Drilling & Tapping Mounting Plates

One of the first tasks in building a Project PANOPTES unit is to drill & tap holes so that each pair of plates (3 ½” thick aluminum plates, and a Vixen-style dovetail plate) can be screwed together, and so that the cameras can be securely attached to the camera plate. The instructions call for doing the drilling one plate at a time, but my experience is that using a handheld electric drill will not produce holes that align from plate to plate. I choose to use clamps to hold pairs of plates together for drilling, thus ensuring that the holes are pretty well aligned.

The nice thing about this approach is that even if my drill holes aren’t particularly perpendicular to the surface of the plates, or not all in the same direction, it doesn’t matter, as they’ll each serve their purpose of pulling the plates together, but not moving it sideways (assuming the angle isn’t too severe).

I drilled the holes using successively larger diameter drill bits so that each one was making the hole a bit larger, but not having to make the full diameter cut. I started with 1/16” bits, but that was really too small; I’d recommend ⅛” as the starting point.

The instructions also specified metric bits, but I didn’t have any of those, nor are they readily available (e.g. Home Depot and Harbor Freight stores don’t have them in stock). The goal of course is to produce through-holes in a pair of plates, after which one will be tapped to accept a screw, and the other will be widened a bit further so that the screw will slide smoothly through the plate on its way to the tapped hole. Given that, I used the imperial (fractional inches) bits that I owned, stopping just before hole reached 5mm diameter. The M6-1.0mm tap I bought included a drill bit of approximately 5mm, which I used as the last bit to go through both plates.

Since I normally use drill bits for drilling through plaster and wood (e.g. for hanging pictures, and other such tasks around the house), I don’t usually think about the sharpness of drill bits. But I found that the bits we had at home were struggling to cut through the 6061 aluminum plates. The bits are Ridgid brand, purchased from Home Depot. When I was shopping for the screws I decided to try the Milwaukee brand bits that were available in a nice package with two each of lots of commonly used small sizes. Wow, they were a lot sharper than the old bits, and greatly improved the rate of cutting.

Summary: clamping plates together helps with alignment, and fresh, sharp bits get the job done faster.

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