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Mod My Model M
NKRO USB Mod Kit
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What is a Model M Bolt Mod?

Bolt-modding an IBM Model M replaces the original melted plastic rivets (×20) with M2 × 12mm screws and nuts, allowing the keyboard to be disassembled and reassembled. Required for internal modifications like membrane or controller replacement. Tools needed: drill with 3mm bit, center punch, M2 screws/nuts/washers. Process: mark rivet centers, drill out rivets, install screws with washers. Time: 1-2 hours. Permanent modification but does not affect typing feel or appearance when done correctly.

IBM Model M Bolt Mod Guide

The bolt mod is essential for any internal Model M modification. This guide covers everything you need to know.

Why Bolt Mod?

IBM Model M keyboards are held together by plastic rivets that are melted during manufacturing. These rivets cannot be removed without destroying them, making the keyboard impossible to disassemble and reassemble. The bolt mod replaces these rivets with screws, enabling:

  • Internal cleaning and maintenance
  • Membrane replacement (for NKRO upgrades)
  • Controller replacement (for USB conversion)
  • Spring replacement or lubrication
  • Case modifications

Tools & Materials

Required Tools

  • Drill (corded or cordless)
  • 3mm drill bit (or 1/8" bit)
  • Center punch or nail
  • Hammer
  • Phillips screwdriver
  • Hex key or socket (for M2 nuts)
  • Safety glasses

Required Materials

  • M2 × 12mm screws (×20) - stainless steel recommended
  • M2 nuts (×20)
  • M2 washers (×40, optional but recommended)
  • Isopropyl alcohol and cloth (for cleanup)

Note: Our kit includes a bolt-mod hardware kit with all screws, nuts, and washers.

Step 1: Disassemble Keyboard

  1. Remove all keycaps (use keycap puller or carefully pry with fingers)
  2. Flip keyboard over and remove all case screws (typically 4-6 screws)
  3. Carefully separate case halves (may require gentle prying)
  4. Disconnect cable from controller
  5. Remove barrel plate assembly from case

Step 2: Mark Rivet Locations

There are typically 20 plastic rivets holding the barrel plate to the case. You need to mark the center of each rivet for drilling.

  1. Place barrel plate on a stable surface
  2. Locate all 20 rivets (they look like small plastic posts)
  3. Use center punch and hammer to mark the center of each rivet
  4. Make a small divot—this prevents the drill bit from wandering
💡 Tip

Take a photo of the rivet locations before drilling. This helps you remember where each screw goes during reassembly.

Step 3: Drill Out Rivets

  1. Put on safety glasses
  2. Secure barrel plate (clamp or have someone hold it)
  3. Start drill slowly at each marked center point
  4. Drill through the rivet completely—you'll feel less resistance when through
  5. Repeat for all 20 rivets
  6. Clean up plastic shavings with brush or compressed air
⚠ Important

Drill slowly and steadily. Going too fast can crack the plastic case. If you feel excessive resistance, stop and check your alignment.

Step 4: Install Screws

  1. Clean all drilled holes with isopropyl alcohol
  2. Place barrel plate back in case bottom
  3. Insert M2 × 12mm screw from top (through barrel plate into case)
  4. Add washer on bottom side (optional but recommended)
  5. Thread M2 nut onto screw from bottom
  6. Add second washer between nut and case (optional)
  7. Tighten with screwdriver and hex key—snug but not overtight
  8. Repeat for all 20 positions
💡 Tip

Tighten screws in a star pattern (like tightening car wheel lugs) to ensure even pressure distribution. Don't overtighten—you can crack the plastic.

Step 5: Test Fit & Reassemble

  1. Place top case half on barrel plate assembly
  2. Check alignment—case should close flush
  3. If case doesn't close properly, check for:
    • Screws too long (protruding through top)
    • Nuts not fully tightened
    • Misaligned barrel plate
  4. Once aligned, install case screws
  5. Reconnect cable to controller
  6. Test keyboard before reinstalling keycaps

Common Issues & Solutions

Drill bit wanders / hole off-center

Solution: Use a center punch to create a starting divot. Start drill at low speed. Consider using a drill press if available.

Plastic cracks around hole

Solution: Drill slower with less pressure. If crack is small, it usually doesn't affect structural integrity. For large cracks, consider epoxy repair.

Case doesn't close flush after bolt mod

Solution: Check screw length (should be 12mm). Ensure nuts are fully tightened. Verify washers aren't too thick. Check for plastic debris in screw holes.

Screws feel loose after tightening

Solution: Add washers on both sides of the nut. Use thread-locking compound (blue Loctite) on threads. Ensure you're using M2 nuts (not M2.5 or M3).

Tips for Success

  • Work slowly and carefully—rushing leads to mistakes
  • Use stainless steel screws to prevent rust
  • Washers distribute pressure and prevent cracking
  • Label screws if doing multiple keyboards
  • Keep a vacuum nearby to clean up plastic shavings
  • Test fit before final tightening
  • Don't overtighten—snug is enough

Ready to Upgrade?

Once your Model M is bolt-modded, you can install our complete NKRO USB upgrade kit.

View the KitInstallation Guide