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Update hollowing jig

 Some time ago I showed my hollowing jig for (female) bamboo ferrules. That version consisted of a small slab of wood with a groove, the depth of which defines the resultant wall thickness, and a spokeshave to remove material from the inside of a strip, down to the desired wall thickness. While functional, that small jig wasn't completely satisfactory, for a number of reasons. In addition, the (unmodified) spokeshaves were less than totally satisfactory, as they kept digging into the surface of the jig when reaching the final wall thickness.

So I updated my hollowing jig, making it from a large, heavy slab of well seasoned European oak (from a 50 year old discarded table, sawn to length and planed to thickness (using a large workshop jointer and a lunchbox thickness planer). I made a number of grooves with a plunge router, of different depth (wall thickness) - on one side for general hollowing (wall thicknesses roughly between 2 and 3 mm), and for female ferrule hollowing on the other side (1 mm depth / wall thickness). This large jig is much more manageable and stable.

Hollowing jig showing the general hollowing side (deep grooves), plus the two modified spokeshaves, the cheap 151 clone (the blue one) and the Stanley 53 adjustable mouth shave.

I also modified two spokeshaves to have only narrow cutting sections on their blades - a very cheap stanley 151 clone for rough planing, and a vintage stanley 53 shave (the adjustable mouth one) for final work - I have a few of those, but not wanting to mess with the blades from those, I found another second hand one that I dedicated to this job. The blades are ground away on both sides of a narrow remaining cutting section, so that once you reach final dimension in planing, the non-cutting parts (i.e. just the sole) of the spokeshave rides on top of the jig, with the cutting section taking off just enough bamboo to reach final dimension and not touching the jig once there. 

Underside of the Stanley 53 shave, clearly showing the short cutting section of the modified blade.

During planing, the (individual) strips are held in place with a piece of wood with a 60 degree groove, helped by a thin strip of rubber (cut from a household glove) and fixed with a glue clamp. The (modified) blades are sharpened with a special, small blade honing guide.

Strip clamped in a groove on the ferrule side of the jig (shallow grooves)

Strip ready to be hollowed

Small blade sharpening guide



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