IBM nut and bolt mod tips & tricks: photoessay (warning 45+ huge pictures)

[njbair]

The thin latex blanket does make for a crisper feel, but a Model M will never be even remotely as crisp as an F.

I would not use the word "ping" for a Model M in the same way that I would for a Model F, since there are very few of the higher overtones in comparison. The sound of the M is deadened somewhat, but not in the satisfying way the way that it is for the F, since the M is rather dead already.

Fohat, your comments remind me of one of my earliest experiences with the Model M. It was back in the late 80's, when the Model M had already replaced the Model F, but Model F's were still available at many surplus electronics dealers. I saw some of them at one such dealer, but passed on the opportunity and opted for an "up-to-date" Model M instead.

My initial reaction to the Model M was much as you describe -- it seemed a bit "deadened" and "plastic-y" by comparison to my memory of the Model F's I had recently seen at the surplus dealer. There was just some elusive, "more mechanical" quality about the F's keystrokes that seemed to be muted in the M. Maybe it was the significant differences in not only the amount of ping, but also the harmonic structure (as you pointed out). The F "sings" when you type on it rapidly, more so than an M.

Furthermore, the "click" on the "F" has a bit more "whack" to it -- probably (as someone else has pointed out) due to the larger and more massive "flipper" in the F smacking down on the hard surface of its PCB; compared to the much smaller and less massive "hammers" (pivot plates) of the M striking the soft rubber blanket in the slightly-compressible "strike zones" of the mylar membrane sandwich of the M, somewhat muting the spring pinging and the buckling click and minus the "whack" component of the F's actuation point.

BTW, can someone confirm that the Model F's flippers actually do make physical contact with the PCB? I'm assuming they do, but I don't know this for certain.

Wouldn't they have to make contact to complete the circuit? Or do I misunderstand how the Model F works?

No contact is necessary in theory -- but may be incidental in the F -- because the F works by sensing the capacitance change in the pads on the PCB. Proximity is required, but actual contact may not be. I guess it depends on the threshold sensitivity of the particular scheme.

I just read all about it on Deskthority and it looks like they happen to bottom out.

However, that same page also says the crisper click of a Model F had more to do with generally superior construction techniques versus later keyboards than any inherent mechanical difference between capacitive and membtane-style buckling springs.

[fohat.digs]

My perpetual argument is that the extraordinary sound and feel of the Model F is due to the multiple rigid plates bent and pressed tightly together generating tension and compression stresses on each other.

I conceptualize that sandwich of plates as something resembling the sounding board of a piano.

Personally, I do not think that the springs, pivot plates, or contact/switching methodology have much to do with it.

[njbair]

My perpetual argument is that the extraordinary sound and feel of the Model F is due to the multiple rigid plates bent and pressed tightly together generating tension and compression stresses on each other.

I conceptualize that sandwich of plates as something resembling the sounding board of a piano.

Personally, I do not think that the springs, pivot plates, or contact/switching methodology have much to do with it.

This makes perfect sense. The whole board on a Model F has resonance just like an instrument. However, the Model M barrel plate assembly is very rigid, especially with a bolt mod, but it's simply resting in between some plastic clips within the case. The sound mostly dies before it even leaves the casing.

I wonder if somehow fastening the barrel plate to the casing would improve resonance.

[SpaceGhost]

I just read all about it on Deskthority and it looks like they happen to bottom out.

However, that same page also says the crisper click of a Model F had more to do with generally superior construction techniques versus later keyboards than any inherent mechanical difference between capacitive and membtane-style buckling springs.

When you think about the differences between the two at the moment of actuation, it seems apparent (at least IMO) that there is more mechanical damping in the M than in the F at the "business end" of each mechanism. Fohat's theory of the inherent tension and compression of the various parts of the F construction is also very intriguing and probably plays a role in the more "lively" feel of the F.

Some time ago I constructed 2 single-unit keyswitch assemblies. Using a 3D-printed set consisting of F-style flipper and F-style single-barrel housing along with an M-style keystem and cap, I made an F-style actuator but using an M-style spring. I constructed another similar one using an M-style pivot plate and spring along with another F-style single-barrel housing. I glued a small rectangle of plastic cut from an old credit card into each housing bottom under the pivot points (but not covering the actuator portion) to constrain the spring and flipper/pivot plate so the assemblies could be handled freely without coming apart.

Then I placed each on top of a sandwich consisting of an M-style blanket and membrane stack on an M-style steel backplate. I pressed each one firmly down on the blanket and pressed the key. The F-style flipper made an enormous difference. The click was much louder and had a bit of the "whack" component I described above. The assembly with the M-style pivot plate was muted and less crisp, although still reasonably satisfying, at least until the comparison is made.

[SpaceGhost]

My perpetual argument is that the extraordinary sound and feel of the Model F is due to the multiple rigid plates bent and pressed tightly together generating tension and compression stresses on each other.

I conceptualize that sandwich of plates as something resembling the sounding board of a piano.

Personally, I do not think that the springs, pivot plates, or contact/switching methodology have much to do with it.

The problem with that theory as I see it, is the foam layer between the top plate and the barrel housings. The foam would damp out a good deal of the resonance within the barrels when the springs buckle and strike those surfaces, as well as damping the acoustic contribution of the top plate. The experiment I described above pretty well proved to me that the F's large flipper striking its PCB makes a big difference in generating the uniquely crisp click of the F, adding to the sound of the spring striking the inside of the barrel.

I should mention that the experiment I did was more dramatic if the membrane layers were removed from the stack and the actuators were striking only the rubber mat on top of the steel, or if only a single layer of mylar was present. The pivot plates in an M strike a soft compressible surface, while the flippers in an F strike a hard surface. That's gotta make a difference.

[fohat.digs]

The foam would damp out a good deal of the resonance

There have been lots of experiments with replacement foam, with original foam being mostly crushed dead anyway.

I prefer a fairly thick and dense foam (1/16" = 1.5mm "art foam" for scrap-booking) which necessitates considerable force to reassemble, simultaneously stressing and dampening the overall assembly.

Someone on DT used the plastic wrapping that the keyboard shipped in (great idea, cheap, quick!) and was very pleased with his results.

I still have a piece of thin and soft neoprene that I got from wcass that I will probably use on my next one.

Others, in general, from the impression I have gotten, go for thicker but softer foams.

[SpaceGhost]

The foam would damp out a good deal of the resonance

There have been lots of experiments with replacement foam, with original foam being mostly crushed dead anyway.

I prefer a fairly thick and dense foam (1/16" = 1.5mm "art foam" for scrap-booking) which necessitates considerable force to reassemble, simultaneously stressing and dampening the overall assembly.

Someone on DT used the plastic wrapping that the keyboard shipped in (great idea, cheap, quick!) and was very pleased with his results.

I still have a piece of thin and soft neoprene that I got from wcass that I will probably use on my next one.

Others, in general, from the impression I have gotten, go for thicker but softer foams.

I can't help but think the combination of tension, compression, and foam would help to keep the sound of the Model F from being too noisy and "uncivilized", while the construction of the Model M makes it all too quiet and "civilized" for Model F fans.

Fohat, is there anything between the PCB and the backplate in a Model F? An electrically-insulating layer of some sort, perhaps?

[fohat.digs]

Yes, there is a sheet of clear mylar.

[SpaceGhost]

Yes, there is a sheet of clear mylar.

Thanks, I thought there would be something like that. Can you see any physical evidence of wear and tear, abrasion, or chipping of the soldermask on the topside capsense pads on heavily-used Model F's? There's no protective mylar or other material (other than screened-on soldermask) on the top of the PCB is there?

[SpaceGhost]

I definitely don't want to kill the (already dampened) crispness of the Model M's buckling springs, which is why I'm going to try the third "secret" item I mentioned above.

Have you (or anyone else reading this) ever tried thin lengths (perhaps cylindrical in shape if possible) of very soft foam material? If soft, round foam-gasket material could be obtained in the appropriate diameter, that might work also...

[njbair]

I definitely don't want to kill the (already dampened) crispness of the Model M's buckling springs, which is why I'm going to try the third "secret" item I mentioned above.

Have you (or anyone else reading this) ever tried thin lengths (perhaps cylindrical in shape if possible) of very soft foam material? If soft, round foam-gasket material could be obtained in the appropriate diameter, that might work also...

This is so close to my idea I'm just going to squawk now. In going to try strips of #16 rubber bands. They are .0625" wide so they should fit inside the springs just fine.

My thinking is that they will be just rigid enough to kill the reverberation of the springs without muffling the sound.

[SpaceGhost]

I definitely don't want to kill the (already dampened) crispness of the Model M's buckling springs, which is why I'm going to try the third "secret" item I mentioned above.

Have you (or anyone else reading this) ever tried thin lengths (perhaps cylindrical in shape if possible) of very soft foam material? If soft, round foam-gasket material could be obtained in the appropriate diameter, that might work also...

This is so close to my idea I'm just going to squawk now. In going to try strips of #16 rubber bands. They are .0625" wide so they should fit inside the springs just fine.

My thinking is that they will be just rigid enough to kill the reverberation of the springs without muffling the sound.

Rubber bands, huh? Oh, snap!

[fohat.digs]

I never expect rubber bands to age well.

[SpaceGhost]

I never expect rubber bands to age well.

True, so true.
But perhaps the rubber bands could be used to make a teeny-tiny slingshot with which to subdue one's lesser adversaries in life...such as incessantly-screaming tots and nuisance-barking small dogs...

[njbair]

I never expect rubber bands to age well.

I didn't think of that. Trying to pry nasty old brittle rubber bands out of skinny springs.

Well, I'll still try it. If it achieves a good sound & feel I can start looking for other similar materials with better durability. And if not, that's the end of it.

[njbair]

OK, to address the issue of rubber bands potentially deteriorating over time, I've ordered some silicone bands which are used for making bracelets and stuff. Silicone is much more durable than natural rubber and not susceptible to oxidation. We'll see how this goes.

[dorkvader]

For those of you who have used the Unicomp white latex blanket to replace the original IBM blanket, I have a question:
Does the Unicomp blanket have any effect on the amount of spring pinging compared to the original IBM blanket? I like the idea of increasing the crispness of the clicks, but am not fond of pinging.

an excellent question. i have both types on hand and will compare ping, though ping isn't too noticeable on a model m already

Yes, there is a sheet of clear mylar.

Thanks, I thought there would be something like that. Can you see any physical evidence of wear and tear, abrasion, or chipping of the soldermask on the topside capsense pads on heavily-used Model F's? There's no protective mylar or other material (other than screened-on soldermask) on the top of the PCB is there?

sethstorm had to repair a model f, but i don't think it was caused by flip wear.

that said, lets keep this on topic. this is a topic about bolt mods. the 'new topic" button exists for a reason.

On topic, I do have the picts for the second half on my flickr and just need to add and caption them.

[njbair]

Hey guys, I just posted a write-up of my SSK "rubber-band mod" here in the Making Stuff Together forum: https://geekhack.org/index.php?topic=71208.0

Let me know if there's anything else you'd like to know!

[Skechup]

Thanks for the tips! This should make my job easier when I get my Model M!

[XMIT]

Thanks for doing this. I need to work on a guide as well. I follow a somewhat modified procedure:

- use a chisel for removing rivets. Way faster than a knife.
- use two one foot long sections of 2x4 to hold the barrel plate. I stack nickels on the edge of the 2x4s and tape them down to create a high point to support the natural curvature of the barrel plate if needed.
- use a dremel with a sanding tool to file down the rivet stubs.
- use a slightly smaller drill bit, in order to ...
- use tiny brass wood screws and washers to screw in from the back. https://geekhack.org/index.php?topic=67263.msg1631718#msg1631718 . (Thanks ezrahilyer.)
- use 3M DP460 epoxy to repair any cracks in first and second generation Model M barrel plates. For this supporting the curvature of the barrel plate is really important to get the epoxy to dry with the plate in the correct orientation. (I repaired an SSK this way.)

I wonder how well original IBM SDL cables work with USB signals. I've considered putting a Soarer's Converter inside the case, putting a USB head on the end of an original SDL cable and just using it as a USB cable. That, or some variation on this theme. I like the weight, color, and coiling of the original cables.

[Muffin860]

Thanks for doing this. I need to work on a guide as well. I follow a somewhat modified procedure:

- use a chisel for removing rivets. Way faster than a knife.
- use two one foot long sections of 2x4 to hold the barrel plate. I stack nickels on the edge of the 2x4s and tape them down to create a high point to support the natural curvature of the barrel plate if needed.
- use a dremel with a sanding tool to file down the rivet stubs.
- use a slightly smaller drill bit, in order to ...
- use tiny brass wood screws and washers to screw in from the back. https://geekhack.org/index.php?topic=67263.msg1631718#msg1631718 . (Thanks ezrahilyer.)
- use 3M DP460 epoxy to repair any cracks in first and second generation Model M barrel plates. For this supporting the curvature of the barrel plate is really important to get the epoxy to dry with the plate in the correct orientation. (I repaired an SSK this way.)

I wonder how well original IBM SDL cables work with USB signals. I've considered putting a Soarer's Converter inside the case, putting a USB head on the end of an original SDL cable and just using it as a USB cable. That, or some variation on this theme. I like the weight, color, and coiling of the original cables.

It shouldn't matter if you are using the original cable, wires from the 80s don't know nor care if the signal they carry is usb or ps/2

[fohat.digs]

Having done quite a few of these myself, I feel like I need to comment on some of these:

- use a chisel for removing rivets. Way faster than a knife.
   *   * I use a chisel tip in my Xacto knife. Much cleaner and thinner than you can ever sharpen a "real" chisel

- use two one foot long sections of 2x4 to hold the barrel plate. I stack nickels on the edge of the 2x4s and tape them down to create a high point to support the natural curvature of the barrel plate if needed.
   *   * The nickels are a good idea. I built a frame that that does not slide apart or let go.

- use a dremel with a sanding tool to file down the rivet stubs.
   *   * Arrggh! Use a fresh chisel tip in the Xacto to slice the tops as tall and flat as possible. I do not have any sandpaper or the like in my kit.
   *   * I use my tiniest Dremel spherical burr to make a divot for my drill bit to keep it from "walking"

- use a slightly smaller drill bit, in order to ...
- use tiny brass wood screws and washers to screw in from the back.
- use 3M DP460 epoxy to repair any cracks in first and second generation Model M barrel plates. For this supporting the curvature of the barrel plate is really important to get the epoxy to dry with the plate in the correct orientation.
   *   * Old-fashioned model cement (aka airplane glue) works great for this, but get the harmful kind that you aren't supposed to sniff!

[☠☢☣ DeadlyRadioactvBiohaz]

Tools:
5.5mm or 5/32" thinwall nut driver.

Error correction: Should be...

5.5mm or 7/32" thinwall nut driver.

[infiniti]

Tools:
5.5mm or 5/32" thinwall nut driver.

Error correction: Should be...

5.5mm or 7/32" thinwall nut driver.

Thanks for pointing that out! I've edited the OP for dorkvader.