Replies

1. 
   RMillard | Sep 24, 2003 01:36pm | #1

   I too use the sand paper adhered to a piece of glass for sharpening , for final sharpening but I still use oil stones for the first steps. I do not use a honing guide. For a scrub plane blade I grind the pronounced curve, and then just rock blade side to side as I go over the abrasive in a figure 8 motion. This is a little like rubbing your stomach and patting your head, but it is quickly learned. Also, The figure 8 motion is hardly necessary on the sandpaper, but I can’t seem to break the habit, I acquired when using oilstones.

   For the almost imperceptible curve of smooth planes, I first establish a dead flat edge , by moving the blade over the oils stone ( a Norton coarse/fine India combination) parallel to the edge. Then when I change to the sandpaper, at the 800 grit level ,I hone in the conventional manner but I take several strokes with more pressure on the outer edges. The resulting curve is so slight, that I straight edge held to the iron will show only a very tiny crack of light at the outer edges. I would guess this to be somewhere in the .003-.005 range. At first this too is a difficult thing to hit right. You will be able to tell if you have a good compromise, between the curve and efficient stock removal if you can get a nearly full width shaving , without tearing at the edges.

                                   Rob Millard

1. 
   b1gcountry | Sep 24, 2003 04:54pm | #2

   What Rob Said, just a little curve is enough to get the sharp edges out of the stock. The other options are to set the blade slightly skew in the blade, so it only leaves track marks on the left side, then plane right to left to remove your marks. You can also round only the corners of your iron by just sort of rolling the blade on the stone. You would be best served with going with the curved edge though.

   Tom

2. 
   MarkRoderick | Sep 25, 2003 03:00pm | #6

   Rob, do you have any special jig or technique for grinding the curve on the scrub plane, or do you just do it freehand?

1. 
   eddiefromaustralia | Sep 25, 2003 03:14pm | #7

   Even though I'm not Rob, I'll jump in and then exit stage left, Mark.

   If you were to draw a line across the corners of the cutting edge on a factory ground #40 blade, you would find that the centre is approx 3/16"deeper than the edges. 

   The exact radius isn't that important - in my opinion it's only a roughing tool and I find that they work better at slightly lesser radius - maybe about 1/8" depth.  I freehand grind them, just pivoting the blade on the grinder rest about a single finger giving pressure/centre of the arc.

   Cheers,

   eddie

1. 
   MarkRoderick | Sep 25, 2003 03:30pm | #8

   Thanks, Eddie. Feel free to respond to any of my dumb questions anytime you please!

   I once purchased one of those little belt-sharpening machines from Lee Valley, which has been gathering dust ever since. Since being introduced to the scrub plane earlier this year, I've been trying to devise a jig for sharpening that radius. But maybe this weekend I'll have a go at doing it freehand.

   I also have the sense that the factory radius is too large. Even with an extremely sharp blade cutting into pine, the cut is only about a half-inch wide - it's deep but narrow. I'm going to experiment with reducing the radius and honing the edge by hand.

1. 
   ChasStanford | Sep 26, 2003 07:23pm | #9

   Mark, just remember that while it would be nice if the scrubber's iron was absolutely razor sharp it really doesn't have to be in order for it to do it's thing.  You'll have to work a little harder, though.  I've let mine go quite dull out of laziness and it still plowed through Mahogany with no problem.  Rock Maple would be another matter.  That's when you'll need to touch her up pretty frequently.

   Do the thing freehanded and quit worrying. 

2. 
   ChasStanford | Sep 25, 2003 01:58am | #3

   I let about two-thirds of the plane iron hang off the edge of the stone and go four or five strokes on the left one-third and right one-third of the iron.  If you use a slow cutting stone you may need a few more strokes than that.

   It's as simple as that and works like a charm.

3. 
   eddiefromaustralia | Sep 25, 2003 03:21am | #4

    Hi Charles,

   I've cut and pasted an answer I gave to this question on another forum.

   In short, I understand your question as:  "how do you maintain a constant angle of honing on a blade that isn't flat", not so much "how do you get the curved cutting edge".  I like the answers given so far - a few tips to try for me too.

   Here's my reply to the first question:

   Hi everybody,

   I'll repost this here, typing quickly as I have to put my two young kids to bed soon.

   Freehand sharpening is easy. There, I've said it. Probably took me no longer than 2 hours to learn.

   Firstly, flat blades, eg: planes & chisels

   Remember, that any properly sharpened tool will show a single glint of light off the secondary bevel if the blade is moved under a bright light (eg: the secondary bevel is uniform in angle and linear). A poorly sharpened tool will have the bevel visible over a range of angles. At each different angle, a different part of the bevel will reflect light.

   So, how do you sharpen freehand. Here's how I was trained by a German master cabinetmaker.

   1) Stand side-on to the stone, approx the same stance as if you're sawing.

   1a) Flatten the back of the blade as per normal, pressing the back down on the stone and moving back and forth in a linear motion. If the blade's been sharpened properly before, this should not take you long.

   2) Turn the blade over, lay the blade primary bevel flat on the stone, pressing down with the fingers of the left hand low on the back of the blade to keep the bevel on the stone.

   The blade needs to be in the middle of the stone, not close to either end (important, see later)

   3) Put the right middle finger under the blade and put the index finger and thumb around the right hand side of the blade (both fairly straight). Hold the blade firmly in position with them, but not so tight that the knuckles turn white this is an important hint here - holding too tight stops the blade from being sharpened successfully

   4) Dig the right elbow hard into the top of your pelvic bone (Right hand side of the body). You'll need to bring your body to the elbow, not the other way around, so that the blade stays fixed in position on the stone. Note, at this point, you still haven't started honing.

   5) Lift the top of the blade slightly (approx 3-5mm, about 3/16") to change the angle of attack of the blade to that of the secondary bevel

   6) Lock the right wrist solid with the blade in it's correct position for honing. The wrist now not move again until the blade is taken off the stone.

   6a) The right elbow is still firmly pressed against the top of the pelvic bone, remember this.

   7) Rock your whole body from the ankles (feet stay still) to hone the blade.

   the first stroke of the blade is to move toward you, very important. This is why you set up the blade in the middle of the stone as it ensures that you create a 'land' to keep the blade flat and in contact with the stone on all subsequent strokes. If the first stroke is a push stroke, there is a good possibility that the blade will roll over and you'll need to regrind the primary bevel and start again.

   To even out wear on the stone, use a figure eight track on the stone, or even two figure eights, one on the half of the stone furtherest away from you and one on the half of the stone closest to you.

   This looks like some distorted tribute to Elvis, but the blade stays in the correct angle of attack all the way along the stone and you get a good edge.

   8) Don't overhone, 5-10 strokes max should do it.

   9) Check reflection from the secondary bevel to see that it is honed evenly

   10) remove wire edge from blade, by first (very light pressure) reflattening the back of the blade and then (very lightly) rehoning the secondary bevel as above. A couple of cycles of this and the wire edge should be gone.

   11) very important, don't forget this step Strop the blade. Use whatever works for you. While I was trained to use my hand, this is frought with danger and shouldn't be attempted, as you'll easily slice through to the bone with a correctly sharpened blade. Instead, I recommend using the end grain of a piece of western red cedar, soaked in oil to soften it up, a felt wheel as used by carvers (who really need sharp tools) or a soft razor strop. For those that don't know, stropping involves pulling the edge backwards across a stropping medium, re-forming the edge after you've snapped the wire edge off.

   12) If the blade is sharp, it will pare fibres from the end grain of pine (not hardwood) with no signs of tearing or marks on the pared surface. Don't try to shave hair or drag on a fingernail as a test, if it's really sharp, you won't feel it cut until you see the blood.

   So that's straight blades, what about curved blades, eg: gouges and scrub plane blades?

   I use the same technique as above with one minor variation.

   The left hand keeps downward pressure on the blade, the right hand rotates from the elbow (wrist still locked in position but turning side to side) as you do the figure eight. I have one corner of the blade in contact with the stone at the bottom of the figure eight and the opposite corner of the blade in contact with the stone at the top of the figure eight. Roll the blade gently and smoothly from side to side and back again as you create the figure eight.

   Softly and gently does it and things work out fine.

   As you become more familiar with the technique, you can press harder and work quicker, but start slowly (as always).

   Hope this helps.

   Cheers,

   eddie

1. 
   CharlieD | Sep 25, 2003 04:22am | #5

   Wow...thanks for all the responses. I can't wait to get on it...

   Ch