corner to select the four of them.

    Don't hesitate to help you by switching the display mode (just at the left of the Axonometric View) between DrawStyleWireFrame.svg Wireframe and DrawStyleFlatLines.svg Wireframe and shadow.

    TBHS-17.JPG
    • Click on PartDesign Fillet.svg Fillet.
    • Set the radius at 20mm.
    TBHS-18.JPG

    Much better.

    Making it more robust

    We need to add material at the base of the cylinders to make them less prone to snap. Because of the printing orientation these small surfaces will be fragile at the junction with the base.
    
    • Select the circles at the base of the cylinders
    TBHS-19.JPG
    TBHS-20.JPG

    Chamfer the edges

    • Select the face under the base, add a PartDesign Chamfer.svg Chamfer of 0,5mm.

    The first layer of plastic is often being squashed a little too much, this will compensate that and save you time in cleaning the model. If the first layer is ok that will make it only nicer

    TBHS-21.JPG
    • Select the edges at the border of the upper face (holding CTRL ).
    TBHS-23.JPG
    • Add a PartDesign Chamfer.svg Chamfer of 1mm. This one is only aesthetic.
    TBHS-22.JPG

    Tadaa !

    Export as a .STL

    • In the Combo View on the left, select the tree view instead of the contextual task menu, click on the last feature (the chamfer).
    TBHS-24.JPG
    • Now you can select "Export..." from the File menu at the top left, and select the file format .STL.
    • Just print it :-)

    Inspiration

    The above model make a good starting point to use FreeCAD, but as a toothbrush head stand it have its flaws : due to the print orientation and small surface the sticks are prone to break.

    Inspired by the variety of solutions other people came up with, we will make this second version which will be much better.

    TBHS-v2.jpg

    Don't worry it is often needed to go through several revision for an idea (e.g. : once the prototype on the picture was used, we added more space between the heads so that they should not touch).

    In this second part you will also learn to use more tools, like the powerful Linear repetition.

    Second idea : a band

    • Create a new document and select the Workbench PartDesign.svg Part Design workbench.

    Create a sketch

    • Create a Sketcher NewSketch.svg New sketch, on the XY plane.
    TBHS-1.JPG
    • Draw a Sketcher CreateSlot.svg Slot
      • Click to place the first center
      • Move to define the length and radius
      • Click to set the second center.
    TBHS2-1.JPG

    You now have a floating slot of unspecified dimensions.

    • Click on one of the horizontal lines of the slot
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 75mm, click OK.
      • that's for a 3 head stand, count 25mm for each, if you want more
    TBHS2-2.JPG
    • Click on one point of the horizontal line
    • Click on one point of the other horizontal line
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 29mm, click OK.
    TBHS2-3.JPG
    • Draw a Sketcher CreateSlot.svg Slot around the first slot.
    TBHS2-4.JPG
    • Make the centers of the second slot coincident with the centers of the first slot with Constraint PointOnPoint.svg Coincident.
    TBHS2-5.JPG
    • Click on one point of the horizontal line of the first slot
    • Click on one point of the nearest horizontal line of the second slot
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 3mm, click OK.
    TBHS2-6.JPG
    • To make the sketch fully constrained
      • Click on the lower left point of the second slot
      • Click on the origin of the XY plan
      • Click on Constraint PointOnPoint.svg Coincident
    TBHS2-7.JPG
    • To leave the sketch, click either on the "Close" button on the left, or the Sketcher LeaveSketch.png icon in the toolbar, or press ESC.
    TBHS2-8.JPG

    Create a pad

    • Click on View-axometric.svg Axonometric among the standard views, to better see what will happen.
    • Click on PartDesign Pad.svg Pad.
    • Enter 30mm and click OK.
    TBHS2-9.JPG

    Create a sketch on it

    • Select the upper face
    TBHS2-10.JPG
    • Create a Sketcher NewSketch.svg New sketch. As a face was selected it will not ask you to choose a plane.
    TBHS2-11.JPG
    • Draw an Sketcher CreateHexagon.svg Hexagon
      • Click to place the center
      • Move to define the radius
      • Click to set
    TBHS2-12.JPG
    • Click on an edge of the hexagon
    • Click on Constraint Horizontal.svg Horizontal
    TBHS2-13.JPG


    • Click on the center of the hexagon
    • Click on the horizontal line of the XY plane
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 15mm, click OK.
    TBHS2-14.JPG
    • Click on the center of the hexagon
    • Click on the vertical of the XY plane
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 10mm, click OK.
    TBHS2-15.JPG
    • Click on the blue circle of the hexagon
    • Click on Sketcher ConstrainRadius.svg Radius
    • A dialog prompts you to set a dimension. Enter 8mm, click OK.
    TBHS2-16.JPG
    • To leave the sketch, click either on the "Close" button on the left, or the Sketcher LeaveSketch.png icon in the toolbar, or press ESC.
    TBHS2-17.JPG

    Create a hole

    • Click on View-axometric.svg Axonometric among the standard views, to better see what will happen.
    • Click on PartDesign Pocket.svg Pocket.
    • Select to the first in the dropdown menu and click OK.
    TBHS2-18.JPG

    Linear repetition

    • In the Combo View on the left, select the tree view instead of the contextual task menu, click on the pocket feature.
    • Click on PartDesign LinearPattern.svg LinearPattern.
    • Set the length at 55mm and occurencies at 3, then click OK.
    TBHS2-19.JPG

    Create a sketch on it

    • Select the inner face
    TBHS2-20.JPG
    • Create a Sketcher NewSketch.svg New sketch. As a face was selected it will not ask you to choose a plane.
    TBHS2-21.JPG
    • Click on Sketcher Circle.svg Circle, click to place the center, move the pointer and click to define the radius.
    TBHS2-22.JPG
    • Click on the center of the circle
    • Click on the horizontal line of the XY plane
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 15mm, click OK.
    TBHS2-23.JPG
    • Click on the center of the circle
    • Click on the vertical of the XY plane
    • Click on Constraint Length.png Distance
    • A dialog prompts you to set a dimension. Enter 10mm, click OK.
    TBHS2-24.JPG
    • Click on the circle
    • Click on Sketcher ConstrainRadius.svg Radius
    • A dialog prompts you to set a dimension. Enter 3.5mm, click OK.
    TBHS2-25.JPG
    • To leave the sketch, click either on the "Close" button on the left, or the Sketcher LeaveSketch.png icon in the toolbar, or press ESC.
    TBHS2-26.JPG

    Create a pad

    • Click on View-axometric.svg Axonometric among the standard views, to better see what will happen.
    • Click on PartDesign Pad.svg Pad.
    • Enter 4mm and click OK.
    TBHS2-27.JPG

    Linear repetition

    • In the Combo View on the left, select the tree view instead of the contextual task menu, click on the pad feature.
    • Click on PartDesign LinearPattern.svg LinearPattern.
    • Set the length at 55mm and occurencies at 3, then click OK.
    TBHS2-28.JPG

    Draft

    • Select the side of each round pads
    TBHS2-29.JPG
    • Click on PartDesign Draft.svg Draft.
    • Set the draft angle at 40°.
    • Click on "Neutral plane" and select the face on which the sketch is drawn.
    • Tick "Invert the draft direction".
    TBHS2-30.JPG

    We could have used a chamfer to do something similar, but the draft is more appropriate in this case.

    Chamfer = left / Draft = right

    TBHS2-30-chamfer.JPGTBHS2-30-draft.JPG

    Finishes

    • Holding CTRL select the bottom and top faces.

    TBHS2-31-bottom.JPGTBHS2-31-top.JPG

      • Add a PartDesign Chamfer.svg Chamfer of 0,5mm.
    TBHS2-31.JPG

    Perfect !

    Export as a .STL

    • In the Combo View on the left, select the tree view instead of the contextual task menu, click on the last feature (the chamfer).
    TBHS2-32.JPG
    • Now you can select "Export..." from the File menu at the top left, and select the file format .STL.
    • Print it instead of the first version or to replace it if it eventually broke ;-)