A die filer is a useful tool to have if you find yourself filing parts on the regular. It’s basically a machine that reciprocates a file up and down for you so you can focus on filing the part to your desired dimensions. They’re not commonly manufactured these days, so [Richard Huberjohn] set about building his own. 

This die filer relies on a simple mechanism to turn rotational motion from a motor into reciprocating linear motion in the vertical plane. A rotating shaft is connected to a crank, which turns a pin in a slotted carrier attached to a linear bearing. As the wheel turns, the pin slides in the carrier, driving it and the linear rod up and down in turn. Attach a file to this, and you have a working die filer. In this case, the rotating shaft is driven by a pair of DC brushed motors, with output stepped down via a gearbox and then a short belt drive. Speed is varied with the aid of an off-the-shelf controller.

If you’re regularly filing small parts, a build like this could speed your work to a great degree. We’ve featured other DIY machine tool builds before, too. If you’re cooking up your own gear for the home workshop, don’t hesitate to let us know on the tipsline!