Tinker's Equation: Making Math Fun Again

John Out West

Registered User
Validated User
#1
Hey There,

I recently made rules for the Tinkering craft, where players can make mundane contraptions. Contraptions like Automatic Crossbows and Grapple Guns, not sentient spinning tops of doom or iron golems that obey your verbal commands. You can see the whole craft here.

As part of my series on "Crafts for Adventurers," this craft is supposed to be used while adventuring and not during downtime. Its another zero gold system. Creating a contraption takes only an hour if you have the parts, and creating a schematic takes a week of pondering (Thinking about it) with an hour of writing each night. Tinker's can't create their own raw materials, so they need to hire or become a Blacksmith to create gears, cogs, and sprockets.

The craft itself is simple. You take a mundane item, like a Grappling Hook or an Axe, and give it an augment. This augment may be to let it use itself or to spin wildly to give you an advantage in battle, among other options. Players use the Tinker's Tinkering Skill when using a Contraption, so even if you have a -1 to strength, a Gas-Powered Grappling Gun will let you use the tinker's +7. This does not translate to attacks.

After the Augment is added, you add the contraptions Power-source, Triggers, and Faults. These are not determined by the Player, but by the Tinker Character who is actually solving the engineering problems of the design, so they are chosen randomly from a list. Players can choose their Power-source or Trigger, but this strain on the Tinker causes more Faults to show up in the design. Faults are the unresolved issues with the contraption, such as overheating, making noise, or the design itself being finicky. Every design as at least one flaw.

With this Tinkering System you can make Grapple Guns, Portable or Stationary Traps, Automatic Crossbows, and Chainsaw Swords. The current Tinkering system is essentially non-existent, which is why this is necessary.

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The Tinkering craft seems to work well, as far as I can see, but I'm adding in a new system for calculating how to deal with the Powersources. The model i was using before was too simplistic, but I fear this new version might be too complex, or that I might be missing something. I'll post it below, and if you have any suggestions I would love to hear them!

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Powersource
Whenever an Augmentation on an contraption is used, such as a gun rotating a barrel or a shield unfolding, the stored units are expended to make the action possible.

Power Requirements.
The equation to determine the amount of Units a contraption needs, you must determine the Contraption’s weight and the distance it moves. The equation is as such:
(Size Units) x (1 + Distance Units) = Unit Requirement

Ranged:
For some contraptions, the purpose is not to move itself but to propel something else. In this case, the Unit Requirement of the contraption is added to the Unit Requirement of the ammunition. The equation is as such:
(Unit Requirement) + (Ammo Size Units) x (Ammo Distance Units) = Ranged Unit Requirement

Size Units:
1/2 Unit = Tiny (Palm Sized) : about 1/4lb
1 Unit = Light (Two-Weapon) : about 1lb
2 Units = Medium : about 4lbs
4 Units = Large (Two-Handed) : about 8lbs
8 Units = Large, Heavy : about 16lbs
16 Units = Huge, Mounted : about 32lbs

Distance Units
1 Distance Unit is added to the contraption for every 5ft the contraption is required to move, always rounding down to a multiple of 5. If the contraption doesn't move, but rather pivots, then measure the furthest angled distance that the pivoting edge has to travel and treat it as a straight line.

Unit Capacity
Each contraption can only hold a certain amount of Units safely. Most Tinkers put in safeguards to prevent the item from exceeding their unit capacity.
Each contraction has a Unit Capacity that is 10x their Size Units.

Units Generators
These generators will convert energy into Units that the contraption can use to activate its features. The energy transferred from the generator will negate from its origin, reducing total damage or movement in exchange for the units. This cannot reduce the damage from incoming attacks, however, if an attack is blocked and the contraptions function is to defend, it may be able to absorb the appropriate amount of damage or movement.

Generators
Roll 1d6 to determine the Generator randomly, or choose your Generator and add a fault to your design. Reroll on a six.
(1) Impact: This lever turns kinetic energy into mechanical energy.
Gain 1 Unit per Strength or Force damage.

(2) High Gear: This tiny gear requires a lot of strength to wind.
Gain 1 Unit per 5x Strength Check.

(3) Low Gear: This huge gear need a lot of winding to rotate.
Gain 1 Unit per 5x Dexterity Check.

(4) Pull: This cord is almost impossible to pull without anchoring it first.
Gain 1 Unit per 5ft movement.

(5) Boiler: Steam pours out of these superheated vessels. Requires a heat source and 1 ounce of water per 100 units.
Gain 1 Unit per Fire damage.
 

Ice9

Still Frozen
RPGnet Member
Validated User
#2
Interesting system, but the issue I see is that you have very specific requirements for energy based on size and movement, but no way to determine what the necessary size and movement are.

For example, what size would a grappling hook need to be to support a 150 lb climber? How much larger would be required to support swinging on the line? How does the type of thing to be grappled onto affect this? I have no idea.

Now the answer could be "research it and do some actual engineering", but at that point the energy requirements would be known too. So I think the system really needs that as a starting point.
 

johnthedm7000

Social Justice Witch
Validated User
#3
This seems like a lot of work for not a ton of pay off. For one, it's essentially solitary play, the sort of thing that only one player can make use of at a time. While you're sketching out ways to maximize the efficiencies of your grapple gun, everyone else is playing the game and *doing* stuff. Don't make players do a crap-ton of math when the fun of playing a tinker/artificer style character is going to be "dude, I can make an automatic crossbow!" or "no one can get a prisoner out of Newgate prison...unless they have an ORNITHOPTER!" Especially in a fantasy setting where clockwork traps and automatic crossbows are a thing, you should look towards designing a system that creates fun *play* rather than busy-work.

What I really do like here is the random power source, flaws, and trigger (although I'm uncertain what the Trigger's roll is: is it code for "What I need to do to activate the device? If so, you should probably make it clear). It gives tinkering a clear "crazy inventor" feel that suggests that creating these clockwork gadgets is as much a matter of personal art as it of clear engineering principles: you might have two tinkers who both make an automatic crossbow in two entirely different ways with different characteristics. That mechanic has personality and gives a clear picture to players and GMs about what to expect from the subsystem.

What I would recommend (related to making sure your tinkering system creates interesting *play*) is giving the player ways to influence the results of these random quirks: some certain, some less so. So building something out of metal is going to make it Heavy but it's also going to make it Durable. Something powered by clockworks requires winding, but it's level of power can easily be adjusted so it might be more precise than something powered by eldritch energies or steam. Let characters choose the materials and the power source, and let those choices influence the sorts of triggers and flaws that get applied (some directly resulting from the tinker's choices, some influenced by random chance).

An example of how this might work might be:

1. A tinker with a knavish friend wants to work on a retractable, foldable knife that can easily be hidden, and build in a one-shot clockwork blowdart into it. Real assassin type stuff. The tinker chooses Metal for the material and clockwork for the power source: the same gears and mechanisms that hold the blade back are what power the needle-launcher. Metal means that it's going to be heavy for it's size, but durable. The clockwork mechanism means that retracting the blade will take time or special tools, and likewise powering up the blowdart, but that it doesn't require special fuel and is low maintenance.

Specifically, me and her have been hired to assassinate a noble asking all sorts of inconvenient questions about the Queen's legitimacy and to steal what we've been assured are false papers claiming that she's the bastard child of a visiting foreign dignitary. The noble will be vulnerable in 3 days. Looking at a table of difficulties, the GM tells me that the difficulty will be Hard (whatever that means in your system). I ace the roll, meaning that I only have to roll once on the flaws table and don't need to acquire special materials, expertise, or assistance. If I had failed, the GM would have given me a list of things to get: alchemically-fortified steel, the assistance of a master clockmaker, schematics from a rival inventor...the sort of thing that could create a cool adventure in their own right. As it is, we've got a Monarchy to save.


2. Based on this, the tinker rolls on a few random tables:

1: Hidden Trigger
2: Elaborate Trigger
3: Simple Trigger
4: Simple Trigger
5: Hair-Trigger
6: Roll twice more (this item has multiple triggers)


1. Noisy
2. A Mind of It's Own
3. Fragile
4. Complex
5. Dangerous
6. Etc.

I end up with "Hair Trigger" and "Fragile" luckily for me, my choice of materials means that I can erase "fragile" (although now it's not Durable, and it's still Heavy). It has a Hair Trigger, which means it's very easy to set off (which could be both a boon or a bane) and means that I might have to design a special sheath for it so that my thieving friend doesn't shoot herself in the leg while climbing down the side of a building. At this point, I could get special materials or expertise to change my results, but a big heist is coming up and I need to get this done quickly.

3. If I have extra materials on hand, special knowledge, or the like I can Augment this design and give it a bigger damage bonus, a longer range, make it easier to wind, make it lighter, etc. But I'm not a skilled blacksmith, and I don't want anyone else to know about my project so I'm just going to hope the poison my thief friend has procured will be good enough to do the deed.

This is all inspired largely by Blades in the Dark's invention system, just with a bit of fun randomness and more player choice. A few other cool ideas that come to mind:

1. Offer Tinkers the opportunity to get "free" augments by rolling additional times on the Flaws table. They don't have to spend additional money or what have you, but their unorthodox design means that their creation is going to be a potentially dangerous prototype rather than a sure thing.

2. Let characters who ace their Tinkering roll get leeway with shifting the results. Skilled tinkers are going to be able to anticipate problems, craft solutions, and make the tradeoffs necessary to make a kick-ass invention.

3. Don't count the specific number of ounces, feet, or what have you that a device can move, carry, or that it requires as fuel. That sort of management invites the worst sort of pixel-bitching. Where you *absolutely cannot* make your steampunk flamethrower work because you only have 40 ounces of coal, rather than 41. Simple and common-sense measurements like "Light" "Heavy" and "Ravenous" fuel consumption will tell players all they need to know. Or abstract fuel the way many games abstract ammo. 1 Power is enough to do the thing, and that power can get generated a bunch of different ways: a bit of coal, lots of winding, exposure to strong ley lines, or what ever.

Weighing the benefits and drawbacks of power sources *is* fun, and is probably the sort of thing that attracts players to tinker characters in the first place. It also directly drives play by creating problems in need of creative solutions. You've created a perfectly silent armor-piercing crossbow that runs on True Love. It's damn powerful, but fuck if it isn't hard to find power for. There's also the question of what happens to the Love you use as fuel.
 

John Out West

Registered User
Validated User
#4
Thanks again for all the feedback everyone! This has been super helpful!
Okay I made some changes based on the feedback:

Unit Requirement
( Unit Weight) x (1+Unit Distance) = Unit Requirement

Ranged Unit Requirement
(Unit Requirement) +(Ammo Unit Size) x (Ammo Unit Distance)

Inertia Calculation for Vehicles.
Assuming your vehicle is well oiled and causes negligible friction, the distance your vehicle travels in a given round will be its Current Speed + any new speed your vehicle generates - The Worlds Gravity x Friction Coefficient. The worlds gravity is 10 (9.8 but lets be simpler) and a normal paved road's Friction is 0.5. (0.2 on Ice, 1.0 in rough terrain) Typically, most vehicles will lose 5ft per round. For now we'll ignore adding the additional weight of the Rider. The calculation is:
(Speed + Acceleration) - (Gravity x Friction)

New Figures
Although the calculations are the same, we now measure by weight instead of by weight class. Now, for each 2lbs of an item, it has 4 Unit Capacity and 1 Unit Size, which can be summarized in: The Unit Capacity is twice the contraption's weight, and the Unit Size is half the contraption's weight.
---------------------------

I've made a small list of items below to show an example of the kind of things you can do, as well as the calculations that go along with them. Remember that its the weight of the original item that is taken into account for Unit Size and Capacity, or in the Grapple Gun's case, a custom item built to fire the Grappling Hook that was given a custom weight specifically to fire the Hook.
-------------------------
Weight . Capacity . Units Size . Distance . Unit Distance Name
6 . . . . . . 12 . . . . . . 3 . . . . . . 0 . . . . . . 0 . . Chainsaw Sword
100 . . . 200 . . . . . . 50 . . . . . 15ft . . . . . 3 . . . .Motorwagen
10 . . . . . 20 . . . . . . 5 . . . . . . 0 . . . . . . 0 . . . . Crossbow
1/8 . . . . x . . . . . . 1/16 . . . 80 . . . . . . 16 . . . .. Bolt
36 . . . . . . 72 . . . . . . 18 . . . . . 0 . . . . . . 0 . . . . Grapple Gun
10 . . . . . . x . . . . . . 5 . . . . . . 50 . . . . . . 10 . . Hook+Silk Rope
250 . . . 500 . . . . . . 125 . . . . . . 0 . . . . . . 0 . . . Bolt Launcher
8lbs . . . . x . . . . . . . 4 . . . . . . 300 . . . . . . 60 . . . . . Huge Bolt
------------------------
Math:
(Size Unit) x (1 + Distance Unit) = Total Unit Cost
------------------------
Chainsaw Sword
(3) x (1+0) = 3 Cost Per use. With Capacity 12 thats 12 uses per tank.
--
Motorwagen
(50)x(1+3) = 200 Cost per use. With capacity 200 that's 1 use per tank. Speed loss is (Speed) - (Gravity x Friction) or (20) - (10x0.5) = 5ft per round lost. Fill tank back up to 200 every 3 rounds or stop moving.
--
Crossbow
(5) x (1+0) + (1/16 x 16) = 5 + 1 = 6 Cost Per use. With Capacity 20 that's 3 shots per tank.
--
Grappling Gun
(18) x (1+0) + (5x10 = 50) =68 Cost per Use. With capacity 72 that is 1 use per tank.
--
Bolt Launcher
(125) x (1+0) + (200) x (4) = 355 Units per use, with a capacity of 500 you can fire it once before recharging.
----------------------

I think that all sounds rather doable, but i would love to hear your opinions! It seems to scale well with small and large items, allowing you to fire large bolts 300ft accurately, and easily making a repeater crossbow or even a basic vehicle.

For the Motorwagen, dealing 200 points of fire damage isn't as difficult as you think, as most trains would have multiple vents to absorb the fire. The real question is: How do you calculate the surface area. If the fire dealt 10d10 Fire damage, for an average of 5, you would need 40 "targets" to have guaranteed full power every round. If it were calculated by Square Inches, you would only need to devote an 8x5 space to it, which is reasonable.

One thing i like to remember is Horse Power, which in this would be twice their movement per round. which is 120 or 24 Units. So Something like the Bolt Launcher could be recharged by a Horse in about a minute. Good for sieges.
 

John Out West

Registered User
Validated User
#5
Interesting system, but the issue I see is that you have very specific requirements for energy based on size and movement, but no way to determine what the necessary size and movement are.

For example, what size would a grappling hook need to be to support a 150 lb climber? How much larger would be required to support swinging on the line? How does the type of thing to be grappled onto affect this? I have no idea.

Now the answer could be "research it and do some actual engineering", but at that point the energy requirements would be known too. So I think the system really needs that as a starting point.

Hey Ice9,

I'm definitely against going outside the system to figure something out. That being said, all the information you speak of should be in the PHB of the game you're playing!

According to the PHB, the weight of a grappling hook is 4lbs, and Silk Rope is 5lbs, which makes 9lbs total. The tensile strength of the rope is actually not the concern of the Tinkering system, as long as its weight is the same. If its cheese-string or an adamantine chain, the system only cares about the item's weight. The rest of the information, like how the building/creature reacts to the grappling hook are really up to your GM.

I think its important to remember that this system, typically, only augments mundane items, so all the information is in the PHB or given by your GM.
 

John Out West

Registered User
Validated User
#6
Okay, the numbers are getting really exciting.

The problem I have now, if you can call it a problem, is that regardless of the weight of the Contraption, it can move a maximum of 15ft per round.

The current equation is:

( Unit Size ) x (1 + Distance/5) = Unit Requirement

The problem is that the Unit Requirement will always be four times the Unit Size, so the max distance any contraption can go, regardless of its size or weight, is 15ft. Another way to put it is:

( x/2 ) x (1 + y/5) = 2x
X = Contraption Size, y = Distance

I've created some solutions to this, including lighter materials that will decrease the Unit Size, and Augments that increase the amount of Units a device can hold, but i'm still not a fan of the idea that I can know for certain that each device can move a maximum of 15ft on its own.

I'm looking for opinions on the matter. If it seems like a silly problem than good, but if it seems like a problem that I need to solve then I would like to hear it. If you have some ideas on how to solve this problem I would also like to hear those.

This is the newest version.
 
#7
I worry about the amount of in-game time these things require to work, specifically the one week of planning to create a schematic. If you don't have a down-time mechanic built in a la Blades in the Dark, I think it's going to be make these rules unimplementable for a lot of games (I feel the same way about the general DND crafting rules).
I assume the goal of the time requirements is to prevent crafting binges, yes? Perhaps you could change your limiting factor to something else - requiring them to spend a point of metacurrency, or capping it according to their intelligence/otherwise relevant stat.
 

John Out West

Registered User
Validated User
#8
I worry about the amount of in-game time these things require to work, specifically the one week of planning to create a schematic. If you don't have a down-time mechanic built in a la Blades in the Dark, I think it's going to be make these rules unimplementable for a lot of games (I feel the same way about the general DND crafting rules).
I assume the goal of the time requirements is to prevent crafting binges, yes? Perhaps you could change your limiting factor to something else - requiring them to spend a point of metacurrency, or capping it according to their intelligence/otherwise relevant stat.
Well, its one week of Pondering, aka, thinking about it, as apposed to straight up crafting. Which means its a week of adventuring, and at the end of that week you have a schematic, and with some gears and an hour you can make a contraption. You can also make it over and over again if you have gears and the schematic, so everyone in the party can pay up some gold and get a motorwagen or automatic crossbow or chainsaw sword.

Obviously, there would be feats that come along with this, like some that allow you to do some tinkering jazz and make a contraption without a schematic in an hour. This would shore up this kind of problem, as well as coming with its own problems. (more flawed and cant be replicated)

We're trying to limit metacurrency's as much as possible when they dont make sense. Blacksmiths have an "experience" metacurrency, and Ritualists have a "Favor of the Gods" metacurrency, but i'm not sure if some sort of "Inspiration" metacurrency would make sense to add.

I think what i'm trying to say is that the current model of:
7 Long Rests = Schematic, Schematic + Gears = Contraption
Doesn't seem particularly broken to me. Now I do have crafts that are designed for games with no downtime or that last only a few days, such as Runeing, Rituals, Herbalism, but I don't think Tinkering should be one of them.

That being said, I'm willing to be convinced.
 
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