THE COORDINATED DRILLING OF HOLES

摘要

I have always enjoyed making things. In my youth it was Meccano, Airfix kits and Keil Kraft balsa wood aircraft. However, from then it was all downhill with girls, a career, marriage and family taking precedence! When I was happy with the alignment of the mounts, I clamped them to the table before removing the locating jig (photo 7). The jig was then raised and replaced with a 3mm drill for starting the first hole. I then decided which hole to do first and moved the table accordingly. My Induma mill (a Spanish copy of a Bridgeport, very old but very serviceable) has 200 thou per revolution of each handwheel. Assuming it is the drive side motor mounts the sequence was as follows: A) With the Y handwheel still set at zero, I advanced the X handwheel 18 complete revolutions (3.6 inches). I then advanced it the further necessary 44 thou to give the required 3.644 inch measurement. B) I then locked the X handwheel and advanced the Y handwheel five complete revolutions (1 inch). I then advanced it a further 176 thou to give the required 1.176 inch measurement. I then locked the Y handwheel, drilled the 3mm hole and then followed this with the 8mm drill (photo 8).