Leveling a single craft class without support of other classes (gathering as well as crafting) is fairly hard and IMO not worth the effort if you don't have time or really enjoy it. The higher you'll get the more difficult it gets and not only due to the dependence of the gathered mats and crafted parts from other classes but also due to the need of the cross-class skills to be able to craft the high level recipies. I've actually fully leveled all my DoHs and DoLs prior reaching 50 at my first DoM / DoW class as I've really enjoyed it so much but that might not be the case for you as it's pretty time consuming but the resulting independence and self-suffiency is great - especially now with improved self repair system.
