Cutting angles

All bench-planes for general levelling, i.e. jointer-, try-, fore-, jack- and smooth-planes, have double irons (Figure 60:1) composed of the cutting iron proper and the cap-iron whose function it is to stiffen the cutting edge and break up the shaving as it is raised so that, robbed of its stiffness, it does not tend to run ahead of the cut in a series of small splits in the surface of the wood. The closer this cap-iron is to the cutting edge the sooner the shaving is bent over and broken, and therefore fine cuts or difficult timbers require a close-set cap-iron and a narrow mouth which, in the case of metal s

60 Cutting angles: planes bench-planes, is easily adjustable. Practical experience will give the best setting of the cap-iron, which may vary from a hair's breadth for the final surfacing of difficult timbers to 1/16 in (1.5 mm) for the first rough levelling. This use of the cap-iron means that the grinding bevel of the cutting iron must be underneath, therefore the cutting angle is dependent on the pitch or angle of the iron in the plane, irrespective of the grinding angle. Usually a compromise angle of 45° is used for bench-planes, for raising the angle gives more of a scraping action and lowering it more of a slicing cut.

In the case of metal shoulder rabbet- and block-planes which are only used for trimming and final levelling, often on end grain, the mouth must be kept as small as possible and the iron supported right up to the cutting edge to prevent clattering. As there is no room for a cap-iron the iron is reversed bevel uppermost, which in turn raises the cutting angle, therefore the pitch is lowered, giving an effective angle of about 50° which is about right for a scraping cut on end grain. Moulding-planes also cannot be fitted with a cap-iron even though the bevel is underneath, and to prevent any tearing out of the grain the angle is raised to about 55°. Toothing-planes which merely score the surface of the wood are set at an angle a little short of upright. The remarks regarding the advisability of preserving one long bevel to cutting edges advocated for chisels equally apply to plane-

irons. Figure 60 illustrates the various pitches: 60:1 for bench-planes fitted with cap-irons whose function it is to support the cutting edge and break up the chip as it rises; 60:2 shoulder rabbet- and block-planes with bevel uppermost; 60:3 moulding-planes and 60:4 the toothing-plane. All these pitches are empirical, i.e. the result of long experience and not scientific enquiry. Whereas a good deal of research has been done into cutting angles for machinecutters, it is a little surprising that manufacturers of hand-tools have not experimented with variable pitch planes, in which the cutting angle can be altered for difficult woods, interlocked grain, etc.

Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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