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close this bookOperations on Wood Turning Lathes - Course: Mechanical woodworking techniques. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 19 p.)
View the document(introduction...)
View the document1. Purpose of Turning
Open this folder and view contents2. Assembly of a Lathe
View the document3. Tools
View the document4. Tool Maintenance
View the document5. Mode of Operation of a Wood Turning Lathe
Open this folder and view contents6. Turning Technology
View the document7. Basic Labour Safety Provisions for Turning

4. Tool Maintenance

Turning tools are subject to considerable albeit varying strain when processing differing wood types. Thus, certain basic requirements must be met by sound tools.

- It must be of high-grade steel which is sufficiently hard and elastic.

- The most suitable taper angle must be ground for the respective wood type.

- The tool must possess sufficient heat conductivity capacity. The subsequently arising frictional heat can cause structural changes to the tool cutting edge. This would denote a softening of the tool.

- The tool must be extremely sharp.

- The tool must be easy to handle as regards its form and size.

Table 1: Tool plane angle related to material and its raw thickness

Processing material

Raw thickness in g/cm3

Taper angle in degrees (º)

soft wood

0.35... 0.50

20... 25

hard wood

0.51... 0.70

25... 35

very hard wood

0.71... 0.90

35... 40

Clean and properly sharped tools are an essential precondition for sound quality of the workpieces being processed and for accident-free operations.

Tools subject to considerable wear and tear are ground on the abrasive wheel. When grinding by means of dry-operating abrasive wheels the tools should be placed in water at short intervals otherwise they can easily anneal.

The taper edge must be heeded according to table one. First of all those tools with straight cutters are ground on the grinding disk (abrasive wheel). Because of the uneven wear and tear of the grinding disk the steel sections and tubes are the last items to be ground. Grinding is completed when all dents and gaps in the cutting edge have been removed and a small burr has formed on the cutter edge. Tool oilstoning is undertaken by a wet oilstone. Thereby the oilstone is moved by hand in a circular motion on the tool cutting edge.

Figure 17 - Oilstone

Flanks and cutting faces are oilstoned reciprocally. If possible, the oilstone should have a fine grain. A specially shaped oilstone is required for sharpening the tubes.

Figure 18 - Shaped oilstone

Oilstoning continues until no grinding traces are perceptible in the cutting edge area. A burr must not emerge during oilstoning.

Tools are only ground anew once resharpening by means of oilstoning is no longer possible.

Blunt tools require considerable cutting forces.
This increases the risk of accidents and inferior surface quality results.