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Spiral-threaded bolt, Part 3: Resizing and scaling the thread components

Getting the bolt dimensions right involves both resizing and scaling operations. In this example, we're converting the standard, 1/4-inch bolt with 20 threads per inch into a 3/8-inch bolt with 16 tpi.

We start with the bolt diameter. Using the Tape Measure tool, measure the diameter of the bolt shank - 1/4 inch, by default.

resizing a cylinder in SketchUp: measure across its diameter

Now, simply type in the new, desired diameter. In this case, we type "3/8" (again, minus the quotation marks) and hit Enter.

enter a new value in the Value Control Box, and select Enter

Unfortunately, while the bolt diameter is right, the thread pitch is not. Still, getting to 16 threads per inch is not difficult.

Use the Tape Measure tool to draw a line parallel to the bolt, starting from the top of the thread, and extending a little past the bolt.

draw a guide line starting at the start of the bolt thread, parallel to it, and just past it

This creates a Guide or guide line. Type 1 and Enter to resize it to 1 inch long. This should be somewhat closer to the top of the bolt than where the thread currently ends.

resize the guide line to 1", the desired length for the threaded bolt section

To resize the threaded part of the bolt only in its length - leaving its diameter unchanged - use the Scale tool. Select all thread segments, minus the Guide line.

select all the components you wish to resize

Select the Scale tool. Hover over the various control points with your mouse until you highlight the two that will cause the selected components to rescale only in the direction of the bolt axis (the Blue axis, in this SketchUp example).

select the SketchUp Scale tool, then hover your mouse over the various control points until you have two that allow you to resize only in the desired direction

Left-click on the closer desired control point, and drag it up until the bottom of the thread lines up with the end of the Guide line. Tip: drag the control point onto the end of the Guide line, and the end of your selection should snap exactly even with this line. Release.

drag the selected control point to the end of the Guide line, to snap the selection even with this line

Congrats! You now have a perfect, 3/8" diameter, 16 tpi section of threaded bolt.


Previous Part 2: Assembling the spiral

Next Part 4: Extending the shank

- PD


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