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displacementexercise

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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

dex

Usage

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

c1 c2

Controller TODOs:

  • server config for bootstrap entire system ! (/url-to-program-location)

  • assign meaning to charts and graphs (date / location / etc)

  • this should be generic json-object making, yeah?

  • save tests as .json objects (optionally) develop program for reading

  • overlay multiples, save images

  • read-in csv as well

  • 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 ? filippos' part number ? nice unit to have.

Building a Displacement Exercise

The machine is made largely from laser cut delrin and 3D printed (commodity FDM) parts.

CAD

Hardware Documenting TODO

  • mcmaster order
  • CAD shuffle and export

BOM

Part numbers are from McMaster Carr unless otherwise linked.

Part Spec Count Notes PN / Link Cost / Per
Delrin (Acetal) Cast Sheet 24x12", 0.25" Thick 2 Fits on 24x18" w/ no mistakes 8573K35 $50.49 / 1
PLA 'Tough' ~ 300g Many 3DP Mechanical Bits Matter Hackers M6E9T65K $52.00 / 1kg
625ZZ Bearings 5x16x5 24 - VXB 625ZZ $24.95 / 20
Bearing Shims 5x10x0.5 37 - 98055A098 $8.62 / 50
Carriage Shoulders M4x5x6 12 - 92981A146 $2.16 / 1
Reduction Shoulder M4x5x10 1 - 92981A030 $2.32 / 1
Idler Shoulders M4x5x20 5 - 92981A042 $2.33 / 1
NEMA 23 Stepper Motor > 56mm Can Length 1 Spec Shaft with Pinion Stepper Online $14.83 / 1
GT2 Pinion 20T 1 Spec Shaft with NEMA 23 Amazon (or) RobotDigg $9.96 / 5
GT2 Closed Loop Belt 280T, 6mm Wide 1 - Amazon (or) RobotDigg $15.88 / 10
GT3 Open Loop Belt ~ 1m, 9mm Wide 1 - Amazon (or) RobotDigg $15.00 / 1
6806 Bearing 30x42x7mm 2 x 6806-2RS VXB $12.95 / 1
M3 Inserts Tapered, 3.8mm Tall ~ 300 - 94180A331 $12.92 / 100
M4 Inserts Tapered, 4.7mm Tall 16 - 94180A351 $14.96 / 100
M5 Inserts Tapered, 6.7mm Tall 4 - 94180A361 $12.00 / 50
M3 Washers 18-8 Standard Flat 300 - 93475A210 $1.62 / 100
SHCS M3x16 100 Pinning T- to the wall, and pulley endmatter 91292A115 $5.87 / 100
SHCS M3x20 100 Pinning T- to one another (?) 91292A123 $6.78 / 100
SHCS M3x25 100 Pinning T- and X-es together 91292A020 $7.23 / 100
SHCS M3x45 8 Pinning the 'squat' together 91292A025 $12.21 / 50
FHCS M3x10 30 Pinning blisters to faces 92125A130 $5.81 / 100
FHCS M3x25 (?) - 92125A138 $11.50 / 100
Steel Dowel Pins 5x8mm 10 - 91585A506 $8.40 / 25
Feet M4 Stud, 15x15mm - - 93115K881 $1.78 / 1
Approximate Mechanical Total $446.80
Loadcell(s) 10, 30, or 50kg 1 Choose Range for Sensitivity Amazon 50kg Amazon 30kg Amazon 10kg $39.00 / 1
Loadcell Amplifier HX711 1 - Sparkfun 13879 $9.95 / 1
Power Supply 350W 24V LRS-350-24 1 - Amazon $32.25 / 1
Rough Control Total: Incomplete 81.20
All Up $528.00

CIC Build McMaster Order includes everything except:

  • PLA
  • Delrin
  • 625ZZ's
  • M4 Inserts
  • M5 Inserts
  • Belt / Pulleys / Motors
  • LoadCell, PSU

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.

dogbones

Controller Desires