The Parting Tool archive

Wednesday 30 September 2009

Nick Arnull takes a closer look at the parting tool

Gallery

The second tool in the basic tool set is the parting tool. It is manufactured in many forms, but when asked by beginners I recommend the 6mm (1/4in) parallel parting tool. The tool in its basic operation will part timber into two separate pieces, but it is used predominantly to make sizing cuts, such as fillets on spindle turning or spigots for chucking methods. However, it can with practice be used to turn beads � this can be great fun and also can be frustrating, but will help build an understanding with bevel presentation of all the other tools that we as turners use.

The parting tool has many uses and is an essential part of any turner�s basic tool kit. As with any tool it will only cut efficiently when it is sharp.

The parting tool is without doubt the easiest tool to sharpen as the edge is short but the bevel is long. The tip of the parting tool should be ground square rather than at a skewed angle.

The diamond parting tool

The blade is shaped as the name infers and will allow the tool to operate with minimal binding in the cut, as the sides have been removed. Therefore, it will generate less heat in use

Tapered/flared parting tools

There are numerous versions available from various manufacturers and they all work in the same manner as standard. The taper reduces binding of the tool in use. The tapered tool from Ashley Iles has a double bevel and according to the manufacturer�s instructions should only be honed on that secondary bevel

The fluted parting tool

The tool is fluted along the length, usually tapered top to bottom and is ground at 45�. The tool is presented to the timber flute down and will score a line either side of the cut, shearing the fibres as it travels into the wood. As a result, it will produce a very clean cut on the base of projects that will require little clean up after removal from the lathe

Beading/parting tool & the bedan

The beading/parting tool is square in section with a bevel ground on two sides (top and bottom) and is extremely stable and versatile in use. It is used to cut beads and spigots as well as other general parting operations. The bedan, believed to have originated in France, is wedge shaped and has only one bevel. It can be used bevel up like the French, or bevel down. It can be a little �twitchy� in use but can be used to produce an excellent finish. The tapered shape here is to reduce binding in the cut

Thin/narrow parting tools

These vary in size and depth; the deeper the tool the more stable it will be in use. The blade can be 2mm (5/64in) thick and produces a very narrow cut. This type of tool is ideal if turning boxes where the grain needs to be a close match

Tool preparation: fettling a new tool

When purchasing your first parting tool it will require a small amount of attention before use. If the tool has sharp corners they will need to be softened using a diamond file or similar to take off the sharpness. This will allow the tool to be manipulated more easily and will also be more comfortable in the hand, producing less damage to the top of the toolrest

Sharpening

When sharpening tools there should be very little pressure applied to the tool against the wheel. Often the weight of the tool alone is enough to sharpen successfully

Freehand sharpening

Place the tool on the toolrest in front of the grinding wheel and adjust to the required angle. Again, remove the tool turn on the grinder and gently present the tool heel first, square to the face of the wheel, lowering the bevel until it is in full contact with the grinding wheel.

It will slide back and forth on the face of the wheel and once the first face is ground, turn the tool over and repeat for the other side. Ensure to pay careful attention to the front edge to keep it square and do not allow it to become skewed

Basic tool presentation & basic technique

The parting tool can be used in two ways: peeling/planing or scraping. The ideal method is a combination of the two. Present the edge supported by the bevel. The handle needs to be kept low and lifted as the cut progresses into the wood. This method can be a little uncontrolled and the cut will be inconsistent. With practise, this �peeling cut� will produce a superb finish in direct comparison to the scraping cut and will also produce feathers at the start of the cut.

The scraping cut occurs when the tool is held with the handle horizontal and pushed directly into the rotating wood, scraping/tearing the fibres of the wood as it travels into the timber. The result is torn and damaged grain that requires some attention to tidy up.

Push the tool into the blank with the handle horizontal. Once it has entered the wood lower the handle to bring the bevel into contact, and travel into the timber raising the handle as the tool progresses further until it is at the required depth. The result will be a clean entry and a good quality cut at the end of the cut. This is made in an arc travelling into the wood

Holding the parting tool

The parting tool can be held using two methods: the single or double-handed method. The single or double-handed methods are both quite straight forward and ensure the tool is stable in use. There are occasions when working with the tool requires it to be held with one hand (see gallery image 6)

Double-handed method

The double-handed method requires placing the right hand at the end of the handle, with the left-hand at the front contacting the toolrest whilst applying downward pressure to place the tool onto the toolrest

Single-handed method

The single-handed method requires the index finger to be placed on top of the tool. The grip is at the fattest part of the tool handle to give greater control while making a plunge cut

Basic turning method

Step 1:

Place the tool on the toolrest cleaning the end-grain. Have the handle low and arc the tool into the wood, working towards having the lip on the centre point line at the end of the cut.

Step 2:

Switch on the lathe and place the tool on the toolrest, initially presenting the heel of the tool with the cutting edge horizontal. Lower the handle until the bevel is in full contact with the wood

Step 3:

Gently lift the handle until the tool starts to cut � at this point push the tool into the blank

Step 4:

Continue until you reach your chosen depth. The motion should be made in an arc from outside to centre. If the tool begins to bind in the cut, withdraw the tool and move it to one side a very small amount, making the cut. This will make the cut wider and generally applies when making deep parting cuts

Scraping cut

Some cuts will result in feathered edges on either side of where the tool enters the wood. Some of this will depend on the timber used. The denser the timber, the less likely it is to happen, but to minimise the risk you can use a scraping cut to start with.

This is where the bevel is not rubbing during the cut, but can lead to an easier entry into the wood and one that is very controllable for those starting off using the tool

Combination cut

Step 1:

Once the tool is in the wood a short distance begin to lower the handle towards a planning cut

Step 2:

With the handle lowered fully this will create the peeling/planning cut. Continue this along the entire length of the blank

Bead turning exercise

This exercise will help beginners to build an understanding of how all bevelled tools work.

Step 1:

Present the tool at right angles and roll to the right removing only the corner of the bead using the right-hand end of the tool edge. At the same time, swing the handle to the right to allow the edge to travel around the corner: the more wood that has to be removed, the greater the movement


Woodworkers Institute

Tagged In:

technique , sharpening , Nick Arnull , Parting Tool , turning tool , diamond

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Parting Tool , Toolrest

Hints And Tips

1. Practise the beading exercise, as it will help build a better understanding of all other bevelled woodturning tools
2. Become familiar with the single-handed and two-handed methods of holding the parting tool
3. Have a selection of tools that are suitable for different applications
4. Rather than making two cuts side by side to relieve binding in the cut use ‘the micro wiggle cut.’ This applies to deep parting cuts and wiggling the tool a small amount to make the cut wider. If you over-wiggle the tool it will be grabbed by the edge and thrown out of the wood
5. Use both the front cutting edge and the sides of the tool – it will give very clean cuts when rotated slightly towards the timber
6. Remember the tool only has a short cutting edge at the front and will need regular sharpening. If you think the tool is not cutting then it is almost certainly blunt
7. Round over the ends of your sizing callipers to avoid a catch

Health And Safety

1. Protect your eyes and lungs at all times and work at a speed that allows you to feel comfortable and safe
2. Always reduce lathe rotation speed when using wood that is not round and when using chucking methods that you are not familiar with. Always turn the lathe off when making any adjustments
3. When working close to the chuck make sure nothing is too close to cause a problem. For example, loose clothing or long hair that could potentially get caught in the rotating parts of a lathe
4. Never work when you are tired or unwell