Scribing torus skirting

[John Rumm]

Depends on your skirting - some have extra curves on the top detail and not just the bull nose. (obviously ogee has curves both ways)

Got a photo?

If you accurately follow the front edge of the profile against the mitre then it can't miss really - unless the skirting you are butting up to is a subtly different profile to the bit you are scribing.

[Phil Addison]

I know I'm late coming to this but what hasn't been mentioned by anyone is HOW this method works - it does sound very baffling without that explanation, but it is really very simple (but needs a lot of words to describe!). The following is based on the methods of Tanner, John, and gilli.

In the first step we cut a 45 deg mitre exactly as if making an internal mitred joint, that is with both sides of the corner mitred at 45 degrees.

However, only cut the mitre on one piece, say the right hand of the internal corner as in John Rumm's wiki illustration

(Incidentally, in that illustration there seems to be an optical illusion that makes it look as if the 1/2 rounded bead section is actually concave. I don't know if that's caused by the shading or what?)

Now the left piece of the corner is cut square, not mitred at all. Try putting the two pieces together in the corner and you will see that the 'pointy bit' of the mitred right-hand piece hits the left, so what we need to do is cut a profile with a coping saw held parallel to the left piece, i.e. perpendicular to the right-hand piece. But exactly what profile should be drawn on the right-hand piece?

Imagine you had made the mitred internal corner with both left and right sides mitred. Note how the profiles on the left and right line up to make a perfect corner, and that the left and right profiles are exact mirrors of each other. To make a scribed joint we want to somehow 'slide' the right hand piece along the left piece towards us, but we find the 'pointy bit' of the right-hand mitre is in the way. The 'pointy bits' just need to be cut off with a coping saw held perpendicular (see below*) to the face and following the edge profile where the mitre meets the face surface.

All that this method is doing, is cutting back this 'pointy bit' to where the face surface of the right piece meets the face of the left piece. We need to realise that the face profile of the line of contact will actually be the same all along the face of the left piece not just in the corner (obvious, yes?). So by taking a coping saw and chopping off the right hand's pointy bit, by following the line of contact of the

45 deg mitre with the face, we will get a perfect scribe.

What's more, this should work with bowed skirting, so long as the left and right bits are bowed the same, e.g. were originally one piece. In this case you do need to cut the mitre all the way down the skirting, not just the shaped bit at the top (as per John's wiki article), and follow the profile all the way down with the coping saw.

• In practice angling the coping saw slightly by a degree or two, to take more off the back surface, will mean that the joint only contacts at the very front edge of the right-hand piece and this will take up any slight out-of-square of the room (or cutting errors). Also the contact edge will be thin and easy to correct if the coping saw didn't follow the profile well enough.

Arfa Daily asked if this would work in a bay window with 135 degree corners. It should work for any angle with modifications. You need to cut the mitred bit at 1/2 your corner angle, 67.5 degrees in this case, and the coping saw has to be inclined at 67.5 (plus 1 or 2) degree to the face.

Sorry if all this was obvious to you, but I found it very puzzling at first. Just wish I knew this before doing my skirting!

Phil

[John Rumm]

I have added some more piccies to help clarify...

Yup, done a picture for that as well/

I might nick that for the end of the article! ;-)

[Phil Addison]

In the (new) pics, the 1st, 2nd, 4th and 5th are clearly convex, but the other two still look concave to me. So yes, clearer.

Not sure about 'rotating' the coping saw - rotating about the blade axis would be the usual interpretation. Would 'swivel' or 'angle' 'away from the perpendicular' make it clearer?

Feel free to nick any of it - I'm not into wiki-editing as yet.

BTW, the title 'Scribed Joints' could cover worktops too. Maybe 'Scribed SKIRTING joints', or simply ' How to make a neat internal corner joint in skirting boards'?

Phil