This was a good justification for needing a 2nd ShopSmith to repair another ShopSmith. Still need to think of the justification for having a third ShopSmith (i.e. "Greenie II" currently under the boat). I know you guys don't need any justification of why to have 3 ShopSmith's but some other individuals, mainly wives, may.
Here's the setup I used to get the holes drilled accurately.
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I did a much better job this time at finding the center of the snapped screws. It was important to find the outside edge of the original threaded holes. To do that, I had to use magnification.
I did use the right angle method to find the centers. From there, I used a spring loaded center punch to hit the intersect mark.
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When initially going in with the pilot drill, the alignment if the drill tip with the center punch mark was critical. The only way you know your off is you'll see a slight deflection of the drill just as it finds the center. The object was to see no deflection at the initial point of contact. The drill bit has to be viewed from both the top and also from the side. If you see any deflection in any direction, you need to adjust your workpiece either by making table height adjustments, or sliding the workpiece back and forth on the worktable until there is absolutely no deflection of the drill as it contacts the center punch countersink. This is when you know that you are centered EXACTLY. If your off, not only will your hole position be out of whack but you'll also snap the drill bit.
Here's the view looking at the pilot hole. Even though it initially looks like it's off center, biased toward the top and toward the right, if you compare the location to the actual extremes of the original threaded hole position, you can see it's real close. The off centering appearance is an illusion due to the thread helix.
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The next bit used was the recommended tap drill size. After drilling, when the hole was viewed all around, you should see evidence of the original threaded hole. This verifies that the centering is pretty good. Here, although you can see that the threads were more pronounced in the left view than the right, it's the result of the hole being subtly off center but it's just the best you can do.
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As with the first attempt, I again ran the tap in from the back side. Picking up the virgin threaded hole on the backside guarantees hole alignment along with entire length of the hole. As I got into the snapped off fastener a little ways, it became too difficult to turn the tap and rather than risk snapping it, I drilled the pilot hole up one more drill size but only to the depth of the broken fastener. I didn't touch the virgin threaded hole. That's all it took to finally get the tap all the way through. As you can see by the last photo, as the tap exited the hole in the front, it had a thin section of the the broken fastener that came out with it. Again, that was another good sign that the centering was almost dead on.
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Getting real close to finally wrapping this restoration project up. Been a long haul.
I wouldn't have spent $60 for a set but may have considered $35 thru Amazon. 