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Planemaking – Casting An Iron Smoothing Plane

Planemaking
Fig. 4. — Casting for Iron Smoothing Plane: Section. Fig. 4 A. — Ditto: Plan.
NOTE: Click on image to enlarge.

Home-Made Tools.
By J. H.

II. – An Iron Smoothing Plane.

In this article I will describe and illustrate a common iron smoothing plane.

Fig. 4 shows the casting for an iron plane of the named type. There is nothing special to be said about the pattern. It is precisely like its casting. Two curved sides, and two ends, each 1/8 inch thick, will be prepared and glued upon the bottom,the merest shade of taper being imparted to the inside faces. The curved sides are properly cut from a piece of stuff which is planed to the depth of the pattern, its curves struck to the radius required, with a pair of trammels, and cut with paring gauge, chisel, and spokeshave. If a thin bit of stuff is planed, and simply bent to the curve, it will be of a less curvature at the top than at the bottom edge, and this will have an unsightly appearance; hence the sweeped pieces from solid stuff. The bottom will be 1/32 inch thicker, to allow of trueing up. The mouth will be a trifle narrower than the casting, for the same purpose.

The remarks made in the last article with reference to the soundness of the casting, and operation of filing, will apply in the main to these examples also, and need not be repeated.

In thin patterns such as these, there is risk of the comparatively deep sides becoming rammed somewhat out of truth in moulding, and this not only involves more labour in filing up the outside, but also increases the trouble of fitting the wood-blocking. I need hardly say that the fitting of the blocking needs to be very close, and in its fitting there is the risk of fracture of the casting occurring if the blocks are driven in too hard. But the more accurate the inside faces of the casting, the less risk is there of fracture occurring. If the casting is not very true, therefore, it will be a judicious plan to true and smooth up the inside with a file before commencing to fit the blocks. Of course we cannot do very much in this way, but we can at least obliterate any rough excrescences; and if the space between the sides, measured at the top edge, is slightly less than that at the bottom, we can produce a fair approach to parallelism.

If several men in a shop were to club together to make several of these planes, it would pay to have a metal pattern — casting it first from a wood pattern made as here described. The metal pattern could then be filed all over carefully, and there would be no risk of its becoming rammed out of truth. All castings would be practically alike, the pattern would be everlasting, so that any number of moulds could be taken from it. This is a suggestion which holds good with regard to many other cast-iron or gun-metal planes.

The advantage of the use of an iron pattern is chiefly found, of course, when the pattern is like its casting, as in Fig. 4. When the casting is cored out as in Fig. 7, there is little advantage in the use of a metal pattern.

Planemaking
Fig. 5. — Lever: Front View. Fig. 5 A. — Ditto: Side View.
NOTE: Click on image to enlarge.

A pattern for a lever, to be cast in brass or gun-metal, will have to be made to the dimensions in Fig. 5, also a pattern for the pinching screw, Fig. 6 A. In each case the dimensions will be slightly in excess of those of the drawings, to allow for filing, turning, and screwing — 1/64 inch will be a proper allowance on the surfaces of the lever for filing, and 1/32 inch on the screw for turning and tapping.

Prepare two blocks of beech, rosewood, or ebony, and fit them into the iron carefully, using red lead paste to indicate contact, and tapping very lightly with hammer or mallet, so making a perfect bedding, without risk of fracture of the iron. The blocks should touch on the bottom, and also be shouldered to fit the upper edges neatly. When fitted, put in the wood screws. The screws should be driven in normal to the curve of the plane body, not standing askew; and their heads may stand a trifle above the face to allow of filing off level. Mark the outlines of the blocks, and work them to shape, Fig. 6. Use a parallel iron, as in the trying plane, make its bedding on the hinder block perfect, and notch the block to allow the tightening screw, A, to pass freely down. Mark the centres of the screws upon which the lever pivots, keeping them precisely at right angles with the centre line of the plane, and at equal heights from its base, so that the lever shall not stand askew. Drill holes of 1/8 inch or 3/16 inch diameter at these centres, file the lever true and smooth, and mark on its edges corresponding 1/8 inch or 3/16 inch “tapping” holes; drill and tap. Two button-headed screws will be preferable to those of the common form, which would require counter-sunk holes for their heads, and so weaken the metal near the edge of the plane. When these screws are inserted and the lever thereby pivoted, try its bedding on the cutting iron, and ease it where necessary, until it beds fair right across the iron.

Now take the casting for the screw and chuck it in the lathe — either between centres or in some form of grip chuck — letting the free end run on the poppet centre. Turn first the end which has to be screwed, and then reversing it, turn the head. Mill the head — properly with a milling wheel in the lathe — or if such is not available, the serrations must be laboriously formed with the edge of a slitting or of a half-round file, the sharp edges being then removed with emery cloth. A milling tool used for this purpose consists of a hard steel wheel having a number of hollowed serrations around its circumference, and pivoted on the end of a stiff bit of bar iron so that it is free to revolve. The wheel may be about 1 inch in diameter more or less, by 1/4 inch or 5/16 inch in width. These serrations are cut in a lathe before the steel is hardened by means of a “hob,” or master tap, set revolving slowly between centres, so gradually cutting the corresponding grooves in the wheel. The hob both turns the wheel and cuts the grooves. After hardening, the wheel is fit to cut a mulled head in a similar fashion. Thus, setting our brass screw revolving between lathe centres with its head next the poppet, support the shank of the mulling tool on the rest, and press the wheel against the edge of the screw head.

Planemaking
Fig. 6. — Section of Smoothing Plane, Complete.
NOTE: Click on image to enlarge.

The wheel will be thus set revolving by contact with the revolving head, and the pressure exercised will cause the hard steel to indent the soft brass, giving the counterpart of its grooves thereto. The latter must be run slowly, and the wheel be held steadily and stiffly to its work, to prevent slip, and the consequent formation of overlapping or of bastard cuts. Use 3/8 inch dies for the screw. Drill the holes in the wedge to 5/16 inch bare, and tap, and make the screw fit its tapped hole with as little slackness as possible.

The iron being now bedded, and the lever and screw fitted, slide the iron down into position, tighten it, note the mouth of the plane, and give to it such enlargement as may happen to be necessary to afford room for the escape of the shavings, but not a particle beyond that. Cleaning up the metal work with emery cloth, the wood work with glass paper, and polishing, will finish the plane.

The above article has been taken from the 1889 trade publication “Work” (Saturday, April 13, 1889 – Vol. 1, No. 4). It should be noted that it is unsure at this stage just who exactly “J. H.” may be, but they do seem to possess some interesting knowledge and insight into the casting process and planemaking in general.

For Part I on Casting An Iron Trying Plane, click here.

For Part III on Casting An Iron Chariot Plane, click here.

For an article on Casting An Adjustable Block Plane, click here.

For an article on Casting An Iron Rebate Plane, click here.

Last Updated: Sep 28, 2021 @ 1:02 pm

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