Corrugated Iron roofing profile

[pgh3]

Good afternoon. I have to cut some material (thin plastic or aluminium sheet) that will snug fit under a corrugated iron sheet.
So it needs to have a sinusoidal cut on one side. Is there a VCarve Pro function that will allow this? Sine or Cosine? Or will I have to plot each series of points then repeat as needed?
I could take a photo of the end of a sheet then scan and scale the jpeg to fit. Or I could trace the profile onto a piece of paper..... etc.... But I thought I would ask this forum if anyone has had to work with corrugated roofing material previously.
Thanks in advance.
Peter

[FixitMike]

There are different profiles. Contact the supplier of yours and you should be able to get the dimensions. I Googled "corrugated roofing profile" and clicked on images to see that they are not actually sinusoidal, some appear to be a combination of circular arcs and straight lines.

Another idea: Most suppliers have a wood or plastic piece that is contoured to fit. You could use one as a template for a router cutter with a bearing.

Hint: You may find it easiest to cut thin plastic or aluminum if you sandwich it between two pieces of plywood.

[pgh3]

Thanks for your reply, FixitMike.
There you go! I looked at the end of a sheet and thought: Yep, that's a sine wave! Serves me right for making assumptions!
I think I will take an offcut and trace out the path onto a sheet of paper then scan that into VCarve - I will be cutting it on a 600 x 900mm gantry machine, so I expect to get a few cycles in.
I think a squirt of Silicon gunk will ensure a snug fit to the underside of the roof.
My local supplier has what he calls an infill made of foam plastic to fill in gaps, but it is far too spongy for taking a template off.
Thanks for the tip re cutting the thin stuff - it will be hard to clamp down to make sure it's kept flat - that's a good idea.

[martin54]

Photopraphing will only work if you can take the picture square to the edge & have an accurate way to scale the picture once imported, tracing would probably be a better option, I would trace, import the trace & then use that as a template to draw manually. You only need to draw a couple of sections then use the copy array tools for the rest, I would also cut a test fit from a bit of scrap material to check fit before cutting the actual material.
Thin plastics tend to bow when edge clamped so some other hold down is also needed, either a board over the top or double sided tape. The painters tape & superglue method people use will work OK

[pgh3]

I ended up tracing gently around the profile on a bit of offcut. I will take a trial cut to match with the roofing; once I'm happy with that, I will cut out the bits needed to complete the job.
As I said earlier, I will be using silicon sealant to keep the pieces together, so accuracy will not be much of an issue.
My cuts will be light and gentle to reduce cutting forces on the sheet; I expect little or no deforming due to stress of cutter moving to hard or fast.
I will attach a picture of my test cut so you can see what I've been talking about.
Thanks for all who shared their experiences about this job, much appreciated.
Peter