How To Make Square Cuts In Dimensional Lumber

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It's important to get square cuts in wood when building certain projects. Square cuts allow you to create stronger joints and allows you to have your pieces fit together properly so that planter bench you're trying to build is straight and doesn't wobble.

There are a number of different ways that you can make square cuts in dimensional lumber such as 1x6's, 2x4, 2x6's, etc., which vary in price. Most will also allow you to make accurate angled cuts such as 45 degree cuts.

As with any tools, make sure to read, understand and follow all instructions that come with the tools.

Good

Speed Square and Circular Saw

The cheapest and quickest way to make square cuts in dimensional lumber if you already have a circular saw is to use a Swanson Speed Square as a saw guide.

Simply place the edge of the square on an edge perpendicular to the direction you'd like to cut and use the edge of the square as a guide to run the edge of your circular saw's fence on.

It's important to follow the guide carefully and to have a good circular saw that will sit flat on it's base and can be adjusted to a true 90 degrees.  I have a cheap circular saw that I bought for around $40 that was used for some demolition. I'm not sure if it ever sat flat or was able to get the blade square but it's difficult to get it to now.

If you're using this method do a test cut to make sure the cuts are coming out square. You can use the speed square to measure the angle of the cut.

Better

Miter Box

A miter box is a plastic box that has slits cut at precise angles that guide the saw to allow you to make fairly accurate angled cuts in molding or dimensional lumber. Years ago you could find affordable wooden miter boxes but these days all I see are the plastic ones like the Stanley 20-600 Clamping Miter Box pictured left which includes slits for a number of different angles, including face angles. It comes with a sharp back saw and cam pins to help hold your wood in place. The pins don't hold the wood that securely so some quick clamps would help.

Contractor Miter Box

The Stanley 20-800 Contractor Grade Clamping Mitre Box is similar to a Jorgensen miter saw I own. The Stanley has holes for cam pins but it's essentially the same. These are slightly more expensive than the yellow plastic miter boxes but are easier to mount on a work bench. The saw has a replaceable blade (click here for replacement blade) which makes it a little cheaper to own in the long run compared to buying an entire back saw. The hardened steel saw blade is also capable of cutting metal. If you need to make straight or angle cuts in metal, this is the best manual miter box to buy.

It may look like you can create almost any angle you'd like but it only will lock in on 5 detents for 90, 45 and 22.5 degreens (on either side). It is very affordable compared to power miter saws and provides accurate cuts. The saw blade is very sharp.

I find it easier to use some Quick-Clamps to hold the wood in place rather than the built in clamps.

If you like the idea of a manual miter saw that is safer, cleaner and quieter than a power miter saw but want something a little better you can have a look at the Nobex Proman Miter Saw.

Best

Power Miter Saw

A power miter saw like the Hitachi C10FCE2 10-Inch Compound Miter Saw is almost 4x as much as the contractor miter box but if you have a lot of square or angled cuts to make will be worth the price.

It's noisier than a manual miter box and sawdust gets everywhere but it cuts even hardwood in about a second and with little effort.  Compound miter saws are adjustable in 2 different directions and have more flexibility when it comes to angles. There are detents for the more popular angles but you can also usually lock them into any angle you'd like.

If you have a lot of cuts to make but don't want to spend over $100 you can look for a Factory-Reconditioned Ryobi ZRTS1141L 9 Amp 7-1/4-in Miter Saw with Laser or rent one for the day.