IBM Model M Screw, Nut and Bolt Mod

[Samdoses]

Do we have to remove all the springs and membranes or can we screw it from the outside

[fohat]

If you just add screws to broken rivet shaft locations, that is a "screw mod" which is an order of magnitude easier.

Many people prefer this, including pseudo-professional refurbishers, but personally I want to take it completely apart so that I can clean all the parts including the membrane sandwich layers.

[Samdoses]

Is there a way to screw mod it without taking apart the barrel plate by just drilling the back and screwing it.

[fohat]

That is exactly what it is. The term should probably be "screw repair" because you are not modifying anything.

[Samdoses]

I meant to say if we could half screw mod it

[ebonarm]

Hi all, I have done the bolt mod and everything went fine (tip: Aliexpress for bolts, washers and nuts amounted to around 10€)

Anyway, my question is, that now I have the following problem: the key 's' sometimes keeps registering as pressed even though the buckling spring returns the keycap. So bassically the mechanical part works just as intended but the key keeps registering.
Example, I press it once and it continues to print infinitely, or until I press it again.

Anyone has any suggestions?

[Jesseg]

Hi all, I have done the bolt mod and everything went fine (tip: Aliexpress for bolts, washers and nuts amounted to around 10€)

Anyway, my question is, that now I have the following problem: the key 's' sometimes keeps registering as pressed even though the buckling spring returns the keycap. So bassically the mechanical part works just as intended but the key keeps registering.
Example, I press it once and it continues to print infinitely, or until I press it again.

Anyone has any suggestions?

I had a similar problem after I bolt modded my M122. I was able to fix it by taking it all apart again ( I know, annoying) and just lightly cleaning and re-adjusting/positioning the membranes a little, this seemed to work in my case.

[ebonarm]

Hi all, I have done the bolt mod and everything went fine (tip: Aliexpress for bolts, washers and nuts amounted to around 10€)

Anyway, my question is, that now I have the following problem: the key 's' sometimes keeps registering as pressed even though the buckling spring returns the keycap. So bassically the mechanical part works just as intended but the key keeps registering.
Example, I press it once and it continues to print infinitely, or until I press it again.

Anyone has any suggestions?

I had a similar problem after I bolt modded my M122. I was able to fix it by taking it all apart again ( I know, annoying) and just lightly cleaning and re-adjusting/positioning the membranes a little, this seemed to work in my case.

Ok, thank you for the tip, I guess It is inevitable. I was really hoping I wouldn't have to open it up again anytime soon
What did you use to clean the membrane? Did you clean it?

[Jesseg]

I think I literally just used a lens wipe, just anything that won't leave any dust, mine was pretty clean anyway so I'm not sure it even did anything but it stopped playing up after that so go figure.. haha

[ebonarm]

I think I literally just used a lens wipe, just anything that won't leave any dust, mine was pretty clean anyway so I'm not sure it even did anything but it stopped playing up after that so go figure.. haha

Thanks man, I will try it again today !

[fohat]

As I often say, overtightening can be a problem.

Remember that you are replacing compliant plastic rods with steel screws, so all you need to do is keep everything in place and keep the plates the same distance apart. There is no need to put the plates into compression by cranking down hard on the screws, and, even worse, inconsistent tightening.

In my opinion, "barely finger tight" is plenty.

[Niels007]

I just got two clean Model M boards for 100 euro, one is already taken apart but the previous owner was out of brave pills to perform the bolt mod. I'm reading up on how best to do it and thanks to forums like these, I think I have a chance of doing it successfully.

Thing 1
There seems to be very little space for bolt heads or nuts at the bottom, especially on the first row or two. I can imagine this can give some issues trying to force the modded assembly in the outer casing. I've seen the limited space thing mentioned a few times but not as often. What's peoples take on this?

Thing 2
Another thing I wonder. After scraping off the rivets, you're left with slightly protruding round bits. In most guides you see people cutting these off with side cutters or a knife. Wouldn't it make more sense to keep them? Seems to me they act a bit like a spacer for the mat and flexPCBs. Wouldn't this prevent some of the issues people have of over tightening the bolt/screws?

I can see an issue if you would use a countersunk screw in your screw mod, as only a flat head screw would work properly in this case, and that might protrude too much and hit the keyboard casing once you slide in the assembly. Still perhaps it would make sense to not fully trim those protruding bits straight away..

[fohat]

There seems to be very little space for bolt heads or nuts at the bottom, especially on the first row or two.

After scraping off the rivets, you're left with slightly protruding round bits.

Without washers the there is just enough room for the M2s to fit. If yours are interfering, you can use a Dremel to make shallow depressions. After the first or 2nd row, start using washers.

I use a chisel tip Xacto knife and shave the tops of the "mesas" flat, then drill through them creating a cylindrical hole.

[anthonymak]

use this.

[Niels007]

I managed to find some nylon locknuts in M2 size, which I think will be more long term than regular nuts, but they're a bit taller. I ended up buying a whole bunch of screws (2.2 and 2.5mm diameter, 6mm and 8mm length, countersunk and normal heads) as well as m2 bolts and the mentioned M2 nylock nuts.

Do you have part numbers / link to those super flat head screws in the picture Anthony?

I'm probably also taking the second one apart to see what its like inside. The cables are a bit tired so when I'm going to have to pay international shipping from Unicomp for a few cables, might as well add some other parts if mine seem suspicious. Two traces on the ribbon cable seem repaired with some solder or conductive silver paint, so I feel I better play it safe and order that as well..

Up until about a month ago I spent $50 on keyboards in my life, now I'm a few hundred in...

[anthonymak]

here are some variety of super flat head m2 screws from aliexpress

https://www.aliexpress.com/wholesale?ca ... d+m2+screw

I managed to find some nylon locknuts in M2 size, which I think will be more long term than regular nuts, but they're a bit taller. I ended up buying a whole bunch of screws (2.2 and 2.5mm diameter, 6mm and 8mm length, countersunk and normal heads) as well as m2 bolts and the mentioned M2 nylock nuts.

Do you have part numbers / link to those super flat head screws in the picture Anthony?

I'm probably also taking the second one apart to see what its like inside. The cables are a bit tired so when I'm going to have to pay international shipping from Unicomp for a few cables, might as well add some other parts if mine seem suspicious. Two traces on the ribbon cable seem repaired with some solder or conductive silver paint, so I feel I better play it safe and order that as well..

Up until about a month ago I spent $50 on keyboards in my life, now I'm a few hundred in...

[Erisie]

A friend of mine recently bolt-modded my old Model M. The old barrel frame was broken, so we ordered a new one from Unicomp. Some keys on the ZXC row (X, B and sometimes N) are registering two keypresses from time to time.

What's causing this behaviour? Overtight bolts? Faulty membrane? Broken hammer springs? I also replaced the controller board for a new one from Unicomp, so that might be a potential issue as well.

[zrrion]

that sounds like an issue with bolts being too tight

[anthonymak]

looks like its faulty trace but I also come across a water damaged model m with its rubber layer swelled and causes the same problem.

[sofakng]

What's the best way to accurately drill into the rivet without a drill press?

I have a dremel and hand drill but is either one better for this type of mod?

1) Should I just purchase a dremel drill press? ($50; most expensive and I don't need for anything else; EDIT: this might not have the depth needed to fit the keyboard...?)
2) Can I use a drill-bit guide from a hardware store?
3) Is there any 3D printable guides?

Any other tips to accurately drill out the holes?

Also, what size drill bit is correctly? The geekhack wiki says "1/16" (#52 or metric 16) drill bit" or the screws are only M2 so isn't metric 16 much too large?

[Bjerrk]

What's the best way to accurately drill into the rivet without a drill press?

I have a dremel and hand drill but is either one better for this type of mod?

1) Should I just purchase a dremel drill press? ($50; most expensive and I don't need for anything else)
2) Can I use a drill-bit guide from a hardware store?
3) Is there any 3D printable guides?

Any other tips to accurately drill out the holes?

Very good question - I ended up getting the Dremel drill press, but I have yet to try it out.

[jmaynard]

I wound up using a Dremel cylinder/end mill bit (flat end) to make the rivet ends square, then a ball mill but to machine a dimple into each one, then a regular drill press with a 1/16 bit chucked up tight in it to make the actual holes. The Dremel was easy enough to control by hand.

I used the drill press not by moving the spinning bit down to the work, but by moving the work up to the bit. Made it easier to control the hole location precisely.

I'd suggest you go ahead and get the Dremel drill press. I think you'll find it useful for much more than this one project.

[sofakng]

I'm so sorry to ask, but can you provide a link to a cylinder/end mill bit and a ball mill bit?

I've just opened my Model M and cut the rivets but they are not completely flat. I used these to cut the rivets as flat/flush as possible:


...but they aren't quite flat so I think that's what you are saying you used the cylinder/end bit:

[jmaynard]

Right. You need to make the cut off part flat to keep the drill point from walking.

What I called an end mill, Dremel calls a cylinder carving bit, and the ball is either a ball carving bit or a ball engraving bit.

[sofakng]

Got it, thank you so much! I see what you're saying now.

The top (tip) of the cylinder is flat (unlike a normal drill bit). You used that (and not the sides of the bit) to make the rivet area more flat/smooth?

It seems like somebody could create a 3D printable jig that fits around that area to perfectly align the bit. (although maybe the PLA wouldn't be sturdy enough or get drilled up in the process?)

[jmaynard]

Yes, I used the flat end of the bit (that's why I referred to it as an end mill). Hold the tool body firmly and use light pressure so it cuts instead of digging i nand getting pulled away from where you want it.

[sofakng]

Thanks again so much for everything.

One last question (I hope!) ... how do I know where the center of the rivet was or where I should drill?

[fohat]

I use an Xacto knife with "chisel" style blade. I shear off the "mushroom heads" and after all 50 the edge is pretty buggered up.

Then I change to a fresh blade and carefully, using both hands, I shave just enough off each shaft to make a nice clean square flat mesa top. I believe that the taller the remaining shaft, the better the plates will stay aligned. After all, that is what went through the hole in the plate before, and it is much larger in diameter than an M2 screw. That screw will be a "core" to the shaft when it is installed.

It seems to me that the screw is there just to create compression between plates, and if the plastic shaft is long enough to go back through the hole that it always fit in, even partially, then your alignment will be dead on.

[sofakng]

That sounds like a good idea to leave part of the shaft, but I already cut mine like shown in the picture above.

I think I still need to locate where the center of the rivet way to make sure it goes through the hole in the rubber membrane and frame, right?

[fohat]

I still need to locate where the center of the rivet

Put the metal back plate in place and use it as a template.