The SMALLEST protractor for drawing (transparent)

by Tol

To cut a long story short: tol-protractor-drawing-assembled-height-04.stl is most likely what you need. The rest is written for advanced users. This model is for drawing. There is also The SMALLEST Protractor for CAD modelling . I found several protractor models in internet, but I didn’t like that they were too large for my needs and most of them were not optimized for transparency. I decided to make the smallest transparent protractor that can be still usable after being printed with 0.4 mm nozzle. I used FreeCAD to find the smallest radius of the protractor that keeps 180 marks with 0.4 mm width and 0.4 mm spaces between them. I found that 5 cm radius seems to be the lowest limit. Of course, if you have 0.2 mm nozzle, you can try to make it smaller, but I don’t have it, so I made it as small as I could print. I made some tests to find out how many layers of transparent (“natural”) PETG can still remain transparent enough to be able to read the text under it. Evidently the less layers you have the better, but I found that 4-5 layers are also transparent enough. Anyway I decided to print only 2 layers because 1 layer is not reliable and 2 layers seem to be quite good. It’s worth noticing that PETG is highly transparent if you print it one line above another like “IIII” or “----”, but it becomes rather blurry if you use a cross-pattern that fills like “XXXX”. It’s up to you to decide how to fill it but if you use only 2 layers, I think the cross-pattern is more reliable (the thing becomes more durable). Another problem that I bumped into is that the font that I initially used was too small and the 0.4 nozzle blurred lots of the digits. This is most likely because I have a cheap printer Ender 3 V2 with the cheapest PETG that I could find in local shops :-) I had to redesign the model to use a larger font. The disadvantage of the larger font is that the numbers 170 160 150… are printed very close to each other, but I think it is better than blurred unreadable small sym