Door Pedal: an Anti-COVID-19 Door Opener

The world needs your help to fight COVID-19! Please help me to beta test this new design.

This is an open source project, started in March 2020, with the goal of inspiring the maker community to come up with more ways to re-engineer the world around us to fight COVID-19. Please re-make, share and improve upon the design. With the provided files, you can easily customize it to your individual needs:

You can find the .STL, .STEP, and .F3D files on Thingverse.

This project is covered under an Attribution-NonCommercial-ShareAlike 4.0 International license.

TLDR Version: The introduction goes into detail on the motivation of this project. For a quick summary, please have a look at the slides I've posted for each step.

Introduction:

The main goal of this project was to raise public awareness of the potential for foot-operated controls to provide another type of sanitary solution for preventing surface-to-surface spread of SARS-COV-2. Ultimately, I hope that this project inspires you to think outside the norm in fighting COVID-19.
Every small invention counts (yes, even the ones outside of biotech), if we want to save the world from COVID-19’s "Grim Equilibrium": the balance between letting our economy get back to work vs. saving more lives.

Devices that slow the spread of the disease can help to further “flatten the curve,” and allow some workers to more safely return to office or factory environments. Additive Manufacturing (3D printing) has enabled engineers and makers the ability to re-design the world overnight in the fight against COVID-19. It allows the world to make these small inventions in a short enough time-span to still save lives with them.

The Materialise door opener concept is a brilliantly simple way to use 3D printing to combat the spread of COVID-19. Their design has so much going for it:

• Fully prevents palm-to-door contact
• Quick to deploy
• Modular and Configurable
• Efficient to print
• Truly temporary
• Good Looks

But, it's possible that it doesn't actually solve the problem it set out to remedy: sanitation. Why? Elbow coughing and infectious droplet production.

The WHO, CDC, NIH, NHS, and other major world players in the public health scene have been recommending that we cough or sneeze into our elbows for years now. It's not a scientific study, but this Mythbusters episode colorfully illustrates how elbow sneezes can more effectively contain droplet spray than other common methods.

A quick tangent on elbow coughing - Even though more scientific studies show that no cough etiquette maneuver is perfect at preventing droplet escape into the surrounding environment - elbow coughing still came out on top of other methods. Unfortunately, the medical community still has limited information on how SARS-COV-2 spreads from person to person. Overall, more rigorous studies are needed to determine the best, evidence based cough etiquette recommendations that we can follow in the pandemic, such as ubiquitous N95 or better masking, for example.

In the end, the elbow cough's main function is to avoid contaminating one's hands. That tends to prevent various items we use from being contaminated, and self-inoculation when we inevitably touch our hands to our face during the day.

While elbow coughing gets around the problem of touching surfaces or other people with contaminated hands, it could pose a problem for using arm-based door opening devices in mitigating COVID-19's spread.

I'll outline a few reasons why, based on my own review of published research, and the best available evidence based recommendations on clothing, skin, and surface transmission of coronavirus strains.

We can plausibly assume that:

a – infected individuals that use elbow coughing will contaminate their elbows or sleeve interiors, and parts of the elbow and sleeve exteriors with viral particles. It is also possible that everyday emissions from un-masked infected individuals could contaminate sleeves, even without using elbow coughing etiquette.

b – infected individuals could transmit those viral particles to 3D printed door opener handles, and possibly any door surface via contaminated sleeves, arms, and/or viral laden droplet spray.

c - FDM 3D printed plastic door handles will likely provide a viable surface for virus particles to remain active upon for >3 days, based on current (limited) evidence. It is unclear if spray or wipe applied disinfectants can reliably inactivate enough coronavirus particles on FDM 3D printed parts to render them safe.

d – since coronavirus particles can be spread from surface-to-surface, including clothing, bare skin, metals, plastics, wood, etc., healthy individuals could pick up viral particles on various arm surfaces. Accidentially touching other door surfaces, or using the elbow vs. forearm could pose greater risk to un-infected individuals. These contact surfaces can include the forearm, elbow interior and exterior, wrist, back of hand, and some of the upper arm.

e- un-infected individuals could then inhale coronavirus particles directly from their sleeves during elbow coughing events. Or, they could easily transfer coronavirus particles onto their face through elbow coughing or face-touching. It is currently thought that these transferred coronavirus particles can also be inhaled, or otherwise lead to infection.

f - infected and un-infected individuals could then spread viral particles from their arms and elbows to surfaces commonly in contact with arms, furthering the problem beyond arm-operated door handles.

Chair arms, vehicle interiors, door handles, counter tops, tables, desks, and many more locations, are all possibilities. 3D printed door handle parts would also be somewhat difficult to sanitize or disinfect with typical commercial means, like liquid chemical disinfectants, due to the vast array of micro-pores that exist due to inconsistencies, and the layer-by-layer extrusion process. What’s worse, since nobody does a surgical arm scrub in the bathroom, and we don’t wash our clothes mid-day, hand washing won’t help in this situation.

Elbow coughing isn’t a very common practice (at least in the USA), but as COVID-19 PSA information spreads further, it could render the arm-operated door closer ineffective.

I think ubiquitous masking will diminish this concern, but how long will it be until the world has a sufficient mask supply, and even then, until everyone gets on board with proper masking practices?

Foot-operated controls are inherently good at preventing the spread of diseases, regardless if they’re 3D printed or not, and they’ve been used in that role for some time. First of all, they save us from having to use our hands to touch high-use hand operated controls, like toilet flusher handles, buttons, or door handles. Most importantly, outside of tying our shoes, adults rarely come in contact with the soles or sides of shoes, or the many secondary surfaces that shoes contact, such as floors, stairs, etc. Unlike surfaces that touch the upper-body, foot controls can remain in a contaminated state without posing as much of a risk to uninfected individuals.

I suspect one of the reasons why we don’t see that many temporary foot-operated controls yet, is that they’re difficult to implement quickly. It took nearly 3 weeks to make this project, for example. Transferring motion upwards by a meter or more isn’t always easy, and often requires the aid of non-3D-printed components. Several moving parts and the challenge of making a design work on most 3D printers both add to the complexity. But, with some out of the box thinking, it’s possible that you can place a mechanical foot-operated control in some unexpected places. I challenge you to take some of the ideas in this concept, and apply them in completely new ways.

Beta Testing:

I currently have no access to a 3D printer at my home. I'm asking for your help to make this idea a reality. It should be printable, and work as is. But, as you all probably know from experience, not every project works as intended the first time around!

Pulling backwards with your toes is an awkward movement, so I'm curious to see how people respond to it.

Things I have in mind to try next:

• An angled pedal surface (tilted towards the door at a 20 or 30 degree angle). That might make it easier to push down on the pedal while pulling towards you.
• A new and improved set of door handle adapters, perhaps with a stronger loop/eye.
• Some kind of locking device to force the pedal to stay in a downward position until you're ready to close the door. This would act like a standard fixed foot grip surface like you see in some restrooms. Might make it easier to open and close when stepping down onto the pedal.

What do you think? I'd love to hear your critique - positive or negative feedback - it's all welcome.

(Required) 5 main .STL files for the project, available, from Thingverse. I also posted the .STEP and Fusion 360 base files for you to modify and improve upon.

• (x1) Main foot pedal file - there are 2 initial versions to chose from.
• (x2) Left and Right rail files - You can choose an Open or Closed rail design.
  • Open means the rail has an upper stop only.
    PROS: the pedal has additional downward travel available. If mounted high enough on the door, the pedal can be removed without removing the rails. If someone stands on the pedal, it won't ruin your door (but may ruin the door handle or knob).
    CONS: if the handle adapter, rope/wire, or pedal ear snaps, The pedal will block the door from operating.
  • Closed means the rail has an upper and lower stop
    PROS: The pedal won't block the door, and the frame stops the pedal from being pushed too far.
    CONS: Inhibited travel range

• (x2) Upper and Lower half door adapter files
  • There are several sizes available- pick the one that's closest to the door handle diameter you're using.

(Required) An FDM 3D printer with 210mm of travel in the X or Y dimensions (in the build plate plane). I designed the longest parts (rails) to be manufactured with the venerable Prusa i3. You can re-design the rail parts to be longer or shorter, depending on your needs.

(Optional) Any other type of 3D printer, that is capable of the required dimensions along one axis (Ex. SLS- the FormLabs Fuse1, or EOS P810)

(Required) Mounting hardware:

4x: 1/4"-20 x 3/4" socket head cap screws (or M6 - 1.0 x 18 to 21mm)

4x: 1/4"-20 hex nuts (or M6 - 1.0 nuts)

Roll of 1" wide mounting tape, at least 15" length (tape should be as strong as possible)

-or-

For Hollow Doors- 4x: Hollow door anchors, with associated #8, or #10 screws (1,1/4" long ideally)

For Solid Doors - 4x: #8 or #10 wood screws, Between 1,1/4" and 1,3/4" in length. Round head, truss head, or similar design. The idea, is that you don't use a flat head screw, so you can adjust the rail-to-pedal gap a bit after installation.

(Required) Tension hardware:

(Suggested) Aprox. 5 ft. length of paracord or suitable rope, rated >100 lbs.

-or-

Wire rope and associated ferrules, thimbles and other permanent mounting hardware. Duct tape, shrink wrap or other material for securing loose wire ends.

-or-

A wire coat hanger, and heavy duty duct tape

These slides show how the Door Pedal operates.

These slides show how the pedal and rail assembly fit together, and an alternative pedal design I've provided.

NOTE: The tongue-and-groove joint height of both v1 and v3 pedals (the original and alternate respectively), is 100mm.

For applications where >80mm of travel is desired, you could either use the open rail design, or modify the rail and/or pedal designs.

You can use the door pedal in one of several ways, depending on the door, or other machine you want to adapt it to.

The initial design was for lever-type door handles. You can also adapt it to round door knobs.

Here are examples of round or tapered handle adapters that can be modified:

This hands free door opener lever design can be easily modified

Another style of round to lever-type handle conversion

You can use this pedal with any other number of things. Try it with light switches, toilets, etc.

You could even translate that downward motion, into a button presser, for example. You could make a pivoting arm that uses a downward pull on the foot pedal, to

Note: This design might not work that well with doors that have an automatic door closer installed.

(Seeking peer-review: If you're a mechanical engineer, please leave your feedback on the analysis steps)

These slides look at the design behind the door pedal, and what goes into choosing the proper location for your door pedal on the door itself.

Mounting the body lower on the door may add stability, and make it easier to open and close the door with your feet.

Remember, you can mount the door pedal higher up on the door (with >100mm of space underneath the rails) if you'd like to be able to quickly remove the pedal body, for deep cleaning, changes, etc, without removing the rails from the door.

You'll also need to be sure that the lever arm is placed close enough to the pivot axis to operate the door with the travel of the door pedal. There is a trade-off to this, however: the lever arm becomes shorter, and thus, the effort needed to operate the door handle increases.

These slides look at some of the considerations for 3D printing your door pedal successfully.

You'll need 2 sets of pedals to convert both sides of a single door.

NOTE: The drill guides should be oriented with the chamfered side up. I put a 0.2mm x 0.2mm cutout around the perimeter of the first layer, as this will enable you to print the part flat on the bed, without the 1st layer interfering with the stencil accuracy. The top side chamfer is there to help your pencil access the tracing surfaces. I can also post the non-chamfered versions should you wish to have a simpler model.

As I mentioned, I haven't had the chance to print these models yet, due to lack of printer access. But, the models all slice well, from 0.1mm to 0.3mm layer heights, and when using 0.4mm to 1.2mm extrusion widths. Those are only the limits that I tested. I'm sure you could push it further, in order for things to print faster.

I do suggest you print this on the high-infill side, to give the pedal additional strength. I suggest a robust infill pattern, like a gyroid, honeycomb, or 3D-structure infill.

These slides review the attachment process.

You can choose one of two attachment methods:

1) Mounting tape - not permanent, and usually non-damaging - you won't be reminded of COVID-19 every time you look at your door. It is possible that strong mounting tape alone will provide a reliable solution.

Note: If the mounting tape you choose doesn't adhere well to the rail plastic, try roughening ("keying") the base of the rails by lightly sanding with coarse grit sandpaper, and re-cleaning the rails. Be careful not to remove much material.

-or-

2) Hollow Door Anchors or Wood screws - Much more secure and reliable. You can use screws or anchors to permanently attach it to your door frame. If you have a painted door, you may be able to get away with repairing and re-touching your door if you want to remove it down the road. Unpainted, wood doors might be harder to color match and re-touch to hide the drilled holes.

This is a weakness of this design, unfortunately, when compared to the arm-style door openers.

These slides look at the rest of the attachment process.

I suggest starting by tying-off the handle adapter first, then installing the handle adapter, and then finishing with tying-off to the pedal last.

It really doesn't matter which order you choose, as long as you are able to accurately adjust the length of the tensile component in the end.

How to tie a Figure 8 Follow-Through: https://www.animatedknots.com/figure-8-follow-thro...

How to tie a Double Bowline (less strength, but a good knot): https://www.animatedknots.com/water-bowline-knot

The world needs your brilliant ideas!

Please feel free to give feedback, or let me know how the printing and installation process goes.

Also, feel free to take this design further on your own... other uses, a more efficient design... generative or adaptive AI design... the sky is the limit!

I'm open to collaboration as well, if you're interested in helping.

Please read this before using the design.