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IBM Model M Restoration Part II- bolt-mod / rivet replacement

Discussion in 'Overclocking & Hardware' started by mr626, Apr 10, 2012.

  1. mr626

    mr626 Member

    Jul 17, 2011
    2017 edit: I changed image host and pics are dead, sorry. If anyone cares, PM me and I'll see what I can do.


    This is part two of my original Model M restoration thread, which can be found here:


    Although, I guess in some ways it isn't a 'true' part two, since this actually involves a different Model M board than last time!

    Rather than go through the whole restoration process, I'll focus on the 'bolt mod' part as I've already covered the cleaning process in my other thread. In many ways this is more of a proper restoration, since unlike my first Model M this one needed more than just a good clean.


    -Apologies for the quality of the photos- camera phone FTL

    -Bolt modding isn't for the faint-hearted. There are numerous ways that you could screw it up and potentially wreck your board. Personally, I waited until I had a 'spare' board to try it on since Model M boards are fairly rare and I didn't want to wreck the only one I had. So, I'm not responsible if you try this and something bad happens!

    -I'm not really covering new territory with this bolt mod- rather, I'm standing on the shoulders of several 'giant's (mainly from the geekhack forums). In particular, I mainly followed this excellent guide here (with a few minor changes): http://geekhack.org/showwiki.php?title=Island:12093

    What do you mean by bolt-mod?

    These keyboards are built tough- I think most people know that. They do however have a weakness. Internally, the different layers that make up the Model M (plastic barrel plate, rubber mat, circuit sheets and metal plate) are all held together by plastic rivets:


    These simply break off over time, resulting in (at best) a keyboard that feels inconsistent and (at worst) a keyboard with non-working keys.

    I was fortunate that with my first Model M it appears to have all the rivets intact, but with this second Model M I knew as soon as I picked it up and heard the tell-tale 'rattle' that it had at least a few broken rivets. Which leads us to bolt-modding.

    As the name suggests, bolt-modding is the process of removing all the plastic rivets in a Model M, and replacing them with nuts and bolts. At this point I can't help but think of this snippet from Daria:

    What do I need to do this?

    Here's what is needed to do a bolt mod:

    A Model M keyboard (obviously). In my case, I used a 'silver label' 1390131 Model M, with a birthdate of 24-10-86


    To remove the rivets that haven't already broken off, you need a sharp chisel and some thick gloves for safety (ignore the nuts and bolts in this next photo- they were nowhere near close to being the right ones). Make sure that the chisel really is sharp and you'll make the job easier for yourself when it comes time to drill


    As mentioned in my other thread, to put apart the outer casing of a Model M you'll need a slim profile 5.5mm nut driver. Something like this (can be found cheaply on ebay):


    You also need a 4mm socket for securing the nuts. My advice would be to see if you can pick up a socket driver kit that has both the 5.5mm and 4mm in one. Note that the 5.5mm one needs to be a slim profile one, otherwise it won't fit into the plastic outer casing of the board.

    As for the nuts and bolts, you need:

    2mm x 8 x .4 bolts (pan heads)
    2mm x .4 hex nuts

    Seen here modelled by my ever-helpful assistant:


    Now, on the geekhack guide I followed, they state that you need 50 nuts/bolts for a 1391401. This may be the case if you were to put a nut/bolt in place of every single plastic rivet. I found that you don't really need this many though. In the end, I used 37 nuts/bolts (actually I used 39, but I did a crappy job on drilling two of the holes for the nuts and didn't end up using them as the nuts wouldn't have lined up with everything else for reassembly. Plus, you don't need to replace each each and every plastic rivet with a nut/bolt. Naturally, a nut and bolt is going to be much stronger and do a better job at holding things together than a plastic rivet, so you simply don't need as many.

    Some sort of rotary tool with sanding/grinding attachments can come in handy if like me you need to do a bit of extra prep / cleaning where you removed the rivets prior to drilling. My poor-man's dremel is a DSE unit:


    For the drilling, you need a 1/16" drill bit and a drill that can take it. Initially, I was going to try and use my rotary tool for this, but the drill bit was way to small to fit in it (the geekhack guide I was following says to use the dremel for drilling). My 'plan b' was to use my trusty Stanley hand drill. Having done the bolt mod, I actually think this is a better option. The drilling you are doing is on a very small scale, in a vary small area and into 20+ year old plastic. DO you really want a 8k rpm rotary tool for this?

    An old, plate bit of wood will come in handy too, unless you don't care about drilling into your work area.

    You'll need a small philips head screwdriver to screw the bolts into the barrel plate. An electric screwdriver is an even better choice.

    Other than all that, you need a flat work area, an old towel or two for padding/protection, and a couple of chunky 'things' to suspend the board at several points during the process. The guide I was following uses two bits of wood, but I just used whatever was laying around (empty CD spindles, mini toolbox cases etc).

    And finally, you need patience and time. My bolt modding experience was spread across a few months (due to having to wait to get the right tools and the right parts) but I would estimate that if you sat down with everything you needed in front of you, you would be looking at about 4-5 hours worth of work (taking it slowly). It isn't something that you want to rush- you are working with ~25 year old plastics so you don't want to be rough with it or you risk breaking things that can't easily be replaced.

    If you have all of the above, you are ready to bolt mod your keyboard!

    Disassembly- outer casing

    Obviously, the first thing that you need to do is pull the board apart. Start with using the slim profile 5.5mm nut driver to remove the 4 bolts on the bottom of the keyboard (in the below photo you can see the four holes along the top which are where the bolts are located)


    You can then lift the top half of the keyboard outer casing right off, and you'll get your first good look at the barrel plate (the black plastic plate with cylinders rising up from it, which hold the springs and hammers that make up the key switches).

    At this point, you are ready to remove the 'sandwich' of metal plate, circuit sheets, rubber mat and barrel plate (with keys attached). You should be able to carefully lift this whole sandwich free off the bottom half of outer casing- none of this is screwed in but simply 'sits' on plastic nubs that are part of the case. Be careful with the controller (located under the metal plate).

    Once everything is clear of the outer casing, the next step is to unplug the controller. There are four cables you need to unplug:

    -One that goes to the keyboard LEDs
    -The grounding cable (braided metal) that goes from the controller to the metal plate
    -Two 'ribbon' cables that connect the keyboards circuit sheets to the controller.


    Looking at the picture above, you need to gently pull the ribbon cables out from the black plastic sockets on the controller. There are no locking/unlocking mechanisms to worry about (which tricked me at first- I thought they might be like the ribbon cables used in laptops etc) they fit snugly in the sockets on the controller and just need to be pulled out and pushed back in when you are done.

    If, like me, your board already has some broken rivets you'll find them at this point floating around in your board. This is why we want to replace them- the damn things break!

    With the board in pieces, it is a good chance to clean the outer casing. Warm soapy water is a good idea. Don't forget about the birth certificate on the underside of the board though- most Model M owners like to keep these intact.

    With that out of the way, we are ready to move on to the next step.

    Removing the plastic rivets

    Lay down a folded towel on your flat work area, and place the 'sandwich' upside down on to it (so, the keys will be on the towel). You should be looking at the shiny metal plate with lots of black rivets. These are what we want to remove!

    Put on your gloves and get ready to use your SHARP chisel. Basically, you want to have the point of the chisel under the head of the rivet and 'twist' in a circular motion. It's a little bit hard to describe, so hopefully these pictures will help:


    If you are doing it right, the heads of the rivets should fly off fairly easily (you WILL be finding them many weeks later- they really do fly off). You are going for as clean a cut as possible to give you a flat stump to drill into later (although you can fix this up later with sanding/grinding if like me your chisel wasn't as sharp as you thought...). During this process you will likely scratch the metal plate (you can see some of the scratching above)- don't worry about this, it doesn't damage anything and once you've put the board back together you'll never see it again anyway.

    Also note on the last picture above- if you have any stickers on the metal plate you will likely have a rivet or two hiding under it. For me, I had two under one of the stickers as shown.

    Continue to remove all the rivets. Be very careful- you are working with a sharp chisel and can easily damage the keyboard, nearby cats or even yourself (hence the gloves). Also take care not to damage the ribbon cables that are hanging out the side (the ones we unplugged from the controller earlier). If you damage these its game over.

    Leave a couple of rivets near the centre of the metal plate intact. When you just have these to do, you need to suspend the board in such a way that the keys aren't being depressed. As you can see, I ended up using CD spindles for this (which didn't work very well actually):


    Disassembly- the 'inner sandwich'

    The aim of this step is to carefully separate the different internal components of the Model M so we are left with a naked barrel plate, ready for drilling.

    Carefully remove the remaining rivets. You should then be able to lift everything else off the barrel plate (when I say 'lift' I really mean 'gently wiggle until everything comes loose'). I found the best way was to first lift off the metal plate and circuit sheets, and then lift off the rubber mat. As mentioned, you may have to wriggle things a bit to get them off the stumps left over from the rivets that you removed (especially if any of them have become 'mushroom topped' as a result of less than perfect chisel work).

    Once that's done, you'll be looking at the underside of the barrel plate, and you'll see the hammers for each of the keys. I must have forgotten to take a photo at this stage, so here's one from later in the process that shows the same thing:


    You should be able to remove these by hand very easily, just be careful not to damage any springs as you remove them. To help with this process, here is a picture of a removed hammer/spring so you can see what you are dealing with:


    Note- the guide I was following suggests that at this point, it is worth thinking about whether or not you want to swap over the hammer/spring of well-worn keys (say, something like the space bar) with a lesser-used key (scroll lock?). I had tested my board prior to starting this mod and all the keys seemed fine, but if you have any keys that felt a bit 'off' before you started this mod its worth taking note of the condition of the hammer/spring when you remove it, and either swapping it with a different one on the same board, or replacing it with a new one (these can be purchased from Unicomp in the USA- I was able to buy some from a US friend I made on geekhack). For me, I didn't worry about keeping track of which hammer/spring was from which key, and I think for most people it won't matter.

    With all the the hammer/springs removed, it is safe to turn the barrel plate right side up. You are now ready to remove both pieces of the keycap.


    The above shows the barrel plate with the function row completely removed, and with the top piece of the other keys removed (other than keys like the Shift, Capslock and space bar, which are one piece keys).

    When you are done, you should be left with a naked barrel plate.

    Drilling the bolt holes

    At this stage, have a good look at the stumps left over from removing the rivet heads. Are they nice and smooth and flat? Or, were you like me and did a crap job with the chisel, and have lots of mangled looking stumps?

    If its the later, you will want to do some clean up work. Remember, for the drilling we need to drill through the centre of the stump left over from the plastic rivet, so it needs to be flat.

    Enter the rotary tool with grinding (and/or sanding) attachment.


    The above is picture with a grinding tool- I found this didn't work that well and ended up using a coarse sandpaper attachment with worked much better.

    Being careful to support the curve of the barrel plate, use your rotary tool to sand back the stumps of the rivets so that they are nice and flat. In the picture below, you can see one rivet stump the the first row that is flat and ready to be drilled, and directly behind it you can see one that is...less flat and needs to be cleaned up.


    IMPORTANT- you may have noticed that around the stumps left over by the plastic rivets there are two crescent moon shaped bumps. DO NOT DAMAGE THESE- they play a big part in how the keys feel, and if you wreck these you'll basically wreck the feel of the board. Thankfully I didn't wreck mine, but I'm just passing on the same warning that I've seen in most other people's bolt-mod attempts.

    Once you are satisfied that the rivet stumps are nice and flat, its drilling time!


    The key things to remember here are:

    -Support the barrel plate and its natural curve, and don't flex it more than is needed. Remember, you are working with very old plastic!
    -Take your time, and aim to drill as close to the centre of the rivet stump as possible
    -Don't damage the half moon crescents
    -Don't worry too much if you screw one up- as mentioned you don't really need to replace every single plastic rivet with a bolt, so you can afford to muck up a few

    I didn't drill every stump- in many areas I just did every second one.

    IMPORTANT- before you drill, check what is on the other side of the barrel plate. For most of them it won't be a problem, but depending on your Model M you will have problems with the plastic latches on the barrel plate that hold the wire stabilisers for the + and enter keys on the numpad.

    Looking at these to pictures:


    The above shows the numpad end of the barrel plate, with two holes drilled.


    The above shows the other side of the barrel plate. See that rivet stump I'm pointing at? If you drill that, you'll go right through a plastic stabiliser latch on the other side.

    As it happens, I thought I was safe with the drilling I did around the number pad area, as I didn't damage anything. But, once I went to install the + and enter keys again, I found that the bolt heads prevented the wire stabilisers from working properly. In the end, I just removed the wire stabilisers from those keys- they still work fine and don't feel any different. Personally, I'd rather have extra bolts for the numpad area and do without the wire stabilisers, but you might be different. If so, be extra careful where you drill/install bolts.

    Continue drilling until you have done as many holes as you want to / require. The actual drilling is quite easy (it isn't exactly hardwood you're drilling after all). Expect plenty of plastic shavings everywhere.


    Once you have done drilling, flip the barrel plate over and check the resulting holes on the other side. You'll be screwing the bolts in from the top of the barrel plate, so make sure that the holes from the drilling are smooth and clear, and free of plastic. I found for many of the holes that I needed to give them a quick drill from the top side of the barrel plate to make sure they were completely clear.

    When you are completely done drilling, consider taking the opportunity to clean the barrel plate. Brush it clean of any leftover bits of plastic, and soak in some warm soapy water and leave to dry.

    With a clean barrel plate and all the holes drilled, you are ready to start putting it back together.

    Install the bolts

    With the barrel plate right side up and properly supported with a towel/bubble wrap etc, start screwing in the bolts. The holes you have drilled are slightly smaller than the bolts, meaning that they can be a little tricky to get started but once the thread catches it will screw in fairly easily. As mentioned, make sure the holes are clean and clear to make this easier.


    When you are done, flip the barrel plate over and hold it at eye level. Examine carefully the threads of bolts that are now sticking through:


    You want the 'rows' of bolts to line up, otherwise putting the board back together is going to be hard. At this point I noticed two bolts near the top of the barrel plate that were quite off course (as a result of less than perfect drilling). I made the decision to remove these prior to reassembly as I knew they would cause problems. This took me from 39 to 37 bolts in total. The board feels fine, so no harm done!.

    A quick way to check that everything is okay at this stage is to make sure that the rubber mat fits easily over the bolts:


    If all is well here, you are ready to start putting the sandwich back together.

    Put the layers back together and install the nuts

    You are now ready to put the board back together and install the nuts on the bolts, to finish the mod.

    First step is to suspend the barrel plate upside down, similar to what you did when taking it apart last time. Why? Because the next step is putting the hammer/springs back in, and you don't want to damage the springs. This picture might help describe things better:


    Install all of the hammers/springs. There are a couple of 'blank' holes that don't require hammer/springs- check the next picture for which ones:


    With all of the hammer/springs installed, now install the rubber mat. As before, this should fit easily over the bolts.

    Next are the circuit sheets, followed by the metal plate (for me, this was one single step as I kept the circuit sheets and metal plate together the whole time):


    The bolts won't go right through the holes in the metal plate- the cure of the metal plate is slightly greater than the nature curve of the barrel plate so the two won't perfectly align by themselves. You need to carefully (WITHOUT damaging any of the springs sticking out) press the barrel plate and the metal plate together, so that the bolts stick through enough for you to start a nut by hand. I started by doing one nut on each end, and then worked my way along:


    You can start the nuts by hand, then finish them off with the 4.4mm socket. Things to remember when doing this:

    -Be careful not to damage the springs: either with you hand when you are pushing the plates together or by letting the whole lot fall off the supports its resting on
    -Don't over-tighten the nuts
    -As always, be careful and take your time.

    Once you are done, it is safe to turn the board over. At this point, its worth installing one or two keystems to check that all is well with the switches:


    If the keys still 'click' like they did before, you're all good. If not...well something probably went wrong when you put the sandwich back together. You may need to undo the nuts and check that all the hammers and springs are properly seated etc.

    Final testing and reassembly

    You're almost done! Continue to reinstall the keys, being careful to align the springs properly when you insert the keys in the barrel plate (if you don't know what I mean, refer to my other restoration thread).

    All of this process is just the opposite of what you did before, so no special instructions here. I would advise that you test the keyboard on a computer before putting the outer casing back together though. Once all of the keys are installed and the controller is plugged in (the ground wire, numpad and two circuit sheet ribbon cables) plug the keyboard into a computer and test that all of the keys work using your favourite method of keyboard testing. For this, I use a free program called AquaKeyTest.

    Results: all good!


    One issue that I did have when reinstalling the keys was the wire stabilisers for the numpad keys (+ and enter). Have a look at this pictures:


    Whilst I didn't go through any of the plastic latches used by the stabilisers, the mere presence of the bolt heads meant that the wire stabilisers for the two keys mentioned don't function as the bolt heads are in the way. The solution was just to remove the wire stabilisers- the keys till work fine without them.

    Once you are happy that the keyboard is working well, you are ready to install the outer casing.

    And with that, we're done!

    Other notes

    This board was much cleaner than my other board, but I still followed my normal cleaning steps as per my original restoration thread. As part of the bolt mod you have an excellent chance to clean the outer casing too so naturally I did.

    One additional cleaning challenge for this Model M was all those stickers that you can see on the keys in the pics at the start of the thread (I guess they are from Wordperfect or something of that era?). Soaking removed most of the stickers, but the 'gunk' was still left over. In the end, it took some of this and some gently scrubbing to remove:


    As always, make sure you test something like this before using it- you don't want to wreck the keycaps. As it stands though, PBT seems to handle this just fine.

    Final pics


    Final Thoughts

    I'm really glad I did this. I know to many people it will seem like a lot of time and effort to spend on a keyboard, but I don't care. Although it was a little daunting at first, once I got into it and started doing the mod it was fairly straight forward. I'm not some sort of master DIY / handyman either- if I can do this then I think most people could.

    Would I do it again? I think so, given the right circumstances. I don't think I'll be spending $100 or so on a Model M with the intention of bolt modding it, but if I was given another one for free or I found one for $10 at a garage sale then I'd give it a shot. If a close friend had a board they wanted restoring I'd be happy to do it. At least if there is a 'next time' it should be much faster since I've got all the parts now and having done it once I know what I'm in for.

    I'm very happy with the end results. The board feels very crisp and new. Compared to my other Model M, the switches on the bolt modded one are slightly more metallic and higher-pitched. The board feels even more solid than it already did.

    Thanks to everyone that has read all this- I know its a massive post to read. I hope that others found it interesting and maybe even inspiring enough to give it a go themselves :)

    Finally, as I hope I've made clear, I don't claim to have invented this particular process of bolt modding. There are quite a few people on places like geekhack and elsewhere that have done this before me. In particular, I recommend this guide that I followed to do my own bolt mod:


    Any question please ask and I'll answer as best I can.
    Last edited: Mar 14, 2017
  2. h2oxide

    h2oxide Member

    Dec 9, 2009
    Great work dude. God I hate Model Ms.
  3. OP

    mr626 Member

    Jul 17, 2011
    :p Thanks. Yes, they aren't for everyone. I wish that more people hated them- more for me!
  4. Tycn

    Tycn Member

    Jul 4, 2011
    Nice work!

    Didn't think I'd lose interest in Model Ms before you finished this...

    BIG.TICKET Member

    Sep 25, 2008
    Great post! Alot of work into the keyboard and the thread. This belongs in the 'forum posts of interest' on the front page!
  6. kandrews

    kandrews Member

    Feb 9, 2006
    South Perth
    Simply Perfect.

    Totally agree, this is one of those valuable "How-to-Guides" that will be soon filling all the Google links within net-space.

    I am amazed at how many bolts you used. In fact I think the "NEW" Model-M will be around longer than me or anyone else here.

    Good to see an Aussie showing the World how it's done - "Properly".
  7. OP

    mr626 Member

    Jul 17, 2011
    Thanks guys. Hope that it inspires some other Model M owners to give it a go. Wasn't as difficult as I expected, you just need to be slow and careful (particularly if you are like me and this is your first attempt at it) :)
  8. ReKleSS

    ReKleSS Member

    May 16, 2005
    Osaka, Japan
    I did this out of necessity - some water got into the keyboard and washed away part of one of the matrix traces. I didn't have drivers for either the nuts nor bolts I used (hex head) - I ended up pushing them through the barrel plate, flexing it enough that I could screw the nut on by hand, then letting it flex back to secure it.

    For cleaning the key caps I used Steradent, denture cleaning powder. The keys come perfectly clean and there's no damage I can see. Haven't done the casing yet, but it should work equally well there.

    My only advice to add is to double-check that all the springs are in before doing the bolts. Inserting keys and realizing there's a spring missing is annoying.
  9. Darmok

    Darmok Member

    Jun 27, 2001
    Hastings, Vic
    It's not quite as vintage.. but I still love my Honeywell 101 keyboard, that I'm using to type right now, on my Home PC.

    It's not a clacker, like the M, but there's still something about the tactileness on this, compared to other modern keyboards...

    I can't type as fast on any other keyboard, as I do on this one!

    I too, have also dissassembled this many a time... usually every 1-2 years, to clean out all the cathair, crumbs and grime... fortunatly, it's quite easy to pull apart.. wash all the keys + membrane, and reassemble.

    I still fine it amusing, that I've got a modern quadcore PC.. 8gigs ram.. blah blah... yet I've got an old AT-era keyboard + 5pin DIN -> PS2 adapter...
    The same keyboard that I got on my very first (bought-with-own-money) PC (P120/8meg/1.2gigHDD)

  10. OP

    mr626 Member

    Jul 17, 2011
    You're game flexing the barrel plate- I try to avoid flexing old plastics where possible.

    I'm well aware of the denture cleaning method for keycaps, and I recommend it to anyone that needs to clean keycaps :thumbup:

    Sage advice about the springs- It's good to be careful at any point where the springs are involves as they are arguably the most fragile component you are working with during the mod.

    That's great that you've got an older keyboard that still soldiers on :) Yes, the contrast between the age/appearance of the keyboard and the computer that it is connected to puzzles a lot of people :lol:

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