Texas Instruments Calculator Front Covers (TI-84 Plus, TI-84 Plus C, TI-90 Titanium, and similar)

I needed a replacement cover for a TI-89 Titanium edition that I was selling on Facebook marketplace, so that the buyer would be satisfied. Luckily, I had another TI-84 calculator that still had its original cover so I could recreate one for my TI-89.

All of the measurements in this post are my own, so they could be not exact to the original part, but the printed part still works splendidly. I am going to include them, a short explanation, and the model files so you can more easily modify/make your own. It would be cool to see a TI calculator cover that had a hinge so the front cover folded open rather than coming entirely off.

The key measurements include:

For the rail/slot cross section profile

• The distance from the calculator front keys to the to the far side of the cover slot.
  • 12.7 mm (0.50 in)
• The size of the cover rail slot on the calculator.
  • 2.0 mm (0.079 in)
• The depth of the cover rail slot on the calculator.
  • 1.27 mm (0.05 in)
• The width of the calculator (from left to right).
  • 84 mm (3.31 in)
• Rail start from bottom of the case ~40 mm and a rail length of 79 mm.

For the case profile

• The distance from foot to head on the front of the calculator
  • 187 mm (7.36 in)
• The curvature of the calculator side cross section
  • Measured to be 10 mm (0.39 in).
• The curvature of the calculator foot front cross section.
  • Assumed tangent to both edges, and measured a foot horizontal length of 34 mm (1.34 in).

I created a rectangular profile with an offset from the calculator body of 0.2 mm, and designed a rail from the side of the rectangular profile with similar tolerances and a 60 degree angle so that it would not need supports.

I went with a 2.2 mm shell thickness. I also created one with an angular side profile so all support are eliminated by not having the curved 10 mm surface.

EDIT

Later, I found a TI-84 model on GrabCad so I am linking it here. There is also a case on there I saw too, but I did not like it very much.