2.1. MyoBone ‘Parallel Assemblies’ - Four Round Tube Fibres¶
2.1.1. Prepare parts¶
2.1.1.1. Step 1: Cut fibres to the desired length¶
Tips:
- Lathe can create a precise cut and avoids damaging the tube
2.1.1.2. Step 2: Mill the tube ends¶
Mill the inside hole of both tube ends in order to create a rough surface for gluing.
Tips:
- Use a round moulding cutter with an automatic screwdriver
- Use gloves to protect you from dust
2.1.1.3. Step 3: Positioning of the tube length¶
Insert the tubes in the tube holding-support and position the tubes with the distance support. Fix the tubes with the screws.
2.1.1.4. Step 4: Gluing threaded pin in tube ends¶
Add glue evenly to the threaded pin and hole. Use the distances according to the MYO-Bone class.
Tips:
- While drying, use a fixture to keep the thread pin and fibre centred and at the correct distance
- Wear protective gloves
2.1.1.5. Step 5: Remove the leftover glue¶
Remove the glue with a cutter knife. Consider the hardening-time of the glue.
Production of spacers
2.1.1.7. Step 2: Drilling and threading of holes¶
Drill and thread the holes of the flexure clamps.
Tips:
- Put small fibers in the flexure clamps to avoid deformation caused by the pressure exerted by the drill bit
2.1.1.8. Production of end plates and flanges¶
End Spacer:
- Selective Laser Sintering (Polyamide)
SB Flange plate:
- Machining (Aluminium)
- Selective Laser Sintering (Polyamide)
Screws, nuts and washers are standard parts.
2.1.2. Assembly¶
Material needed
4 x CFRP tubes with threaded ends
4 x spacers
16 x M2.5x10 countersunk head screw (DIN 965)
2 x end spacer
8 x M4 thin nut (DIN 39)
8 x M4 spring washer (DIN 127)
2 x SB flange plates
8 x M3x25 countersunk head screw (DIN 7991)
8 x M3 thin nut (DIN 39)
8 x M3 spring washer (DIN 6798)
2.1.2.1. Step 1: Assemble fibres and spacers¶
Slide the fibres (1) in the flexure clamps (2) of the spacers.
Tips:
- Slide one fibre through all spacers, and then go on with the next fibre
- Flexure clamp screws should be loose
- In preparation for the next step, regroup the spacers next to each other
2.1.2.2. Step 2: Plug fibres in the end-spacer¶
Plug each fibre in one of the holes of the end-spacer.
Tips:
- Apply sufficient pressure so that the end of the cfc tube is in contact with the shoulder at the bottom of the hole
- Do not press the fibers firmly into the holes
2.1.2.3. Step 3: Screw fibres to the end spacer¶
Screw each of the fibers to the end-spacer using the M4 nuts and the large spring washers.
Tips:
- Screw the nut until the spring washer is nearly flat, not more
- (if you screw further, you may pull the threaded pin out of the tube)
2.1.2.4. Step 4: Attach the other end-spacer¶
Repeat steps 2 & 3 for the other end-spacer.
Tips:
- Make sure the end-spacers are as much as possible:
- Parallel to each other
- Perpendicular to the fibres
- Lay the bone on the table to ensure that it is not twisted
2.1.2.5. Step 5: Adjust the spacers¶
Arrange the spacers equidistantly between the two end-spacers.
Tips:
- Distance between spacers: 51 to 52 mm
- Ensure that the spacers are perpendicular to the fibres
2.1.2.6. Step 6: Check straightness¶
Check that the MYO-Bone is straight and that both end-spacers are parallel to each other.
If necessary proceed to adjustments.
2.1.2.7. Step 7: Attach the SB flange plates¶
Screw the SB flange plates to the end-spacers with the M3 screws.
Use the small spring washers together with the M3 nuts (backside).