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

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When you’re a machinist, your inventory in trade is precision, with measurements in the thousandths of your most well-liked device staying widespread. But when you are a diemaker, your precision game needs to be even finer, and being equipped to place applications and product with seemingly impossibly granularity results in being seriously significant.

For [Adam Demuth], aka “Adam the Machinist” on YouTube, the need to have for ultra-fine resolution machinist’s jacks that would not break the bank led to a design and style employing off-the-shelf components and some 3D printed areas. The style and design centers all-around an inch-metric thread adapter that you can choose up from McMaster-Carr. The female thread on the adapter is an M8-1.25, whilst the male side is a 5/8″-16 thread. The pitches of these threads are incredibly near to each individual other — only .0063″, or 161 microns. To take gain of this, [Adam] printed a cage with compliant mechanism springs the cage retains the threaded elements with each other and give axial preload to get rid of backlash, and permits mounting of precision steel balls at every conclude to make certain the power of the jack is transmitted via a one level at every close. Just about every whole convert of the jack moves the finishes by the pitch difference, foremost to ultra-fantastic resolution positioning. Require even additional precision? Try an M5 to 10-32 adapter for about 6 microns for each revolution!

Though we have noticed distinct thread pitches applied for great positioning before, [Adam]’s strategy needs to machining. And as practical as these jacks are on their individual, [Adam] stepped factors up by employing three of them to make a kinematic foundation, which is finely adjustable in 3 axes. It is not pretty a nanopositioning Stewart system, but you could see how including 3 additional jacks and some actuators could make that take place.