Bolt Modding an IBM Model M122 “Battlecruiser”
The IBM Model M. The greatest keyboard in the history of computing. This version, the M122, is the larger cousin of the iconic M with 122 keys of buckling spring goodness. I bought the keyboard pictured above a few years back with the intention of using the 22 function keys as a macro garden for my VIM and i3 workflow but never got around to it. Now, with an upcoming move for grad school and the prospect of rebuilding my workstation, I thought I’d give the M122 a much needed refurbishing in anticipation of its future use.
Why Bolt Mod?
So a large part of the reason for this refurbishing lay in the way in which the plastic body of these older keyboards decays. Though this keyboard certainly earns its nickname of “battlecruiser” with a steel interior and heavy-duty plastic exterior, the plastic rivets which connect the internal frame assembly to the steel backplate are notoriously weak. A significant part of why I failed to use this keyboard after purchasing it is I had noticed several of the plastic rivets had broken off causing the upper row of function keys’ buckling spring switches to no longer make proper contact with the membrane sheet below which is responsible for registering key presses. Additionally, the plastic of the internal frame assembly had developed a crack that, though not dire, was causing issues with the top row of function keys. Repairing the crack with some E6000 and bolt modding the keyboard should make it once again usable as well as extend the overall lifespan of the keyboard.
Disassembly
Disassembly of the M122 is relatively straight forward and only requires the use of a 7/32 hex bit for removal of the case and a 1/4 hex bolt for removal of the controller from the backplate. Once the casing is off remove the controller as well as all keycaps.
Rivet Removal
For this sage use a knife or chisel to cut away all of the plastic rivet heads. I opted to use a wood chisel due to its sharpness and the simple fact I had one handy. Light tapping and prying should be enough to remove even the most stubborn among them.
“Fixing” the Crack
Okay… so saying I am fixing the crack that developed might be giving me more credit than I am due. Since the crack is thin and contained the combined use of some E6000 on the underside combined with the additional stability the bolts will provide should adequate in both fixing the operational issues associated with it as well as keep it from spreading. The unfortunate thing about the internal frame assembly of this era of keyboards is it grows extremely brittle over time and is designed to bend to the curve of the black plate. This causes stress on the bend points which, when combined with years of pounding keystrokes, eventually leads to the formation of cracks.
Drilling
After completely disassembling the keyboard the first step in the actual modification of the keyboard requires removal of old rivets and plastic studs. For this process I used a pair of small clippers and a handheld drill to remove the excess plastic and drill the holes respectively. I elected to leave a few of the outer studs that were still in good shape just to help with aligning the internal frame assembly with the backplate during the reassembly process.
Nuts and Bolts
I ordered the screws, nuts, and washers from McMaster-Carr per the directions for this modification from the GeekHack wiki. With all the holes drilled thus began the monotonous process of poking the tiny M2 bolts into position and placing the 122 buckling springs back into position.
I elected not to place all of the M2 bolts immediately. Rather, placed those in the corners and a few in the center to initially secure the backplate prior to securing the rest. This has the additional advantage of allowing testing of the keyboard prior the completing the full assembly process.
Once aligned and tested, the rest of the bolts were placed and secured firmly though not overly tight so as not to risk cracking some of the more brittle regions of the assembly.
With this process completed the bolt modification process is officially finished!
