Is there a bushing or something that might the process totally accurate and easy?
I used my drill press, and a step bit, but a lot of folks marked the spots, then used their dremel to scribe an X on the spot. Keeps the drill bit from wandering. You don’t cut all the way through, just kinda make a flat spot.
I was thinking of a tool like this, but since we’re drilling tube/pipe instead of round bar, the same trick for making it won’t work.
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Answering my own question, this should do it: http://a.co/g07JGp8
Or you could use Geodave’s parametric DrillGuide if you have access to a 3D printer https://www.thingiverse.com/thing:1054068
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Hmm… Unsure. Seems like the drill bit will soon ream out the plastic, and then you’ll loose you’re centering. Do you just print extra’s for when that happens?
I did. probabkly good enough for a few holes. If you need more than a few, probably not the ideal solution. But in that case (and if its always the same holes, maybe a “dedicated rig” with properly fixed bushings and some way to clamp the pipes in exact correct place would be good 
You guys are wicked overthinking this. You’re not building an airplane, even then, we left a little slop in the holes… The tool mount and nut trap are clamping each other through the pipe. If the holes are off a little bit, it’s not going to make that much of a difference. Most emt conduit is welded, use the weld seam as your line, mark the hole locations with a finish nail through the tool mount, if the nail makes a good divot, that’s really all you need for the drill bit. If you’re using stainless, then there probably won’t be a weld seam, if that’s the case, lay the pipe on a table with a piece of half inch plywood beside it, use a sharpie to draw a line at the bottom of the pipe, do the nail punch through the tool mount thing again. You’ll probably need to whack it again after moving the plastic part, or do the dremel X method, then drill the holes.
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On top of Barry’s comment, the screws are under 4mm…you are drilling a 8mm hole. If you mess that up well you are gunna have troubles with the rest of it as well.
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There is really not much need for precision here.
The only thing to be careful about here is to not crush the tube by applying too much force. So if you are using a drill press, make sure that you are not pushing it through the tube too hard.
I just marked the spot, hit it with a spring loaded punch to give something for a small bit to bite and worked my way up from there.
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you can try this 3d printed jig I made. some duct tape + drill press
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