Everything scales off two counts
Cylinders and chambers. A hundred and ninety five cylinders with ten of them being replaced leaves 185 to pin, and at six chambers that is 1,110 bottom pins and 1,110 drivers. Two mastered chambers per cylinder adds 370 wafers, so 2,590 segments pass through your hands over the job. None of that is hard; all of it is the sort of number people carry in their head as roughly two thousand and then order against.
The depth that runs out
Spread 1,110 bottom pins evenly across a ten depth chart and each depth wants 111. Real bitting lists are lumpy, and at 18 percent on the busiest depth that one wants 200 — 89 more than the flat figure. That is the depth the tray empties on, and it empties in the afternoon of the second day rather than at the start, which is what makes it annoying.
The page asks for the share rather than working it out, because working it out would mean reading the bitting list, and the bitting list is the controlled part of a system. If you have the counts, they come off that list in a minute; if you do not, the person who holds the system does.
Blanks outnumber the doors
Forty change keys issued three times each with one spare is 160 blanks, plus six masters, so 166 for a job with 195 cylinders on it. Scrap comes on top — miscuts on a job this size are a real line rather than a rounding error. The count that matters afterwards is not this one though; it is the record of which key went to which person, and a rekey with no key control attached to it is an expensive way of buying a few quiet months.
Bench time is the bill
At 8 minutes a rekeyed cylinder and 12 for a replacement, the job is 26.7 hours — about four working days at six and a half hours on the tools. Against 68 dollars an hour that is roughly 1,800 dollars of labour beside about 540 dollars of blanks, pins and replacement cylinders. Materials are a quarter of it, which is why rekey quotes get argued over minutes per cylinder and never over the price of pins.
What no arithmetic covers: the cylinder that will not come apart, the wing where the keyways turn out to be three different ones, the mortise case that needs the door off. Related pages: the master key system capacity calculator for whether the new system has room, and the door hardware schedule calculator for the rest of the hardware on the same openings.
Questions people ask
How many pins does a building rekey take?
Cylinders being rekeyed times chambers, twice — once for bottom pins and once for drivers — plus a wafer for every mastered chamber. 185 cylinders at six chambers with two mastered chambers each comes to 1,110 bottoms, 1,110 tops and 370 wafers, or 2,590 segments. That is the count passing through your hands rather than the count to buy, since a kit gets refilled by depth.
Why does one pin depth run out before the others?
Because bitting lists are not evenly spread. A progression that walks the same chambers through the same few depths on every key concentrates the demand, so a kit carrying equal quantities of each depth empties one tray while the rest are still full. At 18 percent on the busiest depth against a ten depth chart, that depth wants nearly twice the even figure. The actual share comes off your bitting list.
How long does it take to rekey a building?
Set your own minutes and the arithmetic follows. At 8 minutes a cylinder for 185 rekeys and 12 for 10 replacements, it is 26.7 hours — four days at six and a half hours on the tools. The variable that moves it is not skill, it is access: doors that have to be taken apart, tenants who are not in, and cylinders that fight you are what turn four days into six.
How many key blanks should I order?
Change keys times what gets issued plus what gets held, plus the masters. Forty change keys at three issued and one spare is 160, plus six masters is 166. Add your own scrap rate on top, because miscuts on a job of this size are a line item rather than a rounding error, and running out of blanks halfway through a floor is its own kind of expensive.
Does this produce the keying schedule?
No. It counts cylinders, segments, blanks and hours. Which door goes in which group and what each cylinder is pinned to is the keying schedule, and that is the controlled document — it comes from the locksmith or the manufacturer holding the system. This page never asks for a cut and never produces one.