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The Displacement Exercise (DEX)

DEX is a small materials testing machine that should be capable of running tensile and compressive tests at up to 600N of force. The machine can be manufactured by anyone with access to a laser cutter with at least a 24x12" bed, and nearly any FDM 3D Printer. A bill of materials of purchased parts required to complete the machine is below.

dex

Usage

DEX runs a squidworks controller, which is in development but is pulling data from samples successfully.

c1 c2

Controller TODOs:

  • serverside squidworks: machine contained system
  • server config for bootstrap entire system ! (/url-to-program-location)
  • setup and config-it
  • assign meaning to charts and graphs
  • save tests as .json objects (optionally) develop program for reading
  • save images of tests (genpurp canvas save tool?)

Circuit TODO:

  • draw / fab temp and humidity sensor (looks like Bosch BME280 828-1063-1-ND)
  • better implementation of load cell amplifier ?

Building a Displacement Exercise

Hardware Documenting TODO

  • BOM, McMaster
  • CAD shuffle and export

P1 Assembly

  • fixturing, doc and print
  • idler and 125t drive at hearth
  • N23 backside mount

BOM

Part Spec Count Notes PN / Link Cost
Delrin (Acetal) Cast Sheet 24x12", 0.25" Thick 2 - McMaster 8573k35 $101.00
PLA 'Tough' x ~ 300g Many 3DP Mechanical Bits x $52.00
625ZZ Bearings 5x16x5mm Deep Groove Roller Bearings 24 x 625ZZ VXB $50.00
Bearing Shims - - - - -
Carriage Shoulders - 12 - - -
Idler Shoulders - 5 - - -
Reduction Shoulder - 1 - - -
Feet - 3 - - -
NEMA 23 Stepper Motor - 1 - - -
GT2 Pinion 20T 1 - - -
GT2 Closed Loop Belt 280T 1 - - -
GT3 Open Loop Belt ~ 1M - 1 - - -
6806 Bearing 30x42x7mm Deep Groove Roller Bearings 2 x 6806-2RS VXB -
M3 Inserts - - - - -
M4 Inserts - - - - -
M5 Inserts - 4 - - -
SHCS M3x25 x Pinning T- and X-es together x -
SHCS M3x16 x Pinning T- to the wall, and pulley endmatter x -
SHCS M3x20 x Pinning T- to one another (?) x -
SHCS M3x25 x Pinning edge-idlers together, x -
SHCS M3x45 8 Pinning the 'squat' together x -
FHCS M3x10 x Pinning blisters to faces, flush up and countersink x -
FHCS M3x25 ? - - -
Dowel 5x8mm 10 - McMaster 91585A506 $8.40
Feet - - - - -
Loadcell(s) - - - - -

CAD Notes

  • fusion / parameters

Tools for Fabrication

  • laser, 3dprinter
  • soldering iron for inserts
  • arbor press is nice, but not necessary

Dependencies

This repo is for the machine itself, it implements / uses / depends on the projects below:

  • pdbs
  • router
  • stepper driver
  • loadcell circuit (find amp, make board?)

MFG Notes

I used the trotec w/ 80 watts power, doing two passes per cut at 0.25 speed and 100 power. The colors to setup with are:

Black, Red, Blue, Cyan, Green, Magenta

To export from Fusion, use Rhino for layout, export cut files as DXF, for the trotec the best move is to export as 'R12 Natural'. This will keep segments together.

...

fixturing moves / top to bottom

Testing Notes

Use the D683 ASTM Dogbone - normally Type 5

Controller Desires