Looking in the IH, it says that the common quality mining helot augmentic gives a -10 penalty and a chance of insanity. I'm playing a techpriest who's going to be pretty handy at making and implanting cybernetics and such. What should the benefit of a Good or Best quality mining helot augmentic be? Should it reduce or eliminate the agility penalty, reduce the chance of insanity (make it 1d5 or something) , grant an additional bonus to toughness or strength, what? Perhaps remove the unwieldy penalty of the breacher?

As it gives you the Breacher (IH p. 135) as a melee weapon, I would start by treating that as a best Quality melee weapon (+10% WS). For the cybernetics itself, I would be inclined to diominish the penalties insteas of granting additional bonuses. I would suggest -5 Agility for Good Quality, or no penalty for Best Quality. If you're concenred about the Insanity, I would likely allow you to roll 2d10 for the Insanity gain, but keep the lower result.

I've actually been thinking about this quite a bit as well; I really like the Mining Helot upgrade

Yeah, I think only best quality should totally eliminate the agility, although I also think it should kill (or drastically reduce) the insanity gain. But that's just me XD

I really wish they'd already included the stats for good and best quality stuff for all of the implants in IH

It's not necessarily a bad thing: it means that every Best Quality upgrade is potentially unique, and an opportunity to work out something special and cool.

(but yeah - would have been nice to have so extra guidelines at least!)

Note that if the Best quality is applied to the breacher drill, it gets an extra +10 to the attack and an additional point of damage. Then you can make it mono, add Shocking and an Exterminator, and maybe coat it in poison : P

TL;DR version: I work through the crafting rules to try and figure out how to make a best quality breacher drill. I have two major questions which you can skip to the bottom for.

Also, because the crafting rules are a bit confusing and I have a serious issue with them, I am going to work out how I think making a best-quality mining helot augmentic will go, and then maybe I can get some feedback.

Determining difficulty:

MIning helot augmentics are normally very crude both in make and implanting. Therefore, I reason that upgrading this from common to best is hard (-20)

Duration:

I figure that it might take a skilled craftsman a week or two at most to upgrade the drill design itself and the associated cybernetics. That puts me in the 2d10 days category.

Cost:

Reading the entry for the breacher drill on page 135 of the IH, we see that the drill is made of "hyper-dense adamantine alloys". On pg 247, table 9-6 shows that sort of thing to be in the Exotic Metals category, which costs 100 thrones per piece. I don't think that the drill would take more than 1 "plate or beam" worth of material. It might also require some simple or average components, which cost 20 or 50 thrones respectively, and perhaps some better quality muscle grafts, which cost 250 thrones.

Assuming you need all those materials, that's a grand total of 500 thrones max for materials. Now, a mining helot augmentic is listed at 2,000 thrones to begin with, but according to the Improving Craftsmanship section on page 248, it's impossible to make a common-quality mining helot augmentic into a best-quality one, so I think I will have to build the whole thing from scratch. Which leaves me a bit unsure on how much the whole deal will cost. But I can always go mug some heretics for pocket change, so let's put it aside for now.

Making adjustments:

I can make the process take longer, going down to 2d10 weeks, to get a bonus. Then, since my character is a tech-priest and will be skilled at armourer, tech-use, and technomat, (+20 to each). Depending on what other talents are allowed and how some of the others stack (for instance, does binary chatter grant a bonus to electrograft use? Does logic help when crafting things?) I will be rolling under a high number

I should also have access to Inquisitorial or Ad Mech workshops of Best Quality, which makes the difficulty another step easier. It also puts me back on the original time scale of 2d10 days.

I will have a fellow player techpriest who can aid me, but given how high my skills will be (I have an int of 43 base, will be 50 or more when I attempt this) I don't think that, given the RAW, it will be helpful to have him assist me. If he could consult to make my rolls easier, rather than doing the work itself, that would be nice, but I'm not sure if it's allowed.

Now, let's say I roll a 4 and a 7 for those 2d10 days. That puts me at 11 days. Now, so far as I can tell, I make my various craft checks once for each day of work, as per Step Four of the crafting rules on page 248 of the IH. For each degree of success on a test, I can either put it towards the total number of degrees of success needed to make it best, or reduce the amount of time needed.

Now, what number am I trying to beat here? My total of INT and skills should put me at a 73 or less, at the least. I have a -20 for the task being hard. However, that's cancelled out by The increased time and the quality of the facilities. So, I think that in 11 days, I should quite easily amass the 15+ degrees of success needed to make a best-quality mining helot augmentic.

Does this all seem to make sense?

Question 1) I assume I need to make a breacher drill to begin with, because it's impossible to upgrade a common one to best quality. Do I make it separately and then upgrade it, or should I make the whole thing from scratch while aiming for best?

Question 2) I assume the implanting process is separate from the crafting process. Which is what concerns me. My fellow techpriest player should be able to make the requisite checks with Medicae and/or Tech-Use to install it, and we ought to be able to use the same mechanicus facilities, so it should be fairly easy or automatic. But what else can I do to ensure that all the work put into making this thing best-quality isn't wasted on a botched implant roll?

Couldn't you simply assume that the Breacher isn't destroyed upon failed implantation? Unless, of course, you failed horribly...Say, three degrees of failure?

It's not destroyed, but the quality of it goes down as the implanting process was not done correctly. For instance if the nerve endings aren't hooked up into the controls properly, or if the muscle grafts aren't connected in the right places.

Admittedly, the chance is low. But should be minimized as much as possible.