I've been having fun/frustration trying to model wave washers - aka wave springs, the things often used for preloading bearings.

It's fairly easy to generate a 4-lobe washer:

1) Draw circles centered on the origin for the ID and OD and extrude them by the washer thickness.

2) Draw center-point reference lines from the origin at 0º, 45º, 90º, and 135º which extend beyond the OD of the washer.

3) Center-bend the washer up by a small amount (e.g. radius 0.5", angle 8º) along the 0º and 90º lines, and bend it down by the same amount along the 45º and 135º lines. The endpoints of the reference lines are used to define the bend axes.

The only problem with this is that all of the wave washers I've got only have three lobes, not four! I did manage to model a 3-lobe washer that's kind of close to correct, but it was a challenge to figure out:

A) Create a 180º (+90 to -90) segment of the washer from two arcs and two "end cap" lines.

B) Add + and - bends at 30º and -30º, and then add smaller reverse bends at +/-60º and tweak these angles until the 60-90 ends lay flat in the plane. Using my 8º primary bends, I needed 4.6º secondary bends to get this close enough.

C) Make a pie-with-a-120º-bite-missing cylinder from -60º to +60º and subtract this from the washer segment to leave a 120º piece.

D) Polar duplicate the 120º segment to create two more 120º segments.

E) Do two solid unions to join the three pieces together together.

The result isn't an accurate representation of a 3-lobe washer - it should have positive bends at 0º, 120º and 240º and negative bends at 60º, 180º and 300º. But I've spent two hours getting this far, and it's after midnight...

So my question is: is there a better or easier way to do this?

A screen shot of the 3- and 4-lobe washers, and the .tcp file of what I did, are attached.

It's fairly easy to generate a 4-lobe washer:

1) Draw circles centered on the origin for the ID and OD and extrude them by the washer thickness.

2) Draw center-point reference lines from the origin at 0º, 45º, 90º, and 135º which extend beyond the OD of the washer.

3) Center-bend the washer up by a small amount (e.g. radius 0.5", angle 8º) along the 0º and 90º lines, and bend it down by the same amount along the 45º and 135º lines. The endpoints of the reference lines are used to define the bend axes.

The only problem with this is that all of the wave washers I've got only have three lobes, not four! I did manage to model a 3-lobe washer that's kind of close to correct, but it was a challenge to figure out:

A) Create a 180º (+90 to -90) segment of the washer from two arcs and two "end cap" lines.

B) Add + and - bends at 30º and -30º, and then add smaller reverse bends at +/-60º and tweak these angles until the 60-90 ends lay flat in the plane. Using my 8º primary bends, I needed 4.6º secondary bends to get this close enough.

C) Make a pie-with-a-120º-bite-missing cylinder from -60º to +60º and subtract this from the washer segment to leave a 120º piece.

D) Polar duplicate the 120º segment to create two more 120º segments.

E) Do two solid unions to join the three pieces together together.

The result isn't an accurate representation of a 3-lobe washer - it should have positive bends at 0º, 120º and 240º and negative bends at 60º, 180º and 300º. But I've spent two hours getting this far, and it's after midnight...

So my question is: is there a better or easier way to do this?

A screen shot of the 3- and 4-lobe washers, and the .tcp file of what I did, are attached.