Unsinking the Battleship (Model-M)

So the Battleship Model M keyboard stopped working. Keys became unreliable and eventually a bunch around the “S” key stopped completely.

Took me a while to correctly identify the root cause.

Unfortunately there’s a fatal flaw in the Model M keyboards: IBM welded the top plastic shell to the steel brace by pushing the plastic thru the brace and then melting the ends. Over time, the plastic gets brittle and the melted ends snap right off.

What I thought were paper punch confetti in the keyboard was actually the melted “welds” snapping off and floating loose.

After I worked this out, I realised I was going to have to bite the bullet and do the… (Shudder) Bolt Mod.

Yes, this happens so often that it’s well understood and even has a name.

Modifications:IBM Model M:Nut and Bolt Mod – GeekHackWiki

I ordered all the bolts and nuts off Ali Epress and waited for them to come in. 

Meanwhile I disassembled the Model M, including snapping off the few remaining melt welds off with a chisel. I also cleaned all the keycaps and the top and base plastics with detergent and a brush. I also rewound the cord (Heat it gently while it’s wrapped around a dowel) and cleaned it up some more. Finally I repaired a fine crack in the plastic shell with superglue and bicarb. 

When the parts finally arrived (So tiny!) I set up my dremel and carefully drilled through the plastic with a 1.6mm drill bit. There are a LOT of holes to drill so I took my time. No one wants a wonky hole :->

(In the end, one hole was at a slightly “off” angle, and one hole was not needed. Pretty happy with that over 70+ holes drilled)

One by one, I tightened the bolts through the plastic. The hole is tight enough that the bolts actually cut a thread into the plastic.

Once that was in I started rebuilding the keyboard, re-adding the springs, the membranes and finally the steel reinforcement plate. Once the plate was on, I added 5 more bolts “upside down” from the underside at the base of the keyboard, as there’s not enough clearance above for nuts to be added, so these 5 rely strictly on the thread they cut. Since there’s approximately 70 other bolts, it’s not the end of the world.

Now I started adding the teeny tiny nuts to the ends of the bolts poking through the metal plate. So tiny! I only had one adjustable wrench small enough, and it had literally come out of a christmas cracker. It’s amazing how many uses I have for a spanner that’s shorter than my tweezers. After getting the first 12 nuts attached, I snapped, went out to the garage, gathered every single hex head socket I could find of about the right size, and checked them until I found one that was a good fit. After that, the nuts went on a lot quicker.

There were a few minor issues along the way. One of the holes was slightly crooked, and thus needed redrilling. In some of the holes, the remains of the original welded post was still long enough as to cause problems. I simply backed out the bolt and went to town on the plastic with side cutters. I had to apply careful pressure on one or two bolts to get them to poke through enough that I could get some of the thread of the nut onto them so I could tighten them. Finally I had missed two locations for bolts that only became obvious after the rest were in. I simply drilled and added the additional bolts after the rest were done. The bolts were a fraction too short. An extra millimeter or two would have made the whole project a lot easier, without adding any risk.

Once all nuts and bolts were assembled, I did a test fit, and then tested the keyboard itself was working. It was, so final assembly commenced.

I now have the whole beast back together again, and best of all, if needed, the whole thing is serviceable now. Not that I’d want to undo 70+ nuts at any point. 🙂


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