All-Terrain Wheelchair

We built an all-terrain wheelchair for a little boy who has mobility challenges. He wanted a way to go hiking with his family and be able to keep up with his siblings outdoors. We took inspiration from the Extreme Motus Emma X3 and built our own custom version that was specific to our little client's needs.

• Front Wheel - 30cm Wheeleez Balloon Wheel
• 2x Rear Wheel - 42cm Wheeleez Balloon Wheel
• Chair - Kirkey Racing Seat 17.5" Width
• Chair Cover - Kirkey Series 16 Vinyl Seat Cover 17.5" Width
• 2x Wheel Chocks - Hyper Tough Wheel Chock
• Handlebar - Aluminum Bike Handlebar
• Straps - 25 yards of 2" Webbing
• Handlebar Grips - Bike Handlebar Rubber Grips
• Rear Axle - Wheeleez Aluminum Axle 0.75" x 40″
• Front Axle - Wheeleez Aluminum Axle 1" x 18.4″
• Quick Release Pins - 1/4" Diameter Quick Release Pins (Pack of 4)
• Adjustable Handlebar Stem - Adjustable 0-90 degrees Bike Stem
• Aluminum Sheet 6061 (3'x3') 0.25 in thick - The Yard, Wichita, KS
• Steel Angle Bar- Everbilt 3/4" x 36" Plain Steel Angle 1/8" Thickness
• Aluminum Angle Bar - Hillman 3/4" W x 3/4" H x 3' L Aluminum Solid Angle
• 6x Bearings - Trike Buggy Wheeleez High Speed Bearings 1" Inside Diameter
• Paracord - Hyper Tough 550 Utility Paracord Rope 5/32" x 50'
• 1/4" Quick Link - Peerless 1/4" Wide Jaw Quick Link
• Sewing Thread - Coats and Clark All Purpose Polyester Thread
• PLA Filament - Bambu Lab PLA Basic
• 40 bolts - Hillman Hex Bolts 1/4"-20 x 1" (Pack of 5)
• 40 nuts - Hillman Stop Nuts 1/4"-20 (Pack of 6)
• 4 bolts - Hillman Hex Bolts 5/16" x 4"
• 4 nuts - Hillman Stop Nuts 5/16"

Tools

• Hand Drill
• Drill Press
• Plasma Cutter
• 3D Printer
• Slicer program
• SD card or USB (depends on what the 3D printer and plasma cutter you are using needs)
• 11mm socket wrench or adjustable wrench
• 11mm wrench or adjustable wrench
• Files
• 1/4" Drill Bit
• 5/16" Drill Bit
• Lighter
• Scissors
• Chop Saw
• Band Saw
• Tire pump (if one does not come with the Wheeleez)

Pro Tip: If you want to skip a couple steps, using a waterjet to cut out the frame pieces may be easier. The waterjet will make smoother cuts and could cut the 1/4" holes that we will drill later for the bolts.

Use the 1/4" thick aluminum plate to cut out the frame pieces in the attached CAD files using a plasma cutter. The holes for the bolts are 1/4" which may be too small for a plasma cutter to accurately cut, so keep this in mind since these holes are included in the CAD files. We opted to not cut the 1/4" holes with the plasma cutter and instead used a drill press in a later step.

After getting the rough cut pieces of aluminum from the plasma cutter, the pieces were sharp so we used a sander to smooth it out all over. Then we used a hand metal filer to file the inner edges of the cuts.

We marked the dimensions of all the 1/4" holes from the CAD files onto the frame pieces. We then used a 1/4" drill bit and a drill press to drill out all the holes. We stacked each of the identical pieces for drilling, the two frame pieces, the two rear frame pieces, and the two rear axle pieces. This ensures that the holes drilled are uniform. Be sure for the rear axle pieces to line up the 1" diameter hole that the axle will go through and not the pieces' edges since the two pieces will ultimately be aligned by the axle.

Remove the factory bearings from the wheels if intending to use in terrain where small debris could enter the bearings. This can be done by unscrewing the 4 nuts located on one side of the hub and removing the current bearings and discs.

Along with the factory bearing there will be:

• 1 White plastic disc
• 1 small felt disc
• 1 large felt disc
• 1 gray plastic disc

After removing the factory bearings and discs from both sides of the wheel hub:

1. Set the wheel on its side so one side of the hub faces up
2. In the middle of the hub place the white plastic disc
3. On top of the white plastic disc place the small felt disc
4. Place the new bearing on the small felt disc
5. Place the large felt disc on top of the bearing
6. Make sure everything is centered so that the axle can slide through the hub without obstruction
7. Place the gray plastic disc on top of the large felt disc
8. Slide the four bolts, that were removed earlier, through the gray plastic disc and then the hub
9. Hold the bolts and bearing in place and lift the wheel upright
10. Repeat steps 2 through 7
11. Make sure everything is in place and screw the nuts onto the end of each bolt

Tip: The hub is actually two pieces that will move apart when the bolts are first removed, we found that deflating the tire can allow the hub to be pushed back together so that the bolts, new bearings, discs, and nuts can be installed easily. Once the bearing is replaced the wheel can be reinflated.

To connect the bike handlebars to the handlebar frame pieces 3D print one of the attached files. We used PLA and printed this piece with the hubs.

For the front axle, to keep the wheel centered between the two main frame pieces, 3D print two spacers that are in the attached file. We used PLA with a 20% gyroid infill and 6 walls.

Tip: If the spacer doesn't slide onto the axle easily use a file or sandpaper to file down the inner radius of the spacer.

To keep the rear axle frame pieces at 13" apart, 3D print 2 of the 6.5" spacers or one 13" spacer. We printed two 6.5" spacers since our printed did not have the build capacity for 13" height.

To keep the rear wheels a specified distance from the frame print two of the 5.5" spacers

Use a 1/4" drill bit and a hand held drill to drill the holes marked for the harness. The holes don't have to be perfectly lined up since the harness is adjustable.

We used a butterfly harness that was from our client's previous wheelchair, but a 4 or 5 point harness of your choosing can also be used. We measured out where the harness would lay on the chair and marked the holes according to this before drilling.

Once holes are drilled, use 1/4" bolts and lock nuts the secure the harness to the chair. Make sure that the head of the bolt is on the inside of the chair that way the bolt end will not poke through the chair cover and be uncomfortable for the wheelchair user.

Gather the frame pieces that were cut using the plasma cutter or waterjet:

• 2 main frame pieces
• 2 rear frame pieces
• 2 rear axle frame pieces

Use 1/4"-20 hex bolts or other 1/4" bolts of your choice as well as 1/4"-20 stop nuts to assemble these pieces together as follows:

1. Lay one main frame piece on your workspace
2. The rear frame piece will be bolted to the main frame piece at the 1/4" hole near the angled end as shown in photos above, this joint should be able to pivot so do not tighten the the bolt and nut all the way. The rear frame piece should be on the inner side of the wheelchair
3. The other 1/4" hole at the tip of the angled side of the main frame piece will now match up with a hole on the rear frame piece when pivoted, the quick release pin will be placed here
4. On the other end of the rear frame piece there are two 1/4" holes that the rear axle frame piece should line up with. The rear axle frame piece should be attached with 2 bolts and 2 stop nuts on the outer side of the wheelchair as in the above photo with the angled side facing towards the main frame piece that way it will match up with the chair
5. Repeat steps 1 through 4 for the other side of the wheelchair

For the foot rest we used a 1/8" thick piece of scrap aluminum sheet so it was more flexible for moving the frame around when installing the axles, spacers, and wheels. This piece could alternatively be cut from the 1/4" thick aluminum specified in the supplies list. This piece can be cut with either a chop saw or a bandsaw and the dimensions are 13" x 4.25" rectangle. Once you have cut out the rectangle use a file or grinder to round out the sharp corners.

There are 3 pieces needed for the foot rest: 2 angle bar pieces for brackets and an aluminum rectangle for the rest itself.

You will use the 13"x4.25" rectangle you cut out of aluminum.

Cut two 3" pieces of aluminum angle bar using either a cutoff saw or band saw. Use a file or grinder to round the sharp edges. We used a scrap piece of aluminum angle bar so the pictures will show holes already drilled in the angle bar.

Use the main frame piece as reference to mark where holes need to be drilled on the angle bar by placing the angle bar against the three holes drilled near the axle side of the main frame piece and a sharpie to mark the 3 holes. Repeat this for the other angle bar piece and main frame piece. Drill the marked holes with a drill press or hand drill and a 1/4" drill bit.

On the other face of the angle bars drill two 1/4" holes one near to each end of the bar. Set the aluminum rectangle on top of this face of one angle bar and make sure the other face of the angle bar is flush with the 4.25" side of the rectangle. Mark the two holes of the angle bar on the rectangle and drill them with a 1/4" bit using a drill press or hand drill. Repeat this with the other angle bar piece and other 4.25" side of the rectangle.

Use 1/4" hex bolts and stop nuts to attach the angle bars to the rectangle using the 4 holes previously drilled. Then attach this to the frame using the 3 holes on each frame piece and angle piece and 1/4"-20 hex bolts and stop nuts.

Slide the 1"x18.4" axle through the 1" diameter hole at the front of one of the main frame pieces, then slide on one of the 3D printed spacers, next slide on the 30 cm Wheeleez wheel, then slide on the second 3D printed spacer, last slide the axle through the 1" diameter hole at the front of the other main frame piece.

For the mounting the chair to the frame we used a steel angle bar with 1/8" thickness 1-1/2" x 36"

Using a chop saw, cut two 10.5" pieces from the bar

1. Drill four 1/4" holes in the rear frame piece centered between the last four trapezoidal holes in the frame piece.
2. Line up the two 10.5" pieces of the angle bar on the inside of the rear frame pieces, making sure that the top edge of the rear frame piece and the top face of the angle bar are flush.
3. Mark the holes in the rear frame piece on the angle bar
4. Use a drill press to drill the marked holes using a 1/4" drill bit
5. On the top face of the angle bar (the face the chair will be mounted to), drill a 1/4" hole 1" away from one end of the angle bar, then a 1/4" hole 1" away from the edge of the other end of the angle bar
6. Use the eight 1/4" bolts and eight stop nuts to fasten the two angle bar pieces to the inside of the two rear frame pieces
7. Set the chair on top of the angle bars and center it to where you would like it mounted, mark the holes that need to be drilled through the bottom of the chair, using the two holes drilled on the angle bars as your guide
8. Remove the chair and use a hand drill to drill the marked holes with a 1/4" drill bit
9. Use four 1/4" bolts and four stop nuts to secure the chair to the angle bars

1. Cut two 27" pieces of paracord
2. Singe both ends of the paracord with a lighter
3. Fold the paracord in half
4. Slide a quick release pin loop onto the fold of the paracord
5. Bring the ends of the paracord through the loop in the paracord that is through the ring of the pin
6. Make a knot about 1" from the singed ends of the paracord
7. Repeat steps 1 through 6 for the second piece of paracord

The quick release pins can be removed from the frame to fold the front end of the chair up for easier transport. The paracord prevents these pins from getting lost when they are removed.

1. Put the quick release pin through the holes in the main frame piece and rear frame piece that line up when the chair is in position for use
2. Loosen the stop nuts that are keeping the angle bar fastened to the rear frame piece
3. Pull the ends of the paracord under the rear frame piece
4. Tighten the stop nuts that have been loosened
5. Repeat steps 1 through 4 for the other quick release pin and other side of the wheelchair

We cut the strap to a length of 10' 2.5" this length may vary for your build so loop the strap through the chair as you will in the next step then cut to the length you need. Next, mark 2.5 inches from both ends of the strap and singe the cut ends of the strap with a lighter so it will not unravel. Fold the strap at the 2.5" mark on both ends and sew along the strap to make a loop with a seam allowance of 1/8"-1/4" then use a zigzag stitch for extra strength with the bottom of the zig zag near the singed end of the strap.

Thread the straps through the main frame pieces using the same process you would for shoe laces. After the last trapezoid hole in the frame use a 1/4" quick link through the sewn loops to secure the straps together. This is where the wheelchair user's legs will lay.

Added some handlebars to the side to help transport as the customer requested.

1. Cut strap to desired length to leave space for your hands once fastened to the frame
2. Singe the ends of the strap using a lighter
3. Mark where you want the strap fastened on the frame
4. Drill a 1/4" hole through the frame with a hand drill, set a scrap piece of wood on the wheel to prevent any accidental damage
5. Set the strap on the frame and mark where the holes are
6. Cut small holes in the strap where the markings are and singe the edges using a lighter
7. Fasten strap to the frame using 1/4" bolts and stop nuts
8. We used paracord to reinforce the handle using the cobra knot (also called Solomon Bar or Portuguese Sinnet)

Begin by sliding the axle through the two rear axle frame pieces, if you have printed the 13" spacer or the two 6.5" spacers slide these on before sliding the rear axle through the second rear axle frame piece. We were unable to complete the 3D print for these spacers due to time constraints so these spacers are not pictured.

Next slide a 3D printed 3.5" spacer on each end of the axle

Slide a Wheeleez 42 cm wheel onto each end of the axle

Slide a quick release pin through the holes in each end of the axle. We had 1/4" quick release pins so we had to drill through the original hole in the axle with a 1/4" drill bit to increase the radius of the holes to fit the pins.

1. From the leftover steel angle bar, cut two 3.5" pieces using a chop saw.
2. Drill two 1/4" holes into each piece. With one hole being 1/2" away from one end and the second hole being 1/2" away from the other end and both being centered.
3. Place them on the back of the seat between the two horizontal ridges so the outer edges of the two pieces measure 2.5" away from each other
4. Mark the 1/4" holes on the chair using the holes in the angle bars as a guide
5. Drill the marked holes in the chair using a 1/4" drill bit
6. Figure out where you want the handlebar to sit when the two handlebar frame pieces are fastened to the angle bar and mark where two holes need to be drilled on the handlebar frame pieces so that they are can be fastened to the angle bars. The holes should ideally be centered between triangle cutouts and not near the edge of the handlebar frame piece.
7. Use a drill press to drill the marked holes in the handlebar frame pieces using a 1/4" drill bit
8. Use these holes as a guide to mark the holes on the angle bar face that the handlebar frame piece will be fastened to
9. Drill the marked holes on the angle bar using a drill press and 1/4" bit
10. Use four 1/4" bolts and four stop nuts to fasten the two angle bar pieces to the back of the chair
11. Use the 3D printed handlebar stem to mark four holes on each of the two handlebar stem pieces where the bolts will go through the 3D print
12. Drill these marked holes using a 5/16" drill bit and drill press
13. Use four 1/4" bolts and four 1/4" stop nuts to fasten the two handlebar frame pieces to the two angle bars
14. Drill two 1/4" holes 0.5 inches apart opposite the clasp on the purchased handlebar stem
15. Set the 3D printed handlebar stem where it will be bolted into the handlebar frame pieces and find where the two holes drilled into the purchased handlebar stem will be when slid onto the handlebar stem. Mark the two holes on the back of the seat
16. Remove the handlebar stems and drill the two marked holes with a drill and a 1/4" drill bit
17. Fasten the purchased handlebar stem to the back of the chair using two 1/4" bolts and two 1/4" stop nuts. It may be hard to get the stop nuts on inside of the handlebar stem, we used needle nose pliers to hold the higher one in place then screwed the bolt through it then moved onto the lower bolt and nut
18. Slide the 3D printed handlebar stem into the bottom of the purchased one
19. Use four 5/16" bolts and four stop nuts to fasten the 3D printed handlebar stem to the handlebar frame pieces

Unfortunately our first 3D printed stem for the handlebar broke, so we went an alternative route and bolted the handlebar to the chair for the initial delivery to the family. We made a plan to revise the handlebar stem design as well as look into nylon printing for it and install this part at a later time.

Due to time constraints we went with wheel chocks instead of bike disc brakes because our clients priority was a way to keep the chair parked. We threaded paracord through holes that were already in the chair and through the handlebar frame pieces. Then the ends were tied together, creating one big loop. Then slide the wheel chocks into the loop with the smaller end of the chocks pointing down, and the loop should hold them in place.

The chocks can be easily slid out of the paracord loop and placed behind or in front of a wheel or two to keep the wheelchair in place on uneven terrain.

We used padding from one of our client's previous wheelchairs and Velcro to attach this extra padding to the chair where his head would rest.

The seat cover from Kirkey is easily hooked by the d-rings on the side and fits the Kirkey seat.

To clean the vinyl seat cover wipe clean with a non-abrasive cloth, mild soap/detergent, and water.

If the aluminum frame pieces ever get any rust spots, use a wire brush or steel wool to remove the rust. Use a half and half mixture of distilled water and white vinegar, put the mixture on the rust spots and then scrub.

If a wheel gets a flat, using a soldering iron to heat the puncture until it closes.

1. We would create a better option to secure the handlebar.
2. We would have used disc brakes from a bike instead of wheel chocks and 3D printed hubs to attach them to the wheels
3. Wheelez only had certain axle sizes, so if we had more time we would find different axles or modify the length so that the wheelchair could be easily pushed through doorways