i wish to start a small business lettering headstones, can you tell please what equipment ineed to cut out the lettering ie sandblaster, and the specifacations of such a machine. thankyou.

I do not think a sandblaster is what you need. Too coarse. You need to have either a laser based machine for fine sharp, crisp results (extremely expensive).
Or you need to be a good chiseller and teach yourself letter carvng with a fine sense of typography. Carving headstones is not like knocking out sef-adhesive shop signs in day-glo plastic. You need either to invest in top-end and pricey equipment if you are going to mechanise this process - or learn the slowly acquired trade of lettering. No short cuts.