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In:In the Shop, Vintage Tool Talk

Comments Off on A Custom Fishtail Chisel

We make winding sticks… lots of them.  Each set has four trapezoidal pieces of inlay, each with two sharp corners that need to be cleared out.  So for a batch of 50 sets of sticks I have 400 corners to clear.  Thus far I have used my Lie-Nielsen 3/8″ fishtail chisel, but it’s too narrow and the fishtail angle is too shallow to really reach the corners, so I have to reach down from above and scoop out the waste.  It works, but it’s not ideal.

My first thought was to buy their largest size chisel (5/8″), but I scoped it out at the Lie-Nielsen event in Brooklyn a few weeks back and found it was also too narrow and too shallow on the side angles to give me what I wanted.  I decided to try modifying a vintage chisel if I could find one suitable for the job, so here’s the rundown:

I found this Stanley chisel (with steel through the entire body) which had been ground down quite a ways for $9.  Normally I wouldn’t want to pay even $9 for a chisel that was so short, but for this task where I want to be closer to the work it was perfect.  The steel running through the handle also puts good weight in the hand and balances the tool nicely, so $9 was worth it.

The chisel as purchased, prepare to be decimated.

The chisel as purchased, prepare to be decimated.

I painted on some machinist layout fluid, scratched in some general guide lines to grind to, and started hogging off material.  I’ve had a few people as about the risk of removing the temper from the steel during this process so I want to address that up front.  To avoid ruining the steel, you need to avoid over heating it.  This starts by using fresh abrasives.  I was grinding with a freshly dressed grinding wheel from Norton.  I held the tool with my bare hands so I could feel when it started to warm up, then I cooled it in water.  I also don’t grind up by the tip of the tool, this material is so thin that it will heat up too quickly and be ruined.  Any final grinding of the tip was done by hand on sandpaper and finished on waterstones.

Heavy material removal completed from the bench grinder.  Time for the belt sander.

Heavy material removal completed from the bench grinder. Time for the belt sander.

When I had the sides brought in I needed to refine the shape so I switched to my belt sander outfitted with metal grinding belts (Alumina Zirconia).  This worked extremely well and was basically trial-and-error process.  I’d grind some metal, check my progress, draw new target lines occasionally, and grind some more.  Eventually I got the shape I wanted and went from a 40 grit belt to an 80.  Refined things a bit further, then polished it up with a 220 grit belt.

My restored belt grinder... too pretty to just grind metal on, so I covered the walnut with some thick paper to avoid getting metal embedded in the wood.

My restored belt grinder… too pretty to just grind metal on, so I covered the walnut with some thick paper to avoid getting metal embedded in the wood.  Worked like a charm.

Shape being refined on the belt sander.

Shape being refined on the belt sander.

After the grinding was finished, I hand filed a few areas and then sharpened the blade.  I started with sandpaper as this was the initial sharpening/flattening of the tool.  After sanding up to 320 grit I switched to my waterstones and polished the tool up to 8,000 grit.  This was a freehand operation given the shape of the tool doesn’t really fit the standard sharpening jigs.  I use the sharpening jigs whenever possible and am not ashamed to admit it, but I can freehand when necessary.

The finished tool compared to my 3/8" Lie-Nielsen.  I had a slight ding on the bevel near the cutting edge, but it's not at the cutting edge and will be ground off in future sharpenings.  I didn't remove it now because I'd be wasting several sharpenings over a small cosmetic flaw.

The finished tool compared to my 3/8″ Lie-Nielsen. I had a slight ding on the bevel near the cutting edge, but it’s not at the cutting edge and will be ground off in future sharpenings. I didn’t remove it now because I’d be wasting several sharpenings over a small cosmetic flaw.

The chisel being used as designed.  You can see that it can reach all the way to the corner of the inlay pocket and still has a little clearance between the chisel and the pocket's side wall.

The chisel being used as designed. You can see that it can reach all the way to the corner of the inlay pocket and still has a little clearance between the chisel and the pocket’s side wall.

I tried the chisel out briefly and it works brilliantly.  Overall it took $9 and between three and four hours of work, and that’s from the time the tool was untouched to completely finished.  I did give the handle a quick sanding and refinishing, but nothing fancy and now it’s ready for years of service.  Time to get some work done.

-WMT

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