Here’s how to tune almost any type of metal pipe!
Be sure that you use consistent/uniform metal, compute and measure carefully (2x), cut precisely, and the instruments will come out great! I usually cut a couple of millimeters long (to be safe) and shave off the remainder with the cutoff saw blade(abrasive cut/grind wheel), while checking the pitch frequently. After the math is done, it only takes a few minutes per pipe.
Read through the steps, look at the example, and try it!
A few notes about materials
-On several occasions I’ve purchased pipe that has a welded stringer bead (seam) along the entire inside length of the pipe. This weld can very in thickness so be sure it looks uniform for the few inches that you can see inside. Otherwise the extra material will make each instrument behave differently.
-The thinner/lighter the pipe, the faster this process will go. You can fine tune and make cuts in a fraction of the time. You sacrifice resonance, presence, and maximum volume when you go with thinner or lighter metal, but, other than David Lang’s music or other similar “Heavy Metal” scenarios, I see most people using lighter copper, electrical conduit, or other thin-walled Home Depot/Lowe’s pipe. The last time that I used the light conduit, the output was about an octave of instruments per hour.
-Tape measure or meter stick - metric makes your math much easier and worth searching for the metric tape measure
-Poly-foam/caulk saver from Home Depot or Lowe's to put under node of a pipe when checking pitch. Home Depot 3/8" or 1/2" works. Incidentally, this works great to suspend the pipes on a trap table for the performance as well.
-Pencil and scrap paper for your math
-Sharpie for marking your material
-A bunch of pipe of almost any sort
-Metal cutoff saw/angle grinder/ or rotary pipe cutter (rotary is only if you’re using small copper pipe, or electrical tube conduit: the standard electrical conduit like from Home Depot)
*When using the manual rotary cutter, I recommend having a bench grinder or some serious metal files (or confidence in your math that it will work the first time)
*If you're using an angle grinder or metal cutoff/chop saw, you can easily press the abrasive wheel/blade onto the end of the pipe and shave off small increments)
-A tuner app that will show frequency in hertz (instuner works great)
-A mallet to check pitches
-A bucket of water to cool the freshly cut hot ends
-Any safety gear you deem necessary (preferably safety glasses, gloves, and earplugs)
1. You need to first find a constant (K) for your material. It will remain the “constant” number that you’ll use in your simple math problem for finding all the instrument lengths. You need to cut a test pipe to a reasonable length (the raw material from the store may be too long/low and could leave more room for error), and check the Hertz with your tuner. Once you have your constant, this pipe may become one of your instruments (if it's not already too short).
CUT YOURSELF A TEST PIPE (somewhere between 8”and 3’ for most projects) AND CHECK IT'S FREQUENCY WITH THE TUNER APP. THEN USE THAT FREQUENCY TO FIND YOUR (K).
To get your constant (K), here is the formula-
K= (length of pipe) x (square root of frequency in Hertz)
Again, I prefer to use millimeters or centimeters if possible because inches/fractions make the math slightly more complicated.
2. Determine the frequency of your first desired pitch. The website here has a chart of frequencies at different tuning standards (a=440 or perhaps a=442 if you're needing to match mallet instruments).
3. This is the big scary math equation! Once you have your target frequency from the chart (X), divide the constant (K) by the square root of X. Here is that formula.
L is the length you'll need for your first pitch.
4. Measure twice, cut once. Never cut it too short. Unfortunately, you can't add material if you go to far. Bummer.
5. Continue plugging in all of your target frequencies for X (I cut and check one pipe at a time just in case). A metal cutoff saw works best, but you can definitely use the rotary pipe cutters as well. Be sure to account for any blade widths when cutting to an exact length.
If you use a cutoff saw, allow the metal to cool (or dip it in the bucket) before checking pitch and be sure to get any debris out of the pipe (metal shavings will make it go flat, and a hot pipe will expand creating pitch inaccuracies). If your material is consistent and your math doesn't suck, this method is really accurate.
Here's an example of the math!
With my tuner app, I've just determined that a pipe 48.8 cm long vibrates at a frequency of 512 Hertz. Multiplying the length (48.8 cm) times the square root of the frequency (22.63) equals 1104.344. This is a constant for your particular material. To calculate the length of a pipe that should resonate at C4, (261.63 Hertz), divide the constant (1104.344) by the square root of 261.63 (which is 16.174) and you should get 68.25 cm as the calculated length of the desired pipe! THAT’S YOUR C4!