This Rubens tube design was loosely based on the designs outlined on the make magazine website.
For this Rubens tube the following things were required:
Push fit 1/4″BSP pipe fittings (8mm) *2
A length of steel tubing (50mmOD and 1.5 WT)
3 meters of semi rigid pneumatic hosing (8mm).
Push fit 8mm T fitting.
Two latex balloons to cover the ends
Speaker and Amp
Propane with appropriate fittings.
1.5mm carbide twist drill
**Do check all parts used are safe to use with propane**
As I have access to a CNC mill, I CAM’ed up the hole pattern as two setups. Two setups because the holes could not be dived equally. The holes are spaced 11.5mm from each other.
A centre drill op is done first due to the curvature of the tube. If no centre drill op was performed the 1.5mm drill would wonder all over the tube. (NOT GOOD).
I used the vice jaw as a reference point as this allowed me to position the tube offset from the vice. To slide along the tube, I moved the machined to the first hole position and then offset the x by the spacing of the holes and put the 1.5mm drill into the previous hole.
This technique allowed for the angle and spacing to be set with some accuracy. The whole process took about 40 mins, not bad for drilling that many holes and not breaking the drill.
Along with using the previous hole for reference, a line of tape was applied to the tube to confrim the holes were along the same plane.