Rigid Foot Piece

Rigid Foot Piece

The rigid (stiff) foot piece runs from the heel to the tiptoes. Depending on the patient's requirements for the orthosis, a rigid foot piece might be necessary. The biomechanical basics are of help when it comes to choosing the right foot piece.

If you use theOrthosis Configurator, you will receive a recommendation for the foot piece based on the introduced patient data.

Click here to go to the online tutorial for producing a partially flexible foot piece.

 Biomechanical Basics

Step 1/1

 Reinforcing the Foot Piece

Step 1/16

Reinforce the rolling-off area (arrows) of a rigid foot piece with carbon fibre band and a brim in order to increase the orthosis’ rigidity and prevent any movements.
Important! Already consider the shape of the later worn shoe when reinforcing the foot piece in order to gain the best possible fit. The width, in particular, can hardly be adapted subsequently.
Note: If the brim should be too high, it can easily be adapted later on.

Step 2/16

We recommend using electrical scissors (e.g. Easy Cutter) to cut the separate fabric layers (carbon as well as aramid).
Note: Use adhesive transfer tape without backing material to secure the cutting edges. This way, the edges will not fray.

Step 3/16

Scarcely cover a carbon fibre fabric pre-cut with adhesive spray and adhere it to the entire sole. At first, only reinforce the sole and the area below the joint retainer at the foot piece to avoid unnecessary thick edges and gain a high stiffness.
Note: Always only spray the pre-cut which still needs to be adhered and not the already adhered reinforcement.

Step 4/16

Spare the area of the joint retainer.

Step 5/16

Reinforce the forefoot area with unidirectional carbon fibre band (e.g. 10cm width). Always reinforce up to the toes. Have the pre-cuts getting longer towards the heel to gain a smooth transition. Begin with the shortest pre-cut. Mind the direction of the fibres (arrow).

Step 6/16

Attach the carbon fibre fabric and unidirectional carbon fibre band to form an ideal fibre composite. Use as many layers of carbon fibre fabric and band as you need.

Step 7/16

Attach unidirectional carbon fibre band transversely below the joint retainer at the foot piece. Mind the direction of the fibres (arrows).
Important! Make sure to always use the fibres stretched!

Step 8/16

Attach the unidirectional carbon fibre band in a v-shape.

Step 9/16

Apply some insulating wax to the threads of the joint retainers in order to seal them airtight for the following steps.

Step 10/16

Attach the lower end of the carbon fibre braided tube with spray adhesive at the sole of the foot piece.

Step 11/16

Attach unidirectional carbon fibre band diagonally below the joint retainer at the foot piece.

Step 12/16

Keep on reinforcing with carbon fibre band.

Step 13/16

Then, attach carbon fibre band directly below the joint retainer at the foot piece.

Step 14/16

Keep on reinforcing. Use as many layers carbon fibre fabric and band as you need.

Step 15/16

Attach a final layer of carbon fibre fabric to the foot piece. Cover half of the assembly/lamination dummy.
Important! Make sure to use the fibres stretched!

Step 16/16

In order to secure the reinforcement layers, pull a decorative fabric (2) or a PA reinforcement stocking (for a carbon look) over the model (1). Thus, the PVA film tube can easily be pulled over as top film layer (3).
Note: We recommend using a 0.10mm thick film layer.

 Laminating the Foot Piece

Step 1/3

This production technique is especially adapted to our epoxy resin and hardener.
Important! Please consider the processing instructions and the safety data sheets for our epoxy resin and hardener. Precisely stick to the mixture ratio and thoroughly mix resin and hardener.

Step 2/3

Let the fabrics soak completely and rub surplus resin out. Press out the foot piece in order to receive the highest possible fibre volume ratio. While doing so, protect the film with some padding material and make sure to maintain the form of the modified pitch.
Note: Use available shaping dummies.

Step 3/3

Let the model harden over night (at least 10 hours), under vacuum and at room temperature.
Important! Also note the processing instructions for epoxy resin.

 Cutting the Foot Piece

Step 1/2

Use an oscillating saw to saw along the cutting lines in order to remove the orthosis parts from the model. You can see the recommended saw blade in the picture. Thus, you can saw very close to the system joint without damaging it.

Step 2/2

Remove all laminate parts which are no longer necessary. Then, you can remove the orthosis parts from the model.

 Tempering and Grinding the Foot Piece

Step 1/3

Clean all the joint areas as well as the system stirrup before you temper the parts of the orthosis. Heat all wax residues with a hot air blower (1) and blow the liquefied insulating wax out of the hollows (2). Remove all residues with a
cloth (3). Remove the PVA film tube as well.

Step 2/3

Temper all parts of the orthosis before you grind them. Place the orthosis parts into a cold oven and heat it up slowly. When tempered, the parts of the orthosis are stable and can be worked in the best possible way.
Important! Also note the processing instructions for epoxy resin.

Step 3/3

Grind the edges of the orthosis parts (e.g. with an angle grinder). However, it is essential to avoid predetermined breaking points in the metal!
Note: Aramid fibre can be worked with sharp scissors.