To check your rolling mill without wasting valuable metal, get two
straight pieces of clean unblemished copper wire. 12 gauge solid is
good. Cut the wires 4 in. long.
Set your mill for a substantial, though not excessive reduction .
Start both the wire strips at the same time, one on each side, close
to the outsides. Roll normally, do not back up. If the roll is in
alignment vertically, a good micrometer or calipers, should show both
wires reduced the same amount . Measure several times . Do not mix up
the wires The smallest difference is the most desirable and is the
closest to perfect alignment . We are looking for measurements in
1/000’s of an inch. Closer the better.
The rolls ( I have seen ) run in bronze bushings. These rollers need
to be subject to the same forces when testing as they would be when
being normally used . Keep adjusting the left and right geared
wheels. Keep checking and adjusting as needed. Copper wire is cheep
. MAKE NOTES, DRAW PICTURES IF NEEDED.
After you are finished, roll the metal and take turns rolling right
side up, and then up side down . Do not swap ends as I have heard this
can adversely affect the quality of the sheet.
This should equalize any curvature left .