Bringing the IBM PC XT into the 21st Century

[andrewjoy]

I think i may go with this on the next run , i have a spare XT i would just need some barrels as i have stolen them for other things

[Muirium]

Hopefully you can get some barrels and such from Ellipse. He'll become a great spare parts supply if he can manage to produce them well.

Yea, I would definitely add a finish to them. The steel is cold rolled steel, not stainless, and it probably will rust without a finish. Maybe I can go with stainless if there is another run.

Got a suggestion for a clear coat that will work well on these? I like the bare metal look, but not so much the rust!

[XMIT]

I promise nothing, but, if and when sales resume, I did sacrifice a Bigfoot board for parts. It can make a barrel donor for whoever needs one.

[andrewjoy]

i don't need a huge amount. the XT i got was a cap and flipper donor and i still have most of it . i would however have to count

It had a very bad top plate but thats no issue for this

[Muirium]

I'm a few barrels short for my XTant. Because an XTant needs something like 3-5 more barrels than an XT.

(Remember that mods require more than one barrel. It's not a straight key count.)

[vivalarevolución]

I think the XTant needs 84 barrels, and the XT only has 82. Or something like that. Anyways, the answer is in this thread somewhere.

EDIT: Within one of the walls of text on page 7 of this thread, wcass says that you need two extra barrels.

[fohat]

Today I spread out my parts collection and started thinking through the process of building this thing.

I see that the side holes on the new plates match the side holes on the original back plate, so that is good.

I see that the new PCB is the same size and shape as the original, so that helps, too.

But how do I register my new PCB between the plates? I can mark the location of the old plate on the back plate, and "eyeball" the way the pads show through the holes, but is that all there is? Will that be accurate enough?

Thanks in advance.

[vivalarevolución]

I haven't assembled anything yet, but I'm thinking you might have to eyeball. Does wcass's assembly instructions on Page 7 say anything about this?

Just with sandwiching the layers with my hands and visualizing this in my head, the PCB will be secured to the backplate with the screws and new holes that you will drill into the backplate. The barrel plate is secured to that assembly with the binder clips on the the side. Notice that the barrel plate has hole on the side ends that line up with holes on the side ends of the back plate. I'm thinking that if you secure those end holes with screws, everything will line up.

With the setup, the capacitive pads will be aligned towards the lower part of the barrel plate holes. But think about how those flippers arranged in the barrels. The part that flips down and contacts the capacitive pad is towards the lower end of the barrel, under the small pin and hole. You want those pads to aligned with lower end of the hole.

Remember all of us involved in this run are sorta beta testers for the XTant. Wcass did the prototyping and we might be the only people to have the parts to assemble this keyboard besides him. So we'll work out the kinks are assemble and test out the keyboard. But I trust that wcass figured this all out before he decided to provide us with the files and parts to make this happen.

[vivalarevolución]

Also, within the wall of instructions of page 7, wcass mentioned that a couple screws should be used to secure the barrel plate to the back plate. I recommend checking page 7 of this thread for further assembly instructions. If wcass missed anything in his assembly instructions, we can work out the details here.

[wcass]

You need to cut of the original "PCB studs" from the XT back plate. I used a rotary tool, but you could also use a drill for this. I marked the position of the old studs on the back side of the PCB, so when you have the PCB in the right spot, you will be able to see the marking through the holes where the old studs where.

I recommend changing the position of one of the new PCB mount hole from below the backspace to right of Enter between Delete and left arrow - inline with the other PCB mount hole. Hold the PCB up between you and a light and you should easily see the traces on both sides of the board. Mark a spot on the PCB that avoids the traces and make a hole about the same size as the original. If you didn't move the PCB mount hole, you will need to modify the weld nut (trim it to make it skinny) so that it does not get in the way of the barrels.

Press the PCB onto the back plate. You might try big binder clips or clothespins to hold the PCB in the curve against the back plate. Align the hole at the top with the back plate hole. On the back of the back plate, you should see white dots through the old PCB stud holes. Gently flip the assembly over and mark the back plate through the PCB holes. Take the PCB off and drill the holes. I don't have access to a drill press, so used a center punch to help prevent the drill bit from walking.

Attach the PCB to the back plate with two short 4-40 machine screws and weld nuts.

My post from 18 Feb 2015 covers it better - look there.

[fohat]

On the back of the back plate, you should see white dots through the old PCB stud holes.
Gently flip the assembly over and mark the back plate through the PCB holes. Take the PCB off and drill the holes.

OK, thanks, that's what I needed.

With the 2 white dots, I can make everything else work. I knew that there must be a trick that I just wasn't seeing.

[Hypersphere]

<snip>
Attach the PCB to the back plate with two short 4-40 machine screws and weld nuts.
<snip>

Do you weld or solder the weld nuts in place, or are they held in place by friction when you tighten the machine screws? Also, there are many different types of weld nuts. Do you have a pic of the kind that ought to be used?

[vivalarevolución]

They should be held in place by friction. The correct weld nuts should be in the package that wcass sent out with the original PCBs. You only need to solder the controller.

[vivalarevolución]

Working on my first XTant right now. I recommend a 5/32" drill bit rather than 1/8". The holes for the 1/8" seem to be too small for the weld nuts to fit through. Or get thinner weld nuts/machine screws. One of the two.

[wcass]

The weld nuts are the smallest made (that i am aware of anyway). The nuts goes on the "front" to hold the PCB and the bolt on the "back" of the back plate.

[vivalarevolución]

Well, I've got my XTant assembled and working. So that's great. There are a few issues with how all the internals fit into the case, which I will discuss with some pictures in a later thread.

I'm wondering if anybody was able to get theirs assembled and working yet.

[Muirium]

Still a couple of months until I get my hands on it. And I'm short a few barrels, given my plans for an HHKB-style layout and my single donor XT. Any idea how well the board handles when missing a few barrels on the function keys?

I know from experience handling a NovaTouch PCB that Topre capsense pads will detect your finger touching them directly. Wonder if IBM's are the same. Maybe I'll just poke those keys! They're more of an aesthetic desire than a functional necessity. I'm well used to Fn+Number = Function keys.

[vivalarevolución]

I don't they will register anything without the barrels. Think of the keys that have stabilizer inserts.

[Muirium]

Stabiliser inserts are insulating plastic. Capsense is all about conductive materials. Skin conducts well enough for Topre pads to pick it up (I didn't have to press hard, any proximity would do) and indeed all those iPhones out there which use just the same principle to detect touch.

[vivalarevolución]

The way that I'm envisioning an empty barrel is that there will be space between the PCB and the barrel plate, so nothing will be pressing down on them. So that's why I think they will not register anything.

But the only way to know for sure is to try it out and see what happens.

I also would like to get my hands on a real trashed up XT or Bigfoot and use that for donor barrels.

[Muirium]

Barrels are exactly what I'm short of. I'm thinking of just leaving the plate's hole completely open for a few keys, with no barrel, no spring, and no cap on top.

Unless I can source extras. Just like you!

[Compgeke]

If you guys are having a shortage of barrels\etc I'm willing to sacrifice one of the many XTs to the keyboard gods to help out. Not a whole lot of use for ones missing spacebar or whatnot other than parts anyways.

[Muirium]

Great stuff. Any of them got particularly nice cases?

I won't know what I need until December. I'm far, far away from my XTant's bits.

[XMIT]

I did sacrifice a Bigfoot for parts.

[Hypersphere]

It is still possible to find XT keyboards relatively cheap, at least in the US. I don't know what the situation is in the UK or Europe.

[Muirium]

Oh, you can surely take an informed guess: the answer is *expensive* of course! Probably about $120 including shipping for one over here, already located over here, which aren't nearly as common on ebay so you'd have to wait for months as well. Importing costs significantly more too.

Anyway, I'm doing this project in America. And can't afford to leave a great pile of extra parts. Not my house…

[vsev]

I think i may go with this on the next run , i have a spare XT i would just need some barrels as i have stolen them for other things

Will certainly do also, great project here, happy to see it goin' further !

[vivalarevolución]

I built my XTant and got it working, I can post some pictures when I have more time. But wasn't that hard, just like a Model F refurb job.

[fohat]

I built my XTant and got it working,

I really need to get cracking on mine. Everything is sitting there, cleaned and painted, waiting for me.

I bought an F-107 from Orihalcon a couple of weeks ago and I have been working through that restoration. For various reasons, including some awesome paint that requires 48 hours drying between coats, I am still not quite finished.

Pictures forthcoming when I can.

[Muirium]

By the way, how are you guys finding the washer spacebar stab trick in practice?