But where I see a problem with 'pre-covering' then cutting out the center section, with a new blade or not, does it not 'score' the wood underneath any amount, thus weakening it? This is the only reason I have not pre-covered my planes. Just trying to understand. Not like my planes have any life expectancy of great time anyways.... Thank you.
I do understand your concern. And it is of a little more concern with a 1/2A plane than with a larger plane, since the center sheeting is usually 1/16" sheeting. That's why I ensure that I use a brand new blade. If you mark where the covering is to come off with a fine line sharpie (my choice) and then lightly score the covering, you can usually make a good score without actually cutting all the way through. Monokote is actually pretty thick skinned. Once I have the score line, I pick a spot in the center of the wing and carefully cut all the way through the Monokote on both sides of section where the covering would be removed. Usually about 1/2" to 3/4". Then I lift up that little cut section, kind of like a pocket, and cut across from left to right making two little tabs fore and aft. Next, I lightly pull up on one of the tabs and run the blade tip along the score lines, left and right, as I go, making a nice clean cut as the blade follows the score lines and the covering lifts up. Doing this on both front and back tabs of the section to be cut away gets me to the leading and trailing edge where I trim off the tag. Once the covering is cut away, run the sealing iron back along the edge of the Monokote to seal it back down.
If my explanation is too confusing, I'll see if I can make some time to shoot a quickie vid of how I cut the Monokote away.
But, what if I scored the wood underneath? Well, I use CA for most everything, and I figure if I made a little score in the wood, the CA would just wick in and fill in the score. No harm, no foul. I've never had a wing fail on me yet at the center sheeting in the 30-something years I've been using Monokote and trimming this way.
Mark