Welcome to this instructional guide on how to assemble and test strain gauges. In this comprehensive walkthrough, our experienced Strain Gauge Technician, Andi, will show you the process of preparing, assembling, and testing strain gauges to ensure accurate measurements for your projects.

Understanding Strain Gauges

Strain gauges are essential devices used to measure the deformation of materials under stress. These delicate instruments require careful handling during assembly to ensure optimal functionality. Before you begin, create a clean and organized workspace, and gather all the necessary tools and materials.

Safety First

Since this process involves the use of chemicals, prioritize your safety. Wear appropriate protective clothing, gloves, goggles, and follow proper safety protocols to prevent any accidents.

Step 1: Preparing the Substrate

  1. Apply a suitable amount of M-PREP conditioner onto the substrate, the surface to which you'll attach the strain gauge.
  2. Gently clean the area using silicon carbide paper to ensure proper adhesion between the substrate and the strain gauge. This step removes dirt and debris.
  3. Wipe off the conditioner using gauze, starting from the center and moving outward to prevent dirt from being pulled back in.
  4. Apply M-PREP neutralizer to the substrate. Thoroughly clean the substrate using cotton wool swabs to remove any remaining residue.
  5. Wipe off the neutralizer with fresh gauze, again using an outward motion to avoid re-contaminating the substrate.

Step 2: Assembling the Strain Gauge

  1. Repeat the same cleaning process with the glass plate, where you'll initially assemble the strain gauge before attaching it to the substrate.
  2. Using tweezers, carefully lift and position the solder tag on the glass plate, ensuring not to touch the tag itself.
  3. Gently remove the strain gauge from its protective packaging with tweezers and place it on top of the solder tag. The tag provides support and prevents accidental strain gauge damage.
  4. Place Mylar tape over the strain gauge, ensuring it lies flat against the gauge. Trim excess tape with a scalpel.
  5. Align the tape-covered strain gauge onto the substrate. Avoid touching the gauge directly; handle only the tape.
  6. Pull the tape back slightly, lifting the strain gauge off the substrate.
  7. Allow a controlled amount of glue to drip onto the substrate without contacting the strain gauge.
  8. Move the tape slightly to spread the glue evenly across the strain gauge using clean gauze and tape.
  9. Carefully place the strain gauge back onto the substrate. Press down with your finger for about a minute to fuse the glue and strain gauge together.
  10. Gradually remove the tape while holding the substrate, cutting the gauge legs with a scalpel as you go.
  11. Apply a small piece of soft adhesive or masking tape to protect the gauge during soldering.

Step 3: Soldering and Testing

  1. Solder the strain gauge legs to the solder tag using a soldering iron.
  2. Test the resistance of the assembled strain gauge. For a 350 ohm gauge, the readings should align with this specification.

Step 4: Finalizing the Assembly

  1. Strip the wire ends and add a small amount of solder.
  2. Attach the wires to the strain gauge using the solder iron and the existing solder.
  3. Clean off any flux glue and paper using Rosin Solvent to prevent skewed readings due to residue conductivity.
  4. Apply epoxy glue over the wire tips to secure them.
  5. Allow the glue to dry, then evenly spread silicon over the entire strain gauge using a toothpick, being cautious not to touch the gauge.
  6. Clean the edges of the gauge with a cotton bud and allow it to dry.

Congratulations, you've successfully assembled and tested a strain gauge! This meticulous process ensures accurate measurements and reliable results for your projects. We hope you've found this guide useful and informative.