The making of oil-channels or gutters belonging to brasses is usually the last process to which they are subjected. In the middle or other convenient part of each brass is a round hole, which is connected with the lubricator; and when this has been drilled the channels can be formed to properly conduct the oil from the lubricator and distribute it over the surface of the pin which is to be in contact. To cause the oil to spread over a comparative great portion of the pin's bearing, instead of allowing it to be confined to a small part, the brass is furnished with a channel or groove similar to a cross. A groove of this shape is shown in Fig. 983, the middle of the cross being the drilled hole extending from the lubricator. Channels of this character have curved bottoms, and are cut with chisels which have curved convex cutting edges, a few inches of the chisel's end being also bent to a curved form, to make it suit the concave surface of the brass. The deepest parts of a channel are those that adjoin the round hole; and from the hole as a centre, each arm of the channel decreases in depth until it has none at all, each branch or arm terminating a short distance from an edge of the brass. Such oil-ways will effectually oil the entire friction surfaces, but will not greatly tend to waste the oil, by reason of the grooves not extending to the edges.

It is necessary for every oil-way to be smoothly formed, although it need not be straight, except for appearance. After a channel has been smoothly chipped it requires filing with round files having bent portions similar to those of the chisels. Such files can be used also for the final polishing; or, instead of a file, a piece of round wire can be employed, the polishing being done by using the tool as in filing, but with emery cloth wrapped around it.

When a uniform appearance is intended for an oil-way, the brass can be properly lined previous to chipping by means of a card. The card has a straight edge, and it is placed into the gap of the brass and pressed into contact until the card is bent enough to cause every part of its straight edge to touch the metal; it is at the same time inclined sufficient to indicate the oblique direction of the intended groove; and while properly held in position, a scriber is moved along the card to mark a line extending from the round hole. The card is next shifted and put into position for marking another line; and such marking is continued until the required number of lines are scribed.

The practice of filing the faces belonging to a couple of brasses, to provide a space between, should be avoided. Such openings should not be allowed, because they require packing-strips, without which the keying of the strap brings both brasses into forcible contact with the pin or gudgeon, and tends to heat and tear the friction surfaces while at work.