A comprehensive educational community devoted to trim carpentry, finish carpentry and architectural millwork. Hosted by nationally recognized author and finish carpentry specialist Gary M. Katz.
  Baluster Layout with Construction Master Pro  
I use a Construction Master Pro calculator to lay out everything, at least everything I can. It’s the only way to ensure quick, precise layouts on the first try. Sure, I’m supportive of practicing math skills and knowing how to divide fractions, but the CM Pro is much smarter than I am, it never makes a mistake, and it remembers everything—and that’s the key to fast and accurate baluster layout.


Even for radius railings, I start by laying out the centers for the balusters on a thin strip of wood--using a CM Pro--then bend the strip around the radius.  
Whenever I layout balusters I remember a rule that Jed Dixon, a stair specialist in Rhode Island, once explained to me. He said that even though a 4 in. clear spacing is allowable, it’s best if the spaces between the newel and the first or last baluster are about half the distance of the on-center spacing, so I usually start by measuring in from each newel 1/2 the spacing width, then I measure the distance between those two marks. For this example let’s say the spacing is 5 in. on center (so a 4 in. ball won’t fit through the balusters). That means I’d measure in from each newel 2 1/2 in., then measure the distance between those marks. We’ll make that 108 3/8 in. The next step determines exactly how many balusters will be needed in the run. I divide 108 3/8 in. by 5 in.—the O.C. measurement. On the CM Pro this means entering 108 then pressing the “Inch” key, followed by entering 3 -Slash key- 8, then pressing the divide key, the number 5, and finally the “=” key. The resulting sum is 21 11/16. Obviously you can’t have 21 11/16 balusters. The number must be an even amount.

So round up the number to 22, and start over, this time dividing 108 3/8 “Inch” by 22. The resulting quotient, 4 15/16 is the distance from the center of the first baluster to the center of the second baluster. But don’t cut a gauge block 4 15/16 in. long and expect it to work all the way across the railing. It won’t. The CM PRO calculates to thousandths of an inch and rounds the results into useable fractions, which can be programmed by the user. I’ve set my calculator to round fractions to the nearest 1/16th of an inch. Even though the calculator displays a number that’s rounded to the nearest fraction, it still remembers the actual decimal quotient. In order to layout succeeding baluster locations, it’s vital that you use the number in memory, not the number on the screen—just adding the number on the screen to itself over and over again wouldn’t result in an even layout. To use the number in memory, once the quotient is on the screen, press the “+” key ONCE (now you’ve told the calculator to “remember” and use the actual decimal fraction, so don’t press the “+” key again, or you’ll be instructing the calculator to “remember” the new number on the screen!) and then press the “=” key. That sum is the distance to the third baluster. For all succeeding baluster locations, simply press the “=” key and the calculator will automatically add the decimal fraction to the preceding sum and give you layout marks for every baluster in the run. The most your layout will vary will be 1/16 in. Every single time.

  Supported by corporations who care about education in the construction industry.  
  Mastering FInish Carpentry DVDs