Introduction: Accessible PVC Hygiene Chair

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About: Wichita State’s undergraduate certificate in assistive technology and accessible design is an interdisciplinary program teaches students to design and build products that improve learning, working and daily li…

This project involves building a waterproof hygiene chair for an elementary school student, who struggles to sit up independently when using the restroom. This student has a condition called Rett syndrome that has resulted in diminished muscle mass. The chair is designed to roll over the top of a toilet to provide more comfortable and accommodating seating when using the restroom and trunk support via custom-made support straps. While primarily being intended for using the restroom, the chair is also waterproof which allows it to be used in a shower and other applications involving water. This hygiene chair features armrests that swing outwards to allow for easy transfers, an adjustable backrest and headrest to accommodate different heights, and a push bar for assisted traversal.

Supplies

Below are the materials that were necessary to build the custom hygiene chair. Quantities listed take into account expected error with materials (faulty components, human error, etc.). Each item contains a link to the supplier where each of these items were purchased.

PVC

Straps and Headrest Cushion

Wheels and Stoppers

Backrest, Headrest, and Seat

Step 1: Create CAD Model

Attached is the PDF of the CAD model that was created for planning the dimensions of the chair. These measurements take into account the dimensions of the space that the chair will be utilized in, the measurements of the person who will be using the chair, and the expected growth of the user. In your own design, the measurements can be adjusted to better suit its use. Note that the base of the chair was shrunk to fit our needs later in the project.

Attachments

Step 2: Cut PVC

Using the 1.5" PVC, make the following measurements:

  • Two 2" Sections
  • Two 2.25" Sections
  • Twelve 6" Sections
  • Six 8" Sections
  • Three 12.75" Sections
  • Six 14.75" Sections
  • Twelve 20" Sections

After making these measurements, utilize the PVC cutters to cut out each of these sections. If the cuts turn out crooked or uneven, use a sander as necessary. These cuts will be used to make the main frame of the chair.

Step 3: Trim Ends of PVC Connectors

To provide the proper spacing between the PVC pipes, it is necessary to trim the ends of some of the PVC connectors. Cut the following ends off of the following PVC pieces to provide the necessary spacing:

  • Twelve tee connectors with a single side cut
  • For these connectors, cut off one of the arms of the 'T' as far as possible. An image of the cut can be seen above.
  • Two tee connectors with both sides cut out
  • For these connectors, cut off both arms of the 'T'. An image of the cut can be seen above.

These cuts can be made utilizing the PVC cutter or a band saw if preferred. Once the cuts have been made, use a sander to straighten the cut edge as necessary.

Step 4: Internally Sand PVC Connectors

The interior of some of the PVC connectors need to be sanded to allow for them to slide on the PVC pipes. This allows the chair to be adjustable and to grow with the user. The following parts need to be sanded:

- All of the connectors that previously had an edge trimmed off of them will need internal sanding.

- Two tee connectors with no cuts will also require internal sanding.

In our product, we utilized an oscillating spindle sander to achieve this. Start by inserting one end of the connector from the through/long side over the sander. It may help to put a scrap piece of PVC pipe in one end to create a 'handle'. Carefully move the connectors up and down to sand each part of the interior, while gliding the connector around in circles. Repeat this step on the opposite side to ensure that the interior is evenly sanded. Use a file to scrape the interior to remove any melted or stringy excess.

Step 5: 3D Print Collars

The 1.5" collar needs to be 3D printed six times. This collar will be placed on the backrest to keep the PVC connectors in place. The 1" collar needs to be printed twice and will be used with the headrest. The STL files for the print can be found linked below.

The 1.5" collars will use the 1/4-20 wingnuts and screws and the 1" collars will use the #10-24 wingnuts and screws.

Attachments

Step 6: 3D Print Backrest, Footrest, and Headrest

The backrest, footrest, and headrest were all created using a 3D printer. The corresponding STL files can be found below.

The next steps will detail the process of assembling the backrest and footrest. The headrest will need to have the interior loop filed down a bit to allow for better sliding on the PVC that it will be connected to. Later in the document there will be detailed steps on how the headrest section will be assembled.

The headrest will use the #10-24 wingnuts and screws.

We recommend printing these parts with supports.

Attachments

Step 7: Assemble Footrest

To assemble the footrest, the first step is to remove any of the remaining supports from the print. Then, the sides with the holes or pins will need to be sanded so the epoxy, and the other pieces, will have a rough surface to adhere to. A piece of sandpaper was used to sand the pins, the area between them, and the outer surface of the side with holes.

Once everything is sanded, the epoxy can be mixed. Combine equal parts of the epoxy and resin that came in the pack. We mixed them in a disposable cup and used a Popsicle stick to stir and apply the epoxy. The epoxy will go wherever the footrest was sanded. It is recommended to epoxy two pieces together at a time and to firmly hold them in place. It will take about five minutes for everything to fully harden.

Step 8: Assemble Backrest

The steps to assemble the backrest are similar to assembling the footrest. However, the order of assembling the backrest matters since it will be unusable otherwise. Be sure to epoxy the top and bottom halves independently and then connect the two halves.

If the backrest is glued one part at a time, the final piece will not be able to fit.

Step 9: Drill Holes Into PVC Crosses

In the center of each of the PVC crosses, a hole needs to be drilled through the entire section using a drill press to allow the bolt to pass through for the wheel. Use a tape measure to measure to the center of the cross and make a mark. To confirm that the cross is aligned properly on the clamp, use a level to make sure the cross is laid flat. Utilize a 21/64" (5/16" may work as well but it will be tighter) drill bit on the drill press to make a precise, uniform hole.

Step 10: Drill Hole for Caster Wheels

Drill a 5/16” hole into the bottom side of two of the three-way PVC connections. The caster’s stem should fit into this hole and will be tightened using the 5/16”-18 nylon locking nuts.  

Step 11: Drill Holes for Rubber Stoppers

The hole in the stopper will need to be expanded due to awkward size. Center and level the stopper on the drill press and utilize a 1/4" drill bit to create the hole through the top of the stopper. Next, a hole will need to be drilled through the bottom of one of the three-way connectors. This can be done either by using a drill press again or just with a hand drill. A 1/4" drill bit will also be utilized to create the hole in the bottom of the PVC. Once the holes are through both the PVC and the stopper, a 1/4-20 x 1" bolt is then passed through the stopper and into the PVC. Twist a 1/4-20 Nylon Locking Nut on the interior of the PVC as shown in the photo above. Repeat these steps another time to create the second stopper mechanism.

Step 12: Drill Holes for Seat Adjustments

Drill holes through the long side of the tee fittings that rotate around the crossbar of the base. The hole will have to go through both sides of the fitting and the pipe that the fitting rotates about. Then a retaining pin can be pushed through the hole to fix the backrest into a rigid position. We drilled holes that allowed the backrest to stay rigid at 90 degrees from the seat for toileting and about 120 degrees from the seat for showering.

Step 13: Drill Holes for Headrest

For one 12 3/4" inch long section of 1.5" diameter PVC pipe use a 1 3/8" hole drill bit to make two holes with 6 inches between them (between edge of holes not center of holes). These holes will be used to slide 1" PVC through. It may also help to connect the headrest 1" diameter PVC and elbows as described in step 21 to ensure this will allow proper movement.

Step 14: Begin Chair Assembly

Now that each of the components have been properly prepared, it's time to assemble the chair. At this point in the project, you should have the pieces as shown above.

We recommend building the chair as a whole before gluing to make sure that everything is sized correctly. Once the PVC is glued it isn't coming apart. The only way to make adjustments will be to cut pieces and start that part over.

When putting together the frame, use the PVC primer and glue to seal the PVC pipe to the connector. This will increase the stability of the chair and prevent the chair from falling apart.

To prime the PVC, dip the brush connected to the lid into the primer and rub the brush around the inside edge of the can to remove the excess primer. Then begin brushing the outside of the male side of the PVC in a circular motion out about an inch to an inch and a half from the edge. You will need to brush in circles about 20 to 25 times to properly prime the PVC. After doing this, repeat this process on the inside of the female side of the PVC (the connector). Once both sides are primed, you have around five minutes to apply the glue.

To glue each side, begin with the female side of the PVC and brush in circles on the parts that are primed. This part will only need to be brushed around 5-10 times. Unlike the primer, the glue only takes around 30 seconds to adhere, so the gluing process needs to be quick. Next, glue the male PVC piece, following the primed parts similarly to the previous step. Once the glue has been applied to both pieces, insert the male PVC component into the female PVC component and twist. Push the PVC together firmly to prevent it from popping back out and hold it pressed together for around 15 seconds to allow the glue to set. The PVC should now be firmly glued together. In cases where you can't twist the pieces, be sure to hold it together for longer.

Step 15: Slider Assembly

Needed PVC and Connectors:

  • Four 20" pipes
  • Two tee connectors with both ends cut off
  • Six tee connectors with one end cut off

Four sliding pieces are needed to make the seat and footrest adjustable. For the seat, take one 20" pipe and attach a tee connector with both ends cut off to either end of the pipe. Make sure the arms of the tee are free. This will be slider A. Next, take another 20" pipe and attach a tee connector with one end cut off on either side. Make sure the arms of the tee are free and that the remaining ends are pointing the same direction. This will be slider B.

For the footrest sliders, take a 20" pipe and attach a tee connector with one end cut off on either side. Make sure the arms of the tee are free and that the remaining ends are pointing the same direction. Repeat this step twice. These sliders will be sliders C and D.

Step 16: Chair Base Assembly

Needed PVC and Connectors:

  • Twelve 6" pipes
  • Six 14.75" pipes
  • Six 8" pipes
  • Two 20" pipes
  • Two cross connectors
  • Eight tee connectors
  • Two tee connectors with one side cut off
  • Four 90 degree elbow connectors
  • Four three-way connectors
  • Four sliders created in step 14
  • Weighted rod

1. Start with the base of the chair. Beginning with the cross connector, pick a side to be your 'top' end. Add a 6" pipe to the top end and another 6" pipe to the bottom end. Put a 14.75" piece to the left and an 8" pipe to the right. Following the image above, assemble together each side of lower frame.

2. Slide one end of slider A onto the top right 8" pipe. Slide one end of Slider B onto the top left 14.75" pipe. Have the cut end facing outward.

3. Slide one end of slider C and one end of slider D onto the middle left 14.75" pipe. Have the uncut arms of the tee connectors facing each other on the inside.

4. For the 6" pieces, attach a tee connector so the arms are free. Attach a 14.75" pipe to the left end and an 8" pipe to the right end.

5. The sides are made of an elbow connected to a 6" pipe. This connects to one arm of a tee connector with another 6" pipe on the opposite end. This will be capped with a three-way connected. Repeat this process so there are two side pieces.

6. The three pieces can now be connected together. Make sure to have the three-way connectors at opposite corners of each other.

7. Repeat steps 1 through 6 of the Chair Base Assembly to end up with two sides.

8. Insert the weighted rod into one 20" pipe. Then, use the pipe to connect both sides of the 14.75" pipes by placing them into the openings in the three-way connectors.

The rod is used to help weigh down the chair. Since this chair was designed for elementary school kids, extra weight is needed to prevent the chair from tipping backward unnecessarily.

9. Insert one end of the other 20" pipe into the three-way connector on the 8" pipe. Slide the two tee connectors with one side cut off onto this pipe. Make sure to have the uncut ends facing each other on the inside. Then, insert the other end of the 20" pipe into the three-way connector on the other side to complete the base of the chair.

When you are ready to glue, make sure to glue them together after placing the sliding connectors in the proper locations as seen above, adding the weight inside the 20" pipe, and sliding the two tee connectors with one end cut off onto the other 20" pipe.

Step 17: Chair Back Assembly

Needed PVC and Connectors

  • Six 1.5" diameter PVC elbows
  • Six 1.5" diameter 3D printed collars
  • Six 1/4-20 wingnuts
  • Six 1/4-20 zinc plated combo round head machine screws
  • Six 1.5" PVC tees with one side cut off
  • Three 12.75" PVC pipes (one with holes cut for head rest)
  • Two 2" PVC pipes
  • Two 2.5" PVC pipes
  • Two 1.5" PVC caps

1. Start with placing two 20" long PVC pipes into the top of the PVC tee from the base of the chair.

2. Slide a 1.5" diameter 3D printed collar down on each of the PVC pipes that were inserted in the previous step. Make sure to slide these collars all the way to the bottom and use the screws and wingnuts to tighten each collar.

3. Slide down a PVC tee connector with the cut side of the connector facing upwards on both of the 20" pipes and the open female connection facing outwards, parallel to the bars on the lower half of the chair.

4. For each of the tee connectors that were inserted in the previous step, insert a 2" PVC pipe.

5. On each of the 2" pipes, insert a PVC elbow on the end of them, angling them parallel to the bars on the lower half of the chair.

6. Insert 20" PVC pipes to the end of the elbows and push the 1.5" diameter PVC caps on the ends of each of them. These form the armrests for the chair.

7. Slide a PVC collar down on top of each of the PVC connectors that were inserted in step 3. Use the screws and wingnuts to tighten the collar

8. Slide a PVC tee connector down on top of each of the PVC collars, with the cut side facing down and the open female side angled inward, parallel to the the bar on the lower part of the chair.

9. Insert a 12.75" PVC pipe without the holes in the middle in between the two PVC tee connectors from the previous step. It is recommended to rotate one of the connectors outward to place the PVC inside and to swing it back around to insert it into the other connector. This approach was found to be easier than trying to wedge the pipe directly between the two connectors. It is also possible to put them together prior to sliding them onto the 20" pieces of 1.5" diameter pvc.

10. Slide collars on top of each of the PVC tee connectors that were inserted in step 8. Use screws and wingnuts on each of them to tighten them into place.

11. Slide the last two PVC tee connectors on top of the collars with the short side facing upwards and the open female connections facing inwards, parallel to the bar from step 9.

12. Using the 12.75" PVC with the holes in the center, angle the holes facing straight upwards (parallel to the crossbar below) and insert it into each side of the PVC tee connectors. It is recommended to use the rotation strategy as described in step 9.

13. At the top of each of the vertical 20" PVC pieces, place a PVC elbow angled outwards and perpendicular to the crossbars in steps 9 and 12.

14. Insert a 2.25" PVC pipe into the open female side of both of the PVC elbows from the previous step.

15. Insert a PVC elbow onto the ends of each of the 2.25" PVC pipes, angled inwards and parallel to the crossbars in steps 9 and 12.

16. Insert the last remaining 12.75" PVC pipe between the two elbows.


Similarly to the previous step, make sure that the pipes are glued after the collars and sliding PVC connectors are on.


The collars are meant to be adjustable, so if you want to make adjustments to the position of the backrest in the future, you can unscrew the wingnuts slide the backrest up to where it is needed, and screw the wingnuts back into the collar to secure that position.

Step 18: Attach Wheels

Using the bolt that came with the wheelchair wheel, slide a washer all the way to the head of the bolt. Slide the bolt through hole in the center of the wheel and put another washer on the other side of the wheel. Then thread the bolt through the hole in the middle of the PVC cross at the base of the chair. Repeat these steps for the other wheel.

Step 19: Drill Drain Holes on the Bottom of the Chair

To account for any water that has made its way into the chair, drain holes must be created for the water to exit the chair. On the bottom of the chair, each long section will need two to three holes drilled through them. Using a hand drill with a 1/8" drill bit, drill these holes evenly spaced across each of these sections. A photo reference of where our holes were drilled can be seen above.

Step 20: Attach Seat, Footrest, and Backrest

To attach each of these components, the PVC and connectors on the areas that these pieces will be attached to need to be sanded down first. Using sandpaper, rub the PVC in a "wrenching" motion around the entirety of the pipe/connector. Sand around each side of the pipe to make sure that it is evenly sanded. The backs of the footrest and backrest will need to be generously sanded as well to allow them to properly adhere to the PVC.

Once the PVC and components have been prepped, they are ready to be epoxied onto the PVC. To prepare the epoxy, mix an even amount of the epoxy resin and 5 minute epoxy in a plastic cup. We utilized Popsicle sticks to mix and apply the epoxy. When the epoxy has been thoroughly mixed, evenly distribute the mixture on the PVC. Make sure to apply a generous amount of the epoxy mixture to make sure that these components are strongly adhered. Once the mixture has been properly applied, place the component onto the spot and firmly press around the edges that are touching epoxy mixture. Firmly press down on these parts for around 30 seconds and then place a heavy object such as a book bag or stack of textbooks to hold down the sections. Wait for around 15 minutes for the epoxy to fully set and adhere to each component.

When the backrest has been epoxied on, the back cushion will then need to be epoxied to the backrest itself. This step can either be done before epoxying the backrest to the chair or after. To get the cushion epoxied, repeat the steps as described above but with the cushion and the top of the backrest.

Step 21: Create the Headrest Section

Supplies needed:

  • Headrest 3D Print
  • Two 1" diameter PVC elbows
  • PVC cutter
  • 10ft 1" PVC
  • Two 1" diameter 3D printed collars
  • Two #10-24 x 1" bolts for collars
  • Four 1/4-20 x 1" bolts for headrest
  • Four 1/4-20 wingnuts
  • Two 1" diameter PVC caps

1. Using the PVC cutters and the 1" diameter PVC cut the following pieces:

  • One 8 inch PVC sections
  • Two 9 inch PVC sections

2. Using the two 8 inch sections, insert them into separate 1" PVC elbows and rotate the female connections of the PVC elbows to face each other.

3. Using a file, scrape the interior of the main hole to help allow the headrest to better rotate on the PVC. This will allow for the user to angle the headrest in different positions.

4. Slide the headrest through the 8 inch section. Now insert the 8 inch section into each of the elbows.

5. Slide the 1" diameter 3D printed collars to the ends of each of the PVC elbows (not the end near the 3D printed headrest). Use the #10-24 wingnuts to lock them into place.

6. Place the PVC and headrest through the holes in the chair back and place the the 1" diameter PVC caps on the ends of each of the pipe.


This part is not to be glued to allow the headrest to be removed. The headrest can be removed by taking off the PVC caps at the bottom and sliding the PVC bars out of the holes in the back of the chair.

Step 22: Creating the Straps and Headrest Cushion

The next steps in this Instructable will detail how to create the trunk support straps for the chair. These straps provide proper support to the person using the chair to allow them to sit up properly. These straps are designed to also be comfortable, decently waterproof, and adjust as the user grows.

Step 23: Measure and Cut the Straps

Using the nylon fabric, measure out two 25" strips and two 30" strips using chalk. Next, measure out two 10"x6" and two 12"x6" sections of duck fabric. Then, measure out two 9"x2" and two 11"x2" sections of neoprene. Finally, use the fabric scissors to cut out each of these pieces. Hem each side of the four sections of duck fabric using a sewing machine or by hand. We recommend folding the edges over about a quarter of an inch and hemming so the threads don't come loose over time. To prevent the edges of the nylon from fraying, use a lighter to melt both edges by holding the flame close to the nylon without actually touching the flame to the nylon. The edges just need to melt a little to prevent fraying.

Step 24: Assemble the Straps

To make the chest straps, lay out one of the 10"x6" pieces of duck fabric with the tucked in side of the hems facing up. Place one of the 25" strips of nylon on one side of the duck fabric. Place one of the 9"x2" sections of neoprene on top of the nylon.

The process for the waist straps is the same, but with the 30" strips of nylon, 12"x6" sections of duck fabric, and 11"x2" sections of neoprene.

Pick one of each of the chest and waist straps to be used for the female end of the buckles. Take the chalk and mark a 2" wide line 2.5" from one end of the sleeve on the side of the duck fabric closest to the nylon. Carefully make a cut where the line is. Now take the nylon and loop it through this cut instead of the opening 2.5" away. This will allow for the buckles to sit on top of the padding and will be more comfortable for the user.

For each piece, fold the duck fabric over the neoprene and use clips or sewing pins to secure the fabric in place along the long edge.

Step 25: Sew Straps Together

The length of the duck fabric will be sewn together to create a sleeve over the nylon strip. The edges will be left open. The nylon should still be able to move freely but the neoprene should be snug. Repeat this process for all four straps.

Step 26: Attaching the Buckles and Connecting to the Chair

Each piece of the straps will get a slide clip and the chest and waist straps will share a buckle each.

For the straps with the male connectors, loop one end of the nylon strap through the upper slot and back through the lower slot. This piece can then be looped in on itself and sewn to prevent the buckle from falling off. We recommend hemming the nylon here so that the melted edge isn't exposed.

For the straps with the female connectors, the same looping will be done with a buckle and with the nylon coming through the cut.

The slide clips will be placed on the opposite end of each strap and will be used to secure the straps to the chair. The nylon will be looped around the chair in a teardrop shape. For the waist straps, the straps will be attached on the 20" bar behind the seat. Take the nylon ends with the slide clips and wrap the nylon around the 20" bar so the clips are between the bar and the seat. The nylon will go back through the slide clip and this will allow the straps to fit snugly but also be easily adjusted. For the chest straps, the straps will be attached to the chair back between the two bars that hold the backrest.

Step 27: Measuring the Headrest Fabric

Using the duck fabric, measure out a rectangle that is 12"x10". Then, mark 1.5" squares in each of the corners. These corners will be cut out so the shape matches the one shown in the pictures. Draw a line around the fabric about a quarter inch inward to mark where the hem will be. For the four inner corners, draw a line connecting the hemline and the outer line of the fabric. For the outer corners, draw a line from one outer line of the fabric to the other that passes through the point of the inner hemline. This should create a triangle shape.


Using the neoprene, measure two 7"x5" rectangles. This will be used as a cushion.

Step 28: Cutting and Sewing the Headrest Fabric

Cut along the outer line of the duck fabric and the diagonals of the triangles to match the pictures above. The marks on the four inner corners will be cut to allow the fabric to fold easily.

Cut out the two rectangles of neoprene.

Fold along the hemline of the duck fabric to create the hem and use clips or sewing pins to keep the fabric in place. This will help protect against fraying. Use a sewing machine or hand sew the hem.

Using a hot glue gun, glue the two pieces of neoprene together. Then, glue the neoprene to the duck fabric.

Step 29: Adding the Buttons

Using the 3D printed headrest as a guide, lay the headrest on the neoprene and fold the edges over. Use sewing pins to mark where the corners of each side overlap. Moving one corner at a time, mark the spot where the sewing pin is with chalk on the outer fabric. Follow the directions included with the snap pliers to pierce a hole in the fabric. Lay the outer fabric back over and mark the location of the hole on the inner fabric. Then, pierce a hole in the bottom layer. Follow the instructions included in the snap pliers to attach the snap on buttons. We used the longer edge to hold the tops of the buttons and the shorter edge of the fabric to hold the bottoms of the buttons. Once each corner has a set of buttons, the fabric can be attached to the headrest.

Step 30: Works Cited

Located below are resources that were used for inspiration and assistance in creating the chair:

  • Sahlstrom, Benjamin. “How to Prime & Glue PVC Pipe like a Master Plumber.” YouTube, YouTube, 22 Dec. 2017, www.youtube.com/watch?v=8kKVIoUhyYA.
  • The images above were provided by our sponsor Leah Fisher and were used as our main inspiration for the chair design