THE CANNON THAT CAN’T…

I read Popular Mechanics from cover to cover, my son loves some of the articles and my wife denies reading it on the loo. But a question on the kids’ projects: do you check or do these projects before publishing?

Reference the “Ping Pong Cannon” from Augus 2016. Son, daughter and three-year old went doolally when they saw this, so off we went to procure the bits for three cannons. R352 in hardware store and three parts shops later, first snag: nobody knew what TR415 was but they all had the same “standard” tubeless valve. Well, the first parts shop had none, the second had only two and third shop had the third valve I needed. Yes, I should have measured the valve, but with three kids crawling on the work bench… seems the “standard” tubeless valves are 11,3 mm, not 16 mm (discard 3 x 20 cm pieces of pipe with 3 x 16 mm holes; luckily I had extra – this was not my first kiddies’ project).

Then off to the sports shop. Ping pong balls secured. Kids upset, because the glue had to dry a while longer (first gun popped open from pressure on wet glue…) but eventually ready for action, when, hey presto, we discover ping pong balls in SA are standard 40 mm diameter and 40 mm diameter pipe has an interior diameter of 38 mm. Three painfully assembled guns, two packs of ping pong balls, three very disappointed kids. RYAN WESTERN CAPE

( Sorry about the project that failed to end up as expected – particularly because it resulted in three disappointed kids. The problem arose because of differences in the diameters of local vs US pipes. Luckily resourceful Popular Mechanics reader Dale Hillebrand of Pinelands provided a solution, which we previously published, but have reproduced below. – Editor.)