How long does it take to make a crossbow

[ericthered]

My PC's have an urgent need for a heaping pile of crossbows. They've ordered 100 of them, and the folks they've ordered from have 400+ craftsmen who are willing to drop everything and build the weapons, but time is of the essence, and every day of delay counts. The workmen at TL5 for this kind of work (fantasy super metals!), but they don't have the crossbows lying around, and they aren't exactly all weapon's smiths.



There is a saying that it doesn't matter how many people you assign to the task, it takes 9 months to make a baby. How many days does it take to make a crossbow?


Thanks!

[Toptomcat]

I think the answer will depend on exactly what kind of crossbow you’re making- specifically, the construction of the prod. This source claims that the glue that held together the prod of a composite crossbow could take up to a year to dry. As for one-piece wooden prods, my understanding is that freshly-cut ‘green’ wood is unsuitable for this purpose, since wood’s stiffness changes as it dries. This source indicates a year of drying time per inch of thickness, though it deals with modern precut boards rather than anything period. If they have aged, seasoned wood set aside- and they probably have some, but maybe not enough for your purposes- construction would be quick.

I don’t *think* steel crossbows are subject to any similar concerns, so they are likely to be your best bet. Not sure how long it takes to forge a prod, though.

You could make crossbows out of green wood. A clever artisan could probably use a thicker prod to deal with the lack of stiffness: it’d work fine immediately but would gradually become unusable over time as it dried and stiffened up. A not-so-clever artisan would do exactly what they do with seasoned wood: the resulting crossbow might be marginally useful in combat, if needing to launch a lighter projectile for less damage at closer range. And conditions in the field are unlikely to be ideal for seasoning wood, so the resulting weapons would age unpredictably, increasing unevenly in strength and range but also likely getting a higher Malf and playing merry Hell with any attempt to standardize ammunition across a military force: a bolt that’s fine for one crossbow might be too light or too heavy for another.

For a large number of ranged weapons that need to be ready now, I suspect your artisans will recommend javelins or slings instead.

[Sam Baughn]

Going by the numbers in Low-Tech and Low-Tech Companion 3, it looks like a military crossbow has about $650 of labour cost in its price. A TL 4 armourer makes $1,900 per month and I guess a TL 5 one could make about $2,600 going by p. 517 of the Basic Set. Long story short, it looks like TL 5 workers consisting of a mix of skiller armourers and semi-skilled apprentices, etc. can turn out a crossbow with 66 hours and 20 minutes of labour. So in theory 400 craftsmen could make 100 crossbows with two days work.

Since coordinating all this work is likely to take a bit of time, workshops will need to be shifted around, materials located, some of the less trained people shown what to do, plus the extra time needed for metal to cool, glue to set and so on I think it is likely to actually take quite a bit longer than that. At a guess, one day to prepare and one day of waiting for stuff to cool, set, dry, etc. for a total of about four days. You probably can't push the workers with longer hours, since it will be quite hard work anyway and making people who aren't quite set up for the task work long hours will result in a lot of errors.

[Polydamas]

Yeah, Tod's prices suggest that his one-man shop can make a steel-bowed crossbow with no decoration in a couple of days today. It would take more days in a low-tech setting, maybe seven work-days? That fits the rules in LTC3.

Shortages of steel for the bows or good strings are likely to be problems too.

[Culture20]

A steel prod is easy to forge, and the cool-down waits during the heat-treatment are the long parts of the process. But that doesn’t take human-time, so you can stack a lot of prods up as long as you have the materials. The wood parts might take longer.

[ericthered]

ok, we will certainly have to make them out of steel. The craftsmen live under a mountain and have a shortage of agricultural products, but an awful lot of metal. That's going to annoy my players, because as far as I can tell, gurps steel crossbows are a raw deal for anything but piercing armor with a single shot, but this is for mass combat units, and the range will be useful here.

Ok, so its about 60 hours of labor per weapon -- if we treat these folks as armorers. Most of them won't be. I think I'll mostly be treating them as smiths. I'll still let them make the weapons, but They naturally earn half as much, so we've increased the time to 120 hours per cross bow. The actual armorers will be running about allowing the smiths to figure out how to build these contraptions, and absorbed into the whole for mathematical simplicity. That gives us four days to put in the necessary hours.

How long will the cool down waits between heat treatment be? anyone have a ballpark figure?

I don't think a string shortage will be a big deal, though I may make it the player's responsibility and have them run around and solve that.

Can four craftsmen efficiently all work on the same steel crossbow?

[evileeyore]

Originally Posted by ericthered

How many days does it take to make a crossbow?

In this case the hard time consuming step is parts preparation.

That can take years for high quality wooden crossbows. The time dramatically reduces for merely adequate and cheap crossbows. But we're still talking "longer than for a steel bow".

If you have the steel laying around...

A skilled craftsman, at TL 5, can...

- Hammer out a 3-4 steel bows, levers,* and pins in a day. With unskilled apprentices this work doubles.
- Cut and sand out 3-5 stocks in a day.
- Prepare more bow string than the other two craftsman can keep up with.
- Assemble around 10-20 crossbows in one day. It'll take another day or two for the glues to fully cure.

So three skilled craftsman can prepare all the parts in about 25 days. During which time a single skilled craftsman could have assembled almost all of them.

* All the levers and pins could possibly be forged in one day by two skilled smiths and a few apprentices each just doing that. But those are also things they can do while the bows heat and cool, so ...


So by my maths? Four days if you have 25 skilled smiths, 25 skilled carpenters, and at least one skilled apprentice each. However the chances of any given crossbow being Cheap† is probably about 25%. Taking twice as long should drop that considerably. Taking less time (which is possible§), would increase it.


† Honestly though it'll be things like the draw is too high or too low‡, the Crossbow has a Malfunction number (which would render it unusable once it 'misfired - string snaps, lever breaks, pin bends, etc), the winch or goatsfoot doesn't seat correctly increasing reloading time by up to double, etc. Not just that it's 'Cheap'.

‡ With a higher draw it takes longer to reload. It might also wear out faster, but I suspect that's not a factor here eh?

§ I'd say you could cut the entire time to two days minimum. That's everyone working fast and putting in a double day at parts preparation and assembly and leaving at most one day for glues to cure. However every crossbow will probably suffer one of the above flaws and be Cheap.

Originally Posted by Sam Baughn

Since coordinating all this work is likely to take a bit of time, workshops will need to be shifted around, materials located, some of the less trained people shown what to do, plus the extra time needed for metal to cool, glue to set and so on I think it is likely to actually take quite a bit longer than that. At a guess, one day to prepare and one day of waiting for stuff to cool, set, dry, etc. for a total of about four days. You probably can't push the workers with longer hours, since it will be quite hard work anyway and making people who aren't quite set up for the task work long hours will result in a lot of errors.

This is true. My numbers are based on "everyone knows how to do their job". Add a few days for job training and retooling workshops.

[evileeyore]

Originally Posted by ericthered

How long will the cool down waits between heat treatment be? anyone have a ballpark figure?

A couple of hours. For each treatment, usually two (not including initial forging and hammering, just annealing and hardening).

I don't think a string shortage will be a big deal, though I may make it the player's responsibility and have them run around and solve that.

That might honestly be a problem. Most strings back in the day were made from animal bits... if these dwarves don;t have a lot of agriculture... they might have to figure out a good substitute (time to go fight a bunch of giant spiders eh?).

Can four craftsmen efficiently all work on the same steel crossbow?

Yes. One on the bows, one on the 'hardware', one on the stock and one assembling. With some of them swapping off every so often (particularly the bow and hardware smiths, one job is a lot more hammer swinging than the other).

[Pursuivant]

Originally Posted by ericthered

There is a saying that it doesn't matter how many people you assign to the task, it takes 9 months to make a baby. How many days does it take to make a crossbow?

What sort of crossbow?

How much high-quality steel and/or bow-wood is available?

How much fuel?

What sort of workshops do they have?

Additionally, just describing "TL5" isn't particularly helpful, since metallurgical tech changed a lot from ~1650-1900, particularly after ca. 1850.

A TL6-8 weaponsmith with access to a modern woodworking and metalworking equipment and with a source of good quality wood and leaf spring steel, can make a medieval style hand-cocked, steel-bowed crossbow with wooden stock and rolling nut trigger mechanism in ~4-6 hours. Perhaps less if working from plans and with suitable jigs already set up. Assembling a crossbow from parts might take ~15-20 minutes for an unskilled laborer.

Things shouldn't be too different for a mid- late-TL5 armourer in the same situation.

The choke points in production are cutting, shaping, and "tillering" the bow, making the bowstring, and forging the trigger mechanism.

Any competent carpenter can make a simple crossbow stock.

e.g.,

https://www.instructables.com/id/Sim...ger-Mechanism/

The only part of a crossbow which requires actual weapon-smithing skill is the bow itself. Other skills such as Artist (Woodworking), Machinist (Clockwork), Smith (Black or Red), or even Carpentry can be used to make the other elements of the weapon as long as someone with Armoury/TL (Crossbows) is supervising production and assembly.

Contrary to anything LT or other GURPS books might tell you, it is possible to have a low ST, hand-cocked steel crossbow. Just select for thinner, springier bow material and/or less deflex/travel distance by the bow arms. Any bow weight available for bows should be available for crossbows.

Example:

https://www.medievalcrossbow.info/me...stock-design1/


It is also possible to compensate for lower-quality materials by having laminated bows where the laminate layers are mechanically held together with straps. By having the innermost laminate layers (facing the shooter) be thicker and shorter, you can control the strength and flex of the overall bow.

Crossbow ammunition will be simpler than making arrows, since you don't need to "spline" crossbow bolts so that they match the bow and you don't need as many fletches (crossbow bolts usually have just two so they don't get crushed as the bolt lies in the channel, arrows often have three or even four fletches). Since crossbow bolts don't need nocks, that simplifies production as well.

Assuming 400 skilled metalworkers, as long as ~10-20 of them are actual weapon smiths, they all have shops, they have access to a sufficient stock of decent metal to make bows, and they're all capable of working from a single, proven plan, it shouldn't take more a couple of days to produce 100 crossbows. If there's a way to create an assembly line process and/or repurpose existing parts the job might only take a day.

[ericthered]

Originally Posted by evileeyore

That might honestly be a problem. Most strings back in the day were made from animal bits... if these dwarves don;t have a lot of agriculture... they might have to figure out a good substitute (time to go fight a bunch of giant spiders eh?).

The "dwarves" (they're technically goblins, but yeah) will be drawing on the resources of a larger low TL3 community run by the PC's for organic materials. That animal parts are used rather than plant fibers is a surprise, but in retrospect it makes sense. The town is currently awash in butchered animals, but they may have already sold all of the supplies they'd need. From your description, it sounds like bow strings are not the most time consuming part of the process, but that they are a decently large part.



Thanks for answering the other questions, that was helpful.

Originally Posted by Pursuivant

What sort of crossbow?

steel military crossbow.

How much high-quality steel and/or bow-wood is available?

How much fuel?

What sort of workshops do they have?

Bow wood is pretty much not available, though large and exotic forests are.


They have a heaping large pile of fuel, and lots of iron. Both are sitting around in large amounts They won't have the specific steel though.


They have something of a factory setup rather than a workshop setup, though its really between the two. They've got big furnaces and forges. power tools really aren't available beyond a few lathes and presses. They've got access to a wonder metal that can go through steel like cardboard and another that can block the first metal, and their tools are made of these: its expensive but not prohibitively so. They also have exceptionally light metals (think aluminum, but less finicky to work with)

Additionally, just describing "TL5" isn't particularly helpful, since metallurgical tech changed a lot from ~1650-1900, particularly after ca. 1850.

You are absolutely right. I'm an advocate for distinguishing TL5 myself. In this case I'm thinking of early TL5, before large machines really start multiplying industry, but when you still have big furnaces. Their metalurgy is rather custom, as seen above. I hope that helps. Yes, much of it is fantasy hand waving.

Contrary to anything LT or other GURPS books might tell you, it is possible to have a low ST, hand-cocked steel crossbow. Just select for thinner, springier bow material and/or less deflex/travel distance by the bow arms. Any bow weight available for bows should be available for crossbows.

Ok, then how do I stat it? do I loose any spring from using a different material?

Assuming 400 skilled metalworkers, as long as ~10-20 of them are actual weapon smiths, they all have shops, they have access to a sufficient stock of decent metal to make bows, and they're all capable of working from a single, proven plan, it shouldn't take more a couple of days to produce 100 crossbows. If there's a way to create an assembly line process and/or re-purpose existing parts the job might only take a day.

that's quite encouraging. thanks for the input.