Sometimes milling can require some creativity when fastening your part to the cross table. We started our brass bracket project by using a C-clamp to hold the brass casting onto the cross table for the initial milling of the three surfaces for the bolts. Photos 23 through 32 show the steps used for both milling and precision drilling on this brass bracket. Many machining operations require custom set-ups and alignment. Note the techniques we used to secure this brass bracket for milling and drilling operations it required. Be sure to allow for ample room when drilling, especially when working with large bits (Photo 29).
Photo 23 — The brass bracket (rough casting) is held in place using a C clamp to perform the initial milling of the bolt hole areas.
Photo 24 — The milling collet adapter is replaced by the drill chuck and the three holes are drilled into the brass casting, 3/8 for the two mounting holes and 5/16 for the clamping hole at top.
Photo 25 — Now that holes are drilled into the brass casting, it can now be fastened to a slotted angle plate mounted on the cross feed table. Alignment must be done on both sides. A transfer punch is chucked to aid in alignment of the bracket. The wooden block is adjusted and the bolts on the cross table are tightened until the bracket is aligned correctly.
Photo 26 —The bracket is again adjusted for alignment this time using the mounting through bolts into the slotted angle plate. This was intentionally not aligned for the picture to illustrate the angle.
Photo 27 — A drill center/countersink bit is used to show/locate the center hole of this brass bracket. A benefit of using a milling head as a precision drill is that you can change drills in incremental sizes while the part is locked down.
Photo 28 — The hole is progressively made larger using various bits. Checking for wall thickness as you progress will ensure the hole is centered for an irregular shaped part.