Hook Tool Use

Central New England Woodturners

Hook Tool Usage
by Dave Eaton

"Hook" tools are a wonderful woodturning tool, or tool bit, intended primarily for use in the removal of end-grain stock.

In fact it excels at removing end grain, for boxes, vases, hollow forms or even bowls, though we tend to shy away from larger end grain projects since the issue of retaining a pith in the object can lead to problems.

It's unique design provides for easily reaching deep into stock to create an open or hollow form while typically leaving a superior, very smooth finish than other tools such as scrapers cannot do. It can also be an excellent and highly efficient substitute for a traditional bowl gouge when performing side-grain turning especially where a traditional shaped bowl gouge becomes unsafe to use because of depth or other factors. In fact the edge and shape of the hook tool is essentially a gouge's cutting edge on its side (see picture).

A gouge, hook tool and ball end mill

A major issue for many turners is beginning to understand how to use the hook tool. Since this is a specialized tool, not easily made and sharpened, there seems to be a lack of information on it - but it's been around many years.

Del Stubbs, Mitch Wolok and Alan Lacer are reported to have helped this tool emerge to become more popular as of late. Mitch Wolok and Andre Martel each sell a version of the hook tool bit made of hardened steel while Alan Lacer advocates and teaches how to fabricate one yourself using rudimentary metalworking skills.

Home-made tools don't cost the $30-75 that the hardened commercially manufactured bits cost but do wear fast and needs sharpening often. Another alternative is the Termite tool from Oneway Manufacturing. It's more a "ring" tool as the tip is closed. This may aid in some difficult tool tip placement issues but may also clog up with chips more as it does not allow an easy escape for the freshly cut ribbons.

Before using the hook tool, typically the outside of the object will have already been turned to a final shape, at least in the area you desire to be evacuated or hollowed. This gives an approximate shape target and wall thickness to hollow to and alleviates stressing the wood beyond it's structural rigidity limits that may cause fractures in thinner walled turnings.

To turn the interior, there are a few important things to remember:

1) You'll likely need to raise your tool rest to engage the sharp edge and aid the tool in getting a good "bevel rub".

The tool rest needs to be back and high

2) You may need to back the tool rest away from the work a few inches when working right near the "front" allowing the supporting handle or rod to maintain good contact with the tool rest.

3) Though you can start the hook tool cut by swinging the handle well toward the front of the lathe and rotating to about 45 degrees, drilling a depth hole is highly suggested for not only setting your vessel depth, but also greatly aids to the ease in which the hook tool bit can "grab" a new cut. The best size diameter to pre-dill is that about equal to, or greater than, the diameter of the bit curve or outside diameter. For instance 5/8" dia. is ideal in most work using a Wolok bit.

Set depth of drill or gouge using tape

4) The optimum position for the tool to be placed within the vessel will be from the 6 O'clock to 9 O'clock position. This is the area inside the diameter of the vessel with 6 O'clock being closest to the bed ways and 9 O'clock being closest to the front of the lathe, such as where you would usually stand for spindle turning.

Cut between the 6 to 9 O'clock area in the vessel (note: ccw rotation)

5) When reaching far into a turning, the tool rest should be brought closer to the work and possibly raised again to aid the cut. Longer reaches or deeper cuts may even require a more robust holder rod. Usually a 5/8" dia. rod will surface but Mitch Wolok noted that he uses a 1" or 1-1/2" rod for hollow works as deep as three feet with a modified, downward bent tip. (Click here to make your own holder rod)

Deeper into vessel may require higher tool rest

6) For smoothing the interior sides pull the rod close to the vessel wall with the tool almost vertical (safe) to perform a shear scrape. Practice and good tool technique here will leave a finished cut without tear-out.

Use a light scraping cut to smooth sides

7) When cutting the last material in the bottom of the work, starting a cut may become progressively difficult. A scraper may help to clean up.

8) NEVER allow the tool to be rotated to where the entire sharp edge will engage the work. The cut will be extremely aggressive and potentially uncontrollable, likely winding up in a catch or blown up piece.

Use Caution: The Hook Tool should be presented to the wood surface in a vertical position, like a tire is on a car, with the bit end of handle tilted slightly downward. Slight rotation will then initiate a cut.
Never try to engage the tip fully rotated to a horizontal position, like a basketball hoop! You will lose all possibility of the bevel rubbing and it will present like a knife edge to the spinning wood. This is way too aggressive of a cut and you will find a heart wrenching catch results every time.

Remember also, that although hook tools are extremely efficient for most end-grain work, in some situations, if you expect to encounter hard knots or where you may wish to create tightly undercut or rolled edges on closed forms, with sharp angles of departure from the entrance of the vessel where the shape of the tool may not allow the cutting edge to reach well, to protect your hook tool from damage in extreme conditions and maintaining good control over the cut being produced, it is suggested you switch to use of a machinist tool bit tool like a Two Flute Ball End Mill or a heavier, more stout bent tool like Andre Martel's extra large bit.

If you wish to experiment with vessel shapes you also may choose to try different shapes of hook profiles, which may accommodate your need quite well. The cutting characteristics of one shape might be useful and could offer areas of performance where another shape may fall short.

Generally the tool, when presented to the wood in a proper manner will cut very well, generating long thin ribbons of waste. It will tend to pull itself backwards into the vessel once the cut begins as well. If it seems not to be cutting quite as nice as you hope then it is likely dull.

Sharpening the outside of the bit can usually be done easily and quickly by making a few strokes flat across the outer diameter or bevel edge of the bit using a fine flat honing stone. For more aggressive sharpening needs, a Dremel tool with a sanding drum works great. The sanding drum is not extremely aggressive in its surface removal and therefore allows the turner a little more leeway in "grinding" than other, way too aggressive methods like a grinding wheel, which would certainly make quick work of sharpening the bit... and reduce its life many fold if any sharpening errors occur.

As you may perceive, what we look for in re-sharpening is not removal of material but rather a fine dressing of the cutting edge. As the tool bevel becomes narrower it will become more aggressive.

To sharpen the inside, it is best to use a fine round or cone shaped diamond dressing stone or a "slip-stone" with a round or conical shaped edge. Stroke along the inside edge of the tool maintaining a flat contact at all times.

Once a sharp edge is developed, typically the interior of the tool bit will take many light dressings before the outside of the tool will need any touch up as well.

If you maintain your edges with a fine hone rather than more aggressive methods, your tool bit will last for a very long time.

The bottom line with this tools is: