HAND WOOD-WORKING TOOLS 431 



17. Describe the cutting action of a knife. 



18. Why is it not possible to saw a board with a knife? 



19. Compare the cutting action of a knife and a saw. 



20. When should wood-working tools be ground? 



21. Describe the kind of stone upon which wood-working tools 

 should be ground. 



22. Why is it necessary to have the grindstones frequently tried? 



23. Describe the brace and bit. What is the mechanical prin- 

 ciple involved? 



24. Explain a wood plane. 



25. Name the different kinds of planes. 



26. Describe the kinds of chisels. Why should chisels be kept 

 clean? 



27. Why is it necessary to use squares? 



28. What is a gauge? 



