Rotary Pen laser etch holder

thingiverse

This is to hold a standard lathe finished pen for laser etching using awesome T2Lasers rotary tool profiles and an eleksmaker A3 laser etcher. Parts needed to make this one as pictured are 2 x 250mm 3/8 steel rods, 6mm x 270mm threaded rod, motor and connectors to attach to the Mana SE, and a 22mm x 7mm bearing. You don't need anything like 250mm, I just used that because I had a 500mm length sitting around and figured I might want to repurpose it later for something larger. Using a cheap 28BYJ-48 motor plugged into a Y axis plug with the other Y axis motor disconnected is crucial. The motor is bipolar modified - pop off the blue plastic cover, cut the centre track connecting the two poles, and remove the red centre tap wire. This can be easily googled, for example by visiting http://www.electronicsmayhem.com/?p=13. I used a 12V version of the motor so I had no need to drop motor currents on the stepper driver - resistance is far too high to overheat. The motor gearbox has some endplay which this rack removes by clamping, however gearbox backlash is another issue that can be tolerated if you want to raster burn but may cause unwanted artifacts when using vector. I set it up in T2laser's Rotary axis setup as 32768 steps/rotation (other models of the motor have different gearing - your mileage may vary) and set the diameter of the workpiece. Due to such a high number of steps, you will likely need to perform a $111=100 to drop Y step rate to something the little motor can handle. Attached designspark files are available for remodelling - the little handle is pretty much a joke, so you may want to add a base. The end support is to stop the weight of the rods from pulling the end down if more than half closed, which isn't needed for correct length rods. I also needed a 6mm tap to get a nice thread and a 3mm drill/tap for the motor mount holes. I ended up drilling the slider holes out to 10.2mm to make it slide easily - just the drill bit I had to hand. Drill 3d printed plastic with the drill running backwards to stop it from being torn apart by big drills. If you want to use it to hold something else, create a suitable spindle_pen and bearing_pen to suit your item.