WORK IN PROGRESS

Open-Pull

These are all the files you need, to build your own DIY Universal test machine.

SUPPORT my work via PATREON or PayPal.

Watch my YouTube video about it: https://youtu.be/uvn-J8CbtzM

DISCLAIMER: This is no professional test equipment! I won't be responsible for any damage that occured due to the data you gathered with this machine. Only use with appropriate safety equipment!

Build one

Hardware/CAD

CAD files of the whole assembly are available as stl, step and Fusion360 files.

Bill of Materials (BOM)

• 2x NEMA 17 Stepper Motors 1.68A, Geared 14:1
• 2x Trapezoidal Lead Screw 10x2 500mm
• 2x Coupling 8/10mm
• 2x Trapezoidal Nut 10x2, Steel
• 2x Trapezoidal Nut with Flange, Brass
• 2x Angular Contact Bearing, 3200 2RS
• 2x Ball Bearing, 6202
• 4x Ball Bearing, 608
• ...

Electronics

Currently the electronics are only as schematics and as images. I'd be happy if anyone made a PCB design for it for easier use.

Bill of Materials (BOM)

• 1x Arduino Nano
• 2x A4988 Stepper Motor Driver
• 1x HX711 Load Cell Amplifier
• 1x 24V fan
• 1x 5A 24V Power Supply
• 1x Load Cell of suitable size (AEP TC4 - 5kN in my case)
• ...

Software

Software is currently only the Arduino code for the machine itself, very rudamentary and not optimized. Everything is controlled via the serial terminal.

UPDATE: OpenPull Web-Controller(by Iqwertz): https://github.com/Iqwertz/OpenPull-Web-Controller

The general functionality is explained in this video: https://youtu.be/uvn-J8CbtzM

Commands

• M10: Slow test (1mm/min)
• M12: Tare
• M13: Modulus test - 1mm/min for 30s, then 25mm/min
• M14: Fast test (25mm/min)

Evaluation

The data is currently analyzed via EXCEL sheets.

The strain data is captures via an optical extensometer using a standard camera. I explain the procedure in my video, the tracking marker export script can be found in Documents.