Installing And Rolling The Flues On The Bottom Flue Sheet
In the photo a 1/16Ē thick refrigerator magnet serves as a distance gauge for how much a flue is to extend past the face of the lower flue sheet. Flues to the lower left of the photo have been installed and rolled using the Elliott Roller. The flexible magnet insured the roller did not push the flue flush with the flue sheet while being rolled.
There are two recommended methods for powering the tube roller and rolling tubes. The first is to use an electric motor that includes a very precise current monitor. The amount of current drawn by the motor indicates the amount of rolling of the tube taking place. The alternate method is called the mechanical method where the roller is operated until a mechanical indication stops the rolling process. The mechanical method is the oldest method used but is also has less accuracy than the electric method. For this boiler the mechanical method to roll the tubes was employed as the electric method requires expensive tooling. The mechanical method relies on a stack of washers placed between the rollerís drive shank mandrel and the back of the rollerís cage & bearing assembly.
Difficult to see in the photo, the roller has a stack of small washers on its shaft that serve as the mechanical stop. The roller is dipped in light oil, inserted in the flue, and turned with an air drill until the washers on the shaft become tight as the shaft turns into the roller to expand the flue tube. The drill is reversed and the roller is removed. Setting the proper number of washers on the shaft determines how much a flue tube is expanded.
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