A hobbyist's 4x6 bandsaw is not a high-performance car or a military jet aircraft, nor is it a naval nuclear propulsion plant as I dealt with for 30 years.? To equate their maintenance needs is a gross exaggeration.
Appropriate (not "good" or "frequent") maintenance is essential for the durability and functioning of any machine.? Excessive maintenance is wasteful at best and harmful at worst.? Making a clear plastic gearbox cover for a hobbyist 4x6 is unnecessary to properly maintain the saw.? The effort to make one is a waste of time and materials - unless you want to try your hand at doing it, in which case the experience and enjoyment is very valuable because that's exactly what having a hobby is about.
Kurt Laughlin
