Why does McDonough use cast iron band mill wheels?
The longer a saw blade keeps its tension, the better it will run, right? Heat in the saw blade robs it of tension. By using a cast iron wheel you absorb and radiate heat faster than steel. By greatly reducing the heat generated by the saw, you maintain saw blade tension. The graphite in cast iron is also a natural lubricant, which helps dissipate heat and keeping the wheel round and in balance.
On the other hand, steel wheels and steel saw blade (Steel-on-Steel) generate heat that leads to hot saws and hot wheel faces. Many Saw Filers claim saw blades coming off steel wheels are too hot to touch. Not on a McDonough. The result, a loss of tension in your saws.
Steel wheels, because they are fabricated (welded together) will get hard spots over time making annual wheel grindings much more difficult. The heat generated and the instability of a steel wheel will ultimately result in an egg-shaped wheel.
So why doesn’t everyone use cast iron wheels? Bottom line is, the patterns to make a cast iron wheel are very expensive to build and maintain, but it’s worth it.
A casting pattern also allows McDonough to have 'balance pockets' in the wheel for perfect hand balancing by our skilled assemblers. This perfectly balanced wheel eliminates any vibration as the wheel spins, resulting in a better sawn lumber. To try and balance a steel wheel, you have to weld on pieces of steel to an area of the wheel.
So, next time you are considering a Band Mill, remember how important cast iron wheels are. It’s just one of the many qualities that set McDonough apart from the rest.