3/8" diameter copper coil for Foden boiler fire tubes.
![](resources/Fire_tubes/copper%20coil.jpg.opt650x474o0%2C0s650x474.jpg)
Below is a homemade coil straightening jig.
![](resources/Fire_tubes/coil%20strightening%20jig.jpg.opt650x536o0%2C0s650x536.jpg)
The coil was first uncoiled by hand to just over 3'. Then cut from the coil into 27. 1/4" lengths. The final straightening was achieved using the jig. Each Length at 27. 1/4" will allow for three fire tubes to be cut from each length and finished to a size of 9".
![](resources/Fire_tubes/fire%20tubes.jpg.opt650x597o0%2C0s650x597.jpg)