Lathe chuck drilling guide

I recently bought a cheap 100mm independent 4 jaw chuck for my Lathe. The hole pattern on the chuck was for 4 holes whereas the spindle on my lathe has a 3 hole pattern. I wasn't confident I could mark out the holes accurately, so I thought I would try a simple 3D printed guide to position the holes. I used one of the existing 4 holes to locate the guide with a screw and pilot drilled the other 2 holes then opened them up to an 8mm tapping drill size, I also used the guide to help guide the tap to start it off vertically.
I have to admit the holes are exactly where they should be, more thanks to the guide than any expertise on my part, hopefully someone may find this helpful.