Introduction: Plate Stabilizer

The Plate Stabilizer device was designed to accommodate a forearm crutch user who was looking for a way to independently carry food at school and at home. The device is a stable, durable, and hands-free attachment to the crutch that does not impede mobility. It is low-profile, and minimizes the chances of causing an inconvenience to others. The user can carry a full plate on the device, but it is compact enough to be carried in a backpack.

The device features a two-tier rail to enable the accommodation of a wide variety of plate sizes as well as the ability to collapse into a storable item. The bottom of the plate is intended to rest on the central hub of the device. The rubber, inset into the top part of the hub, cause friction that prevents slipping while the extendable arms prevent translation. These arms are then locked in place with a cross-shaped pin. This causes the plate to remain stable while the crutch swings and meet the user’s goals. The plate stabilizer attaches to a crutch clamp that remains on the crutch shaft. The clamp has a inner lining of felt to prevent slipping or the crutch from being damaged. The clamp is semi-permanently attached and can be attached/removed using a standard phillips head screwdriver. There are also also optional extension pieces that can increase the size of the arms.

Step 1: Gain Access to Neceassary Software and Hardware

Access to 3D Printer:


Access to CAD Software:

All parts were designed using Solidworks 2017 and 2018 by Dassault Systèmes. If modifications need to be made to any parts, you will need to use Solidworks 2018 or later.

Attachments

Step 2: Materials

  • Phillips Head Screwdriver
  • Hot glue gun (with glue stick) or superglue

Bill of Materials:

Crutch Clamp:

  • 2 1”x1.5” pieces of felt, 1mm thick (thickness can vary, most felts should work)
  • Clamp Left Piece
  • Clamp Right Piece

Central Hub:

  • 1 Top Piece
  • 1 Mid Piece
  • 1 Bottom Piece
  • 1 Cross Pin
  • 2 Upper Arms
  • 2 Lower Arms

Fasteners:

Optional: Arm Extension

  • Extension pieces can be added to the plate stabilizer system to allow for other types of dishware such as cups and bowls to be carried.
  • Arm extensions can take any form necessary to hold into the desired item as long as the slotting mechanism fits within the slots on the arm pieces in the main assembly (see Step 4 for modification instructions).

Optional: Crutch Clamp Modification

  • The crutch clamp was designed for specific use on forearm crutches (WalkEasy Ref. 490 https://walkeasy.com/shop/crutches/forearm-elbow/... See Step 4 for modification instructions.

  • All other components of the plate stabilizer do not depend on the design of the crutch clamp as long as the support bar can fit into the slot connecting the plate stabilizer to the clamp. Therefore, to adjust the system to be used with other mobility aids, only the crutch clamp needs to be modified.

  • By modifying the clamp, the plate stabilizer can used with underarm crutches, wheelchairs, strollers, walkers, etc.

Step 3: How to Fabricate

  • Open all STL files and send them to the 3D printer.
    • (Procedure varies depending on the 3D printer being used)
  • After the print is completed, clean the support material from the parts.

Step 4: Assemble Central Hub

  • See exploded view of all parts (The colors were added at random to differentiate the parts in images):
    • Key:
      • Yellow: Cross Pin
      • Black: Rubber
      • Red: Central Hub Top (CHT)
      • Green: Central Hub Mid (CHM)
      • Blue: Central Hub Bottom (CHB) (w/o I-beam for simplicity)
      • Gray: Arms
  • Place the cross pin aside for now.
  • Cut the 1/16” rubber into 4 isosceles triangles such that the congruent sides are 1.25”.
  • Start with the CHB piece. Take the 2 taller arms labeled “LOWER” and place them in the slot such that the holes on the arm can line up with the holes on the CHB piece.
  • Take the CHM piece and match the alignment edges (shown below) with the ones on the CHB.

  • Take the other 2 arms labeled “UPPER” and place them on the CHM as you placed the “LOWER” arms on the CHB.

  • Place the CHT on top of this assembly, aligning the alignment edges.

  • Use 4 1/2” screws and 4 accompanying lock nuts to secure the pieces together. You can insert the cross pin to hold the pieces together while to perform this step.

  • Use glue to secure the triangular rubber pieces into the insets that match their shape and allow to dry.

  • See Exploded view, Alignment edge, and Full Assembly attached.

Step 5: Assemble Crutch Clamp

  • Deciding where the crutch clamp should be located is a subjective choice and can be adjusted later if needed.
  • To avoid slipping, glue or epoxy the felt along the inside of the clamp.
  • Take the Clamp Left Piece and Clamp Right Piece and use the 1-3/4" long screw and associated lock to act as a hinge to connect the 2 parts.
  • After determining an appropriate placement for the clamp and assembling the clamp, secure the crutch clamp to the crutch using the such that the T-slot section of the crutch facing the intended forward direction.
  • Use 1 3/4" screw and 2 accompanying lock nuts to close and tighten the clamp around the crutch shaft.

Step 6: Modifications (Optional)

Crutch Clamp:

  • The crutch clamp was designed for crutches with a diameter of 2.5 centimeters.
  • It can work for crutches that are slightly larger, and additional layers of felt can be added for crutches with a slightly smaller diameter.
  • For crutches with a significantly different diameter, the crutch clamp’s diameter will need to be modified in Solidworks 2018 (or a later version). In order to do this, you will need to modify two SLDPRT files named “CrutchClamp_Left” and “CrutchClamp_Right”. Select the sketch titled “Sketch 1” and change the radius dimension to the desired size.

Tolerances:

  • Depending on the resolution of your 3D printer, you may need to increase the tolerances in the SLDPRT files.

Extensions:

  • The slots in the arms allow custom extensions to be used for different plates and bowls.
  • Three different extensions have been designed and included. In order to design your own, open the “ArmExtension_1in_Lower” file and make any desired changes.
  • To ensure that it fits into the arm slots, keep the half-oval profile the same. In order to ensure that the arm extensions are the same height, make two to your desired height for the top arms and two that are ¼” taller for the bottom arms.

Step 7: Repairs

If the plate stabilizer needs any repairs, you can attempt to salvage the parts by using epoxy, however it is recommended that you replace the parts.