Edge Finding Tricks: Where would we be without edge finders? This is one of the first tools an apprentice machinist learns how to use. The next time you use yours, try this little trick – when the head of the edge finder “kicks” (moves off center), input ˝ the diameter of the edge finder head either + or – depending upon which side of the part you are on *. Now you are all set, no more re-dialing and re-zeroing.

* Coordinate rule of thumb- with your left hand, using your forefinger and thumb make an L. Lay this L down flat on the mill table with your left forefinger pointing at the column of the mill. If the intersection of your thumb and forefinger is zero, everything in the quadrant that is encompassed by your finger and thumb is positive so that, as you are facing the mill and you use a .200” edge finder on the left side of the part (x axis), input minus .100”. Now if you pick up an edge on the far side of a part in the y axis (ie: stationery side of a part held in a vise) with the same edge finder, input plus .100”. If these numbers don’t work properly on your readout, the polarity of your DRO may be backwards.

Parts with Long Irregular Edges: Sometimes we have to work with parts that have been torch cut, saw cut, sheared or are just hacked up nasty and we don’t have a way to accurately find an edge, much less indicate the edge parallel to an axis. To solve this problem, place a nice heavy straight edge over the irregular border (either hitting the high spots, hitting the low spots, or taking an average of highs and lows). Now, we can easily indicate the part and find an edge.

Very Little to Work With: I once had to accurately pick up the edge of a feature on a part that was only .003” high. This part was kind of like a printed circuit board but not exactly. After a little head scratching I came up with this trick – using a ground 3/8” square high speed steel tool bit about 1” long, I pushed the tool bit up to the low profile step. This created a nice square vertical surface that I could work with and made picking up an edge quite easy. This is a little bit off the wall and you may never use it but it worked great for that job.

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