How to Cut Wood Square by Hand or With a Miter Saw
3 Ways to Cut Timber
Making accurate square (90 degree) and mitred (angled) cuts in timber is an essential skill when making joints in furniture and in building construction. Even if you don't attempt any serious DIY, the need sometimes arises to cut a length of timber reasonably accurately. For instance, architrave may need to be cut around a window or doorway, skirting at the base of a wall has to be renewed, or a board from the cladding on your home or shed gets damaged and must be replaced.This hub shows you three methods to cut timber.
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How Can Wood be Cut Accurately?
- Mark and cut by eye. Not terribly accurate but ok if measurements and squareness isn't critical
- Use a mitre box. This guides the saw and gives better results
- Use a mitre saw. This is the most accurate and accurate method of cutting lengths of timber
Method 1 - Cut Without a Guide
The most basic method of cutting timber is to simply mark it and cut by eye. For basic work where accuracy isn't important, this is quite adequate. However unless you have a good eye and have become skilled from years of practice, the results are variable, and beginners will end up with crooked cuts on the end of timber.
Step 1 First Mark the Dimensions on the Timber
Use a sharpened pencil to produce a thin marking line on the wood. Hold the tape close to one of the edges and mark the required dimension.
Note: If you buy lumber from a store, the end will likely be a 90 degree cut, but check it before hand with your carpenters square. If it isn't, initially follow steps 2 to 4 of the marking out and cutting instructions below to remove a small section at the end of the timber (keep about 1/2 inch in from the edge). Once this is done, you can continue to measure, mark and cut the required length.
Step 2 Use a Carpenters Square to Mark Top Side
A carpenters square allows you to make a right angled mark across the timber. You can also use an engineers square or a triangle (set square in UK English). Hold the "stock" or handle of the square tightly against the wood while marking. Ideally you should position the tip of the pencil on the mark you made initially when measuring, and slide the square so that it butts against the tip, then mark along the square.
Step 3 Mark the Two Vertical Sides
Continue to mark the two vertical sides of the timber.
Step 4 Hold the Wood Securely and Cut With a Hand Saw
If you have a vice, use this to hold the wood securely while sawing, alternatively use your knee and a stool, low table, Black and Decker Workmate or whatever.
Use the pencil lines on the vertical surfaces of the timber as guides while sawing and try to keep the saw blade straight.
Method 2 - Use a Miter (Mitre) Box
This gives improved accuracy when cutting. A miter box has slots in its vertical sides which act as guides and prevent the blade of a saw from sloping from the vertical. Metal, wood and plastic versions are available. Some need to be held in a vise while others have a "hook" or raised edge on the underside which can be butted up against the edge of a bench.
A miter box enables you to make 90 degree cuts in timber and usually 45 degree cuts also.
When cutting timber, cut on the waste side of the line rather than the center line.
Using a Tenon Saw
A tenon saw is shorter than a "normal" hand saw and is less cumbersome to cut with. It also has smaller teeth (the pitch is greater), which reduces the tendency of the blade to tear or chip the ends of wood fibers whilst cutting. Thirdly the rigid spine of the saw stops the blade from curving and warping too much while cutting. All this helps to give better results, which is important if you are making furniture or other stuff where accuracy and finish is important.
When cutting, position the blade and teeth of the saw so that you cut on the waste side of the pencil line rather than cutting along the center of the line. The kerf or width of the saw cut can produce "gaps" if you are cutting joints or doing other fine work. The slight error in length due to the kerf of the saw when cutting on the center of the pencil line, can accumulate and cause a greater error (e.g. if several pieces are cut to size and placed side by side)
Making and Using a Marking Knife
A pencil is fine for rough work, however a marking knife never gets blunt and produces a fine line, allowing you to produce more accurate results when cutting joints. You can make one by cutting a 45 degree angle on an old dinner knife with an angle grinder and then sharpening it. You could use a Stanley knife, however the advantage of a long bladed flexible knife is that it can reach into tight spaces. (This knife also comes in handy for spreading silicone sealant and putty!)
Method 3 - Using a Miter (Mitre) Saw
A miter saw (spelled "mitre" in UK English) is a power saw designed to produce rapid and accurate 90 degree and angled (mitered) cuts. It's a virtually essential tool when framing, i.e. building stud walls. A basic saw will cut timber up to 4 x 2 in size, but a sliding miter saw has a cutting head which slides on a rail, allowing timber up to 9 x 3 to be cut without requiring a huge diameter disk.
Blades are available for miter saws with a varying number of teeth. Coarse toothed blades cut rapidly through timber. Blades with lots of fine teeth are slower but give a cleaner cut.
It is usually possible to calibrate the saw by way of adjusting grub screws to ensure that the saw actually does give a square cut. You can check your cuts with a carpenter's square to see if the saw is cutting accurately and make adjustments as necessary.
The kerf, which you'll remember is the width of the saw cut, is normally wider, typically 2 or 3 mm (1/8") for a miter saw blade than it is for a hand saw. So it's more important to cut on the waste side of your pencil line to avoid inaccuracy.
Like any power tool, a miter saw can be dangerous.
- Make sure the guard on the saw is operating correctly and covers the blade when the cutting head of the saw is returned to its rest position
- Hold timber securely against the back fence of the saw while cutting, and ensure that long lengths of timber are adequately supported so that they don't overbalance the saw or rise up and hit the blade. Usually clamps are provided on the saw for holding timber in place while cutting
- Don't work with power tools if you are tired. Poor concentration can cause accidents
- Don't use a blade with blunt teeth or teeth which have lost their tungsten carbide tips. A blunt blade can snag in timber
- Don't work in wet conditions
- Keep your hand clear of the blade while cutting. You might loose fingers!
- Always wear safety glasses in case you hit knots or nails/screws in waste timber. If you are doing lots of cutting, wear ear muffs or plugs and a dust mask
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