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.
Usage
DEX runs a squidworks controller, which is in development but is pulling data from samples successfully.
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
- 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 |
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
- cyclic loading
- direct upload -> materiom (generic: databases) ... MQTT (and nodered)
- https://cookbook.nodered.org/mqtt/ (and: https://cookbook.nodered.org/)
- add to data: humidity, temperature, location, time ...