I've been experimenting with tinkering characters again, and these are my thoughts so far (although most of this isn't new):
1. There is a huge amount of luck involved in an Artifex's start, since their starting disks are random; some are incredibly useful, and some are basically worthless.
2. If you don't get the ability to craft a basic grenade, you're unlikely to actually do much tinkering early on, even if you're playing a dedicated tinker. My best successes with tinkers mostly involved building another character with some intelligence, and ignoring tinkering almost completely for the first twelve levels; or raising an Artifex's dexterity to 24 and focusing entirely on that for the first twelve levels. Currently, there's very little useful tinkering you can do with only the lowest-tier bits, and you're unlikely to be able to afford anything but your starting disks early on.
I would suggest having Artifexes start with more (and less random) tinkering knowledge. For example, guarantee that they start with a tier 1 grenade recipe,
I'm not sure if it's possible to craft compound bows; I haven't seen a data disk for them. I'd suggest making them craftable using only tier 1 ingredients, and maybe even ensure that an Artifax starts with the reciple. The main reason for this is to give them an easy way to turn bits into turrets. (Granted, this assumes there aren't more dramatic changes to the underlying system, which might be better -- but this seems like an easy way to ensure that an Artifax will play "like a tinker" early on.)
Possibly also give them a third recipe, which is guaranteed to be a hard-to-craft tier 2 weapon (to give them something to shoot for.)
Another semi-related problem I noticed with tinker characters is that there's surprisingly little benefit to having a lot of intelligence. The difference in skill points between low and high intelligence is nice, but not huge; being able to identify artifacts better is also nice, but it's not something that you can base your character's survival around (and Tinkers actually care less about identifying stuff, because they can repair things and theoretically craft their own items.) Additionally, as far as I can tell, there are no skills that get better with higher intelligence. This hurts tinkers indirectly because whereas you can go "all in" as a dex or strength fighter or as an ego esper, getting dramatically more benefits from your heavy investment in that area, you can't really go "all in" as a tinker. The most basic T1 tinker recipies are the ones you'll use the most often; and unlike a fighter's attacks or an esper's mutations, they're not going to scale as you raise your main stat or go up in level.
Compare to Strength, Dexterity, or Ego, for example; a character built around any of those will become dramatically more powerful when they raise them two points, while also getting numerous side-benefits in addition to their core competence. My experience is that any tinker really needs to have one of those as their actual primary focus to survive, which means that in practice tinkering becomes a side-thing that your fighter or esper does for minor benefits, rather than something you'd base your character around.
(I mentioned this earlier, but my thinking when building a tinker is often along the lines of "all right, I'll put 24 points in int, and to survive, I'll put 20 in this other main stat... you know, really, int isn't going to help me aside from getting the high-int preq skills, so maybe I can lower it to 21 and let my level-up stat boosts raise me to the thresholds I need. In fact, I'll just go for 18 int and learn Tinkering 1 eventually, it doesn't make a big difference to this build." There needs to be more of a route to surviving with tinkering as your primary thing, which I think requires some way for it to grow dramatically more powerful as you invest heavily in Intelligence the way that physical combat or mental mutations improve when investing in their relevant stats.)