Hi mrNOB2020
Photoshop is primarily a pixel based applicatoin and printers are also pixel based when printing. So to the first order you likely do not have enough pixels to resolve down to .0005 inches (or .0001) inches) out of your 1.1875 dimension
At a viewing distance of 10 inches, the human eye only resolves about 300 ppi which is about the true print density of most printers. So that is only a resolution of .0033 inches. So you are looking to print something with about 6 times more resolution then that.
On an 11 inch length of paper, if you wanted each pixel to represent .0005 inches, you would need those 11 inches be represented by 22,000 pixels. The 8.5 inches would be 17,000 pixels or 374 megapixels and for a color image of 3 bytes per image you have a base file of over a Terabyte for a single Layer file (so it goes up from there). I can't remember if CS6 supports that size of pixels yet the newer version do.
The other limit is what will Photoshop allow when entering numbers/parameters. I dont know for sure yet if entering by inches, I don't think it will retain that many digists past the decimal point. To get around this you would need to enter the value in pixels and do the conversion your self. e.g. if each pixel was .0005 inches to create a 1.1875 size you would need to use 2375 pixles. And that should work. If you need resolution down to .0001 or 1/10 thousandth of an inch you would put in 11,875 pixels for the size.
Alternatively you could do your work in a vector program such as illustrator.
Hope that gives you directions to consdier
John Wheeler