# How do I create a disk with a wavy top

I’m still new to Sketchup, so I need some help from someone more experienced. What I want to do is to create a disk 60 mm in diameter and 15 mm thick. That part is easy. What I then want is to make one of the surfaces wavy. Imagine dividing the disk surface into 4 quadrants and imposing a sine wave on it such that there is a peak every 90 degrees. I want to height from valley to peak to be 5 mm.

Why do I want this part? I am working on an idea to make a cam system. I will attach the disk to a vertically mounted DC motor. A vertically mounted rod with a tiny wheel would be above the disk and it would go up and down following the wavy surface of the disk. Think of a piston rod riding a camshaft in a car engine.

Ideally, someone can send me a file I can import into Sketchup or a tutorial on how I can do this.

Thank you.

@Gully_Foyle demonstrated this back in the (now lost) previous iteration of the Help Form.

Thanks. The question is how to apply it to a circular disk so that the top surface is a sine wave.

-Gully

Edit–Gosh, Geo, I had forgotten about that older one. @OttawaMaker, to see how that one works (it’s a bit different from this one), you have to download the model from the 3DWH. -G

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Wow. Now we’re talking. Since I already have pulleys like the one shown below and they mount to motors perfectly, I would stack the wavy cam disk on top of the pulley and either bolt them together with 4-40 hardware or glue them.

Notice that the difference between the one for which @Geo gave a link and the one I have depicted here is that in the first one all the radial elements are horizontal (perpendicular to the axis), while in this one the radial elements all converge on the center of the disk. Obviously, it’s up to you which best suits your application, which is still not entirely clear.

-Gully

just messing around (or maybe jumpstarting someone else to go further with this )

plotting a sine wave around a cylinder:

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Jeff,

In your picture I see RotZ has a value of ‘=copy*7.5’…

is that referencing an attribute that was defined elsewhere, or it just similar to an excel cell where the ‘=’ sign has to precede all functions?

yeah… same thing as excel

the only reference being made in that example is copy which is coming from Copies … there are 47 copies being made so for RotZ (rotation around the Z axis), the first copy will be rotated 7.5º… the next one is 15º… then 22.5º… then 30º etc…

Pretty cool Jeff … Bookmark!
This cam and follower stuff reminds me of the beer can trimmer Geo Sr. cooked up back in the slide rule era.

Hmm… my HASM must be acting up again.

Jeff,

How do you do that? I created a cylinder and turned it into a component, but I can’t find where to change the attributes like you show.

the cylinder is not part of it and is only shown for visual reference…

the component is just a construction point at (60,0,0) with its axis set on the origin (the blue highlighted part in the picture… it looks like it might be line but it’s just the bounding box of the component)

that said, it’s a Dynamic Component which is a sketchup pro feature only. (well, you need suPro to create them… you can use premade dynamic components in suMake).

when i get back to the computer, i’ll upload the file so you can see what’s going on a little better

hey, I need the exact thing that is discussed here. can somone give me a file of this wavy disc?

How about following Gully’s tutorial and drawing it yourself? Or do you wish to hire someone else to draw it? If the latter, you should post in the Commercial and Collaboration forum.

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