Easy edge finding +/-0.001'' (25um) on the Othermill

Picture of Easy edge finding +/-0.001'' (25um) on the Othermill
Edge finding is one of the most important steps in any complex milling project. Edge finding allows you to very accurately locate the position of your workpiece after it's been mounted on the stage. This is absolutely essential if you need to accurately mill features between re-homing, for locating backside features, or when modifying an existing part.

In large milling machines edge finding is done using a special tool called, you guessed it, an Edge Finder! Unfortunately it's pretty rare to find an edge finder that will fit in the Othermill. See the wikipedia article on Edge finders: http://en.wikipedia.org/wiki/Wiggler_%28tool%29

While Otherplan has locating feature for getting pretty close it's very hard to much more accurate than a few thousandths of an inch. I still use the built-in edge finding for locating a new rough material within the mill.

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Step 1: Find your tools!

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Things you need:

A good dry erase marker

A bit with a precise 1/8" shank, a broken bit is fine, as long as the shank is in good shape. I would recommend a bit you don't care too much about, e.g. a carbide bit is way too easy to break when mounting as a probe.

Optional: a caliper or external micrometer to verify the 1/8th tool shank.

A mill of some kind, but I expect if you have a mill other than the Othermill, you likely already have an edge finder ;)

Step 2: Mount your tooling

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Using the standard Othermill tool change procedure:

Mount your bit in the collet upside down making sure that the shank engages at least 1/4'' (~6mm) into the collet

Select tool type 0.125'' probe

Step 3: Mark your tool

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While spinning the spindle with your finger lightly mark the end of exposed tool with the dry-erase marker. The goal is to keep the ink thin but uniform.

Step 4: Index the corner!

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Using the manual controls in Otherplan, move near the edge you would like to index. In this case I am indexing the Y edge of the work piece.

Slowly step closer by progressively using 1mm then 0.1mm. But don't get close enough to contact the piece!
wingman3586 months ago

Wow this is a great little trick! Thanks :)

Thanks for sharing this.