Wall top angle measurement

[Anonymous]

Hi,

I've been doing a bit of landscaping over the summer (?) and have terraced my garden with a few low retaining walls. My intention was to buy some stone (or concrete) blocks to work as coping stones, but I've failed to find anything suitable and so have bought some preasure treated wood to do the job instead.

Having messed up some skirting a few years ago by not correctly measuring the angles of the corners of the room and assuming them to be 90 degrees (please, nobody else do this) I would like to get the wooden wall tops fitted with tighter joints, but how do I accurately measure the angles?

Does anyone have any foolproof techniques to measuring internal or external angles of walls for use when calulating mitre cuts? Ideally i'd prefer some method whereby I don't have to go out and buy a special angle measurement tool (ashamedly I don't even have a sliding bevel), and i'd even consider maths as a way out so long as it works!

Any thoughts?

[Dave Plowman (News)]

It's usual to scribe skirting for internal angles rather than mitre it.

I use a sliding bevel then transfer that angle to my compound mitre saw - read off the angle and half it.

[John Rumm]

There is a very simple drawing technique you can use for any non standard (aka "Bastard Mitre") mitre joint. You may be able to use it in this case. Technique described here:

[stuart noble]

A sheet of paper. Fold it to fit the angle and then fold it in half. As Dave says, the 2 angles must be the same. Lining paper's quite good for that sort of thing

[The Natural Philosopher]

Bit of string and a calulator. Use trignometry.

[The Medway Handyman]

Not sure I understand. Is the timber going on top of the wall in the same way a coping stone/stones would?

As others have said, you don't mitre internals when doing skirting boards, you scribe them.

Going back to the garden walls, if the timber is going flat on top like a coping stone would, there is a simple way of doing it, which is harder to explain than to do.

Lets say the two walls are like a capital 'L'. The angle may be 90 or 88 or

92 it matters not.

Cut a board for the upright of the L with a 45 mitre at the end, call it piece A. Leave this to one side for the moment.

Place a board (B) on the crosspiece of the L of appropriate length. Place board A on top with a scrap piece of timber under the other end to keep it level. Adjust the boards so that they align with the walls, then mark a pencil line on board B along the angle of A.

Cut along this line and the boards will fit. The join will match the wall angle whatever it is and the mitre will fit. It won't be a 90 mitre but it doesn't matter.

[stuart noble]

But then the two angles won't be the same, and therefore neither will the length of the cuts. Rather like coming round a 135 bay with 1 x 90 and 1 x 45

[Malcolm]

To extend Dave's method, once again more difficult to describe than do. Take the two pieces of wood you want to use and lay one piece on one of the walls as you would want it to be, with one corner over the outside of the angle of the 'L'. Lay the other piece over it, supporting it so that it is horizontalso that the outer corner is exactly over the outer corner of the first piece. At the inner part of the corner mark both pieces of wood. Cut both pieces from the mark to the corner and you have bisected the angle.

I have used this method with paving slabs to turn a corner. Thry it indoors with card to convince yourself

HTH

Malcolm

[The Medway Handyman]

But for timber on top of a wall its good enough. Done it many times edgeing decks, second cut will be a fraction longer but not really noticeable.

Wouldn't work for skirting etc granted.

[Anonymous]

Malcolm,

I like the sound of this method, no measuring and it must fit as that's how it was marked. Hopefully the weather will be kind to me this weekend and I can give it a try.

Thanks,

[Anonymous]

Yeap, exactly that.

[The Medway Handyman]

Thats better than my method, thanks. Bit more time to set up, but much more accurate.

[John Rumm]

Its pretty much what is described in the link I gave before:

[Mark]

My son-in-law uses one of these

's saved him 6years learning how to cut an angle by eye.

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