![]() ![]() Put a 3mm x 1mm magnet on the end of a short piece of 1/8" drill rod and glue on the rack. So, I went with a 9g servo and designed a gear and rack system. It worked, but got very hot and the image was faint (the RoboClock design uses a similar method and is also faint). I extended the end pivot shaft and wound on some magnet wire. My original plan was to use an electromagnet to draw the time. To set the time, use the example included with the Adafruit RTC library. If you want a more precise device, try the Adafruit DS3231. Update the "#define" for NUM_FONTS in the code and upload to the Arduino.The directories must be sequential numbers starting with 1. Save these files into a new directory on the SD card.Look at the included directories for examples. Do the same for the colon and hmtx files. Find the glyph files for 0 thru 9 and rename them to only include the name (ex: zero.ttx, one.ttx, two.ttx.This will extract the binary ttf file into a lot of XML text files. Open a command prompt to the directory where your font is saved.Google Fonts and Font Squirrel are good places to find free fonts. I didn't have any luck with Open Type fonts (otf). Find / download your favorite TrueType font into a empty directory.Install FontTools for python: fonttools.Just save the numbered directories to a SD card that is formatted in FAT16 or FAT32. I have included several free fonts in the zip file. If it doesn't draw anything, this may be the reason. I have it set to hold 100 points, but you can increase this number. The program has to store all of the points of each "contour" in an array. Use a font with a little space between the characters.If not, the eraser will wipe away part of the previous digit. Each character of the font should be contained in its own rectangle. Don't use an Italic font or one where the characters intrude in the space of others.I found that TrueType fonts are just made from lines and quadratic Bezier curves that I can make in the program.Īlmost any TrueType font should work, but here are some tips for choosing them: At first, I was looking at Hershey fonts, but wanted more variety. I wanted to use a better looking font with the design. I used a 5/8" diameter x 3/8" thick piece of UHMW plastic on the bottom of this joint to slide on the screen without scratching. Slide on the right bottom arm and press on the thin cap. Drill out a cap to fit the smaller tube and put underneath the left arm. The small tube should extend almost to the drawing surface and up to the thin cap. Press or glue a 1-1/4" piece of the smaller tube into the left bottom arm. The outer pieces should be tight on the drill rod and the middle should be free to spin.įor the bottom joint (pen): Glue a 0.35" long piece of the larger tube into the right bottom arm. Press a 7/8" long piece of 1/8" drill rod into top arms, slide on the bottom arm, and press on a cap. The arms only use two sizes of the brass tubing for the joints: The one with a 1/8" inside diameter and the next size up.įor the two middle joints: Glue a 0.35" long piece of the smaller tube into both of the bottom arms. The SCARA design is known as a "5 bar parallel arm". ![]() You can measure it, but I found it is best to draw a large rectangle and tweak the values until everything is straight (see sub DrawRect). Change the #defines HOME_X and HOME_Y in the code to match this new location. Hold everything in place and glue the cradle to the screen with hot glue. ![]() Find a position near the top of the screen (but not touching the top). We can use one of these positions as a home. ![]() These are the main coils aligning everything before the microsteps kick in. You may notice that when you power up the stepper motors, they will "jump" to a new position. My original plan was to use "sensorless homing" with the TMC2130 drivers, but I couldn't get it to work the way I wanted. Unlike servos, the stepper motors need a way to set a startup position. I am still using a short body stepper motor for the eraser, but the longer one will work better. Because of the change, I had to bump out the Magna Doodle by 3/4" due to the way I am mounting everything. I originally designed this around short body NEMA 17 stepper motors, but the two top units didn't have enough torque and got very hot. It came out so rough on mine that I pushed it on a piece of 1/8" rod and smoothed it out on the lathe. Everything should print well, except for the rack (which needs supports). But, your normal material and settings you use should work fine. I made the 3D printed parts from PLA, 20% gyroid infill, 4 layers on top / bottom, and 4 perimeters. ![]()
0 Comments
Leave a Reply. |