Modular Translation Flexure

This is actually a very cool device for precise translations in the micrometer range. It is a modular linear translation flexure based on the folded beam principle. It produces a very good linear movement without tilting and displacement which makes it suitable for optical experiments (e.g. Interferometer) when assembled and mounted properly.

The second picture shows the white light interference of a white LED torch from a Michelson Interferometer with retroreflectors. One Reflector is mounted on the flexure translation stage. When interferometer arms have same length interference pattern appears. The length difference for White light interferences is typically only some micrometers where it is for common laser diodes a couple of mm.

The flexure blades can be easily exchanged. You can try out different lengths, materials or thickness.
You can cut blades yourself from various sheet materials. Even plastics sheets from packaging material are working.
But Metal would be the best if available.

(The moving Shuttle has a 10mm wide grove for a position magnet array)

Dimensions:
Length: 90mm, Width 140mm, Shuttle width 30mm, Overall Height 23mm
Shuttle with 3mm mounting holes
Driver bore diameter: 10mm
Holes for Voice coil motor: 3mm diameter, 16mm apart

Translation range: theoretical +/- 10mm, practically 5mm
as PLA begins to deform plastically under high loads, With metal one could acheive probably longer range.
For the negative side one needs an actuator that can pull it. (E.g. Iron screw + manget on the shuttle)

3D Part descriptions:
To buld this flexure you need to print in 0.2mm resolution (80% infill) :
1 x Base: Modflex1.stl
4 x Fixation frames Modflex2.stl
1 x Shuttle Modlfex3.stl
2 x Middle Block intermediate stage (outer beam) : Modflex4.stl
4 x Blade joiner intermediate stage Modflex5.stl
4 x End Blocks intermediate stage : Modflex6.stl
4 x Flexure Blades: Modlfex7.stl ( 100% infill, print 0.1mm Resolution, flat)

Optional Parts:
Actuator knob: Modflex-Rad.stl
10mm diameter cylinder with hexagonal inset, which can hold a 5.5mm wide hex distance element with 3mm thread: Drivekernel-Hex.stl
10mm diameter cylinder with center bore, in which you can cut a thread of your choice: Drivekernel-simple.stl

Post processing:
Holes should be drilled to correct diameters prefereably in a drill stand,
Threads can easily be created by using M3 screws with hex nut and an Allen head screw driver with long lever

Hint:
The length of the blade joiner is 20mm - 1.6mm =18.4mm which fits to blades with 0.8mm thickness. When experimenting with thicker blades scale up Blade joiner in slicer such that blades are not distorted.
For example: you want blades with 1mm thickness. Then your blade joiners have to be 20- 2 x 1mm = 18mm long. This scale length to 98%

Additional parts:
In addition to this you need some screws:
16 x M3 x 10 , Flat hat
8 x M3 x 35 (or longer) Flat hat
1 x M4 cylinder, Hex hat or filed Flat hat

For mouting:
2 x M4 x 15 for mounting

To achieve best results the stage should be screwed to a rigid aluminium or steel profile.
An aluminium strip of 4mm height improves the structure significantly.

For Actuation:
Actuator can be mounted
a) in 10mm center Hole and secured with M3 Worm screw

• Micrometer Screw 10mm shaft diameter, Actuation length: 20 mm, ball Head

• 3mm Screw Acuator with 3D printed Drive wheel
  Drive Train: (see third picture)
  40mm long 3mm screw in Hex-socket with Turning knob
  Steel ball
  4mm diameter Nd-Magnet in Shuttle
  Actually this is really cool as with the magnet coupling you can use both directions of the flexure. The friction of this drive is very low so very low moment is transferred to the stage and the stage can be actuated much faster than with the micrometer screw.

  (when you have a hexagonal brass distance element with 3mm thread please use Drivekerne-hex.stl
  if you don't have this, you can cut 3mm tread into part made from Drivekernel-simple.stl)

b) 2 3mm holes 16 mm apart

• Voice Coil motor (e.g. GEEPLUS VM2618-112)

c) Not tested: Use long thread rod for actuation. You need to cut thread into shuttle and thread rod should run in ball bearings;
actuation can be done with stepper motor