2. Types and Mode of Action of Smoothing and Sanding Tools
Smoothing of flat wood surfaces by planing is performed by means of the double plane. Smooth surfaces are achieved by planing by
1 narrow opening in the plane face, 2 plane cutter edge, 3 distance of the flap breaker edge to the cutting edge, 4 distance of the cutting edge to the face
Profiled and curved surfaces are planed by means of special planes, such as
- double rabbet plane,
The hand tools for size-finishing and smoothing of curved surfaces are rasps and files of different shapes. The chips are removed by successive cutting edges which are called “cuts”. The cuts are cut or milled into the basic body, the blade. At the top end the blade is designed as tang to which the handle is fixed.
1 cuts, 2 blade, 3 tang, 4 handle
Rasps are used for rough-smoothing of the workpiece. Files are used for the subsequent finishing by removing very thin chips. The files differ according to the different jobs and quality requirements. They differ with respect to
- the arrangement and distances of the cut rows,
There are single-cut and double-cut files. Single-cut files have an angle of 110 to 115 degrees between the cut rows and the axis of the file.
Double-cut files have, in addition to the undercut, a second cut (overcut) at an angle of 52 to 56 degrees to the axis of the file.
1 single-cut file blade, 2 axis of the file, 3 angle of the undercut rows to the axis
1 double-cut file blade, 2 axis of the file, 3 angle of the undercut rows to the axis. 4 angle of the overcut rows to the axis
The following rules apply to the selection and use of the files:
- Single-cut files and big distances between the cut rows remove bigger chips.
The shape of the file blade depends on the purpose of use. The main shapes are:
- flat file,
1 flat file, 2 flat round file, 3 half round file, 4 round file
When filing resinous and glued woods, the cuts of the file are filled with chips, resin and glue. The files are to be cleaned as follows:
- Softening and swelling of the dirt in water.
Small irregularities of the surface left after planing or filing are removed with a scraper. The sheet-steel scraper has a length of about 150 nun, a width of 50 nun and a thickness of 1 mm. The fine chips are removed by a uniform, sharp ridge at the longitudinal edges of the tool.
Sharpening of the scraper involves the following operations:
• Scraper burnisher to be firmly pressed on the wide face during burnishing.
- Burnishing of the ridge by moving the scraper burnisher along the longitudinal narrow faces and pressing it towards the wide face.
1 filing, 2 filed and whetted, 3 burnishing, 4 burnished, 5 whetting, 6 burnishing of the ridge, 7 scraper in use
Finally the surfaces are fine-finished by sanding using flexible sanding tools.
They consist of
- the flexible abrasive carrier
Abrasive carriers mainly used are:
- water-proof and non water-proof paper,
and for special applications:
- metal or plastics or a combination of these materials.
Abrasives are sharp-edged and very hard mineral or synthetik materials. Synthetic abrasives are harder than mineral abrasives.
The table shows the types and hardnesses of the abrasives.
Table 1 - 1. Types of Abrasives
The quality of the sanded surface depends on the size of the abrasive grains and on their distance from each other (distribution density). The following rules apply to the selection and use of the abrasive grains:
The tools for manual sanding are sanding pads around which the flexible sanding tools are clamped. Wide faces are sanded by means of sanding pads consisting of
1 softwood, 2 felt support
Hard-wood sanding pads are used for sanding of narrow faces. Profiled and curved faces are sanded by means of sanding pads with counterprofile.
1 workpiece, 2 sanding pads with counterprofils
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