Like many Americans, my family had a spring break vacation planned just as the Coronavirus pandemic began to spread in North America. For weeks while looking forward to spring break we had been watching the dramatic growth of COVID-19 and steps taken to contain and control the virus in China, and more recently in Italy, Iran, and South Korea. We decided to cancel our vacation and begin social distancing. While disappointed, it was immediately clear that we made the right decision for ourselves as we would have likely been stranded away from our home in the USA and for everyone else in this time of aggressive spread of a highly infectious disease that hospitalizes 1 in 10 and kills 1 in 50 people.
We made our decision on Saturday the day before our flight was to leave, we all thought about social distancing and what we should do to protect ourselves and potentially others from us (two of us had recent colds and were uncertain if we caught it and symptoms were mild). Hand washing, not touching our faces, sanitizing everything around us were discussed, but when I found out that COVID-19 could last an astonishing 3 days on metal and plastic surfaces I immediately noticed all the doorknobs in our house. A doorknob you have to grasp with hour hand requiring a lot of contact, a door handle you can open with your elbow, or at least one finger. After you’ve been out in public touching door handles, railings, shopping carts, elevator buttons, ATM’s, money, gas pumps… You have to touch the exterior doorknob to enter the house before you are able to wash your hands, and everyone needs to touch it.
I also felt like I wanted to do something to help. I decided to design and share a customizable 3D printable handle that could be easily and nondestructively be attached to doorknobs. Not only are they more sanitary, but they turned out to be immensely convenient when carrying in groceries, or walking out with a beverage, etc. Below are links to my models and source code on Thingiverse, along with the write-up that accompanies them.
Updated stronger customizable doorknob handle with more options: https://www.thingiverse.com/thing:4228668
Note: Thingiverse customizer does not work with this model, it may be too complicated. Download Knob handle v5.scad*, open in OpenSCAD, and enable the Cusomizer UI in the View menu.
Original door handle: https://www.thingiverse.com/thing:4224517
Unfortunately this was inspired by Coronavirus COVID-19
If you think these may help you, your family, or others, please feel free to customize and print as many as needed.
If you would like to manufacture and commercialize this product please contact me, we can work something out.
Novel Coronavirus or COVID-19 is spread like cold and flu viruses via
contact with droplets (sneezes, coughs) from an infected individual.
It has been proven viable in the air for 3 hours and has been
demonstrated to contaminate surfaces for up to 3 days where it may be
picked up on hands. A potential vector for infection is touching your
face (mouth, nose, or eyes) with the virus on your hands. Frequent
thorough hand washing with soap and water and minimizing touching your
face are suggested ways to reduce the likelihood of contracting the
Novel Coronavirus COVID-19 infection.
Centers for Disease Control: https://www.cdc.gov/coronavirus/2019-ncov/prepare/transmission.html
The use of round doorknobs require a hand to grasp and twist to open a
door. Entry and exit doors in particular must be touched by everyone
entering a household, are usually touched before having access to a
sink, and after potentially touching public handles, railings, shopping
carts, elevator buttons, ATM’s, money, gas pumps, rest rooms… Doors
with handles can be opened with elbows and forearms which are less
likely to relay infection.
This handle is easy to print and clamps firmly, gently, and non-destructively to round doorknobs.
An added bonus: Handles are easier to open while carrying packages, groceries, or beverages!
There are two styles, flat (push) and curved (pull).
The flat version will likely print more easily and is perfectly fine for doors that push open.
The curved version is tailored for doors that need to be pulled and in general is more universal.
I can open our doors inside and out with my elbows, but even if you
can’t get your elbow in there, at least you can limit exposure to one
finger rather your whole hand grabbing a doorknob.
You can customize the length, style, size of the doorknob and more in
the OpenSCAD parameters in the file (even more if you dig into the code
– have fun!).
The default size is 54mm diameter, 23mm thick doorknob. The model can accommodate slightly larger and smaller sizes as is.
To fit your doorknob you may either scale the STL file before
printing (measure your doorknob diameter D and scale by D/54), or adjust
the parameters in OpenSCAD, render (F6), save STL, and print your
The door handle may be installed horizontally but I like ours
elevated (rotated “up”) 30-50 degrees to provide more of a usable
rotation arc with my elbow.
Attach to doorknob
- Slip handle over your doorknob, it should fit snug but not crack
- Fasten with a machine screw or bolt (M3, 4-40, 2-56, or anything that will fit)
- Lock nuts are preferred to regular nuts
- Use of washers on both sides is recommended to distribute forces
- If snug enough, it may work fine without a screw
- Optional: If your handle slips, you can slip or wrap a rubber band
between the doorknob and the ring before tightening the screw. You do
not need to put the rubber band around the doorknob (that would be very
difficult), it just needs to compress the rubber against the doorknob in
one location to improve grip. Alternately, (more easily) you could
wrap a rubber band around one arm of the handle ring prior to
installation as pictured, but the rubber band will be visible once
Note, there should be enough friction to open the door with your elbow or knee
but the plastic handle may not be able to grab the smooth metal doorknob with enough force to secure it against any force without slipping. Simply slide it back to the original position or you can try installing a rubber band for more “gription“.
I will never know, but I hope this is helpful. I hope this has a
chance of preventing at least one person from getting sick – even if it
is not against Coronavirus, perhaps against one of the 200 viruses known
to cause the common cold, or influenza (8,200 deaths in US in 2019), or
Maybe you just want to make it easier to bring in your groceries.
If you would like to support invention for the greater good, you can donate to your local makerspace… or mine: http://blog.workshop88.com/
(they will need support during these times of social distancing and isolation)
Also, please don’t judge my filthy garage/workshop doors too harshly… I have to go scrub them now.
Stay well, wash your hands, and don’t touch your face!
D. Scott Williamson