Compound Mitres

Hi All,

Attached is a drawing for a lid I need for a woodturning project. The timber thickness is 18mm. I can’t work out how to get the compound angle for the segments to fit together.

Thanks again for all the advise.

TropicalGuyCns.Compond Mitre for top lid.skp (25.8 KB)

Compond Mitre for top lid.skp (57.7 KB)

See the attached.

If you want to show the segments ans individual parts, make a single part as a component. In this case, make one segment and use Copy/Rotate to make the rest.

In step two you can open one instance of the segment component and use Intersect Faces or you might find it easier to understand what’s getting cut if you use the Line tool to trace where the faces pass through the neighbor. I placed only two instances of the component in hopes it would be clearer what’s going on. In practice, I would go ahead and make all the required copies from the beginning. Then I would open one instance of the component for editing and trace where its neighbors intersect on both sides.

After those lines are drawn, erase the waste sides of the lines.

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And here’s the sawdust on the laptop get an answer in the shop quick and dirty method.
(took longer to name it than to do it)


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Hi Dave,

In your drawing showing the completed lid, its elevated as it should be, the rise will be 40mm, my drawing is shown as flat. How do I get the correct rise. I have in another drawing been able to rise from the centre but that drawing shows no thickness in the segments.

I’m not quite sure what you mean. I used the angle of the segment from your file.

attached is flat section.seg layout for lid.skp (146.3 KB)

sorry wrong file

Compond Mitre for top lid.skp (25.8 KB)

as you can see there is no thickness to the piece.

I see.

You’ve used Push/Pull before, right? Do that here after you’ve deleted all but one segment.

Ok ,done as suggested, what next to fill back in the rest of the segments

Hi Shep,

Thanks for the prompt reply, I’m a newbie and it takes some time for it all to sink in. I have drawn what you have shown, mine just shows the vertical line not the overlap.



It’s possible that I got it wrong this morning. If the surface in your earlier model is the underside, the face should be pulled up not down. Sorry for any confusion if this is the case.

Away from sketchup machine,

Attached is another drawing of what I 'm trying to achieve. I need to be able to measure the compound angle to cut the segments for the lid. Please explain in simple terms as I’m getting more and more confused. Thanks again.


TropicalGuyCns.Ex10.skp (37.4 KB)

Does this help?
Ex10Box.skp (160.3 KB)

No That’s not what I need, each segment will be wedge shaped as depicted in red in the attached drawing.

Regards, TropicalGuyCns.

ex11.skp (18.0 KB)

I’m not sure what you want.
I simply took the wedge from your model and set it into a block so you could see the angles to cut.

I went searching the net and found the exact information I needed, maybe the information will help somebody else.
Making splayed miter joints gives a table with many calculations for this exercise.



All the ciphering, measuring and layout, only to finalize the fit with a belt sander. I don’t know why but I find that amusing.


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