A couple definitions of a square are:  1)  A rectangle with all four sides equal and 2)  An instrument having at least one right angle and two straight edges used especially to lay out or test right angles.

What prompted or inspired this impromptu short story was the recent construction of a toy box and/or blanket chest for our youngest Grandson Xander McKnight Gonzales, whereas I was having some difficulty getting things squared up.  On smaller construction projects less than 8 to 12 inches in length, a little bit off is not near as noticeable as something that is over forty (40) inches in length x 21 x 21 or more.  Using regular marking and layout tools, you can only get so close depending on your ability to transfer and/or mark a line or reference point which is subject to human error.  The human eye can only distinguish and discern but so much accuracy and that is when precision measuring tools and instruments come into play such as micrometers, machinists squares, etc.

Prior to building the toy box, I made special fixtures for doing right angle and forty-five degree miter cuts using several different wooden sleds that reference off the miter slots on my table saw.

Example below of my custom made miter sled for forty-five degree picture frame type cuts:

I used this fixture for trimming a forty-five degree angle on the ends of my turkey box call lids but it is just as simple to use a fixture or free hand sand on a 6 x 48 inch vertical belt sander to do the same thing and maybe quicker without fear of chip out.  I later used the fixture for cutting custom made walnut moldings for the custom keepsake boxes I made last year.  You could use a miter chop saw but that would be a lot of rotating the saw from left to right cutting miters and the sled is the way to go.

While building the custom  keepsake boxes, I had trouble getting the forty-five degree miter joints to a perfect ninety degree (right angle) fit and had to abandon the usage of a framing square and a couple other smaller squares and keep adjusting the angle on the fixture until I could get a near perfect ninety (90) degree fit which was difficult.  I later purchased a used Starrett Model No. 20 6 inch machinists square as my standard and totally pleased with it.

Just recently, I found that my framing square and three or four other smaller squares and right angle indicator tools were not perfect enough, but only in the ball park.  If you place two squares on a flat surface back to back and you can see daylight between the two longer side blades, one of the two is not square.  It doesn't take but a few thousands of an inch to throw four miter joints out of square.  When you are using those type tools in combination with something like a hand held skill saw, that is probably as accurate as you need to be; no disrespect to the vast number of craftsmen that use those tools quite efficiently.  But for something more precise where your angles have to be near perfect as can be, it is a challenge using tools that are not accurate enough to begin with.  Then again, it all depends on what a person will settle for his or her own personal standard!  Anything worth doing, is worth doing right.

Below is a pix of some of the right angle tools that I have accumulated since the late 1960s:

All of the above right angles/squares are not square except the lower right Swanson 7 inch Speed Square tool but the forty-five (45) degree angle side is off.  The framing square is at least 1/32 inch off on the long side even after I adjusted it by penning a few dimple holes with a punch to displace some metal but it was too far out to correct.  The yellow handle multi-purpose tool was way off also. 

The next pix shows two Starrett model No. 20 machinists squares that I now use for all my reference work and set-up, etc.  You don't see any daylight between those two blades back to back and each one will register square on all sides.

I purchased the used 6 and 12 inch square off EBay and if you purchase the 6 inch Starrett Machinists Square No. 20 new, it will set you back well over 400 bucks in a 6 inch length one and that is an expensive tool in my book.  Without a precision square as perfect as you can get, you will never have a near perfect cut.  You are only as accurate as your precision layout tools and your ability to properly transfer a reference line from them and that is a FACT!  As I have said so many times on this website, "Most of the time, you get what you pay for."

Below is pix of the fate of four of the right angle squares in the above pix:

I recently purchased a used Starrett Machinists Square Model No. 20 off EBay that is 18 inches in length and got an exceptional deal on it.  I watched the bids sit for a few days and placed my maximum bid a half minute before the sale ended and outbid the pack of 22 bids.  I might need a wheel barrow to haul it around since it is heavy......grin if you must!

The above square will be used as my master to calibrate all my jigs, sleds and fixtures as needed!  Sometime in the future, I will make a plywood case with piano type hinge to store it properly.

Starrett manufacturers precision tools and when I had my musical instrument shop in the late 1960s, purchased a good amount of their measuring tools which was a necessity.  A local manufacture, Coffin Hoist let me use a few of their larger 11 to 14 one inch dial micrometers for the measurement of pre-war Gibson banjo components, whereas I later purchased a large Starrett 24 inch vernier caliper for the bulk of my instrument measurements as well as smaller micrometers, etc.    

My next project will be the recalibration of my miter and ninety degree table saw sleds to get them as perfect as I can and hopefully my next woodworking project will be a little easier and more precise. 

Web published by Bill aka Mickey Porter on 04-02-16 and updated on 04-06-16.