The Multitalented Combination Square A whole lot of tool in one small package By Andy Rae Far more than just a tool to a combo square to true up that, I’ll discuss the two arenas in for checking “square,” the workpieces, lay out joints, and which the tool excels: measuring combination square is a do-all set up shop machines–all with a and laying out. Measuring shop tool. With its sliding ruler degree of precision that elevates includes performing machine locked to the head, you can use its status over other tools. setups, such as squaring bits it as a depth gauge, a marking To ensure this level of accuracy, and blades to tables and fences, gauge, a miter square, and a try as well as checking joints and square. Loosening the lock in the acquire a square that’s worthy of assemblies for accuracy. Laying head releases the rule for use yourthe first work. order Not of all business combination is to out involves making marks on as a straightedge or ruler. In a squares share the same quality your work, from drawing parallel pinch, you can employ the head and ease of use. In this article, lines and angles to marking as a small level, and a sharp awl we’ll take a look at the parts and centerlines and pinpointing tucked inside is always at the nomenclature of combination hardware locations. Read on to ready for marking. Thanks to squares, and I’ll describe what to these attributes, you can turn look for in a good tool. Following versatile tool to good use. find out how to put this extremely 50 woodcraftmagazine.com Feb/Mar 2015 Sizing up a square Anatomy of a Combinati on Square Virtually every If you want precision and differently on all four edges, combinati on square predictability in your work, you’ll often need to reverse it on the market Ruler is anatomically you’ll need an accurately made in the head for the measuring similar, although tool. Referring to Anatomy of needs at hand. So look for a the quality can vary (right) rule that slides out smoothly, widely between a Combination Square manufacturers. Lock post keep the following features and a lock post that rotates (inside head) in mind when shopping for easily inside the head so you 90° face a combination square. The best squares are made reinstall it without struggle. from forged or tempered steel or Withcan flip the the locknut ruler tightened,over and then Pullout a combination of both, and should the ruler should feel solid and awl last beyond your lifetime. Look never slip or creep in the head for smoothly-machined contact during use. Last, but not least, a Head Bubble level faces on the head and a ruler good tool will lock dead square and stay that way at any point Locknut increase accuracy and allow you along the ruler. This degree 1 45° face towith target finely even etched 64" incrementsmarkings that of accuracy comes at a cost, 1 (Photo A though: quality squares are ⁄16" graduati ons (opposite ⁄ 1 is preferable to a shiny surface, face has ⁄64" divisions) ). A satin chrome finish as it reduces glare under bright cheap hardware-store versions. 1 ⁄8" graduati ons (opposite 1 light, making reading easier. twoBefore to five relying times theon any price of face has ⁄32" divisions) The ends of the ruler on a high- end tool are ground square, for precision at 90°. If you have Alternatively, you can check a precise measuring and layout, and asquare, reference first square check itsthat you square using a mechanical pencil for verifying parallel and square. know to be accurate, simply or knife, and a panel with a Cheaper versions are chopped, nest it against the square in dead-straight edge, as shown in often leading to rough, out-of- question, inside-to-outside and Figure 1. If you’re square square ends that inhibit accuracy. then outside-to-inside, holding is out of whack and you Because the ruler on a them up to a strong backlight to combination square is graduated ensure that they mate exactly. recommend returning it. paid more than $40 for it, I Figure 1: Checking a Square for Square 1. Place square Plywood, against straightedge 10" or wider and mark a line. 2. Flip square and move close to mark. If ruler is parallel with mark, square is square. Dead-straight edge A Unlike the square at right, with its plasti c head and stamped increments, the all-steel square at left has a smooth-sliding ruler with clear, etched markings. Photos: Andy Rae; Illustrati on: Greg Maxson Feb/Mar 2015 woodcraftmagazine.com 51 Measuring A combo square really shines to place the head onto the work when it comes to determining dimensions. This includes the surface until the rule contacts calculating distances, such as thefirst, adjacent and then surface. slide it Look firmly for along any the depth of a mortise or the light (or shadow, depending on thickness of a board, as well as your situation) between the work measuring relative surfaces, like and the rule. If you see even a tiny the angle on the end of a board glimmer, the work is out of square. B or the squareness of a drawer To measure inside corners, For inside corners of drawers and or other box construction. use the outside of the square. casework, check at the top, bottom, 1 As for simply checking Retract the ruler about 16" into and middle of the construction inside and outside corners, a the head, and then position⁄ the to gauge both square and twist. combination square mimics a square so that the blade and traditional brass-and-wood try body touch the work (Photo B). check by holding two miters square in every way, except that To read outside corners, together and then checking for the sliding ruler on a combo extend the rule so it’s at least square on the inside or outside square adds a lot of versatility. as long as the surface being corner. Nevertheless, testing And thanks to its tempered measured, and position the head and forged-steel construction, on one surface before sliding the and the miter square will get a combo square can withstand rule against the other surface youthe miterthere. itself To check is the for first 45°, step, more knocks and dings than (Photo C). The best scenario is to hold the angled face against the its softer brass counterpart. view the work directly in front of work (Photo D). Because the The “try” in the tool’s name a strong light source, with your head’s 45° face is relatively small refers to offering the tool up to eyes level with the ruler. This when used for larger work, you the work to test whether adjacent arrangement lets you see even can balance the tool by sliding the tiniest light leaks at the rule, the ruler past center to help Perhaps the uncertainty of the as shown in the photo on page 50. counter the weight of the head. wordsurfaces “try” are stems flat and from square. the fact Because most miter cuts result As an adjustable end gauge, that misreadings are common in a 90° joint when assembled, a good combo square offers the due to poor technique. The key is advantage of having a sliding rule it’s prudent to make a final C D E Use the outside of the head and Check a miter cut for 45° by holding Inspect tenon cheeks for rule to square a miter gauge to the the angled face against the work, parallelism to the work face by tablesaw blade, touching the rule and then sliding the tool until the extending the rule to the cheek to the plate instead of the teeth. rule touches the adjacent surface. and sighting for intimate contact. 52 woodcraftmagazine.com Feb/Mar 2015 F G A combo square can take a measurement of a Check a mortise’s depth by holding the head on the router base-to-bit distance as reference for setting work while sliding the rule into the recess until it fences and jigs for dado and groove work. bottoms out. Lock the rule, and then read the distance. with precision-ground, square the distance from the edge You can also use a combo ends. You can use the ends in of a router baseplate to the square to check if your boards several ways. The best technique perimeter of a bit–by registering are the same thickness from the head against the router side to side and end to end–good the ruler until the end touches base, and extending the rule info during the machining and theis to work, register and the then head lock first, the sliderule to touch the bit (Photo F). dimensioning stage. Lock the to take a reading. For example, to Checking the depth of ruler so its end is even with one gauge parallelism of tenon cheeks, mortises and other stopped corner of a board, and then check hold the head against the stock, recesses is easy. Simply the other three corners using and push the rule until the end register the head on the work, the same setting (Photo H). contacts a cheek. Look for full and then slide the rule until Of course, you can also use contact between the rule and the it bottoms out in the mortise the ruler on its own to measure cheek, as the slightest gap tells (Photo G).