Glad you enjoyed. Let us know how your project goes.

and measure hole to hole distance on small holes

I think what you are looking for is a set of trammel point attachments that will work on calipers to mark center distances, most tool companies carry these at a reasonable price. Starrett also makes Center distance attachments for a pair of calipers. I believe that part number is a PT26151, these would allow you to measure center to center distances on holes bigger that .400. We don't have a set but I would like to get a pair. I have also seen what are called hole pitch calipers or center line calipers that basically are used to measure the distance between to equally sized holes. Hope this helps to answer your question. The Ole Man

Glad you enjoyed the video. As far as the book goes, I see them every once in awhile at flea markets and estate sales really cheap. People who aren't in the trade usually pass them by without any thought to all the valuable info contained within. I've picked up several over the years for family and friends. Keep an eye out. The Ole Man

If you don't have the book, the math is not hard to do on paper. Make a circle and draw a chord on it. Then draw two lines from the circle center to the ends of the chord. Now you have a triangle. Two sides are the radius of the circle and the angle between them is 360° divided by the number of holes you want. Split the triangle in half, and now you have a right triangle that you can use the Sine function to find the opposite side, and double that to get your chord length.

Glad you enjoyed the video. We will add knurling to the list, hopefully we can get something out on that subject in the near future. The Ole Man

Unfortunately I don't have a copy of 28. I do have a 26th addition and its under Circles then Chords for Dividing Circumferences on pages 955-958. Hope this helps. Please let us know if that gets your there in your addition. Thanks for watching The Ole Man

Thank you for taking the time to help me out. Unfortunately I still am unable to locate the charts you used. My 28th addition does not list Chords for Dividing Circumferences under Circles. My pages 955-958 discuss broaching. I have located some formulas for determining the chord length but not the charts you have. LMS has a helpful program for giving the x and y coordinates but the way you divided the circle seems so much simpler. I'll continue to search the internet and again, thanks for the help.

I was able to locate a copy of the 28th that a friend had. You are correct the chart that I used is not in that addition. Not sure why other than maybe space savings. the newer additions have a lot of CNC type material that the older ones didn't. The closest thing available is on page 707. That will give you a chart. On that chart it has you taking the diameter of the circle you are doing and multiply by the length of the chord. Example would be if you had a 3-1/2" circle you would find the number of holes you want then the chord length provided multiplied by 3.5. Hope this helps. Keep your eye out for older addition you wont regret the purchase. The Ole Man

Sir, you are the man! The chart on my page 708 will help a lot. How you found it is impressive. You are the real deal and I'm in your debt. I'll definitely be looking for a copy of #26 or earlier. I agree that the newer additions of the Handbook are geared more toward CNCs and DROs and so as a hobbyist with old school machines I need old school books. Thanks to you my hobby has just been stepped up a couple degrees. I look forward to watching more of your informative videos.