Joinery- how to cut a perfect right angle with a handsaw

[tonyjeffs]

I'm making formwork for concrete blocks, essentially 8" boxes, out of plywood. It would be better if my saw cuts were exactly 90 degrees, but I'm not visually accurate enough. I can do better by holding a square to the side of the saw, but could do with a third arm. Is there an easy way or a carpenter's technique that I'm missing?

Thanks Tony

[dom]

How I was taught to cut to the line:

(I'll take it as read that you've marked your line accurately and sufficiently boldly that you can follow it - *around all 4 faces*).

1. Saw with the widest face towards you if possible.

1. Get the saw embedded in the rearmost portion of the line on that widest face, only as far as required to stop the saw sliding side to side (use your left thumb to position the saw).

2. Extend the saw cut across that widest face, *but don't go any deeper at the back*. i.e. your eyes are only following the point where the saw enters the top of the face and keeping *that* on the line.

1. Once you have your saw cut across the widest face (just a groove in fact), then start following the line down the front (but *still* no deeper at the back) until you've sawn half-way through (but in a triangular shape). i.e. You're dropping the handle end of the saw relative to the tip.

2. If you're less experienced you can turn the job round and repeat step 4. Or once confident - use your thumb and eye to keep the saw upright as you saw down at the back - but *not* sawing out the central mass. You're dropping the tip end of the saw this time relative to the handle.

1. Finally saw out the central mass.

This technique creates guides for sawing the parts you can't see, from the parts you can see. It also considerably reduces damage from the last part of a cut splitting away a corner.

This is overkill for handsawing shuttering - it's the kind of thing that gives you sub-millimetre precision for joinery - but once learnt becomes instinctive.

[nightjar]

can also put all the careful work into making a sawing guide. Get a couple of bits of timber, about 2" x 2", taller if you prefer more guidance for keeping your saw vertical, long enough to span the timber to be cut and overhang both sides. Under each end, fit a packing piece of timber as thick as the depth of cut you want to make, positioned so as to just drop across the timber to be cut. Connect the two main bits by screwing joining timbers up under the packing pieces, so that the two main bits are just wide enough apart to accept the saw blade. Make the joining timbers long enough so that, when you drop the guide over the timber, it holds the sawing slot at right angles to the timber. You now have a guide that will keep you cut square, help keep the saw vertical and show you how deep to cut. If the cuts are all at the same distance from the end of the timber, you can also add a stop for that.

Colin Bignell

[George]

I'm assuming the boxes have already been assembled?

Make a sleeve out of 2x2 wood that fits over the boxes so that you have to weave the 2x2 boxed sleeve over the shuttered box. Measure the sleeve from the edges of each four sides so that its level all round,do this to where the lines needs to be cut. Pin/nail the sleeve to four sides so that it doesn't move. Saw all the way round using the sleeve as a guide for the saw..

[George]

I'm a bit confused how you're attempting to make these (shuttered boxes) as they're called on site.

Basically alls you do is measure the correct size of the panels,make sure they're straight at the edges with a set square. Nail 2x2 pieces of wood to each end of the panels then screw the panels together via the 2x2 wood. This will then be as square as you will get without having to saw the box constructed.

[Arthur2]

Mark it up and clamp a piece of 2 x 2 along the line and use the side of the 2 x 2 to guide the saw.

Arthur

[The Wanderer]

Err, others have suggested 'mechanical' ways to keep the saw blade on the line, but are you holding the saw properly? Are you (wrongly) wrapping your index finger around the saw handle? That's the most obvious reason for not making controlled cuts with a saw.

Your index finger should be extended and point down towards the end of the saw blade.

[MM]

You can make a shooting block. You need a jack plane. That will get you your right angle. See

and scroll up to page 95 (this takes you to Google Books displaying The Practical Woodworker).

MM

[tonyjeffs]

Thanks for all the suggestions. Some are so good that Im wondering "Why couldn't I think of that?". I'm confident I can do it now. I'm also inspired to make a drill guide to ensure my drill holes are perpendicular; - an appropriately sized block of wood with a true hole through it.

cheers Tony

[stuart noble]

I've got a thing like a plunging router frame. Woolcraft I think. Not expensive and comes in very handy once in a while. Letter boxes etc

[tonyjeffs]

Stuart An elderly guy in our street loaned me one of them many years ago. Really good. I assumed it was one of those ideas that never took off and was no longer available... But here it is:

might buy one. Tony

[George]

Hide quoted text -

You can buy a drill press for £30

[Man at B&Q]

What do you think

?MBQ