John Stankus
07-28-2020, 10:47 AM
I have always struggled with getting my chisel backs flat. In the past I had been able to get all but the last couple of millimeters flat (the part that needs to be flat :mad: )
A little history first. I took a Rob Cosman class up in Calgary probably about 10 years ago. It was a good class, but Rob's procedures can be a bit on the prescriptive side. In the class he had us start the back flattening at our coarsest stone. If you have shaky technique you can actually make a whole heck of a lot more work for yourself (I know I did on a brand new set of LN chisels). I realized later (much later) to start with the finest stone and see what you are dealing with, which I felt was a great improvement and was a little impressed with myself until I watched Deneb Pulchaski suggest the exact same thing in a LN video from quite a number of years ago.
During this quarantine, I figured it was time to get all my chisels up to snuff including a set of Hirschs I have been avoiding dealing with since my small set of LN chisels was such a pain to get flat. (side note: a single edged razor blade was the easiest way remove the lacquer coating on these) So I ran through the process, all the way up to a 16000 Shapton GlassStone. I still had issues with the very tip. I kept backing off, going to coarser grits, even getting down to my 140 Atoma diamond plate. Still no dice. After doing a hack job on most of the set, I realized it must be my technique (not that that was much a surprise :rolleyes: ) My technique was to hold the tip flat on the stone with one hand and move the chisel with the other, holding on to the part off the stone. I realized that I must be rocking the blade by pushing from further back on the chisel.
Now the insight
Looking around to observe other techniques, I saw Derek's webpage https://www.inthewoodshop.com/WoodworkTechniques/Lapping%20the%20Backs%20of%20Blades.html (from 2007 no less) on lapping the backs of blades, where he has a plane blade held by a magnetic base to focus all the forces on the front end of the blade. I realized my issue was due to pushing the chisel from a distance away from the leading edge I must have been rocking it. Not having a magnet available, I thought I could use a stick on wire clip (little nylon clips with peel and stick adhesive on the back) to put a handle on the tip of the chisel to be able to manipulate it on the stones. I couldn't find where my stash of those clips are :( Then I realized I could use tape and put a little tab on the end of the chisel. Basically putting a loop in the tape (make it like an upside down T)
437767 437766 437765
So with the tape tab the only place I was touching the chisel (handle was free floating off the edge of the stone) I worked my way from 1200 Atoma, 4000 Shapton GlassStone, 8000 Shapton GlassStone, 16000 Shapton GlassStone. I did have to spend a bit of time on the Atoma to erase my prior sins :rolleyes: but only did an up and back on each of the glasstones (three rows of strokes up, rotate and double check flatness, and three rows of strokes from the other side). And its flat to the edge. I did have to replace the tape occasionally as the water would loosen it. I might try some electrical tape next time.
Quite a bit less frustrating than my prior "technique" (if you could call it that). I do like the Atoma plates and wished that they would go to finer grit. I guess DMT has an 8000 diamond, might try that.
I'm happy to have figured out a method that I can manage. And thanks to Derek for showing the magnetic base as a handle, which gave me the insight to how I was screwing things up :)
John
A little history first. I took a Rob Cosman class up in Calgary probably about 10 years ago. It was a good class, but Rob's procedures can be a bit on the prescriptive side. In the class he had us start the back flattening at our coarsest stone. If you have shaky technique you can actually make a whole heck of a lot more work for yourself (I know I did on a brand new set of LN chisels). I realized later (much later) to start with the finest stone and see what you are dealing with, which I felt was a great improvement and was a little impressed with myself until I watched Deneb Pulchaski suggest the exact same thing in a LN video from quite a number of years ago.
During this quarantine, I figured it was time to get all my chisels up to snuff including a set of Hirschs I have been avoiding dealing with since my small set of LN chisels was such a pain to get flat. (side note: a single edged razor blade was the easiest way remove the lacquer coating on these) So I ran through the process, all the way up to a 16000 Shapton GlassStone. I still had issues with the very tip. I kept backing off, going to coarser grits, even getting down to my 140 Atoma diamond plate. Still no dice. After doing a hack job on most of the set, I realized it must be my technique (not that that was much a surprise :rolleyes: ) My technique was to hold the tip flat on the stone with one hand and move the chisel with the other, holding on to the part off the stone. I realized that I must be rocking the blade by pushing from further back on the chisel.
Now the insight
Looking around to observe other techniques, I saw Derek's webpage https://www.inthewoodshop.com/WoodworkTechniques/Lapping%20the%20Backs%20of%20Blades.html (from 2007 no less) on lapping the backs of blades, where he has a plane blade held by a magnetic base to focus all the forces on the front end of the blade. I realized my issue was due to pushing the chisel from a distance away from the leading edge I must have been rocking it. Not having a magnet available, I thought I could use a stick on wire clip (little nylon clips with peel and stick adhesive on the back) to put a handle on the tip of the chisel to be able to manipulate it on the stones. I couldn't find where my stash of those clips are :( Then I realized I could use tape and put a little tab on the end of the chisel. Basically putting a loop in the tape (make it like an upside down T)
437767 437766 437765
So with the tape tab the only place I was touching the chisel (handle was free floating off the edge of the stone) I worked my way from 1200 Atoma, 4000 Shapton GlassStone, 8000 Shapton GlassStone, 16000 Shapton GlassStone. I did have to spend a bit of time on the Atoma to erase my prior sins :rolleyes: but only did an up and back on each of the glasstones (three rows of strokes up, rotate and double check flatness, and three rows of strokes from the other side). And its flat to the edge. I did have to replace the tape occasionally as the water would loosen it. I might try some electrical tape next time.
Quite a bit less frustrating than my prior "technique" (if you could call it that). I do like the Atoma plates and wished that they would go to finer grit. I guess DMT has an 8000 diamond, might try that.
I'm happy to have figured out a method that I can manage. And thanks to Derek for showing the magnetic base as a handle, which gave me the insight to how I was screwing things up :)
John