1. The document discusses using 3D sketching abilities and surface splines in CAD software to more easily create interesting geometries for cam and slider surfaces. 2. As an example, it walks through creating a barrel cam and cam groove in a part, starting with a simple cylinder that reference planes and default planes are used to create split lines on. 3. Spline on surface and sketch tools are used to draw the basic profile for the barrel cam recess, with a semi-circle also drawn on the top of the cylinder above the spline. The cut is then swept using the sketches as guide curves.

1. Making interestinggeometryinregardstopotential camandslidersurfacesismade mucheasierbyuse
of the 3D sketchingabilitiesandsurface splines. Fora brief example,we will be creatingabarrel cam
and the appropriate camgroove inthe part.
To start, I useda simple cylinderof radius50mmand thicknessof 50mm. Once I had a cylinder,Iused
reference planesanddefaultplanestocreate the splitlinesshown
Once I had my cylindersetupwiththe geometrypatternpre-sketched,Imovedontothe actual sketch.
Opena new3D Sketch

2. Once you have that open,itistime to start oursketch. Using the spline onsurface tool,draw the basic
profile forthe barrel cam recess.

3. Then,usingthe top of the cylinderasthe sketchplane,draw a semi-circle of the same radiusasthe
cylinderabove the sketchedspline.
Afterthis,Idrewa square onthe frontplane,withthe followingrelationsshowntothe spline
From there,we are readyto do the funpart and actuallysweepthe cut.Notice the settingsusedandthe
use of one of the sketchesasa guide curve. Thisiswhyit isimportantto make 2 sketchesasthe swept
cut tool doesnot allowthe pathand the guide curve to come fromthe same sketch.
Witheverythingselected,itshouldlooksimilarto this.

4. Once you have the half cut, youcan mirror the feature toget a full encirclementof the cam profile. One
isprobablytemptedtoaskwhy the spline wasnotdrawnall the way aroundthe cylindertoavoidthe
mirrorstep. However,the programwill notproperlyevaluateaclosedloopfora sweptcutas itresults
inzero-thicknessgeometry.Assuch,buildingitasa half and mirroringitisthe properway.
Witheverythingmade andmirrored,one shouldbe leftwiththe following.

5. It isworth notingthatthisfeature can alsobe made by definingaspline byasetof 3D parametric
equationsthatwouldalsowork. Inthiscase,one couldgenerate twocurvesand sweepthe profile.
The equationdrivenspline worksslightlydifferently,usingthe equationtorenderthe spline in3Dspace.
For these parameters,the Xt andZt define the circle withthe coefficientequal tothe radiusof the spline
circle.The Yt parameterdefinesboththe vertical positionof the curve andthe amplitude of the wave.It
isalso importanttonote that the t parametergoesonlyfrom0 to pi,and nota full circle. Thisisonce
againthe closedcontourproblemmentionedearlier.
I hope these tipshelpyoumake more successful atsweepingcutswhilereducingthe fearof the
complicatedsweepcutoptions.