|
HIGH SPEED STEEL (HSS) TOOL CARE & MAINTENANCE
Re-Grinding HSS Woodturning Tools
HSS tools can be ground and sharpened with conventional equipment. However, the normal carborundum wheels supplied with most bench grinders are likely to ‘glaze’ fairly quickly and result in lost efficiency. A glazed wheel will also cause overheating of the tool and possible damage to the cutting edge.
We recommend the use of white Aluminium Oxide wheels. These soft bonded wheels break down more quickly and significantly reduce ‘glazing’ by revealing fresh, sharp particles of aluminium oxide.
For re-grinding HSS, a 60 or 80 grit wheel (or abrasive disc/belt) is recommended. A 36 grit wheel is better for reshaping or heavy removal of metal.
IMPORTANT Whilst it is common practice to quench Carbon Steel to prevent the temper being drawn, this should be avoided when grinding HSS tools. Subjecting it to rapid cooling by dipping it immediately into water causes stresses which may result in hairline cracks at the cutting edge.
Grinding Angles
Gouges
Angles are normally about 45 degrees. When working deep bowls, the angle will need to be increased to 60 degrees or more in order to keep the bevel rubbing at all times.
These tools can be used directly from the grinding wheel, abrasive disc or belt.
Skew Chisels
These are finishing tools which benefit from honing or even polishing the bevel on each side. The inclusive angle is about 30 degrees, but unlike bench chisels they should not have secondary bevels!
Scrapers
Scrapers are available in various shapes and sizes. The bevel angle should be about 80 degrees. The burr produced during grinding will give a fine finishing cut. The tool should trail downward slightly during use to enable the burr to cut.
Parting Tools
You should maintain the original angles and use them directly from the grindstone.
|
|
|
