Hey guys, I'm trying to model a radial groove on a cylinder. The groove has a sin wave shape with the frequency = 1 rev of the cylinder. I'm having trouble sketching this. I tryed a revolve feature, but that just gives me what's in the image.

I then plan on machining this on a fourth axis. So if you can picture an endmill cutting a groove, that is what I'm after.

2. Hi Shaun
The feature you want to use is called a sweep. To create a sweep you need a profile to sweep and a trajectory to sweep the profile along. You need to define a datum curve around the periphery of the cylinder as the trajectory and the profile will be the engagement of the end mill into the cylinder. The trajectory as per your requirements is a sin wave of period pi * d of the cylinder.
Have a go and if you cant do it I'll give you a hand.

Cheers

3. Ok so I guess the fun part is to define the datum curve. I'm starting out with a blank cylinder with a dia of 2 in. Ok now what datum curve option do I use? Thru Points, From file, use xsec, or from equation?

The profile would be just a square, right?

4. Hi Shaun

Use 'from equation'. It is not very intuitive how to use it so I'll give you a starting point and you can play from there.

x = -diameter/2 + t*diameter
y = amplitude * sin ( t*180 )
z = 0

will give you a sin curve from 0 degrees through to 180 which you can project onto a semi-circular surface the same diameter as the cylinder you intend to cut (2" in your case). So its parametric, create a parameter called 'diameter' and a parameter called 'amplitude'. This way you can easily experiment with different diameters and amplitudes of the sine wave without having to re-define the curve each time.

Profile is just a square or rectangle if you want.

Prerequisites are the cylinder is revolved about an axis through x and z plane

To make it easy to model I have placed the cylinder with no offset from that axis

The procedure is

• define parameters amplitude and diameter
• create datum curve using equation as per notes above
• create a semi circular surface to project that curve onto (use diameter parameter to drive the diameter of the surface)
• create a solid cylinder (use diameter parameter to drive the diameter of the cylinder)
• create a sweep using cut and sketch your desired profile

this should create the first 0-180 of the sine curve then simply copy rotate that sweep feature to the other side and voila, a sinusoidal cut with the profile always perpendicular
to the cylinder surface ready to be machined with your 4th axis.

Cheers

5. Ok that's a lot to take in, whew!

I have defined my parameters, but I'm having trouble projecting the curve. Do I use the style tool?

Is what I have so far, close?

6. Hi Shaun

The attached picture may help. I have shown it in wireframe so you can see the 'original' sine curve and the projected curve onto the semi-circular surface. The projection feature is under Edit, Project.

Cheers

7. Here's the solid version with only half of the swept cut. You would now use Copy, Paste Special, then do a rotate by 180 degrees.

Are you making a cam?

8. Oh so the axis of the cylinder is on the y axis. I see it now.

9. Hold the phone, I think I have got an easier method.

10. i think i almost got it

11. I just projected the curve onto the 2 surfaces of the solid protrusion and then drove the sweep of that curve. When you select the curve it will most likely only pre-select half of the curve. Right click and you should be able to select the full projected curve as the trajectory for the sweep.

Both methods work but this is more efficient.

12. And your method is another method again. Once you have sweep the cut you would just mirror the features.

More than one way to skin a cat.

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