To sharpen a Micra, I use a Medium grit diamond DMT "credit card" sharpener. I open the scissors, put the beveled edge on the card and scrub to form a burr. I do this for each arm. Then and deburr each arm by laying the flat side of the scissor arm on the card and scrubbing.
Tuning involves bending the arm to ensure just the right amount of pressure of the arms against each other. Too little and materials can fold in between the arms without cutting. Too much and the scissor bind when you close them to the point of not opening.
The basic idea of tuning is to use pliers to gently bend the blades either in or out to adjust the pressure. The trick is to position the pliers just where you want to change the bend.
To do this, I get some fine thread to test the scissors. If the scissors can cut thin thread, they'll cut most anything else I encounter. I start near the pivot and test the scissors by cutting the thread. If the thread folds instead of cuts I note the location where the problem starts and will bend both arms closer to each other with the pliers. If the blades bind, I note where that occurs and bend them out a bit at that point. I continue the process of rechecking by starting at the pivot and working my way towards the tip. Note, adjustments made near the pivot will have huge impacts out near the tips.
This is patient and fiddly work, much like learning to sharpen a knife blade. Like sharpening, this may be too much hassle for some people.
The other bit of advice I can give is that you need to dive into this with no regard or hope of having a working Micra when you're done, at least when you're learning. I buy used Micras in bulk off of auction sites and give them away like candy. It's easy to wreck the blades bending them as I describe and so I suggest you try it on throw away Micras at first.
I can generally bring a Micra back from unusable to being able to push cut through wrapping paper.
Hope this helps.
Untitled by
Pinnah, on Flickr
