You are correct that the numeric indicator is not required for measurement tools such as a ruler or protractor. You haven't said whether your graphic is just an image of what a protractor looks like, or whether there is also an actual angle measurement added to the illustration. Since these usually have to be enlarged to the full width of the braille page in order to have room for all the labels, and since you want the completed tactile graphic to be as uncluttered as possible, I would suggest that you do [u]not [/u]show the numbers for each 10 degree increment. This is a similar concept as simplifying a cartesian graph to show only increments of 5 or 10 along the axis lines with unlabeled tick marks inbetween. There is no need to show all of the tick marks either, as braille protractors cannot accurately measure very small increments. I would suggest making tick marks for every 10 degrees, and labelling the 30, 60, and 90, etc. measurements. I'm sorry that I do not have an example at home that I can attach for you to see.
Feel free to post either a scan or your page or request further clarification if necessary.