Making bigger bolt holes

Since day one of setting up the OESH factory, I’ve been learning. Tons. In fact, I believe I’ve learned almost as much these last few years as I learned in medical school.  Every day I wake up with at least one manufacturing dilemma that I know is easily solvable, yet, I do not know how to solve it.

Today, for example, I knew I had to mill out larger holes in a metal mold that I had already made. I had no clue how I was going to do it such that the holes would be perfectly aligned with bolt holes in another piece of metal that I already had anchored inside the injection molding machine. The mold of course is a new prototype OESH sole mold that I’ve been working on for the past year that I can HARDLY WAIT to get done!

Initially, I had 3/8 inch bolt holes which per all the correct engineering calculations, was more than sufficient. But when I put the mold in the injection molding machine for the first time and flipped a few switches, I got this intuition thing telling me that I ought to use bigger (1/2 inch) bolts.

By now, I’ve got to say, my machining skills are pretty darn good. I can operate these manly metal cutting monsters using computers like nobody’s business. I can generate programs resulting in thousands of lines of code that make precise cuts into just about any kind of metal. But as of this morning, I did not know how I was going to make these bolt holes just a tiny bit bigger.

In fact, I was about ready to just make a whole new mold. It would only take me a few keystrokes to edit the program to accomodate bigger bolt holes. But running a new program would tie up the milling machine for the rest of the day and of course, it would be wasteful.

So I learned there are two ways to center the milling head over a pre-existing hole. One method involves finding the edges of the hole in two axes, with a cute little device called an “edge finder,” and dividing by two to find the center. The other involves a more sophisticated device called a “coaxial indicator” which is essentially an offset rod mounted on a measuring dial, which when placed in the center of the hole, rotates evenly all around so that the dial doesn’t move. I used both methods (and tools) and found they worked pretty much the same.

I entered the numeric positions of each of the centers into the computer and let it and the machine do the rest of the work…while I did a little mill-side yoga. Everything went smoothly, which I now define in my own terms, as (1) no unusual noises (that only I can hear) coming from the machine and (2) no broken anything.  By the time I finished with my hip flexor stretching, I had some beautiful, bigger holes, that lined up perfectly with the holes in the injection molding machine.

13Y Bolt holes 2 of 2















Woo hoo! Ready to shoot material through the mold…as soon as I figure out where the “inject” button is…

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