Jim H
08-25-2004, 03:49 PM
On Sharpening Shipwrights Tools
For the subjects of this topic lets stick with plane blades, chisels, slicks, adzes and drawknives, shall we.
Recently there was a thread in Building and Repair on Metal Planes and several good points on tuning a metal plane were brought up including the plane blade and chip breaker fit. The metal planes owned by most of you have the thin factory type blades rather than the thicker aftermarket blades. Aftermarket blades can be obtained from the likes of HOCK, Japan Woodworker etc..
Factory thin blades are sufficient in most cases...if properly fitted and sharpened. The blade and chipbreaker make up the essential unit.
The type of sharpening stones and or papers is yet another matter to consider. All have strong points and perhaps a weakness or two.
At this time the Scary Sharp system seems to be very popular followed by Japanese type waterstones. The old standbye of natural or man made Oil Stones is seemingly less popular nowadays. Scary Sharp is nothing more than using fine grit Wet or Dry abrasive papers on a flat sheet of some hard material. Float glass, marble, steel or cast iron are all to be considered when setting up to do the Scary Sharp technique. Just how to, is freely available on the 'net', so no need to go into detail here.
The Oil Stone way is still used bye many and worthy of consideration.
What ever system and, it each is a system or method of doing, do the research and practice on some old 'klunker' blades before approaching your user blades.
Blades, most all blades, come less than perfect from the factory and must be checked and finessed for the best performance.
The back of the blade, that part that fits with the chipbreaker is many times ignored and is the first part of the blade that should be worked on. Lay backside flat on sharpening surface and make a pass or two across the sharpeing medium and then look at the blade. Chances are you will see shiny and dull areas close above the back of the cutting edge, this tells you that the back is not flat and will not mate tight with the chipbreaker. This is ***the critical area*** to be made as flat as possible. If this area is not flat and the corresponding edge of the chip breaker don't meet tight, chips or shavings from the work will become lodged in between the blade back and the chipbreaker and cause you much grief. Don't forget that the edge of the chipbreaker should be sharp too, so that it makes a tight connection with the now flat blade back.
Once this critical mating is been achieved the next area is the actual cutting edge itself. On thin blades, I don't try to hollow grind the edge at all. Just make it a nice straight sharpened edge. On the thicker aftemarket blades I would definitely consider hollow grinding the cutting edge, depending upon the wood to be planed.
Chisels should be looked at similar to the plane blade. Flat backs nicely polished do make a difference in use. Here again Flat or Hollow grind is a matter of use. For paring with thin bladed chisels I personally would not hollow grind the edges and for hefty Mortice type chisels again I don't favour hollow grinding. The edge is under a lot of strain and whilst the Mortice type is good and stout in cross section, there is a potential for weakening the edge with hollow grinding. On most other chisels
hollow grinding should be considered.
Hollow grinding the edge is of course followed by honing with progressively finer grit materials. You will wind up with a fine cutting edge. .
Slicks are used as a paring tool and I favour a nice hollow grind followed by honing.
Adzes are a bit of sharpening problem nowadays for most of us. In other times, a yard would have a big old hand powered or one converted to motor power, grinding wheel. The width of the wheel would be shaped to fit the narrowest adze blade used,
usually a 3 inch flat adze. All other size adzes either lipped or flat could be ground on that wheel as well. Final honing was with hand held stones though in a pinch I have seen fine Mill Smooth metal files used for all sharpening. Dressing a Lipped Adze was no easy task. It took several stones, one just to hone the inside corners where the lips turn almost 90 degrees.
Drawknives rarely needed the grinding wheel as they were used mostly on dressing already milled stock and there was less chance hitting a stone or a pocket of grit with one. Fine circular oil stones with one handle held in the crook of arm and smooth strokes of the stone would bring the edge back to shape in not much time. If more severe sharpening was needed then a jig or fixture was not uncommon mounted on one side of the sharpening bench. It held the drawknife bye both handles and allowed the shipwright to use both hands on sharpening the blade.
Note: these comments are brief and don't in any way completely cover the subject.
For the subjects of this topic lets stick with plane blades, chisels, slicks, adzes and drawknives, shall we.
Recently there was a thread in Building and Repair on Metal Planes and several good points on tuning a metal plane were brought up including the plane blade and chip breaker fit. The metal planes owned by most of you have the thin factory type blades rather than the thicker aftermarket blades. Aftermarket blades can be obtained from the likes of HOCK, Japan Woodworker etc..
Factory thin blades are sufficient in most cases...if properly fitted and sharpened. The blade and chipbreaker make up the essential unit.
The type of sharpening stones and or papers is yet another matter to consider. All have strong points and perhaps a weakness or two.
At this time the Scary Sharp system seems to be very popular followed by Japanese type waterstones. The old standbye of natural or man made Oil Stones is seemingly less popular nowadays. Scary Sharp is nothing more than using fine grit Wet or Dry abrasive papers on a flat sheet of some hard material. Float glass, marble, steel or cast iron are all to be considered when setting up to do the Scary Sharp technique. Just how to, is freely available on the 'net', so no need to go into detail here.
The Oil Stone way is still used bye many and worthy of consideration.
What ever system and, it each is a system or method of doing, do the research and practice on some old 'klunker' blades before approaching your user blades.
Blades, most all blades, come less than perfect from the factory and must be checked and finessed for the best performance.
The back of the blade, that part that fits with the chipbreaker is many times ignored and is the first part of the blade that should be worked on. Lay backside flat on sharpening surface and make a pass or two across the sharpeing medium and then look at the blade. Chances are you will see shiny and dull areas close above the back of the cutting edge, this tells you that the back is not flat and will not mate tight with the chipbreaker. This is ***the critical area*** to be made as flat as possible. If this area is not flat and the corresponding edge of the chip breaker don't meet tight, chips or shavings from the work will become lodged in between the blade back and the chipbreaker and cause you much grief. Don't forget that the edge of the chipbreaker should be sharp too, so that it makes a tight connection with the now flat blade back.
Once this critical mating is been achieved the next area is the actual cutting edge itself. On thin blades, I don't try to hollow grind the edge at all. Just make it a nice straight sharpened edge. On the thicker aftemarket blades I would definitely consider hollow grinding the cutting edge, depending upon the wood to be planed.
Chisels should be looked at similar to the plane blade. Flat backs nicely polished do make a difference in use. Here again Flat or Hollow grind is a matter of use. For paring with thin bladed chisels I personally would not hollow grind the edges and for hefty Mortice type chisels again I don't favour hollow grinding. The edge is under a lot of strain and whilst the Mortice type is good and stout in cross section, there is a potential for weakening the edge with hollow grinding. On most other chisels
hollow grinding should be considered.
Hollow grinding the edge is of course followed by honing with progressively finer grit materials. You will wind up with a fine cutting edge. .
Slicks are used as a paring tool and I favour a nice hollow grind followed by honing.
Adzes are a bit of sharpening problem nowadays for most of us. In other times, a yard would have a big old hand powered or one converted to motor power, grinding wheel. The width of the wheel would be shaped to fit the narrowest adze blade used,
usually a 3 inch flat adze. All other size adzes either lipped or flat could be ground on that wheel as well. Final honing was with hand held stones though in a pinch I have seen fine Mill Smooth metal files used for all sharpening. Dressing a Lipped Adze was no easy task. It took several stones, one just to hone the inside corners where the lips turn almost 90 degrees.
Drawknives rarely needed the grinding wheel as they were used mostly on dressing already milled stock and there was less chance hitting a stone or a pocket of grit with one. Fine circular oil stones with one handle held in the crook of arm and smooth strokes of the stone would bring the edge back to shape in not much time. If more severe sharpening was needed then a jig or fixture was not uncommon mounted on one side of the sharpening bench. It held the drawknife bye both handles and allowed the shipwright to use both hands on sharpening the blade.
Note: these comments are brief and don't in any way completely cover the subject.