Solidworks: Springs, Threads + Surfaces




  • When unselecting “merge results” upon feature creation, a solid bodies folder is created and the sections of a part can be treated as separate entities.
  • You can cut only on desired bodies using old bodies by selecting to effect “selected bodies only”.
  • Then you can stitch it all together by right-clicking on selected bodies and choosing “combine”
  • You can also use subtract in this option to create negatives on other bodies > THIS WILL BE REALLY HANDY FOR MAKING MOULDS THAT WILL BE VACUUM FORMED (REVERSE SHELL)
  • You can use the multibody function to do this circular pattern roughly and cut it away from the interior.


MAKING SPRINGS + THREADS (it’s a sweep!)

  • Draw the profile of the full diameter of the spring, then draw the profile of the thickness of the spring.


  • Insert / Curve / Helix Spiral (customise menu if not visible)
  • Select main circle sketch / Pitch + revolution / Constant or variable pitch / Start angle: play with angles to find the right start point (or do step 1 now).
  • After creating the helix, it’s time to do a sweep.
  • Grab the small circle for the profile and the helix for the path. It should create a spring.
  • Use the inside diameter of the spring for measurements and then put the profile on the outside of the helix path (or other way around)
  • Variable pitch – can change pitch, number of revolutions, diameter.
  • Number of revolutions: numbers count up in chronological order, not in additive amounts.

For a thread you can use this same process OR you can use the thread tool

  • Feature/thread tools/thread
  • Can choose # of revolutions or specified end distance, then cut/extrude thread.
  • Solidworks will allow you to put any size thread on any size cylinder, which can be incorrect. Use thread data charts to check correct threads:
    • Maryland metrics thread data charts:
    • Find minor diameter to see main profile diameter
    • M5 x 0.8 = 5ø x 0.8 pitch between
    • Turn on sketch profile to measure major diameter.
  • When modelling from existing product, just use real measurements over the data chart.

To taper the thread, either use the variable helix option and taper the diameter at the start and end, or do this:

  • Run a line co-linear to the direction of the thread
  • Make another line perpendicular to this one.
  • offset a line parallel to the perpendicular one so it takes off the end of the thread in a straight ende when you cut it.
  • Start a new sketch on this flat face and trace the profile of the thread.
  • Make an axis away from the sketch so you can revolve it at a wide angle, into the neck.


  • Insert sketch picture (into sketch) Tools / Sketch Tools / Sketch Picture
  • Double-click photo to edit.
  • Create templates for as many planes as you want/can/is reasonable.
  • Tangent arcs – use like a pen tool. Anchor points and fiddle with others. (or use splines). Make it run tangent to a horizontal construction line so that it will join tangent to the other half when mirrored.
  • Horizontal relation between arc points on front and side sketches
  • Remember to use “pierce” on guide curves for lofts.

FullSizeRender 2.jpg

  • When creating the loft, select “normal to profile” on start and end.
  • Lofts don’t need closed sketches
  • You can edit the loft by adding new guide curves/sketches to it. Just roll back to right after the feature and unabsorb the sketches.


  • Use a new sketch. Copy the first tangent as a reference line, then follow the scollop from the side view image.
  • At the end, put in a tangent arc that is co-radial with the reference one.
  • Fix the top arc in place and put a tangent line from it into space.
  • Make this a closed sketch, then move onto the bottom plane.
  • Make a guide curve on the bottom plane, then sweep a cut between the two.

FullSizeRender 2.jpg

  • Keep tweaking the guide curve and checking it until it looks right.
  • When finished, add a variable fillet to the scollop. It should be tight up the top and open near the bottom.


To finish the bottle:

  • draw the base of the neck on the front profile + revolve it.
  • Shell the thing to 0.1 thickness (leave all faces on)
  • Now you can draw the rest of the neck on the top + shell it to a thicker width than the rest
  • (make sure there’s a fillet joining the interior of the two shells.


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