Author: Bjørn Madsen

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.

Doorknobs are one of the filthiest surfaces in your home as far as bacteria are concerned. Don’t even get me started on public door knobs and pull handles. Just think: all sorts of people are using public locks and pull handles. Do you think all of them wash their hands after blowing their nose, picking up dog feces and going to the bathroom?

If you have to go through a public door, my advice is to avoid touching the door with your hand. Push doors open with your shoe or elbow. If there is a button for the disabled to open the door I push that button with my foot or knee or elbow.

An interesting development in the lock world is the invention of antimicrobial finishes. Here is an interesting article about them. The gist of it is that many lock manufacturers now offer their locks with an antimicrobial finish that inhibits growth of bacteria on the surface of the lock!

Obviously if somebody gets yogurt or cheese all over your doorknob the antimicrobial coating won’t be able to do much to help but if the hardware isn’t soiled, research shows that these coatings are effective. If you manage a public building, let me know if you want a quote for hardware featuring antimicrobial coatings. It may not require replacing your locks altogether, just the parts that people touch are coated and so that is the part that would be replaced.

Schlage Connect and Sense came with programming instructions in a paper booklet but the newer Schlage Encode no longer includes this. Instead there is a thin glossy insert that implores you to install an app on your phone. Many of us are loathe to do this. There are many reasons not to, like hating smartphones and refusing to have one on general principle. The Venn diagram of people who hate cellphones but want an electronic deadbolt is very thin I am sure but you are here because you want to know how to program your lock without the app. Note that if you use manual programming procedures your work will all be deleted if you use the app later on. Here is how to program your lock manually:

1. Get the programming code from the glossy insert in the box or off the lock itself. It’ll be in very small 6px print on a sticker.
2. Follow the instructions on page 8 of this pdf, or look at some screen captures below.

Usually the cylinder for Schlage doorknobs can be removed by turning the key in the knob and pushing a spring-loaded retainer to pull the knob off. On really old Schlage knobs this retainer wasn’t there, you had to “backdoor” the knob: completely disassemble it from the rear. This is much harder than taking the cylinder out of modern commercial knobs. In fact backdooring a Schlage A series was part of the test for the NWLA certified professional locksmith certification.

I can’t find any identifying information about this knob, I can only say that it is the predecessor to the modern a series. I put this here in case anybody runs into one and wants to know how to take it apart, the owner of this one told me that two locksmiths had told him it couldn’t be rekeyed. It absolutely can. The cylinder can even be replaced. I hope that these pictures help somebody!

I don’t like to bite the hand that feeds and much of my business comes from organic search results but it is important that this gets out there. Google is helping the locksmith scam succeed and getting a cut. They do this through “Google Guaranteed”, a service Google established to make money off of searches for business services.

Google Guaranteed is an advertising service that you pay for. Subscribers will have their ad listed at the top of Google search results. They will pay Google $15-30 every time somebody clicks on one of those ads. How does this affect you though?

If you click on one of those ads you are going to pay at least $15 more than you would pay if you called somebody not paying for these ads. More likely you will pay $100 more because you have to cover all the other clicks of people who didn’t hire the business. It’s much more expensive. Read some of the reviews for the locksmiths in Seattle under Google’s guaranteed businesses. You will see people leaving five star reviews for somebody unlocking their car for $150. A tow truck driver would use the same tool and do the same thing for less than half that.

Maybe the quality of service is worth it, you tell yourself. This business has 100 positive reviews! I’ll let you in on a secret: a lot of those reviews are probably fake. None of my reviews are fake, but I’ve heard for years that people are running review mills in the Philippines, selling reviews for $5 each. Now one of these review mills got ambitious and sent me an offer to write me positive reviews for money!

This is not a revelation to me at all, because the locksmith community is not a very big one. Interestingly I’ve never heard of the majority of these businesses using Google Guaranteed. Sometimes people call me when they’re locked out and tell me that they called somebody from Google Guaranteed who showed up and didn’t know how to unlock their door and they want me to come do it.

The point of all of this is to be distrustful of online reviews, and especially those on google. Yelp reviews are much harder to fake which is interesting since Google is somehow able to identify spam in 99.9% of cases. I would think if they applied their algorithmic magic to their reviews they would be as successful as Yelp but they are making plenty of money with these companies using fraudulent reviews already, so why change?

Bottom line is whether you are looking to get your carpet cleaned or your locks changed or your fence repaired, get a few quotes and make sure one of them is from a brick and mortar store. Ask a neighbor who has lived locally a few years for recommendations.

I don’t know why satin nickel finish takes on a yellow hue in sunshine but after a few years it turns yellow. Schlage warrantees against this just so you know. This also happens to Kwikset locks. I am not aware of this happening to other finishes.

Why would you do this? Probably because you hate getting locked out or you want to have an electronic lock on the same door but don’t want the appearance to change very much. If you need a key or code to lock your door when outside you are far less likely to get locked out but most mortise locks allow you to push a button to lock the door before walking out and realizing they are locked out. I get a lot of requests from people wanting to install an electronic deadbolt on their front door, but there is already an antique mortise lock installed. There are a few issues to consider for this scenario.

I can easily install an electronic deadbolt above an old mortise lock but eventually somebody will lock the mortise lock and everybody relying on using a code to unlock the deadbolt will be left high and dry. There are a few solutions to this problem but each has drawbacks. You can replace the mortise lock but the replacement options will either be expensive or ugly or both. You can modify the mortise lock to not lock at all, but that is somewhat expensive.

Replacing the mortise lock is probably the most professional approach. The manufacturer of your mortise lock probably makes one with the same hole pattern in a passage function. This is a drop-in replacement that will ensure you don’t get locked out. Mortise lock cassettes usually cost at least $100-200. Expect to pay another $100 for me to come out and install it. The nice thing about this approach is that you can use the same trim, meaning that the lock will look exactly the same on all sides of the door but you can’t get locked out (easily, nothing is impossible).

Replacing the lock with a tubular or cylindrical lock requires modification of the door, either with remodeler plates or a wraparound plate or with extensive carpentry to plug the numerous holes left by a conventional mortise lock with custom cut pieces of wood. The remodeler plates often come only in garish colors like brass and steel.

The slumlord solution which is cheap and effective is to superglue the buttons on the side of the lock and cut the spindle for the deadbolt’s thumbturn on the inside of the door. Then break a key off in the cylinder. This is nearly free and will prevent the mortise lock from locking by all but the most determined person. The mortise lock is deactivated, and the electronic deadbolt above it is the only functioning lock. Not very elegant, but saves some money and the antique lock still looks nice.

My favorite solution which is for most locks reversible is to take the mortise lock apart and remove the buttons on the side of the lock. Nobody can casually lock the door and walk out unless they lock the mortise lock from the inside and exit via a different door. The deadbolt can be blocked from use by inserting a screw into the strike for the deadbolt.

The lock looks mostly the same and can’t be locked, making the electronic deadbolt the only means of entry on the door. Your antique lock can be returned to full functionality by removing the woodscrew in the strike hole and putting the removed parts back if desired.

Following is a description for how to modify a typical Baldwin mortise lock for passage function. This is not hard to do for somebody who is mechanically inclined. If you screw up it will be hard to put the parts back the way they were. It will void any warranty the lock has. This is a great play to make if your mortise lock is malfunctioning and you don’t want to buy a new cassette too (last ditch hail mary kind of thing).

I am not responsible for what you do with this information, and you should know that this will void Baldwin’s warranty for their mortise lock, though that warranty I believe is only valid if you are the original purchaser of the lock. The directions aren’t going to explain how to take the lock out of the door, if you can’t figure that part out you probably don’t have any business performing this procedure. I will say that you must loosen the set screw for the mortise cylinder, not remove it. Don’t use a wrench to remove the mortise cylinder either. Ok here goes:

Take the mortise cassette screws out and lift the top off the cassette body. Next is time to remove the buttons on the side of the lock, along with the spring and ball bearing that go with the buttons. Following are before and after pictures of the parts inside the mortise cassette. If you want the deadbolt to still work, your cassette should look like the second one with the buttons removed. The coordinator can remain, without the buttons it won’t do anything.

Ok if you made it this far you either have a working lock or you screwed up somewhere or there is a broken part in your lock that needs replacement. If the former, congratulations. I would charge around $150 to come out and do this kind of job so you saved yourself a lot of money! If you are in the latter camp, you have what I call a shoebox job. Bring the shoebox full of parts in to a walk-in locksmith shop and if they are competent they can reassemble the lock as long as you brought all of the pieces, and maybe even if you did not if they have spare parts.

I’m putting this information here because the economy is crashing and people are hurting financially and need security but don’t necessarily have the money to pay somebody to do this. Let me know if you found this information helpful, I’m going to make a youtube video about this subject in the near future.