Introduction: Jen's Front Porch Shoe Sanitizer
My niece, Jen, called and asked me if I could make something to clean the soles of peoples' shoes before they come in the house. She had a pretty clear idea of the basic design she wanted, and how it would work -- you would step on something that would pump a spray of cleaning solution on the soles of the shoes, and have brushes to scrub the dirt off -- she just needed some help on the maker side.
I had Jen's description and a few basic criteria in mind when I went to the drawing board. The device should be as simple as possible, usable by adults and children, made from inexpensive and durable materials, and be easy to clean. I don't know what cleaning solution Jen had in mind, but I wanted to avoid metal parts as much as possible.
I started with the idea that the mechanism would sit inside a container that would hold the cleaning solution and catch the splatters. I wanted to use a recycled container, if possible, and the jugs they sell cat litter in are about the right length to fit adult shoes. I made the design to fit inside one of these jugs, but in the end, I decided that a plastic wastebasket would be more attractive and easier to get your feet in and out of.
It was pretty clear that the best way to squirt cleaning solution on the soles of shoes would be to have the brushes mounted on a foot-plate, with sprayers embedded among the bristles of the brushes. A foot-powered pump mounted under a hinged plate is the obvious way to power the washer, but I didn't want to use a metal hinge. I settled for a loose-fitting mortise and tenon joint, for the hinge, with tenons (tabs) at each end of the foot-plate. To keep the foot-plate stable and prevent it from sliding out of the mortise it would need a vertical slot for the foot-plate to slide up and down in at the other end. Add a couple of side pieces to hold the mortised toe-piece and the slotted heel piece, and the basic design is complete. Mount the pump, attach brushes on top and tubing on the bottom of the foot-plate, and and you're done. Simple enough, and it really was fairly simple, in concept. Getting the plumbing together and installing the sprayers was actually pretty challenging, and I'm not entirely happy with the results. The basic concept is pretty functional, but with some tweaking it could be much better. I have included suggestions to improve the design at the end.
Jen's shoe sanitizer is composed of three basic parts: the tank (container); the support frame (with the pump mounted inside); and the foot-plate (which includes tubing, brushes, and spray emitters). The support frame and shoe-plate are made from 1/2-inch thick high density polyethylene sheet, similar to a plastic cutting board material.
I have not worked with this High Density Polyethylene (HDPE) before, but it cuts easily and is easy to work with hand tools, and doesn't make dust or need sanding. It should also hold up well to any cleaning solution and be easy to clean. Hopefully the joints will hold up well over time.
The pump is kind of pricey ($30), but well worth the money. It's designed for boats, so I'm optimistic that it will hold up over time.
Note: I'm showing some PVC pipe fittings in the picture. I had planned to use these to make a handle for support, but I dropped that idea due to space issues. Hold onto a wall or something.
Recycled Cat Litter Jug (The assembly fits inside any container at least 7-inches wide by 11 1/2-inches long.)
Plastic Waste Basket (7-gallon) (or cat litter container) [Jen just uses a dish pan.]
Stainless steel screws 1 1/4-inch long
10 short pan-head stainless steel screws 1-inch long
Side Brushes (4)
Tubing Connectors (14)
10-feet 1/2-inch (ID) Clear Vinyl Tubing
Drill/Screwdriver, bits (one 3/4-inch diameter)
Dremel Tool for adjusting fit
Sharp Utility Knife
Step 1: Find a Jug or Container
Find a jug (or other container) and cut an opening large enough to put a large foot inside, leaving about 5-inches of the base in tact. I just did this freehand, it doesn't have to be perfect, just make sure the front edge is not too low, or solution could splash out of the container.
I actually like this seven-gallon waste basket better, as a container for the shoe washer. The only difference in the design would be to make all the support frame pieces four-inches tall (instead of 4 1/4-inches), which would result in a slightly wider foot-plate (~7 1/2-inches, rather than 6 1/2-inches). Also, I would make the back slotted piece taller so the pump stroke could be longer. I only trimmed about a 1/2-inch from the length of the foot-plate and base frame parts, so it would fit in this waste basket fine just leaving the material at the stock length (11 3/4-inches).
If I was keeping this I would have cut an opening in the front of the waste basket, but since I'm shipping this to Jen, I decided to keep the waste basket in tact to prevent it from cracking during shipping.
Step 2: Cut Parts and Assemble the Support Frame
I used a power miter saw to cut four, 4 1/4-inch wide strips of HDPE for the base frame. This leaves about a 6 1/2-inch wide by 12-inch long piece to make the foot/brush plate.
The long base-frame parts and the foot plate are trimmed to about 11 1/2-inches long to fit inside the jug. The other two 4 1/4-inch wide pieces are cut to make the end parts of the base frame. One of these needs to be about seven inches tall, and the other needs to be about six inches tall. This will leave two four-inch wide pieces, one about five inches long, and the other about six-inches tall. I'm using one of these (the five-inch long piece) to mount the pump between the two side pieces. The other piece will be cut in one-inch strips that will be attached to the top of the foot-plate to allow the side, front, and back brushes to be mounted at angles, leaning toward the center.
The foot-plate is made to be reversible, so when the brushes start to show wear, you can pull the foot-plate out and turn it around to get more use out of the brushes. Trim off the corners of the foot-plate at 45-degree angles, about 1 1/2-inches in from the corners (just remove enough to fit the foot-plate into the container you're using).
The end pieces to be attached at the front and rear of the base-frame will be modified to hold the foot-plate. The front one will have a rectangular hole (mortise) cut in the end, to allow the front "tab" (tenon) of the foot-plate to fit through the hole, making a fulcrum (hinge point). The rear upright piece will have a wide slot cut to guide the foot piece so it can slide up and down as the pump is activated. Drill some holes and use a jigsaw to cut the mortise, and cut the slot piece to the same width.
The support frame is screwed together with stainless steel screws. One of the left over pieces will be mounted crosswise between the support-frame side pieces to mount the pump. The height for mounting this piece is determined by how much you want the pump to push each time the foot-plate is pressed down. I left the pump sticking about 1 1/2-inches above the sides of the support-frame.
Use a jigsaw to cut two-inch wide tabs a half-inch long sticking out from each end. These tabs are sized to fit in the mortise and the rear slot. Clean the edges up with a file and a sharp utility knife.
If you want to use cleaning solution from an outside container, drill a hole near the middle of one of the support-frame side pieces to rout tubing to the outside container.
Step 3: Cut the Handles Off the Brushes
I'm using two kinds of brushes. One (the blue one) has about 3/4-inch long bristles. The four white brushes have longer bristles. By mounting the longer bristle brushes at angles, the brush assembly sort of makes a bowl-shape with sanitizing solution squirting from sprinkler heads around the sides and in the middle.
To mount the brushes you'll need to cut off the handles. This is pretty straight forward, and doesn't need to be pretty, as the cut parts will be hidden against the foot plate. I tried using power tools to cut off the handles, but I don't recommend that. Just cut the handles off with a hand saw or hack saw.
To get all the brushes to fit on the foot-plate, I trimmed about a half-inch from each end of the blue center brush.
Step 4: Mount Support Blocks and Brushes
The brushes and feed tubing will be mounted to the foot-plate, but I thought it would be a good idea to "tilt" the front, side, and back brushes angles toward the center. I used the one-inch wide strips cut from the scrap piece of HDPE to mount at the sides and ends of the foot-plate to allow the brushes to be mounted securely at angles. The one-inch strips are screwed in place with shorter (1-inch) stainless steel screws to avoid having sharp things sticking through the foot-plate. Use the same short screws to mount the center brush flat against the foot-plate.
Arrange the front, back, and side brushes leaning against the side blocks and butting tight against the center brush. Drill pilot holes and mount each of the brushes securely with two screws.
Step 5: Make a Manifold, and Attach Tubing, and Emitters
Arranging the manifold and mounting it, with the drip sprayers connected through the brushes and foot-plate is the most challenging part of this project.
Take your time and figure out the arrangement for where you need tubes to feet the drip sprayers. You may be able to get all the spray you need from only two feed-tubes running the length of the foot-plate. I built the manifold first, keeping in mind where I wanted sprayers on top. The thing to watch out for is to plan the layout so that you don't have to connect a drip fitting to the hard plastic 1/2-inch tubing connectors.
Because there is a lot of stuff that has to fit into a small space, I ended up having to cut down most of the 1/2-inch drip fittings. I tried to save at least the first barb, but for many of the connections there wasn't enough room for this. I decided that the fittings that didn't have barbs should have hose clamps, but this added to the difficulty of fitting the parts together.
After cutting the fittings to length, take care to scrape off all the little bits of plastic and blow the fittings clean. Otherwise you will plug up the drip sprayers.
You will need to connect the manifold to double-end drip connectors on the underside of the foot-plate, with short pieces of 1/4-inch drip tubing, connected to the other end, extending up through the brushes. This is a difficult connection, and it's made worse with the brushes mounted at angles. You can make it a little easier by drilling large (~1/2-inch) holes through the foot-plate, but stopping before going through the brush. (To guide where to drill, use the manifold to figure out where you can get drip connectors to line up with the vinyl parts of the manifold.) These larger holes allow you to turn the foot-plate over and drill between the bristle clusters to hit this larger hole. I used a combination of measuring and guessing to aim for the large holes, when you drill through the brush. I tried to miss the bristle clusters, but it's hard to drill the holes without damaging some bristles.
Feed short pieces of 1/4-inch drip tubing through the brush and foot-plate, then press a double-end 1/4-inch drip connector onto the end of each drip tube. Once all the holes are drilled and the drip tubing pieces are in place, cut the drip tubes to length (they should extend just a bit above the base of the bristles on the top, and be just about flush with the underside of the shoe-plate on the bottom.
To mount the manifold, align the manifold above the double-end drip connectors sticking out of the underside of the foot-plate, and carefully mark where you want to pierce the vinyl tubing to make the connections. The larger holes through the foot-plate give you a tiny bit of leeway, but you still need to do this carefully. Pierce holes through the vinyl tubing at the places you marked, and press the manifold onto the underside of the 1/4-inch drip connectors. It may help to warm up the tubing before trying to push it onto the connectors. I bought some hold-downs, but found that the drip fittings hold the manifold in place without them.
If I made another one of these, I think I would try to arrange the manifold differently. There are lots of options so think about what will work best for your situation. In particular, I wish I had decided against having part of the manifold extend through the support-frame at the corners. This seemed like a good idea but caused a lot of difficulty. I'm sure I could have gotten spray to the sides without them.
You want to be able to lift the foot plate up for cleaning, changing filters, and such, so leave an extra couple of loops of the vinyl tubing between the foot-plate and the pump. The vinyl tubing can be stashed under the pump or just crammed in so that it doesn't interfere with the pump.
Step 6: Attach Hoses to the Pump
You're almost ready to go, just attach the tube from the foot-plate onto the output side of the pump. For this pump, the left hand fitting (holding the pump with the fittings pointing up) is the output side and the right hand fitting is the intake side.
Lastly, you need to connect the intake side of the pump to a short piece of tubing that will get as close as possible to the bottom of the tank. I'm using an elbow fitting that can just be rotated down to reach the bottom of the tank, and be rotated up for changing the filter. The filter is just a bit of scrubby material I wrapped around the tube and fixed in place with a little zip tie.
Before adding that last bit of intake tubing to the elbow piece, think about whether you want to attach the intake to an external tank of cleaning solution. If you want to use an outside source for the cleaning solution, use one of the holes you drilled in the support-frame to rout the tubing from the pump to the outside of the washer. If you didn't drill that hole, do it now.
Step 7: Put It Together and Clean Your Shoes
You're done, just put your shoe sanitizer in a container, add some cleaning solution and the setup is ready to go. Place your foot on the foot plate, press down a couple of times to squirt cleaning solution through the emitters. Scrub your shoe back and forth and side to side a couple of times. Step onto an old towel to dry your cleaned shoe. Repeat with the other foot and you are safe to enter without having to worry about Jen yelling at you to take your filthy shoes off.
This prototype actually works, but it could work better. If I do this again, I will make a few changes. First, it wasn't worth the effort to prop the side and end brushes at angles. My main reason for doing that was because I was trying to fit this inside a recycled container. It would fit fine in the wastebasket with the brushes lying flat. Also, using the blocks under the brushes just made it more difficult to add the sprayers.
The pump pushes enough water to feed the sprayers, but I used way too many of them. There are a dozen sprayers in this model, and I think fewer sprayers, with more pressure, would work better. You can get more pressure by having a longer pump stroke, but if you raise the pump very far, you will have a problem getting the back "tab" to fit into the guide track. You can get around this problem by moving the pump further forward (being careful to avoid the manifold), but as you do this the pump becomes harder to push down because it's farther from the fulcrum point. If you are making this for lots of small people to use, you might consider making the back part with the slot taller to allow for a longer pump stroke.
The whole contraption kind of has too much going on in too small of a space. Trying to get the pump to operate without getting in the way of the tubing was really difficult, and with the small space, I had to modify a lot of the half-inch fittings, which meant that the fittings needed hose-clamps, and the hose clamps got in the way of the support frame, requiring a lot of tweaking the pieces to get them to fit. In the future, I think I would splurge for a larger piece of HDPE, and make the base-frame wider so I wouldn't have needed to rout some of the tubing to the outside.
Lastly, I don't know if using all 1/4-inch drip tubing and fittings would work, but it might be worth a try. The half-inch tubing and connectors took up quite a bit of room and it was a pain having to add clamps to a lot of the fittings. In general, I think it would have been worthwhile to try out different manifold arrangements to see if there's an easier way to connect the sprayers.