Practical automaton sizes

Have you ever asked the question:
Can I walk my 10 HD automaton down a dungeon corridor?

No, well, never fear for I am here to ask it anyway, well, my players asked it ok!

TLDR - I allow them to be 25% heavier than the maximum in Lairs and Encouners.

What is a dungeon corridor and what is a large creature?

Lets keep this simple, I'm going to assume a 10' by 10' corridor, ye good old standard. Under normal rules we assume a "large" creature can fit into such a corridor.

In ACK's a large creature is defined in L&E (p.150) as being 401-2000 lbs and 8' to 12' long/tall.

The large size is important as it is the point at which a creature fits inside a 5' foot square (if you use them). and can navigate corridors with relative ease in a standard internal environment for a game.

What kinds of creatures can we use to check an automatons weight?

A good example of a large creature is the ogres (600 lbs, 9-10'). but they are made of flesh. 

Some benchmarks for weight per cubic foot tell me:

Water - 62 lb per cubic foot

Meat in a freezer - allow 35-40 pounds for cut and wrapped meat

Metal - 500lb for a solid mass of iron/copper

Gold - 1,200 lb for a mass of gold in a cubic foot

So strait away I want to allow some deviation, noting an automaton is not a solid mass of metal and has spaces in it. At the very least Automatons should be in the upper mass of any band of size.

We don't have weight for golems, which are close to automatons.

An interesting reference point here is the humble Iron Golem, ACKs doesn't give weights for these.  Google says that in some editions they are large, 12' and 5,000 lbs. This puts them a bit over double the mass of a large creature.

Bronze Golems in ACKS are Large in DaWC but carry 300 stone... for a humanoid 0.033 CCF this would indicate a mass of 90,909 lb. This puts them more at Gigantic/Colossal, which matches what I saw on Jason and the Argonauts on Netflix the other day. I wonder if this was the original inspiration for the bronze golem? My Cyclopedia says they are 16' tall for 20 HD as well, Putting them more in the ACKS huge. Either way this is not helping.

Visitor technology is hard to match and seems lighter in most cases, the 5HD large warbot is only 1,000 lbs. While the vehicles are sized more of actual size rather than mass.

Should automatons follow the same mass rules?

Well, normally yes. But sort of no... Let's go with no, I think they can be heavier per size category than the normal amounts. But in most cases it's easier to follow the standard rules for mass bands in L&E. 

The key question here is how heavy an Automaton will I allow to fit into a dungeon corridor? Players can after all use the mass rules in automatons to "shrink" the down relative to their HD.  

Let's look at BME to match size to mass. Ogres are 1.734 to get a 4 HD match, a bit under the Human 2.176 to get a 1 HD match. Now in BME terms automatons are an easy 2 in L&E terms. We can put all this in a table as follows:

BME comparison mass (lbs) and automaton size (dark grey as large)

	Ogre	Human	Automaton	Automaton
HD	1.734	2.176	2	Size
1	54	150	100	Small
2	180	678	400	Medium
3	364	1,638	900	Large
4	600	3,063	1,600
5	883	4,977	2,500	Huge
6	1,211	7,400	3,600
7	1,583	10,350	4,900
8	1,995	13,840	6,400
9	2,447	17,883	8,100	Gigantic
10	2,938	22,491	10,000

That means under standard rules for mass to HD the automatons of 3-4 HD are large, and no others are. But I have allowed Automatons of up to 5HD to be large in the case of Clockwork Stevedore's. To date this has been a bit of a benchmark (2,500 lbs), but should it be more?

The humble Iron golem seems to be 2.5 times the standard mass under other editions. But this seems very powerful as a rule of thumb. 

Using a rule of thumb

Ultimately I will chicken out and say a Judge should use the mass relative to the needs of their campaign, but I think a starting rule of thumb is about double the upper amount of mass to size should be a usable upper limit for consideration. This still allows for HD to location size that pushes my boundaries though. At this weight a judge should weight off the designs impact on their game. 

A more conservative 2,500 lbs upper limit for large category (25% increase on upper mass, the 5HD benchmark) is a much safer line to use if you need a hard limit with your players. This allows for strong automatons to size but still ramps up the cost if players want to cram in the most HD to location for their automatons. This means the size bands are 500 man sized, 2,500 Large, 10,000 Huge, 40,000 Gigantic, and above that Colossal.

As a quick check the following table may assist showing hit dice and weight reductions impacting size of an automaton:

Automaton large size weight (lbs) to hit dice using +25% rule (dark grey as large)

	No	one	two	three	four
HD	reduction	reductions	reductions	reductions	reductions
1	100	50	25	13	6
2	400	200	100	50	25
3	900	450	225	113	56
4	1,600	800	400	200	100
5	2,500	1,250	625	313	156
6	3,600	1,800	900	450	225
7	4,900	2,450	1,225	613	306
8	6,400	3,200	1,600	800	400
9	8,100	4,050	2,025	1,013	506
10	10,000	5,000	2,500	1,250	625
11	12,100	6,050	3,025	1,513	756
12	14,400	7,200	3,600	1,800	900
13	16,900	8,450	4,225	2,113	1,056
14	19,600	9,800	4,900	2,450	1,225
15	22,500	11,250	5,625	2,813	1,406
16	25,600	12,800	6,400	3,200	1,600
17	28,900	14,450	7,225	3,613	1,806
18	32,400	16,200	8,100	4,050	2,025
19	36,100	18,050	9,025	4,513	2,256
20	40,000	20,000	10,000	5,000	2,500