Bits and Pieces
Builders' Tip - Tube Forming
By Ian Brown, Editor - Bits and Pieces, EAA 657159
This handy tip comes out of the Sport Aviation archives for the month of April 1963, exactly 50 years ago. The author mentions spending 30 years before he discovered this useful application of a rubber mallet, and it seems that 50 years later it is still a great tip to have in your back pocket.
In the example shown, author Stephen du Pont was trying to form a small tube almost 2 inches in diameter and 4 inches in length in order to insert a temperature sensor in the ventilator duct of a sailplane. A 3/4-inch piece of steel - slightly longer than the piece of 032 aluminium used to form the tube - is placed so it straddles the jaws of a vice. The roll in the tube was roughly formed by hand and in the vice. It was then placed over the steel rod and beaten with the mallet.
Apparently the curve that developed in the tube depends more on how hard you hit rather than the diameter of the steel pipe being used as a former, although you probably want a smaller diameter than desired rather than larger; or you'll run into trouble once the diameter is getting close.
Check out this issue's "Word of the Month" for something else that came up while researching this article. And please share your own builder's tips with your fellow readers by e-mailing to firstname.lastname@example.org.