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Thursday, August 21, 2014

Travisher Blades: Grinding and Sharpening

Okay now, I know taking any new blade to the grinding wheel can be intimidating, but despite the curved blade, the same principles apply as if you were grinding any other plane blade. 

First things first, dressing the wheel. Square your tool rest to the grinding wheel, doesn't have to be perfect, eyeballing is fine, this is just to keep your dresser steady. With the grinder on, come in with your dresser working it across the wheel to true up the wheel and remove remaining metal.   

If you've got a freshie wheel, you will to have to round over the outside corner. As you can see mine is rather extreme, the radius does not have to take over the whole wheel only about 1/8" is necessary. With your dresser in the same position as the photo, removing material from the front of the wheel, start easing the corner about 1/8" in from the side. As long as the radius on your wheel is tighter then the radius of your blade, you're in good shape.   

Setting up the bevel angle, I grind the blades to a 27 degree bevel. With blade fastened to the jig, set up and angle fence to keep the established angle. My process for setting the fence starts with sighting it by eye to get in the ball park. Once close spin the wheel by hand and scratch the blade, this way you can see exactly where the wheel is making contact on the bevel. With the tool rest slightly tightened, tap the fence at the front if the wheel needs to shift towards the top of the bevel and tapping at the back to shift towards the bottom.  

Once you see the scratch pattern spanning the entire width of the bevel you are good to go. For people like myself who are less visually inclined, take a sharpie and color in the bevel to make it easier to see the scratches. 

Now you are set to turn that sucker on and with a relaxed stance and steady but not overbearing pressure move the jig side to side on the tool rest grind away that bevel.

Now this takes time and practice to finesse, but you want to grind the bevel, coming as close to the edge as possible without a burr on the wheel. It's safer and protects the flatness of the edge to roll the burr in the stoning process. Will you ruin the blade by picking up a small burr in on the wheel? No way man! Its not the end of the world and you will still be able to get it sharp on the stones.  I only tell you this as proper practice to strive for. 

Water Stones, you got your: coarse stone (1000), hard stone (4000) and polishing stone (8000)


Starting off buy picking up a burr on your coarsest stone. Working the blade in a rocking motion along the stone. Putting pressure down with your thumbs on both edges, starting with your leading thumb down transferring the pressure to the back thumb as your arms are pushing the blade up the stone. Difficult motion to describe but it becomes highly intuitive once put into practice.  As a visual aid to help you out the next three photos depict the motion. 

Next switching to your hard stone and sharpening the blade

and finishing off on your polishing stone

This guy: DMT diamond cone. After working the back of the blade I use the diamond cone to to hone the bevel and work the burr back to the back side.

You will work the diamond cone back and fourth on the bevel with balanced contact to establishing a nice even hone along the top and bottom on the hollow grind. Pinching the cone directly, instead of holding by the handle gives you much better feed back on where contact is being made. More visual aids to help understand the motion in the next 3 pictures



Polishing the hone. Chuck up an 'ol peice of hardwood and turn it into a round around 2" dia.

 Mark off 1 1/2 " sections and smear on some diamond paste. I start with 5 microns working down to 2.5, 1.5, 1, and finishing off with green rouge  

Carefully with the lathe on, your hair safely in a bun, and the blade slightly skewed you will polish the bevel by working down the grits of diamond paste. I'm all about the visuals so again the next three photos will show the motions of this step. Keeping firm contact with the bevel to your round and pushing it forward against the rotation of your polishing blank. 



No lathe? No problem, you can take a dowel and apply the diamond paste or wrap it in wet dry sand paper. 

You will work it across the bevel with the same motion as the diamond cone

Now its back and fourth battle royal between the polishing stone and the strop to remove the burr. 



Working with the end of the strop making firm contact with the bevel pulling from front to back while moving side to side along the bevel. Don't use the strop on the flat back of the blade.

And of course more visuals to give method to my written madness



Within these last two steps you can watch the burr curl off, once all remainder of the burr is gone and you've shaved off all your arm hair, cause you just wanted to cut a few hairs to see how sharp you actually got it, then you are good to go my friends. 

Also friendly reminder: proper maintenance of the blade between uses will keep it from getting dull. I recommend the last two steps of the sharping process: a few passes on the polishing stone and working the bevel with the strop.

5 comments:

  1. One question,

    Not long ago I got the same diamond paste but the smell of the oil is really a killer for me. Does it go away with time? It kinda gives me headache so I'm not using it at all...

    Regards
    Sebastian

    ReplyDelete
    Replies
    1. Sebastian, I can't say for sure that the smell goes away over time or I've just gotten use to it. That being said, if its a bummer for you then there is no need for it, just go with the wet/dry sandpaper and a dowel.

      Delete
  2. Thanks Claire

    Great information

    ReplyDelete
  3. Excellent blog! I like your post about Blades Grinding and Sharpening. Thanks for sharing.


    Diamond blades

    ReplyDelete