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Scrapers consist of high-grade, mostly alloyed tool steel; after drawing-out they are hardened, ground and whetted. The selection of the scraper depends on the shape of the surfaces to be worked.
Flat scrapers
Pushing scrapers for pre-scraping and spot scraping of plane surfaces, suitable for removing larger quantities of chips;
Figure 2 - Flat scraper
Pulling scrapers
Scrapers for finishing and pattern scraping of plane surfaces, suitable only for removing smallest quantities of chips.
Figure 3 - Pulling scraper
Half-round scrapers
Tools in the form of solid or hollow scrapers for scraping curved surfaces or bore holes.
Figure 4 - Half-round scraper
Three-square scrapers
Tools in the form of solid or hollow scrapers for scraping curved surfaces or bore holes as well as for deburring edges
Figure 5 - Three-square scraper
Note:
The cutting-wedge angle of the scraper has to be ground according to the material; it is between 70° and 90°.After having been given an angle by grinding the scraper must be deburred on an oiled whetstone, so that it remains sharp for a longer time and does not become dull too soon.
In doing so, the scraper has to be drawn over the oilstone from either side of the cutting edge alternately and in an inclined position till the burr - which this way is bent for several times - is neatly removed.
Figure 6 - Whetting of a flat scraper
What is the flat scraper used
for?
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What is the pulling scraper used
for?
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What has to be done after
scraping?
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What happens if one fails to carry out this last
operation?
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