Metric And Inch Threads Fight It Out For Ultra-Precise Positioning

Metric And Inch Threads Fight It Out For Ultra-Precise Positioning

When you are a machinist, your inventory in trade is precision, with measurements in the thousandths of your most well-liked unit currently being typical. But when you are a diemaker, your precision recreation desires to be even finer, and getting able to posture equipment and content with seemingly impossibly granularity becomes definitely crucial.

For [Adam Demuth], aka “Adam the Machinist” on YouTube, the require for extremely-great resolution machinist’s jacks that wouldn’t split the bank led to a layout working with off-the-shelf hardware and some 3D printed pieces. The style and design centers all around an inch-metric thread adapter that you can decide up from McMaster-Carr. The woman thread on the adapter is an M8-1.25, when the male side is a 5/8″-16 thread. The pitches of these threads are quite shut to every other — only .0063″, or 161 microns. To take edge of this, [Adam] printed a cage with compliant system springs the cage holds the threaded sections collectively and supply axial preload to take out backlash, and makes it possible for mounting of precision metal balls at just about every end to make absolutely sure the pressure of the jack is transmitted by means of a single stage at each conclusion. Just about every total transform of the jack moves the finishes by the pitch variation, leading to ultra-good resolution positioning. Want even much more precision? Attempt an M5 to 10-32 adapter for about 6 microns for each revolution!

Although we have seen unique thread pitches used for high-quality positioning right before, [Adam]’s solution needs to machining. And as valuable as these jacks are on their individual, [Adam] stepped issues up by applying three of them to make a kinematic base, which is finely adjustable in a few axes. It is not very a nanopositioning Stewart system, but you could see how adding a few more jacks and some actuators could make that come about.

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