Introduction: Archery Prosthetic

Hello and welcome to the Cambridge Bio-Augmentation System’s OpenSource archery prosthetic. This project was born out of John Willis’ Road to Rio Challenge, where he participated in every Olympic and Paralympic sport in the lead up to the Rio 2016 Olympics/Paralympics. He wanted to show that sport doesn’t have boundaries and no matter the impairment, able bodied and impaired people can inclusively play together. So it is very fitting that the devices that we designed to help John hold sporting equipment, we are now releasing into the public so that true to John’s goals, the boundaries of sport are eliminated.

Step 1: Design Notes

• Any archery bow and grip type is usable with this device.

• For safety, it is advised to keep string poundage low and increase slowly.

• 3D Printing

– The minimum printer requirements are:

Print Material (in order of preference): PLA, ABS

Bed Size: 150mm x 150mm x 140mm (height)

Printing Resolution: 0.2mm

Shell: Thick (2mm)

Infill: 30%

– We recommend looking on for printers that can make these parts at a low cost.

Step 2: Selecting Your Device(s)

• These devices will work for either left or right handed archery (please ensure the correct grip section is selected).

• The bow grip device will only work on residual limbs longer than 270mm (shoulder to stump end).

Step 3: Bow Grip

Step 4: Labelled Device: Bow Grip

1- Elastic Bands

2- Polymorph

3- Grip Section (3D Printed Part)

- If using a left handed bow then use the ‘RH Grip Section’ STL.

- If using a right handed bow then use the ‘LH Grip Section’ STL.

4- Mid Section (3D Printed Part)

5- Bolts

- M4

- 20mm

6- End Section (3D Printed Part)

7- Carbon Tube

- 6mm OD

- 4mm ID

- 313mm length

8- Strap

- See step 6

Step 5: Bow Grip STL Files

End and mid sections are common for both left and right hand devices.

'LH Grip Section' is for left side amputation.

'RH Grip Section' is for right side amputation.

(when discussing grip sections, we are referring to body handedness and not left and right hand shooting).

Step 6: Bow Grip

- Tap the holes in Grip Section with an M4 thread (indicated on the picture).

Step 7: Bow Grip

- Use Epoxy to glue carbon tube into the grip section.

- Allow to cure.

Step 8: Bow Grip

- Slide the mid section over the carbon tube so it fits into the the grip section.

- Make a mark on the carbon where the carbon tube disappears into the mid section then detach the mid section.

- Paste a layer of Epoxy between these two marks.

- Paste a layer of Epoxy onto the contacting surfaces between the mid and grip section.

- Slide the mid section back onto the carbon tube and marry it to the grip section.


Step 9: Bow Grip

- Screw the M4 bolt into the mid section.


Step 10: Bow Grip

- Slide the end section over the carbon tube so it fits into the the mid section.

- Make a mark on the carbon where the carbon tube disappears into the end section then detach the end section.

- Paste a layer of Epoxy between the mark and the end of the carbon tube.

- Paste a layer of Epoxy onto the contacting surfaces between the end and mid sections

- Slide the end section back onto the carbon tube a marry it to the mid section.

- Wipe off excess glue and allow to cure.

Step 11: Bow Grip

- Make a strap to go around your arm and the device. We suggest that you make a strap that goes through the strap hole in the end section.

- We made our strap from stitched leather with a Velcro release, however there are many ways that you can make this part.

- Suggestion: A simple option would be to wrap a bandage around the device and your arm. This won’t be as convenient as using a permanent strap but will be sufficient

Step 12:

- Heat the polymorph in a cup of boiling water.

- Once soft, press the polymorph into the cutaway in the Grip Section. This should fill all 3 sides in the U shape leaving a slot in the center that’s thinner than the bow grip.

- Don the device and adjust the bow until it is in the right position.

- Press the bow into the polymorph so the polymorph takes it’s shape.

- Allow to set.

- NOTE: the polymorph sets quickly as it cools, however can be re-molded by heating up again. This process may require heating up a few times before it is complete.

Step 13: Full Assembly and Use

•To use.

– Fit your residual arm into the hollowed out section.

– Fasten the device with the strap.

– Fit the bow into the polymorph and secure with elastic bands.

• If the bow is not suitably positioned, this can be adjusted by re heating the polymorph and repositioning the bow.

Step 14: Shoulder Mounted Release Aid

Step 15: Shoulder Mounted Release Aid

- This device was fashioned to slide over the the arm and sit around the shoulder. The trigger mechanism is operated by pressing your tongue against the inside of your cheek.

- It was made by converting a ‘bow wrist release aid’ (a common archery tool that can be found on Amazon or archery stores). We recommend finding one with a Velcro strap so that it can be easily extended to fit around the shoulder (see image).

Step 16:

• Liability

– Cambridge Bio-Augmentation Systems does not accept any liability in relation to these devices, or any of their remixed variations. Any breakage, injury or death are solely the risk of the user and by manufacturing you agree to relinquish Cambridge Bio-Augmentation systems of any responsibility.

• The OpenSource license

– These devices are released under the creative commons license: attribute – noncommercial – sharealike.

• Any queries please contact