[MacMarty]

Hi, all - I have a "methods of work" question. How can I drill and tap into the edge of a sheet of plastic

I have a recurring project using HDPE plastic, and I am trying to increase quality and reduce effort by setting it up with CNC. It's a simple rectangular box, four sides approximately 16" wide and 6" high. Open on top and bottom. Just four sides with butt joints.

It's trivial for me to cut my rough blanks to finished size, and same for drilling the 6 holes that are perpendicular to their sides. But is there any automated way to drill the corresponding (undersize) holes that are in the edges of the mating sides? So far, clamping them up on edge in the drill press seems like the only solution. (Then using a steel pattern to guide the drill bit to the appropriate spot.) Is there any clever way to automate this? Or at least leave a mark on the edge, maybe with an end mill that has a ball larger than the shank size?

[keebler303]

You could use a "ball" or "lollipop" cutter to mark it. In the production world, they use right angle heads that can be changed by the toolchanger. Mere mortals must rely on something more laborius. If you have a lot of them to do, it may be helpful to make a fixture that will hold the plates vertical with stops to align it, then just have some drill bushings in the proper places so you can quickly drill the holes repeatably.

Matt