got tired o fusing grid system and projectors to blow up line art and images.
for me Microsoft Excel works great. just drop you image into a new cell in a new workbook, stretch it to the size you want, ( page marks will be on screen, I always set page size to letter size) then print. it wil print on multiple pages, get your tape and scissors out, tape it together and you have a full size pattern, a little carbon paper and you are done.