David C":3botosxk said:
Shortening a new blade by 0.5 to 1.5 mm is often a good way of mopping up faults on the back.
Things like rounded corners, or falling away near the edge, perhaps with deep grinding marks..
These would take far too long to remove by working the back only.
I am intrigued that Peter finds RT useful for stubborn blades, but fails to see that the benefits are applicable to all blades (except chisels).
Having established flatness of width at the edge, on an 800g stone, polishing probably takes no more than 2 minutes on an 8,0000g stone.
Flattening and reducing manufacturers grinding marks is the real work. I find blades irritatingly variable. A good one might take 10 minutes and a poorly ground one 40 minutes.
There are some which are better returned to the manufacturer.
Best wishes,
David Charlesworth
The fattening and polishing of the back of the blade is a one off process in the life of an iron, so between 10 and 40 minutes for a blade that lasts years.
My feeling is this is a small investment in time to get a flat back. This is common practice with a chisel and it doesn't seem to be a major issue, although they are smaller and need to be a reference face. I use a very similar technique as the article, but I use Industrial Scary Sharp (PSA) backed stuck on glass.
http://www.finewoodworking.com/item/106 ... ished-back
I do teach students how to use oil stones, diamonds plates and water stones either as part of short sharpening courses or as the first stage in my 9 month course. I am happy for them to use any of these techniques (on their own tools) including your ruler trick which I demonstrate.
I have individual tool set box's for all the students to use, which have planes with polished blades in them that were previously worked on by past students. These blades have polished backs up to 3 micron 8000/9000 grit they only ever need maintaing with the 3 micron or at worst 9 micron.
I also teach students to fettle their own old planes and commission new ones, I guess we work on at least 100 planes a year, all different makes and qualities.
Different sharpening mediums including water stones benefit from different working methods. A2 steels are hard and water stones are soft so flattening the entire back of a plane iron may prove very hard work, making the ruler trick helpful (on that medium). I feel this is the main benefit of the ruler trick but not one I need. I feel it is easier to maintain a blade with a flat back rather than one with a 0.5 degree angle meeting the bevel side, which has to be maintained or ground out.
As has been said there are many different ways of achieving excellent results, not better just different and something that will be talked about on forums forever with no conclusion.
We try and make the non productive time spent on sharpening as painless as possible so we can spend our time making furniture and paying the bills.
Cheers Peter