hide phone in ti 85 calculator case (Slide Housings)
Build a visible, removable carrier that holds a phone beside a TI-85, rather than disguising the phone as part of a working calculator. Measure both devices before making anything, allow room for cases and controls, and test the fit without force. Keep ports and heat-dissipation areas open, and follow exam, workplace, and security rules.
Cleaning is easiest when the phone can slide out and the carrier has open, smooth surfaces. A sealed pocket may collect dust and can make it harder to spot wear or a trapped warm phone. The design below is for carrying two recognizable devices together, not for hiding one or passing it off as the other.
I would start with a removable carrier that leaves the TI-85’s screen, keys, labels, and body visible. Check your school or workplace rules before bringing a phone into a restricted room. If phones are not allowed, use an approved storage option instead.
Planning: Identify the Exact Calculator and Phone
A TI-85 and a phone can vary in size because of model, case, and accessories. Record the exact devices before drawing or making a carrier. Use manufacturer information where available, then check key dimensions yourself. Treat this as a transport accessory, not a change to either device.
Write down the phone model and the TI-85 you own. Measure the phone with the case you plan to use; include any raised camera area and screen protector. Note the location of its buttons, speakers, microphones, cameras, charging port, and any area that becomes warm during use.
Check the calculator’s body and controls, too. Its screen and keys must remain easy to see and use. Do not plan to remove covers, alter the battery area, or attach anything to the calculator’s internal parts. There is no single building code for a handheld carrier. For powered electronic equipment, IEC 62368-1 is a relevant product-safety framework, but it does not certify a homemade case.
Planning record
| Item to record | Why it matters |
|---|---|
| Phone model and case | A case changes the phone’s outside size |
| Phone width, height, and thickness | These set the phone pocket’s starting size |
| Camera bump and raised edges | These can catch on a tight slide |
| Controls and ports | These must stay open and reachable |
| TI-85 body and control locations | The carrier must not block the screen or keys |
| Material and finish | Shrinkage and rough surfaces can affect the fit |
Measure the widest and thickest points, not just the flat body. Keep a simple sketch with the measurements and mark which way the phone enters the carrier. This avoids a common mistake: designing a neat shape that blocks a button or traps the camera bump.
Access and Clearances: Measure Before Making the Slide
Clearance is the small gap between two parts that lets them fit or move without being forced. For a phone pocket, start with 0.5–1.0 mm of extra room per side around the phone in its final case. This is a design target, not a phone-maker specification.
For example, if the phone with its case measures 75 mm across, a pocket about 76–77 mm wide is a sensible first mock-up. This gives the target gap on both sides. Check the phone’s thickness and height the same way, allowing for raised corners and camera parts. Do not squeeze the device to make it fit.
For the slide interface, start with 1–2 mm of total running clearance across the matching dimension. A slide that fits on paper may bind after fabrication because materials can shrink or have a rough finish. Test a full-size paper or foam mock-up before making a finished part.
Keep the design open around all phone features. Do not cover vents, speakers, microphones, cameras, buttons, or the charging port. There is no universal airflow number for a passive carrier, so do not treat a vent or gap size as a guarantee that the phone will stay cool.
Mock-up check
- Cut a full-size pocket shape from paper or foam.
- Place the cased phone in it without pushing or bending the material.
- Check access to each button, port, camera, speaker, and microphone.
- Slide the mock-up on and off the intended carrier surface.
- Look for snags at corners, camera bumps, and raised screen edges.
- Confirm the calculator remains clearly visible and usable.
If the phone only fits when you press hard, revise the shape. A fit that depends on flexing the phone, calculator, or carrier is not a good fit.
Execution: Build a Removable, Nonconductive Carrier
A nonconductive carrier uses material that does not conduct electricity, such as a suitable plastic. A positive stop is a small end feature that keeps a sliding part from moving past its intended position. Both features can help make a removable holder easier to handle and inspect.
Keep the carrier separate from the calculator’s electronics and battery compartment. A visible side pocket or rail can hold the phone beside the calculator, while leaving the calculator’s face exposed. Avoid a shell that makes the phone look like a built-in calculator part. Do not use magnets or metal parts that could interfere with device operation.
Make a simple mock-up first. If it fits, use it to guide the finished carrier. Choose a removable, nonconductive material and round the edges that your hands may touch. Add a positive stop so the phone cannot slide out by accident, but make sure you can still remove it without force.
Do not add a sealed cavity for a phone or battery. Do not charge the phone inside the carrier. A close-fitting enclosure can hold heat, especially during charging or heavy phone use. If the phone feels unusually warm, take it out and let it cool in a safe place.
Build sequence
- Survey: Confirm the exact models and measure both devices with planned accessories.
- Plan: Mark controls, ports, camera areas, and the phone’s slide direction on a sketch.
- Mock up: Make a full-size paper or foam version and check access and removal.
- Fabricate: Make a removable carrier from nonconductive material. Do not alter calculator electronics or its battery area.
- Finish: Smooth rough edges and remove loose material that could scratch either device.
- Test: Check the slide, stop, controls, and phone removal without forcing or compressing anything.
A rough edge can snag a pocket or scratch a device. Smooth the part before regular use, and check it again after any change to the shape. If the design needs a tighter fit to stay on, use a different design rather than adding pressure.
Verification: Check Fit, Controls, and Heat
Verification means checking that the carrier works as intended before relying on it. Test insertion, removal, retention, and access to controls. Also check for snags and warmth. Passing one fit test does not prove the carrier is safe in every setting, so repeat the checks if you change a phone case or carrier part.
Slide the carrier on and off several times. It should move without catching, scraping, or needing a hard push. Check that the positive stop holds the phone during normal handling, but does not make it difficult to remove.
Use this checklist:
- Can you remove the phone without pulling on a cable or pressing hard?
- Can you see and use the TI-85 screen and keys?
- Are phone controls, ports, cameras, and audio openings unobstructed?
- Does the carrier stay in place without squeezing either device?
- Are edges smooth, with no loose or sharp parts?
- Does the phone remain at a normal temperature during ordinary carrying?
Do not charge the phone in the carrier. If it becomes unusually warm, remove it and stop using the carrier until you understand why. Do not cover heat-dissipation surfaces. A carrier is not a cooling device, and a simple fit check cannot show how the phone will behave in every use condition.
Fit-Test Scenarios: Learn From the Bench, Not Guesswork
These are reproducible test scenarios, not claims about a specific user or a field study. They show how small design choices can change the fit. Record what happens with your own devices, since phone cases, materials, and finishes differ.
Scenario 1: The case was not included in the measurement. The bare phone fits the mock-up, but the phone with its everyday case catches at the opening. Re-measure the cased phone and remake the mock-up. Do not force the case through a narrow slot.
Scenario 2: The phone slides, but a camera bump catches. The main body clears the pocket, yet the raised camera edge snags during removal. Adjust the opening around that feature and test again. Keep the camera uncovered.
Scenario 3: The holder blocks calculator controls. A combined sleeve covers part of the screen or keypad. Change the layout to a visible side carrier that does not cover those areas. If the calculator cannot be used normally, the design has failed its basic access check.
Scenario 4: The phone warms inside a close-fitting pocket. Remove it, stop charging it there, and check whether the carrier blocks an opening or holds heat. Keep the carrier open and do not use it as a charging enclosure.
Write down the result of each check. A short record makes it easier to spot why a later version fits differently, especially after changing the phone case or material.
Use the Carrier Without Breaking Rules
A transport carrier should make it clear that it holds a separate phone. Do not make the phone appear to be part of a working TI-85, or use the carrier to bypass exam, workplace, security, or device-inspection rules. If a rule bans phones, do not bring the phone into that setting in a disguised holder.
If you need audio or notes, use only methods allowed in that room. Ask for permission when the rule is unclear. A visible carrier may help organize devices, but it does not change the rules that apply to them.
Key next step: Measure the phone with its case, make a full-size mock-up, and check the relevant policy before fabricating anything.
FAQ: TI-85 Phone Carrier Questions
These answers focus on a visible carrier for transporting a phone and TI-85 together. They do not cover disguising a phone as a calculator or bypassing inspection rules. Check your device documentation and local rules, and test the fit with the exact devices you plan to carry.
Can a phone fit in a TI-85 calculator case?
It depends on the phone, its case, and the case design. Measure the phone in its final case and compare it with the available space before making a carrier.
How much clearance should I allow around the phone?
Use 0.5–1.0 mm per side as an initial design target. This is a fabrication allowance, not a manufacturer requirement. Confirm it with a physical mock-up.
How much room should the slide have?
Start with 1–2 mm of total clearance at the slide interface. Test the fit, because material shrinkage and surface finish can change how it moves.
Should the phone stay in its own case?
Measure it with the case you plan to use. A case changes the phone’s size and can add raised edges around the screen or camera.
Can I cover the TI-85 screen or keypad?
No. Keep the calculator’s screen and keys visible and usable. If a carrier blocks them, change the design.
Can I charge the phone inside the carrier?
No. Remove the phone before charging. A close-fitting enclosure can trap heat, and the carrier should not block heat-dissipation areas.
Can I use magnets or metal to hold the carrier in place?
Avoid them. The design should use a removable, nonconductive carrier and should not risk interfering with device operation.
Do I need to modify the calculator?
No. Do not alter its electronics or battery compartment. Make the phone holder removable and separate from those parts.
Will this carrier be allowed during an exam?
That depends on the exam rules. A carrier does not make a prohibited phone acceptable. Ask the exam administrator or leave the phone outside the restricted area.
What should I do if the phone gets stuck or feels warm?
Do not force it out or keep using the carrier. Remove the phone carefully if you can, stop charging it there, and revise the fit before using the carrier again.
(This article was written by one of our staff writers, Samuel Thornton. Visit our Meet the Team page.)
