Only one tile (10 training spears) is needed for an effective training room:
#=wall
D=door
S=spear trap
A=armor stand or weapon rack
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DSDA#
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Set the door on the left to "tightly closed" (no pets) and the door on the right to "internal, forbidden, tightly closed." Set the armor stand to Train and size it so it covers just the spear trap, internal door, and armor stand. Your squad will train in only the square with the spear trap since they can't open the door.
Do you need to attach a lever and have a dwarf keep pulling it when the squad is standing there? Or is it enough that there are spears sticking up where they are training?
Yes, a lever set to repeat is a must... but you can place it anywhere in your fortress. I used to put mine in the dining hall or other meeting area (however I no longer use the danger room since reading this thread with all the awesome advice for training).
Ok, I finally got tired of my three squads of 10 dwarfs that train and spar, but were so wimpy they couldn't even take on a goblin ambush without significant losses - they all have iron armour.
So I made this room, created a new squad so I could see what sort of gains they would get, told the new squad to move somewhere so they would all go and get their nice shiny armour and weapons, which they eventually did. I then set the room as their barracks, and set them to train in the schedule, and set the lever to repeat pulls.
The results were spectacular. Within a few minutes several were lord of their weapons, and high in other military skills like Fighter, Shield, Dodge etc...
So I removed the other squads from their old barracks, and added them to the new room. Within a couple of minutes four of the new guys (from the old squads)were dead - impailed on the wooden training spears.
What went wrong? Is it possible that despite being in those squads for some time that they never collected their equipment?