Author: Bjørn Madsen

Careful with the key safes. If you cheap out you could end up spending a lot more if somebody busts it open and gets the key out. A good one costs close to $100 which is much less than it costs to have a locksmith come out and rekey a building with numerous keyed entries.

The Supra S7 is a more appropriate choice, especially when throughbolted on the wall. Use some cheap little woodscrews and the box will easily be pried off the wall like the one in the picure above, which was attached with a few short woodscrews.

One of the problems endemic to people with houses more than 100 years old is inevitably the sticky mortise lock knob. This is probably a lock on an original door with a crystal glass knob but it could also be brass. When you turn the knob the latch doesn’t spring back out. There are a lot of possible reasons for this and I have pontificated at great length elsewhere online about this but I am going to explain the most common problems and solutions right here.

First I will list the problems that can be fixed without taking the lock apart. Number one problem is people overtightening the knob because nobody likes door hardware that feels flimsy, it seems natural that the knob shouldn’t wobble around on the door. Usually these knobs are screwed onto a spindle. You screw the knob on and then tighten a set screw at the base of the knob to hold it in place. You or your family may have inadvertently overtightened your knob when this set screw loosened, allowing the knob to turn independently of the spindle. Sometimes people spin the knob the other way and it loosens. Then the door doesn’t open and they call me in a panic.

This problem can be solved by screwing the knob onto the spindle only tight enough that the latch still springs back when the knob is released. If you tighten the knob more than that, the friction of the base of the knob against the rose (plate on surface of door) will be greater than the force of the spring inside the lock and the latch won’t come back out. (I never thought I’d use anything from honors physics. Thanks Mr. Elder, you are a peach!)

Once you have found that optimal sweet spot for your knob then tighten the set screw. If you are a type a personality and want to do the job right/don’t want to ever think about this again, buy something called threadlocker in the blue color and put a small dab on the set screw before screwing it in. This prevents the screw from backing out and loosening which may be what got you into this mess in the first place.

Ok so that covers the most common and easiest fix. That eliminates maybe 75% of you. On to the next most likely problem: alignment of the spindle within the lock. We have already examined the problem of friction between the knob and the rose, or “base plate” for those not familiar with door hardware terms. Other variables can cause excessive friction or wobbling in your lock too. The two main problems here are overtightening of the screws holding the mortise lock in place and misalignment of the rose or base plate on the door.

The mortise lock when installed should have the hub centered perfectly in the door between the two holes in the metal plates on either side of the door. If your door has no metal plates then that is a problem. Originally there probably were plates but some helpful person decided they were unnecessary and, well, here you are! Turns out they are necessary to support the knob and keep it from wobbling around.

Back to lining up the holes. If you look through the holes in those plates on your door, it should be a straight unobstructed hole through the lock. If it is not then you need to take some cardboard or something and put it behind the lock when you screw it in. You need to make it so that when the screws are tight, the lock’s hub is centered with those holes. The idea is that the spindle will spin without rubbing against anything.

Maybe the lock isn’t the issue though. Maybe the roses are too high or too low. Maybe they aren’t screwed into the door at all! Many times when people call me to look at these locks I take the rose off the door and find a perfect circle of little holes drilled into the wood at intervals because over time the holes got stripped and people rotated the screw holes on the rose for fresh wood. After 100 years of handymen and weekend projects, there isn’t any fresh wood left! Then it is time for either a different rose, plastic wood filler, or an entirely different solution like rivnuts or some other esoteric fastener.

Sorry I got off on a tangent. The main idea we’re on is making sure the roses are installed in the right spot. A lot of times they aren’t. To find out where they should be installed I like to take all the screws out of the rose and then tighten the knobs so that they are snug; don’t overtighten or you may distort the shape of the rose which brings us back to one of the earlier troubleshooting steps.

Once the knobs are snug and assuming the door is perfectly flat and free of paint ridges that the roses might slide into, we can assume that the roses are optimally placed. The screwholes may not line up with where they were originally and there may be a different color of paint showing. Unfortunately there is a decision to be made: will your antique lock work properly or will your door have some unsightly paint from yesteryear peering out? If you choose to have a properly functioning lock, stick a sharp object into the screw holes to mark where you need to put the screws.

Now you remove the knobs and drill pilot holes. These holes need to be smaller than the screw and they shouldn’t go into the body of the lock. I know that one is the very definition of a pilot hole and the other is also obvious but I’ve seen some stuff, okay? Make sure that the screws aren’t longer than the hole they are going into. These screws are usually really short which is why the holes always get stripped out. Ace Hardware has a great screw selection and even have antique brass and oil rubbed bronze finish wood screws in the appropriate sizes. I like the Maple Leaf Ace Hardware for my fastener needs.

We have now covered the easy fixes. On to the harder ones.

Sometimes knobs and/or spindles have stripped threads. This causes overly muscular or determined people to turn the knob past where it is necessary to open the door, and can also overtighten the knob. The solution, aside from removing caffeine/television/twitter and other stressors from your housemates’ lives, is to replace the knob and/or spindle. I mentioned Ace Hardware a little bit earlier. They also sell mortise lock knobs and spindles. These work in most interior mortise locks. They probably are inappropriate for exterior mortise locks and may cause a big problem if used instead of a split spindle.

The Ilco mortise knob set comes in either glass or brass finish. The brass one is made either of a very weak metal or plastic, I’m not sure which. The glass one may also be made of plastic. There are more expensive options but nobody wants to spend $120 on one of these doorknobs. If somebody does I have some actual crystal glass doorknobs to sell you, new.

Follow me into the weeds and we discuss opening the mortise lock. There are lots of reasons inside an old lock that the latch might not spring out. The latch might be bent from abuse, there may be some foreign object or broken spring blocking it, there may be paint on it because painters frequently don’t bother to tape off locks and just paint right over them causing the bolt to stop working unless you pay me to take it apart and clean it.

There may also be a broken spring. People are forever mailing me locks with broken springs. The two most common kinds of spring are the coil spring which wraps around the latch and the flat spring which either directly forces the latch back out or acts on a lever of some kind at the top of the lock connected to the latch.

The coil springs are stocked at Ace Hardware. The flat springs are used by gunsmiths. They can also be taken out of old windshield wipers or street sweeper blades found in parking lots if you want to fix it on the cheap. Usually the shape of the spring can be determined from looking at the broken pieces of spring inside the lock. Oftentimes these are missing after some enterprising individual from the past removed them when trying to fix the lock. You may find a bent paperclip or rubber band in its place if you’re lucky. In this case either deduce the shape from the features of the lock or mail it to me.

I hope that this information helps you fix your lock. Many of you are spending more time at home due to the Covid 19 pandemic, drop me a line with comments related to this and I may update it in the future.

There are a few situations I kind of wish people wouldn’t call me out on. Not because I don’t want the money. More because people could do the job easily themselves. Of course there are two groups of customers, those who have the time to do it themselves and those who don’t.

Before calling me to rekey your house check to see if you have Kwikset Smartkey locks installed. These are really easy to rekey yourself and though they do fail occasionally during the rekey process, they usually don’t. All you need is a smartkey tool and a Kwikset key that is different from your current key. It should be factory original. They have buckets of these at Home Depot and will sell them to you. You may have problems if your key does not say “Kwikset” on it. If you don’t have the tool, you can actually use almost anything that is stiff and will fit in the little slot next to the keyhole on the face of the Kwikset smartkey lock cylinder.

I don’t mind doing the work for those who don’t have the time. I feel bad doing the work for people who are just scared to try though. Let’s look at the cost benefit analysis for calling me out versus having a new knob shipped to your door.

I charge $75 to come out to your house if you live nearby. This is much higher than somebody who delivers groceries or take-out, but lower than some trades like plumbers. If you just want to rekey one lock on your door, consider the cost of just replacing that lock. This is a viable option if your house or apartment is of modern construction. Townhouses fall into this category. Usually only a Philips screwdriver is required to remove or install a lock in these houses though Allen wrenches and flathead screwdrivers may be required if more decorative or import locks are installed by the builders.

A new Schlage F51a knob is running $26 plus tax and shipping. A Schlage deadbolt and doorknob already keyed alike costs $47.97 plus tax and shipping. If you paid me to come out and install that one knob I would charge $20 per lock*, bringing my total to $95 to install just a knob or $115 to install a knob and deadbolt*.

*This cost assumes doors are already prepped for tubular locks. If not then more labor and thus higher costs are required.

In our hypothetical situation of changing one doorknob to a new key the cheapest solution is definitely replacement. If you have the time and bring me the knob with a working key I only charge $15 to rekey it so that is the absolute cheapest you can do without rekeying the lock yourself, though that would necessitate obtaining either pre cut keys or blank keys that you file down and either re-using the pins in your lock or obtaining new pins.

When people call me about replacing a lock, inevitably we start talking prices. One of the variables I spend more time explaining is whether or not the door is prepped correctly. If a door is prepped for a modern tubular lock it must have a 2 and 1/8″ cross bore and a 1/8″ side bore.

In the old days people didn’t have access to inexpensive electric drills or were too cheap to buy the correct auger bit to drill 2 and 1/8″ holes. They reasoned, why don’t I use the 1/4″ bit I have and only drill out those holes that are strictly necessary? Sometimes they didn’t even drill holes, sometimes they chiseled the hole. The lock they bought at Home Depot requires a nice round 2 and 1/8″ hole though and that means I have to drill the hole.

That requires equipment, it makes a mess and it takes time. That’s why I charge $10-55 labor to install a replacement lock in labor alone. $10 is the cost if I can install the lock without modifying the door at all. This is a low price because you could do it yourself with only a hand screwdriver and 5 or 10 minutes.

You could also do the work if you buy a jig from the big box store and some hole saws. Measure twice and cut once though, the guy who installed the last one might not have centered the side bore on the cross bore. Don’t mess up your door by drilling in the wrong spot.

Recent events on the west coast have left us with air that is so dirty as to be considered unhealthy. It is recommended that people at this time stay inside to avoid breathing this dirty air which is dirtier even than the most filthy air in the industrial cities of China. This makes you wonder how much safer it is inside than out. The air that you breathe is coming through the walls and windows of your house that aren’t perfectly sealed. If it wasn’t it stands to reason you might die of CO2 poisoning after a time of not opening your door or window. This is actually possible with modern manufactured homes that are made to more exacting specs, or so I’ve heard.

I coincidentally was reading about the dangers of particulates in the air we breathe several weeks before the fires of the West Coast destroyed everything and decided to buy some sensors to attach to my old fleet of raspberry pi’s that were languishing in a box. The sensor can be purchased from here. It has a little tiny impeller fan that drags air through it and fires a laser through this air to measure particulates. Essentially, “the SDS011 using principle of laser scattering, can get the particle concentration between 0.3 to 10μm in the air“.

A great primer on the use of the SDS011 sensor and how to use it with a raspberry pi is found here. Unfortunately I wasn’t able to get the software from that writeup working so I found a different github account and used their software and got working results.

The results can be saved in a database or csv format. Here is an example from my kitchen:

‘2020-09-12 15:24:12.303115’, ‘11.9’, ‘18.5’, ‘18054’]
[‘2020-09-12 15:29:12.718003’, ‘27.3’, ‘44.6’, ‘18054’]
[‘2020-09-12 15:34:13.122560’, ‘27.1’, ‘44.7’, ‘18054’]
[‘2020-09-12 15:39:13.534483’, ‘29.8’, ‘46.2’, ‘18054’]
[‘2020-09-12 15:44:13.932565’, ‘34.3’, ‘54.3’, ‘18054’]
[‘2020-09-12 15:49:14.345529’, ‘33.7’, ‘54.2’, ‘18054’]
[‘2020-09-12 15:54:14.779727’, ‘34.6’, ‘54.6’, ‘18054’]
[‘2020-09-12 15:59:15.213513’, ‘36.0’, ‘60.4’, ‘18054’]
[‘2020-09-12 16:04:15.638646’, ‘41.6’, ‘69.0’, ‘18054’]
[‘2020-09-12 16:09:16.063939’, ‘40.2’, ‘75.1’, ‘18054’]
[‘2020-09-12 16:14:16.481698’, ‘45.3’, ‘88.6’, ‘18054’]

First is a timestamp, then the aqi measurement of 2.5 micron (pm2.5) followed by 10 micron and then the device id. It is measured every five minutes.

It is pretty easy to install the software to get this to work. You need to be able to ssh into your pi. Then install git, python3, and python3-pip. Then type

git clone https://github.com/menschel/sds011.git

cd sds011

pip3 install .

At this point you will have the program installed. Next you have to change directory to ./sds011/sds011/examples/ and edit sds011_console_test.py. I like nano. You have to delete the # in front of the information about five minutes. Here’s my working python file:

from sds011 import SDS011

port = “/dev/ttyUSB0”

sds = SDS011(port=port,use_database=False)
sds.set_working_period(rate=5)#one measurment every 5 minutes offers decent granularity and at least a few years of lifetime to the sensor
print(sds)
import csv
try:
with open(“measurments.csv”,”w”) as csvfile:
log = csv.writer(csvfile, delimiter=” “,quotechar=”|”, quoting=csv.QUOTE_MINIMAL)
logcols = [“timestamp”,”pm2.5″,”pm10″,”devid”]
log.writerow(logcols)
while True:
meas = sds.read_measurement()
vals = [str(meas.get(k)) for k in logcols]
log.writerow(vals)
print(vals)

except KeyboardInterrupt:
#sds.sleep()
sds.del()

To see if it works, type:

python3 sds011_console_test.py

If it is working, you will see this:

SDS011 Device ID: 4686
Firmware Date: 2018-11-16
SleepWorkState: sleep
DataReportingMode active

Unfortunately only one of the three sensors I got actually worked correctly. I’ve verified this by plugging all three into the same raspberry pi I got a sensor working on. One of the sensors displays DataReportingMode as query instead of active:

SDS011 Device ID: B118
Firmware Date: 2018-11-16
SleepWorkState: work
DataReportingMode query

Apparently one can change the reporting mode if they know how to program, it is set by default to report in active mode from the factory though and I don’t think I changed it since I don’t know how. The other sensor exhibits a different error. After running the same program on a different sensor, I get the following traceback:

Traceback (most recent call last):
File “sds011_console_test.py”, line 5, in
sds = SDS011(port=port)
File “/home/pi/.local/lib/python3.7/site-packages/sds011/sds011.py”, line 130, in init
self.probe()
File “/home/pi/.local/lib/python3.7/site-packages/sds011/sds011.py”, line 138, in probe
fwdata = self.get_firmware_version()
File “/home/pi/.local/lib/python3.7/site-packages/sds011/sds011.py”, line 223, in get_firmware_version
return self.request(cmd)
File “/home/pi/.local/lib/python3.7/site-packages/sds011/sds011.py”, line 228, in request
resp = self.rx_cmd_resp_queue.get(timeout=10)
File “/usr/lib/python3.7/queue.py”, line 178, in get
raise Empty
_queue.Empty

The author of the python program I’m using suggested that the raspberry pi3 is at fault, he stopped buying them after raspberry pi 2 because of some technical issues:

Long story short, uart0 is corrupted on PI3 or PI4
if you don’t disable the adaptive CPU frequency scaler. I stopped
purchasing PIs after they screwed this up on the PI3.
On USB everything should work.

>  it never leaves query state
Check if the sensor spins the fan. If that’s the case you have a
communication error on the RX side, e.g. rx_handler() does not receive a
valid frame.

Unless you actively set it to query mode
by calling set_data_reporting(modesel=”query”)
It should not change the data reporting mode to query.

Cheers,
Patrick

Masterkey systems are popular for buildings with several different units. They are useful to a building owner because they allow quick access to all rooms with one master key, but every tenant can have an individual key that doesn’t work on any of their neighbors’ locks. In other words, the master key is very convenient for the owner. It is also convenient for the fire department in an emergency. They don’t need to try fifty keys on a keyring to open a door, just one master key will suffice.

A masterkey system is essentially a matrix of keys that are compatible with the master key but also guaranteed not to accidentally work in more than one unit. Many building managers don’t use a master key system and sometimes a resident accidentally discovers that their key works in their neighbor’s lock. This is called accidental cross keying and is exactly what a master key system is designed to prevent.

Today I was called out to a building in Seattle to rekey a lock to the manager’s master key and a key of her choice. I assumed that this key was part of a master key system that she had established. My heart sank when she gave me an old worn key off a keyring of numbered keys. She was recycling keys from her master key system. That is to say that some tenant from five or ten years ago had the same exact key in the same exact building.

Interestingly this key was not even compatible with her master key. To be compatible, the depths of a key must be cut to either the same depth or to a depth that differs by at least thirty thousandths of an inch for each chamber. The key she gave me was only a difference of fifteen thousandths of an inch, meaning that the lock would probably jam up and somebody would get locked out if I rekeyed it to work with both keys.

The locksmith preceding me took a different approach to rekeying this lock to work with a key incompatible with the master key. Their solution was to not use two out of the five chambers and to use bottom pins as top pins so that pinning could be off by as much as .075 inches and still work with both keys. This is not very secure; it means that a fairly large number of random Schlage keys would work in this lock facing a busy street near the Burke Gilman bicycle trail, a major artery for lots of creeps prowling around. Maybe 30% of the shlage keys out therewould have worked in this lock with only three chambers and six shear lines with a bogus top pin. All of these mistakes also make it more likely that somebody could pick this lock.

This situation was kind of bad all around for the last tenants. Who knows how many decades’ worth of people had lived in this building using the same key? I guarantee at least a few other tenants in this building could open this lock with their key, given the missing chambers and sloppy masterkeying seen in this lock. Then we have to consider keys around the property left under rocks or in bushes either accidentally or deliberately by previous tenants. A bored junkie could have a profitable afternoon by spending half an hour looking in the bushes by the front gate of an apartment building!

Once I dropped a masterkey into a large juniper bush in front of just such a gate. When I searched the juniper I was surprised to find not only the master key I’d dropped but two additional master keys along with several tenant keys from the past. Maybe I could’ve found more but I was searching very carefully because of the many used needles found in such places on Capitol Hill in Seattle.

This brings me to the final problem with the master key system I encountered. The point of giving people new keys is so that the old key won’t work. If somebody leaves the old key under a rock next to the building and a junkie finds it and needs a hit, they will try that key in every single door. They don’t care that it used to work in unit seven or unit three fifteen years ago. When the door opens, they will steal stuff. If the tenant finds out that the masterkey system is stale and keys were reused I believe they could sue the building owner, and just imagine the liability if somebody got hurt by the hypothetical junkie!

It was a little difficult for me to wrap my head around why this person was having me re-use a key from their small masterkey system to begin with. She didn’t have more than one key so she wasn’t saving any money on existing keys. I think she may have believed that only the keys she had could work with her master key, though in fact they wouldn’t work well at all. A system for Schlage SC1 such as she had should have hundreds of possible change keys, not just the ten she had on a keyring.

The short version of this meandering screed is this: Proper use of a master key system involves using new keys every time a tenant moves in or out. In order for the master key system to fulfill its promise of no cross-keying, you must hire a reputable locksmith because all chambers must be used and bottom pins must not be used as top pins. Dopey locksmiths know that the owner won’t see that they left chambers empty and so they will get away with it.

There is a lot of information on the internet about comparisons between electronic deadbolts with regard to ease of programming, looks, and wireless features. I haven’t seen a lot of information about the actual physical security of these locks anywhere though. I am going to conduct a test of popular electronic deadbolts as soon as I find a building that will be torn down so that I can install these deadbolts and actually kick the doors in myself, but until then I thought a comparison between the bolts and strike plates would be in order.

I installed a couple of the Yale electronic deadbolts a few days ago and was struck by how small the strike plate is. Kwikset isn’t much better either. The strike plates are smaller than most manufacturer’s strike plates. The standard size I encounter most is 1.25×2.75″. This is the size that commercial doorframes are prepped for. Schlage makes them this size. When replacing larger strike plates these don’t fit the mortise. The smaller strike plate looks terrible in a wooden doorframe with wood exposed around the small strike. The small strike wouldn’t even be installable in a commercial metal door frame.

The screws that come with the Schlage strike come in two sizes. The really long thick screws and the really thick strike plate go under the thinner strike plate which is decorative. Two small screws hold the decorative strike plate over the more secure strikeplate.

The screws that come with the Yale strikeplate are long but much thinner. The screws that come with the Kwikset are even shorter. The Schlage electronic deadbolts which all come with this package of decorative strike and thicker more secure strike with long thick screws win hands down over the competition when it comes to strikes and screws.

Next comes the boltlatch; the bolt that, when extended, keeps the door secured. The Yale bolt seems a little on the thin and cheaply made side. I suspect this bolt will be the easiest to defeat when kicking a door in but this is just a hunch until I actually conduct a test with repeatability. The Kwikset boltlatch is fairly unimpressive but due to it being used on a lot of lower income properties subject to more crime I have seen the results of their being forced and they stand up to a surprising amount of abuse.

Schlage B500 boltlatches are quite resilient though they will be defeated if the gap between the door and frame is large and the door is kicked hard enough of course. The bolt itself is a larger piece of metal than the Yale and Kwikset bolts.

Schlage electronic locks don’t come with B600 series boltlatches but they are compatible with Schlage electronic locks, though the tailpiece on newer Schlage models have to be modified or replaced (more on that later). The B600 bolt is leagues ahead of the competition. If you want a secure electronic deadbolt you can’t do better than a Schlage Encode or Connect with a B600 bolt. The bolt is probably 50% thicker. If you feel it in your hand you will note it is better constructed when compared to the other two.

Another component to be considered is the lock cylinder itself. The Kwikset smartkey cylinder is admittedly very difficult to pick. There is a trick I won’t reveal here that makes many of these pretty easy to remove from the door and put back on without any visible damage. These lock cylinders are also fairly vulnerable to tryout keys. I think you only need 200 keys cut in specific half-depths to open all Kwikset smartkey locks. What it does have that is great is a sidebar and that makes it fairly hard to drill out.

The Yale has a regular Kwikset cylinder without any bells or whistles. It’s pretty trivial to pick these, though criminals don’t tend to pick residential locks around Seattle very often. The danger with the Yale and the Kwikset is that entry could be obtained without any obvious sign, making insurance difficult to collect if anything was stolen.

The Schlage has a fairly unexciting lock cylinder. It is a five pin lock cylinder with some security pins and some hardened steel inserts. It isn’t difficult to drill it out, much easier than the Kwikset if you want to know the truth. What sets it apart is that the lock cylinder that comes with Schlage electronic locks comes in a standard form factor called a 99 type key in knob cylinder. While not exactly standard, it means that with a little work the lock cylinder in these can be replaced with one from any manufacturer. This means that the Schlage electronic locks can be upgraded to a very secure cylinder that can’t be picked or drilled very easily at all. I have installed Medeco, Multilock, Primus, CX5 and Protec2 cylinders in these locks. The only thing necessary to get them to work right is to either replace the bolt with either a B500 or B600 bolt, or to grind the tailpiece of the cylinder so that it will work with the special bolt that comes with the lock.

So if you are concerned about somebody kicking your door in, remember these differences when you are shopping for one of these deadbolts. The reasons listed are why I recommend people buy Schlage electronic deadbolts.

Yesterday I was called out to rekey some locks at a mental health service provider. If locks are in good shape this is a slam dunk and four locks would take me twenty minutes. The locks at this location were not in working order. They were very cheap and not fit for use after only a year. I save used locks to give to the poor but these I pitched directly in the metal recycling bin. I replaced them with generic import locks but of reasonable quality.

The locks I encountered were generic grade 3 locks sold under the brandname Maxtech. These locks have their place. They are useful for low traffic and low security like a storage locker for old paint buckets or an interior door that is only accessed once a month. I cannot recommend these locks for use on a home and especially not on an office used daily by multiple people. They are so cheap that it is difficult to use them, the deadbolt jams and falls apart quickly after installation. The keys that come with these locks are so far off the Schlage standard that they won’t work in a schlage lock without modification.

Usually when I encounter these locks on a home or business it is a sign that a ripoff artist preceded me. If somebody is trying to sell you Maxtech locks for more than $10 each they are probably what is called a locksmith scammer. These locks cost $7-10 each, they are what people used to secure houses with that were foreclosed on in the mortgage crisis. Guys used them because they got paid $50 to drive out to the house, break in, disable all the locks, and then install a new lock on the front door.

Take home is that if some guy tells you they have a great Maxtech lock that is way better than your old lock, don’t believe them unless all you can afford is a $10 lock. If that is the case go to the hardware store and buy a $10 lock there which will probably be better. There may be no worse lock than a Maxtech. Maybe a Tell. There are some really bad ones. I would say I wouldn’t wish them on my worst enemy but that would be false.