Thursday, September 11, 2008

More on Sharpening

Where two planes collide...

That says it all doesn't it? Two planes, the front bevel of a blade, and the back; these two surfaces meeting...well, almost meeting. No pressure, right? My previous post showed a couple of tricks while using the Veritas Honing guide on Sandpaper and Glass, this time I'll cover my entire sharpening process. To be honest, since I've moved to my luxurious basement shop I've been using water stones. My last shop out on the Coast wasn't heated so water stones were never an option. I do however still keep my sand paper on glass for honing and dressing my card scrapers. I'll cover that method in the future but for now, let's begin...

Wet Grinding

To establish the bevel of a cutting tool I use a slow speed wet grinder. Mine is manufactured by Jet and has served me well for the past few years. I like the wet grinder over a dry one for a few reasons. Number one: there's no way in hell you'll ever burn an edge on this machine and two, it has a nice tranquil watery sound when it's running...kind of like a cool mountain brook. (just kidding) The Jet model has a speed control and a torque which I find extremely useful. To begin, I'll clamp the iron into the jig/holder which came with the unit. A quick set-up and we're off...I apply moderate pressure here and work the edge back and forth so not to wear one side of the wheel more than the other. A minute or two and I'm done. Take it out of the jig and dry it off. A quick look to see how you've done and we're on to the water stones.

Water Stones

I use three different grades of water stones; all by Norton. These cut really fast and are a pleasure to use. A 1000 grit, a 1000/4000 combination stone and finally an 8000. I decided to go with the 1000/4000 combination stone because I want to keep my stones dressed before, during and after every use. Before starting I'll take my 1000 stone and dress it with the 1000 side of the combination stone. Then while I'm using it I'll continue to dress it every few minutes. This will ensure you're stones stay flat; the most important point when dealing with water stones. I like to check the bevel to confirm I'll be setting up my honing guide properly. In this case I'm sharpening my Iron from my jointing plane which has a 35 degree bevel. This is a high angle that takes care of difficult grain and leaves very little if any tear out. The whole stone dressing thing is something I picked up from Rob Cosman, he has a great sharpening video out that's worth watching. One aspect where I differ from Rob is he free hands when sharpening and I'll use a honing guide. I've sharpened without the guide but feel that sometimes I'd get small discrepancies in my bevel...the honing guide is reliable, easy to use and doesn't take much more time to set up and use. If you can reliably sharpen by hand and achieve favourable results every time, than do it. If you're like me though and may wander off a little while trying to establish a main bevel, secondary bevel and finally a micro-bevel on your edge, then use a guide. David Charlesworth address this point on using honing guides quite well in one of his books...I believe it's volume two.?

Honing Guide set-up

The Veritas® Mk.II Honing Guide is a great jig for repeated, reliable sharpening. First time users may have a slight learning curve with it's set up but once or twice and it'll be second nature. Once I've determined my bevel angle I'll take the registration jig that comes with the tool and set it for this 35 degree, high angle bevel. One other nice thing about this jig is you can do high angles, standard angles as well as back-bevels with a simple adjustment. So now we have the desired angle we can slide the registration jig onto the main body of the guide and lightly tighten it. When doing this part there's small registration lines so you can set it to the desired width depending on what size blade your sharpening. In this case it's just over 2". Next, flip the jig over and slide your plane iron in. The registration guide makes it error proof to square up the iron and establish the proper length protruding from the guide. Tighten up the blade clamp knobs and we're ready to go. One other point to mention is before you start, double check the micro-bevel knob; make sure when starting on your 1000 grit stone it's in the 12:00 position. Then after each stone grit you'll go from 12 to 3 to finally 6:00 finishing on the 8000 stone. This is what establishes the standard bevel, a secondary bevel and finally the third micro-bevel which at that point will cut the hair off of your arm! Let's begin...

I splash a bit more water on the stone after I've dressed it before beginning. Apply moderate, consistent pressure and gently move back and forth over the 1000 grit stone. Be careful when you first touch the Iron to the stone you don't dig into it. I always like to begin by placing the edge of the Iron at the top, furthest point of the stone and gently draw the guide back towards my body. Then on the first couple of push strokes I'm careful not to rock the jig. A few passes and you'll start to feel the primary bevel becoming established. The water will actually start to grab the tiny edge and suck it into the stones surface. A minute or two at most and I'll grab my combination stone and re-dress the surface using the 1000 grit side. Rotate the stones frequently while you work checking the bevel often. Another minute or two and we're done. Again before putting the 1000 grit stone back into a water bath, dress it quickly with the combination stone. Next I'll insert the combination stone, 4000 grit side now, and adjust the micro-bevel knob to the 3:00 position. Now we're gently working on this secondary bevel. A minute and we're done. Again, dress the stones and move on to the 8000 grit. This final stone is quite soft and should be used with great care. The same procedure applies but I try to take some extra precautions while using it. Before I start I'll again reset the micro bevel knob to it's final position at 6:00. This creates a tiny micro-bevel that when properly done will scare you; this is really sharp! Another minute or two is all that's needed to establish this final bevel; when complete, carefully remove the Iron from the jig and dress the stone again. Another small splash of water and we can hone the back surface of the blade.
Moderate pressure and even strokes up and down the stone will insure desirable results. I constantly flip the stone end for end and redress often. Flattening the back of a new blade may take up to 10 minutes like this. Keep re-applying water, turning the stone over to wear both sides and try to use the entire surface of the water stones.The Iron I'm working on today has already been properly flattened and only requires a few seconds to cut-away the tiny burr left behind from the previous steps. When I can see my ugly mug in the reflection, I'm done! Time to put it to work. Carefully dry the Iron and insert it back into the body of the plane being sure not to catch the edge on the way. This final picture shows some shavings from a piece of Walnut. These are end grain shavings! This is really sharp and the entire process I've just described took no more than 4 to 6 minutes at best.

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