Modern Machine-Shop Practice Part 219

The pulley that drives rope E is shown in Fig. 3189 at R.

The feed motions for the work table are shown in Fig. 3189, and the construction is such that for ordinary work the table has a quick return motion, while for heavy work the feed and return motions of the table are speeded alike.

The driving pulley B, Fig. 3189, for operating the feed mechanism, receives motion by belt connection from the countershaft, and drives the shaft on which are the bevel gears _b_ and _d_, and from these gears the feed motion and quick return are derived, while from gear _e_ and pulley R the cutter head may be raised and lowered by belt power as occasion may require. Beginning with the feed motion, the gear _d_ drives gears _e_ and _f_, which are a working fit on the shaft S. Between these two gears is the clutch _r_, _r_, which is operated by the handle shown in the perspective view, Fig. 3187, at _v_.

To operate the feed, clutch _r_ is operated to engage gear _e_ with the shaft S, upon which is the friction wheel _m_, which engages with the internal surface of the wheel or drum _g_, which drives the rope wheel A, which drives the rope for the work table traverse--wheel A and the rope being seen in the perspective view, Fig. 3187. The shaft N has bearing in a piece that is virtually a sleeve eccentric, because its bore is eccentric to its circ.u.mference; to this sleeve is attached a lug _h'_ to which the handle _h_, Fig. 3187, is bolted. Now suppose that handle _h_ is depressed, and then G will partly revolve wheel _g_ and cause it to engage with the friction wheel _m_, which will drive _g_, and therefore A.

Diametrally opposite to _m_ is a friction wheel _n_, which is driven by the bevel gear _c_, and which is brought into or out of action with _g_ by the eccentric action of sleeve G, it being obvious that when the sleeve G moves _g_ in the direction of _n_, _m_ is engaged and _n_ disengaged from contact with _g_. Raising the handle _h_ therefore places _n_ in gear with _g_, which revolves it in the direction necessary to draw the work table on the back or return stroke.

The return motion of the table is more rapid than the feed motion because gear _c_ is of smaller diameter than _b_, and _n_ is larger than _c_ and than _m_.

In the case of heavy work, however, the return motion may be made to have the same speed as the feed motion by simply moving the clutch _r_ so as to engage wheel _f_ with the shaft S.

The rope groove in the pulley A is waved as denoted by the dotted lines, and this prevents the rope from slipping, notwithstanding that the rope envelops but half the circ.u.mference of A. The wire rope from A operates a drum, in which are waved grooves for the table traversing rope which winds around this drum, and attaches to pins (K, Fig. 3187) carried in brackets at the ends of the table, and one of which is shown in Fig.

3187, at _z_.

The slack of the rope is readily taken up (as occasion may require) as follows:

[Ill.u.s.tration: Fig. 3189.]

The pin _k_, to which the rope is fastened, has at one end a squared head to receive a wrench to revolve the pin and wind up the rope, set screw _l_ locking the pin after the rope tension is adjusted.

We have now to explain the method of holding the work, which is as follows:

The side frames forming the bed are bolted to the main frame and form the ways on which the work table travels. The table frame J, Fig. 3187, is provided with rollers, which rest on the upper surface of the bed and reduce the friction.

The table is made in convenient sections bolted to the table frame J, and at their points of junction the work-holding dogs are placed, the construction being shown in Fig. 3190, in which T' is the end of one, and T" the end of another section of the table. Referring now to Figs.

3187 and 3190, upon the edge of the table are the abutment pieces _a'_, _a"_, against which the work is pulled by the dog, which is operated by the screw, which is squared at its outer end to receive the handle M, Fig. 3187.

The rate of work feed is 30 feet per minute and the quick return motion is 60 feet per minute.

MOULDING MACHINES.

In moulding machines for light work the feed rolls and cutter head overhang the frame, such machines being designated as outside moulding machines.

Fig. 3191 represents a machine of this cla.s.s constructed by J. A. Fay & Company.

The table T slides on vertical ways on the main frame, being adjusted for height by the hand wheel W.

The work while fed over table T is pressed against the vertical face A by the four springs shown, whose pins swing to suit the width of the work.

[Ill.u.s.tration: Fig. 3190.]

[Ill.u.s.tration: Fig. 3191.]

The two feed rolls are made up in sections or discs and the pressure bar is pivoted and has the weight shown to adjust its pressure to suit the work, and is combined with the bonnet whose shape throws the shavings outwards from the side of the machine. The particular machine here shown is constructed substantially enough to permit of its being used for light planing or work not exceeding 6 inches in width, a head with planing knives being shown in place on the machine. In a machine of this kind it is essential that the cutter head spindle and its bearings be rigid, and with ample journal bearings and free lubrication to prevent wear, and for these reasons the arbor is of steel running in self-oiling bearings of large diameter. The arbor frame is capable of lateral movement to enable an accurate adjustment of the cutters to the work.

The term _sticker_, as applied to a machine of this cla.s.s, means that it is suitable for light work such as window sash and door stiles, blind slats, etc., etc.

Fig. 3192 represents a machine termed by its manufactures (the Egan Company) a "double head panel raiser and double sticker combined." The term panel raiser means that the edges of the work may be dressed down so as to leave a raised panel. To fit the machine for such work the bed or table T is made wide.

The upper feed rolls are in sections, and the lower one extends nearly across the bed. The upper feed rolls are held down by a spring, whose tension may be regulated by a hand wheel with an adjustment at the back end to give a lead to both rolls. By this is meant that the plane of revolution of the feed rolls inclines toward the cutter head so that as the rolls feed they exert a pressure on the work, holding it securely against the face A.

A long spring extends from the front of the feed rolls past the back or bottom cutter head, pa.s.sing as shown beneath the pressure bar, and is adjustable for height from the bed or table face T by having its ends pa.s.s through two studs in which they may be secured by set screws. This serves to keep the work down to the surface of T.

The cutter heads for panelling have three cutters set askew or at an angle to their plane of revolution so as to give a more continuous and a shearing cut, which is conducive to smooth work.

The bed above the lower cylinder is adjustable for height by means of the screw at H.

MOULDING CUTTERS.

[Ill.u.s.tration: Fig. 3192.]

In the ordinary or common form of moulding cutter, the front face is flat and the lower end is bevelled off and filed to shape so as to give the required shape and keenness to the cutting edges, Fig. 3193 giving examples of such cutters.

[Ill.u.s.tration: Fig. 3193.]

Cutters of this cla.s.s must be sharpened by filing the bevelled edge, which requires considerable skill in order to preserve the exact shape of the moulding.

SOLID MILLED CUTTERS.

[Ill.u.s.tration: Fig. 3194.]

[Ill.u.s.tration: Fig. 3195.]

In the solid milled cutter the bevelled surface at the cutting end of the cutter is a plane, and a curved, stepped or other shape is given to the cutting edge by cutting or milling suitably shaped recesses on the front face of the cutter as shown in Figs. 3194 and 3195, the former being a tongue cutter for cutting a groove, and the latter a grooved cutter for cutting a tongue.

[Ill.u.s.tration: Fig. 3196.]

[Ill.u.s.tration: Fig. 3197.]

Other examples for such cutters are given as follows:

Fig. 3196 represents a cove cutter and Fig. 3197 an ogee. Fig. 3198, a double beading, and Fig. 3199 a bevel cutter, and it is obvious that by a suitable arrangement and shape of groove cutting edges of any of the ordinary forms may be produced.

[Ill.u.s.tration: Fig. 3198.]

[Ill.u.s.tration: Fig. 3199.]

The advantages of such cutters are that the plain bevelled face or facet of the cutter may be ground (to sharpen the cutter) on an ordinary emery wheel or grindstone, and the shape of the cutting edge will remain unaltered, providing that the cutter is always held to the grinding wheel or stone at the same angle, so that the length of the bevel remains the same.

A common practice is when making the cutter to so regulate the depth of the grooves or recesses in its face that the cutting edge will be of the required shape when the length of the bevelled facet is equal to three times the thickness of the cutter.

The method of finding the shape of cutter necessary to produce a given shape of moulding has been fully explained on pages 80 to 85, Vol. II.