Open Wheelchair Assembly Instructions
Before you Start
This is important! Do not glue or cement the PVC joints. Instead, drill holes and then use screws to lock the PVC joints. If you glue the joints, there will be now ways to fix the chair if there is a problem or adjust the chair as the child grows.
Step 1 - Measure your Child's Physical Dimensions
You will need a tape measure to measure 6 of your child's physical dimensions. These dimensions are entered into the Pipe Length Calculator on the parts list page. The calculator will tell you the length of each pipe segment and the total length of PCB piping that needs to be purchased.
Step 2 - Purchase and Gather Materials and Tools
Purchase the the various parts listed on the parts list page.
Step 3 - Cut the PVC pipe segments
Cut the PVC piping using a PVC cutter or saw, into the various 12 segments that are indicated in the parts list. Remember that the length of these segments is dependent upon the measurements of the child that you've taken. Because so many pieces need to be connected it is important that the cuts are straight and accurate. You can use a hand held PVC pipe cutter or a circular saw.
If using a saw, to save time you can bundle together the pipes such that their ends are aligned with masking tape and then cut them with a single stroke. When cutting the pipe remember to factor in the curf (width) of the saw blade in your calculations so that the length is accurate. Remember to wear safety goggles when using the saw.
Step 4 - Assemble PVC Base
The PVC frame will be assembled in 2 parts: the base, and the top.
The assembly goes much more quickly if you organize each of the PVC parts into labeled piles. You can take a piece of paper and label it with the number 1-12 and letters A-F, then set the PVC parts on the appropriate labeled paper. With the PVC pieces labeled you can quickly grab the correct part, as you assemble, rather than sorting through a pile of random parts, and then measuring each item to make sure it is the correct length.
Gather the various parts for the base assembly as listed in the following table:
Assemble the pipe segments and connectors as shown in the following figure. Connectors have square annotations and pipes circular.
Step 5 - Assemble PVC Top
Gather the various parts for the base assembly as listed in the following table:
Assemble the pipe segments and connectors as shown in the following figure.
Step 6 - Secure Motor Bracket Assemblies
The motor bracket assembly consists of 2 3D printed parts: an outer motor bracket and an inner motor bracket which are joined together around the bottom-forward A-Connectors with 3 #10-32 x 1.25 inch socket cap screws and 3 #10-32 nylon lock nuts. The motor is fastened to the outer bracket with 4 M4 x 10 mm screws.
The following pictures show various views of the motor bracket assembly mounted to a wheelchair. The front views shows how the PVC screws which connect the A-Connector to the PVC tubing are inserted between the slots in the bracket.
Step 7 - Secure Front Wheels
The wheel hub connects the wheels to the shaft of the motor, and consists of two aluminum parts: The set screw hub, and the hub adapter.
Insert the hub onto the shaft 1/8’’ from the motor bracket. Orient the hub so the set screw inserts into the grove of the motor shaft. Apply Loctite to set screw and tighten. Using 6-32 x .5” bolts attach the hub adapter and the wheel to the assembly. Be sure to use the outer threaded holes on the hub adapter. Apply Loctite to each mounting bolt. This step requires a standard metric hex wrench set.
Step 8 - Insert Back Casters
Press fit the 2 caster adapters onto onto the 2 caster posts. Insert the PVC connector onto the caster adapter. Drill a 0.1 inch hole using a #38 or 7/64" drill bit centered on the pipe 1/4 inch (6mm) from the edge of the connector as show in the pictures below. Fasten the PVC connectors to the caster adapters by screwing #6-20 pan head 3/8" length sheet metal screws into the drilled holes.
Step 9 - Route Joystick Cable and Mount Joystick
The joystick may be mounted to either the left or the right handle side, depending on the right or left-handedness of your child.
The joystick cable needs to be routed through the tubing of the wheelchair. You may have partially disassemble the chair to get the cable to go around corners inside the tubing. The joystick cable comes with a 6 pin terminal block on one end, and a a 6 pin modular jack (Ethernet jack) on the opposing end. The modular jack inserts into the corresponding receptacle inside the joystick enclosure, and the terminal block inserts into the corresponding receptacle on the controller board.
Remove the terminal block from the cable, by unscrewing the 6 screws. Then wrap some masking tape around the stripped wires so that the cable can more easily be spooled through the tubing of the chair. Starting with the handle insert the cable into the tubing, removing any corners that are blocking the progression of the cable. Drill a hole at the bottom tubing of the chair,located under the vertical shaft, so that the cable can exit through the bottom of the chair. Route the cable through the drilled hole, and reassemble any connectors that you removed to complete the routing of the cable.
Wire the terminal block back onto the joystick cable, in the same color code order. See the picture for a reference.
Mount the joystick to the handle of the wheelchair, by sliding it onto the PCV handle. The joystick enclosure has a small hole on the underside. Drill out the PVC tubing using the joystick enclosure hole has a guide, and insert a screw so that the joystick is fastened on the tubing.
WARNING: When inserting screws into the PVC tubing and connectors be very careful not to damage the joystick cable, by screwing into it.
Step 10 - Secure Pipe and Connectors with Screws
The PVC frame is held together with #6-20 pan head 3/8" length sheet metal screw, rather than glue. This allows the frame to be expanded as the child grows. To fix a pipe to a connector, insert the pipe into the connector, and drill a 0.1 inch hole using a #38 or 7/64" drill bit centered on the pipe 1/4 inch (6mm) from the edge of the connector as show in the pictures below. Make sure that piping and connectors are secured tightly in place before drilling and screwing them.
After drilling holes avoid twisting the pipe so that the holes stay aligned. Drilling and and inserting screws in each of the 3 sub assemblies and then combine them. Screws should be inserted on the bottom or facing inside where possible so that they are out of sight. It is easier to drill when the sub assemblies are oriented so that the drill is facing downward.
Be careful not to drill or screw into any cable that might have been routed inside of the PVC tubing.
Step 11 - Secure Seat Belt
Loop the metal bracket around the PVC tube below the seat rest and align the holes with the seat belt strap and secure with a nut and bolt. This will require a 2.5mm hex wrench set and a 10mm wrench as shown.
Step 12 - Cutting and Securing the Back Rest and Seat Platform
The seat platform, back rest and foot rest can be made from whatever sheet materials that are readily available such as plywood, sheets of plastic such as polyethylene, or sheets of metal if overall weight is not a concern. The advantage of polyethylene over wood, is that it is easier to clean and doesn't have splinters. For the purpose of these instructions, we'll assume the use of polyethylene sheet. 1/4 inch polyethylene sheets are readily available from www.amazon.com.
Cut the back plate from 1/4 inch polyethylene sheet to the outer dimensions of the back seat frame (see step 3). Round the edges with 100 grit. Pre-drill holes centered on the joint (as described in step 10) and 8 inches below on each side. Secure using PVC fastener screws.
Step 13 - Seat Cushion
The seat cushion can be custom made, or can be optionally purchased as designated in the parts list. The cushion can be secured to the PVC or polyethylene sheet with velcro tape, such that it is easily removable for cleaning.
Step 14 - Mount Battery and Controller Board
There are several options for mounting the controller board and the battery. For example they can be placed inside another box. Our recommendation is to directly mount them to a platform underneath the seat with velcro, such that they are easily accessible, removable, and viewable. The control board has diagnostic LEDs which show the state of the wheelchair. The controller board is enclosed between two transparent acrylic sheets, and so there is no need for an extra enclosure. Mounting the batteries with velcro strips on the bottom of the battery allows the ability to quickly swap out discharged batteries with charged batteries.
Step 15 - Wire Up Controller Board.
See controller board documentation for hook up.
The Open Wheelchair hardware design is licensed under CERN Open Hardware Licence v1.2 and the Software is licensed under the GNU General Public License Version 3. By viewing or using the design posted on this website you are agreeing to these licenses. To view the license see our license page.