Metric And Inch Threads Fight It Out For Ultra-Precise Positioning2 min read
When you’re a machinist, your stock in trade is precision, with measurements in the thousandths of your preferred device currently being popular. But when you’re a diemaker, your precision sport demands to be even finer, and currently being in a position to situation applications and product with seemingly impossibly granularity turns into really significant.
For [Adam Demuth], aka “Adam the Machinist” on YouTube, the need for extremely-wonderful resolution machinist’s jacks that wouldn’t break the lender led to a design applying off-the-shelf hardware and some 3D printed sections. The structure centers close to an inch-metric thread adapter that you can decide on up from McMaster-Carr. The woman thread on the adapter is an M8-1.25, although the male facet is a 5/8″-16 thread. The pitches of these threads are really shut to each and every other — only .0063″, or 161 microns. To take benefit of this, [Adam] printed a cage with compliant mechanism springs the cage holds the threaded parts with each other and offer axial preload to take out backlash, and enables mounting of precision steel balls at just about every conclude to make certain the force of the jack is transmitted via a one level at every single end. Every entire turn of the jack moves the finishes by the pitch change, primary to extremely-fine resolution positioning. Need to have even more precision? Attempt an M5 to 10-32 adapter for about 6 microns for each revolution!
While we have witnessed distinct thread pitches used for great positioning just before, [Adam]’s approach desires to machining. And as helpful as these jacks are on their have, [Adam] stepped points up by employing a few of them to make a kinematic base, which is finely adjustable in three axes. It’s not really a nanopositioning Stewart platform, but you could see how incorporating 3 extra jacks and some actuators could make that occur.