Beam Spring IBM 3278 A02 restoration

[Monster-Toys]

Thx
It is more time consuming than i thought it would be, hope it will be worth the effort.
Does anybody has an idea how i could brighten up the symbols on the mod keys without brighten up the whole key?

[Hypersphere]

Thx
It is more time consuming than i thought it would be, hope it will be worth the effort.
Does anybody has an idea how i could brighten up the symbols on the mod keys without brighten up the whole key?

Regarding keycaps, I recommend soaking in mild detergent then scrubbing with a soft washcloth if needed, followed by rinsing and drying overnight. You could also wipe them down with 70% (v/v) isopropyl rubbing alcohol. I would avoid harsh treatments such as Retrobrite or other peroxide treatments.

[Halvar]

I think since this is ABS, retrobrite would be the only way to go if you really wanted to brighten up the white legends. I have the same problem and don't dare to do that yet though. I will just leave it as it is for now. It might be worth trying retrobrite on the backside of one key to see if it affects the black.

[Monster-Toys]

It might be worth trying retrobrite on the backside of one key to see if it affects the black.

Good idea

[Halvar]

Today in "Monster Toys loves his Beam Spring Board": Derust
...

Wow this is impressive! I'm still too much in denial to really start with this. Looking forward to how it turns out!

[xwhatsit]

Monster-Toys: what are you going to do for the foam now you removed it? I only ask, because I removed it on my 5251 board, and now the keys are terribly rattly. Like with the Model Fs (and their barrels), the foam kind of helps hold the beamspring modules in place, and takes up some slack between the top plate and the tops of the square part of the modules.

Because of the way the beam springs themselves work, removing the foam (or having worn-out foam; my new 3278 data entry keyboard seems to have slightly worn-out foam compared to my 3727) also lowers the activation point for the keys. That is to say, you have to press further before the key clicks and actuates.

[Monster-Toys]

I hope using vinegar was ok... maybe it was too agressive. The rusconverter is now totaly black what means it converted a lot of rust (in very short time), tomorrow i will rub it of and try to find some baking soda to neutralize any remains of acid (there should be no remains, i cleaned it thoroughly with water and soap but i have no other idea. This is virgin soil for me but somehow i will get this to work).

The form will be replaced with 2 mm thick "Moosgummi" (sort of foamed rubber for handicraft work, i do not know the correct english word). I used it for my Kish before and it worked good:

Spoiler:

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[xwhatsit]

Nice! I bet that is not a 5 minute job, cutting the holes. As Murium said—the keyboard went to the right owner

[Halvar]

I agree with that!

And thanks Monster-Toys, you motivated me (well together with xwhatsit's approaching GB deadline...) to at least take off the contamination shield now ( this was actually still usable, but not any more...)

It seems like I will have to do something similar this weekend...

[Monster-Toys]

@Halvar: When you will do a vinegar bath, too, use normal "Branntweinessig" (5% acid). I was thinking of using "Essig Essenz" (25% acid) but now i think that would be much too aggressive. As rust converter i used Fertan what has good reviews, 30 mm is enough and costs around 7 to 8 euro.

[Halvar]

Thanks a lot! I will look out for that.

I mean we both know that as soon as we're done, some Cindy or Mandy or Sandy or Tinnie will show up in this forum and sell mint condition 3278-A2s to everyone for $25 ...

[Monster-Toys]

i would be the first to taking one or two of them then (i know i am niggling but this one abrasion on my Operator Control Panel and the crumbled lettering on the Operator Control Panel switches makes me a little bit sad )

[Muirium]

Wow, I like what you did with your Kishsaver! Do you have a template I could use for a similar job myself?

[Monster-Toys]

I used the barrel plate as template. I marked the centers of the holes with pins using a paper circle as positioning device and then used a cutting circle to cut them out. I used 3 mm rubber foam but that was a little bit to thick, so 2mm should be good. (It is not my kishsaver anymore btw., i sold it).

[Muirium]

Thanks. I'll keep a look out for 2mm rubber foam. I fear I've crappy skills at measuring / guessing dimensions in 3D while everything is free to move, but something tells me Wcass might have a template for this. He had one for some keyboard I was interested in at least…

Hope you made good beam spring money from your Kish! I could never sell mine. I haven't seen another board I want more.

[Monster-Toys]

Would not have sold it if it wasnt a really good offer and i needed money for my other passion: I am illustrator and comic artist and need a light tracer
For the remaining money i hope to find a 3278 A2 in good condition some day (or at least a control panel in good condition* and enough beam spring switches for a project i have in mind.)

*i speculate on halvar getting crazy over refurbish his 3278 A2 and pay me for taking it away from him

[Muirium]

Ah, so you're the source of your avatar!

If Hypersphere starts showing off a Kishsaver (ideally posed in the centre of several beam springs) then I'll know exactly what's happened…

[Halvar]

*i speculate on halvar getting crazy over refurbish his 3278 A2 and pay me for taking it away from him

I'm halfway there ...

Damn "IBM Nasty Foam"®, damn rust ...

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[Halvar]

Some short update notes: Vinegar bath worked great, rust remover worked, too (I used a different one). Then I got the bad idea to paint/varnish the inner sheet metal. With a brush, too. A bad brush. Doesn't look too great but doesn't really matter, either ... oh well...

Yesterday I learned the art of reattaching fly plates to switches, today I learned (the hard way) that my 2mm rubber foam ("Moosgummi") from the art supplies shop is probably either too thick or too strong/hard for the switches to go through the sheet. I think 1mm would be better, or a softer foam, but they didn't have that. Need to hit town to find something better tomorrow.

[Hypersphere]

Ah, so you're the source of your avatar!

If Hypersphere starts showing off a Kishsaver (ideally posed in the centre of several beam springs) then I'll know exactly what's happened…

Not to worry. I am still looking for a Kishsaver.

[Hypersphere]

I hope using vinegar was ok... maybe it was too agressive. The rusconverter is now totaly black what means it converted a lot of rust (in very short time), tomorrow i will rub it of and try to find some baking soda to neutralize any remains of acid (there should be no remains, i cleaned it thoroughly with water and soap but i have no other idea. This is virgin soil for me but somehow i will get this to work).

The form will be replaced with 2 mm thick "Moosgummi" (sort of foamed rubber for handicraft work, i do not know the correct english word). I used it for my Kish before and it worked good:

Spoiler:

021.jpg

I haven't started yet to refurbish a beam spring keyboard. When I refurbished my XT, I sanded the barrel plate to remove corrosion and old paint, and then applied 3 coats of Rustoleum satin finish spray paint (the variety with primer and paint combined), lightly sanding between coats and allowing 2 days for drying for each coat. This was a lot of effort, but it worked very well.

For the foam layer on my XT, I used 1/8 (0.125) inch (3.18 mm) silicone foam. It was a tight fit, but it worked. However, for my next Model F, I think I might use 3/32 (0.09375) inch (2.38 mm) foam instead.

For marking the holes in the foam, I used the barrel plate as a stencil. For punching the holes, I used a laboratory cork borer with a diameter slightly bigger than the diameter of the holes in the barrel plate.

Perhaps these same techniques would work for the beam spring as well.

One thing I am unsure about is the plastic shield layer in the beam spring. I am considering omitting this and just covering the keys with a solid plastic "roof" when the board is not in use. Do you think this would be adequate, or should the shield be replaced, using something like "Saran Wrap"?

[Halvar]

Some more pictures from the rest of the restoration.

This was how the plate looked after disassembly:

Rusty plate with IBM foam

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Rusty plate upper side

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After an overnight bath in vinegar, the rust was completely gone. I painted the plate with a brown varnish. I would not do that again because a) it didn't turn out looking that great and b) the paint layer turned out to be too thick around the switch holes and I had to scrape it off partially to put the switches back in. Moreover, the paint didn't stick very well, seems like it would have needed sanding of the surface or a grounding.

I cut out the holes from 2 mm rubber foam that I got in an art supply store (where black was sold out ...). I basically just used the plate as a canvas to mark the holes and cut out round holes with a pair of nail scissors. Some of the holes in the picture turned out too small, so I had to do it a second time cutting with a larger diameter. The holes in the rubber foam that I used in the end had holes the size of a Eurocent coin (16 mm), which is a tiny bit larger than the holes in the plate.

As you can see by comparing with the picture above, my rubber foam is much thicker that the original IBM foam, and I would go for 1 mm or 1.5 mm thickness if I had to do it again. With 2 mm thickness I had to press the switches in with more force than I would have liked to apply on them.

rubber foam

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more switches in rubber foam

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PCB and switches before reassembly

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The PBC surface didn't look too great even after cleaning. It didn't become smooth like its back was, but stayed rough like someone had sanded it. It worked without a problem though. I also cleaned the surfaces of the fly plates from particles with a soft cloth, careful to not apply any pressure which would either send the fly plate flying quite literally (I did have to search for one under the table), or more often lat it get stuck in a way that I would have to take the whole switch out and unstick it.

After reassembling everything, plugging in the controller, finding the right threshold for the controller (147 for this board, see xwhatsit's controller thread for my post about that and my layout file), it now works very nicely and the key feel is great. I didn't bother yet to replace the contamination shield on this board.

Good luck to everyone who's still in the process!

Done!

IMG_20140921_111716 (Large).jpg (248.4 KiB) Viewed 5760 times

[mtl]

So nice Halvar! How does it feel typing with the solenoid?

[Halvar]

I don't know yet - so far I only have a rev3 controller from xwhatsit that isn't able to activate the solenoid. A rev4 controller and solenoid driver are on their way to me.

[andrewjoy]

That thing is beautiful, i would trade my soon to be delivered full sided beam spring for one with the switches on the top any day. CAN you use the expansion header to use the buttons for things like caps lock power wake and so on ?

[macmakkara]

Nice. You need to modify it if you want to use those for capslock etc. It has own cable also.

[Halvar]

CAN you use the expansion header to use the buttons for things like caps lock power wake and so on ?

Not yet, but I hope to do something like that with a second little microcontroller board. I will have to learn something about programming microcontrollers first though ...

Easiest but not very elegant way would be to use a Teensy as a second keyboard controller with Soarer's or hasu's software.

[Arakula]

How does it feel typing with the solenoid?

Remembering the time when I actually worked with these beasts in the early '80s - I didn't use that feature much. Too noisy, and too slow. It reacted with a slight delay, which is rather irritating if you're beyond hunt-and-peck typing.

[xwhatsit]

How interesting. Looking at the original controller, it takes the signal from the terminal, not from the controller itself. I wonder if it waited until it actually got the character away and over the serial link before it triggered the solenoid? Or maybe it got an ACK for the character? I'm not sure how the 3278 or 5251 protocols worked... did they send an ACK?

With the new controller it should activate somewhere between 1 and 10 milliseconds (currently it's fired off the USB report, although that's changing in the current rewrite). It feels more or less instant to me... I think. There is of course some mechanical lag from the solenoid itself which would add to that.

Halvar—has your order still not arrived? I seem to remember with the old Rev3 controller it took a while to get to you, was that right? Still it's been a long time... hope it hasn't disappeared in the post >.<

[Muirium]

Makes sense. I reckoned the solenoid was there to "confirm" the keystroke with the host. With some of the old computers I still use around here, I could use that feature myself if it were even possible with USB. Browser text fields can often get laggy when the web's so full of javascript!