I decided I needed to change the sprue and runner layout on a multiple piece stacker plate low pressure injection mold. I don't have to recut all 11 pieces (10 cavity mold). I just needed to modify the first two. Rather than recut them I decided I would modify them.
Now remember, other than getting paid to CNC machine molds and a few other parts. I'm not a "real" machinist. I didn't apprentice in a shop sweeping floors and sharpening drill bits for a hundred years first. So, while I know how (or can figure out how) to do a lot of things I'm not super skilled at a lot of basic things a more experienced machinist would be.
Plate 2 is no big deal. Just machine half of a sprue and two runners into the face of it. No existing machined feature is an issue. Both machines I cut these plates on are still indexed to just drop the plates back in place with a table mounted work stop still in place. Since I didn't want to recut them I had to pin a couple holes. I spent some time thinking about it, and some more time hunting up the smallest stock on hand I could turn down to make the pins, then I hunted for pieces that are already to short for another project I'll be starting on shortly. Finally I turned down some pins to press in. Of course I droped one in the chip tray. After five mintues of hunting for a .163 c .30 pin in all that debris (I cleaned it out a couple weeks ago) I just cut it again. Then I made a pin guide for the small one to make sure it would start straight, and finally I pressed them in. Now I am ready to put the two pieces on the machines and make the new sprue and runner cuts.
Well, I just looked at the clock. If I had just walked out to the saw and whacked off another piece of stock and recut the top plate from scratch I'd have been done an hour ago. LOL.