SGI Granite Restoration thread // Plate done, looking for switches!

[scottc]

I'm right in the middle of restoring an SGI Granite board that I got from Wodan (thanks, Wodan!) who got it straight from a recycler. It was clear from the beginning that this board needed some TLC. The board worked perfectly, but it had a couple of problems that prompted me to perform a complete disassembly with a plan to completely restore the board. I'll use this thread to ask for advice and document the process.

Problem #0: The Keycaps

When I got the board, the keycaps were quite dirty and looked a little bit shiny. Since they're made of PBT (apart from the spacebar, which might have its own section later), I just took them off using my trusty keycap puller and cleaned them using my ultrasonic cleaner. I didn't take photos to document this because it was a pretty simple process: I just split the keycaps up into 2 batches, then put each batch through the ultrasonic cleaner with de-ionised water and a little bit of dish soap twice on the 8-minute cycle.

Pictures to follow...

Problem #1: The Plate

The plate is particularly in need of some love. Even after lifting off much of the dirt and dust using a hoover, I was left with this:



So this is my first break to ask for advice: what are the best ways to treat this? So far I've had people suggest/thought about doing the following:

- Soak the plate in vinegar to treat the rust (being careful to use a baking soda solution to completely neutralise the vinegar afterwards) - thanks emdude!
- Sand the plate down (starting with coarse sandpaper, then gradually reducing to lower grit paper)
- Spray the plate with either paint or some sealant to avoid more corrosion

Any suggestions on how best to do this? This is my first time really dealing with restoring metal so any help would be very much appreciated!

[DMA]

Just tried to find what paint to use for alps plate. Was really sad there's no answers. Then noted the post time

Anyway. What to do with the plate? Sanding, of course. But which rust converter and/or paint to use afterwards?

[pr0ximity]

I've used Rustoleum on a handful of boards. Not really possible for me to tell you how effective it was, since rust wouldn't propagate fast enough for me to tell yet, but over 1-2 years I haven't seen any issues.

As long as you're taking good care of them afterwards I think even a mild rust sealant would do fine. Just remember to do a number of thin coats rather than one or two thick ones.

I've done a little bit of rust converter too, but that stuff's expensive. I'd reach for that more when the piece is fairly small and you want to preserve material instead of removing it. A thick plate is fine to sand.

[n__dles]

I'd suggest using an anti-rust primer, like Rust-Oleum Rusty Metal Primer. Give it a couple coats of primer, let it dry for a few days, light sand, couple of coats of paint and let it dry for as long as possible.

In my experience Rust-Oleum paint alone isn't enough to prevent old rust from creeping back through. But this is with lawn furniture, so you might be able to get away with sanding and paint alone on a keyboard.

[seebart]

Soak it in vinegar and be sure to REMOVE vinegar afterwards! Does that guarantee the rust is gone "forever"? I don't think so. Sanding is quite a bit of work and you may end up with problematic areas. I see three spots that seem to have more rust. You should have bought my ISO Granite Scott, more € but no rust (just kidding).

[DMA]

Soak it in vinegar.

That will leave very porous surface* - which will rust again in seconds. So it will need to be sanded anyway it seems
Now, the question is what paint to use after sanding?

*) best case. Worst case rust converts to iron acetate (III) - which is not water-soluble and has about the same color

[seebart]

Soak it in vinegar.

That will leave very porous surface* - which will rust again in seconds. So it will need to be sanded anyway it seems
Now, the question is what paint to use after sanding?

*) best case. Worst case rust converts to iron acetate (III) - which is not water-soluble and has about the same color

That's not my experince with soaking metal in vinegar generally but I'm sure it depends on the metal and how long you soak it.

[Khers]

The idea with the vinegar is that the acid etches the oxides (and the metal, but to a lesser extent), creating a clean, but rust-prone surface. Thus, protecting that surface is essential for rust not to resurface. Due to the nature of the etching, the surface will be slightly porous, but this should generally not be a problem, as long as the etch time is kept reasonably short (vinegar is a rather dilute solution of acetic acid which is a rather weak acid so "short" is in fact rather long).

[seebart]

Right, I'm sure if one soakes metal objects in vinegar "long enough" they will very much become porous. I remember soaking some old Key Tronic FF metal springs in vinegar for a couple of hours, they looked and felt great but how long is too long I do not know.

[Wodan]

True, I have treated a couple of rusted plates with vinegar so far and I really like it. It is VERY important to continue processing plates after removing them from the vinegar though. I usually just rinse them unter clear water, scrub them thoroughly and then rub them dry, spray them with isopronanol alcohol and rub them again then immediately apply a primer. do 3-5 layers of primer and 3-5 layers of paint ... ROCK SOLID!

Just make sure when you take it out of the vinegar, you are committing yourself to finishing the next steps fast ... no slacking before at least three layers of primer have been applied.

[seebart]

Just make sure when you take it out of the vinegar, you are committing yourself to finishing the next steps fast ... no slacking before at least three layers of primer have been applied.

1+ to this!

Edited my post above because I can.

[DMA]

Edited my post above because I can.

Yeah, immediate rinse and priming are the key.
I wasn't quick enough on a second step long time ago - so I'm just resorting to the sandpaper now

Anyway. What's a good primer and what's a good paint - keep in mind, they must be thin or those switches not fitting back.

[seebart]

Edited my post above because I can.

Yeah, immediate rinse and priming are the key.
I wasn't quick enough on a second step long time ago - so I'm just resorting to the sandpaper now

Anyway. What's a good primer and what's a good paint - keep in mind, they must be thin or those switches not fitting back.

You learned the hard way! Happens to me all the time.

[scottc]

Alright, the case restoration will continue this week! So far I have some distilled vinegar, and based on your helpful info I think I'll:

- Buy some sandpaper, THIN primer and spray paint
- Sand the sucker down to try to get as much rust off as possible
- Soak the plate in the vinegar or a solution of the vinegar to get the rust off
- Thoroughly rinse and scrub the plate IMMEDIATELY to remove all of the vinegar
- Get a few layers of primer on, then paint

I'm excited! I think Problem #2 will be the switches, and what I'll do with them. I wasn't exactly blown away by the cream Alps, so I'm hoping to come across some nice blue Alps to put in the chassis. I might have to wait a while, though.

[XMIT]

I would use phosphoric acid ("naval jelly") to remove the rust chemically, then sandblast it and paint it.

[scottc]

Unfortunately I don't have the resources to sandblast anything, that would be quite nice though!

I opted for the sand and vinegar bath approach that I described above. The vast majority of the rust came off with sanding alone, which was a pleasant surprise! I then tried to give the plate a vinegar bath, which wasn't as successful. I didn't have a container large enough to submerge the entire plate, so I ended up only part submerging it which meant that parts of the plate were splashed with vinegar and exposed to oxygen which meant that some darker rusting appeared on the rusted parts, but I sanded this off and all was well again.

Here's a teaser picture of the plate after the first coat of primer:

[scottc]

Lots of progress has been made here! Unfortunately, I forgot to take pictures after sanding the plate. I managed to sand off the vast majority of the rust, which was a huge relief. I bought a mixture of sandpaper in a range from "coarse" to "very fine", and sanded the plate three times (once with "coarse", once with "medium", once with "fine" sandpaper). Then it was time for the primer:



After the primer, I applied a few coats of the black spray paint. After the first, the plate still looked a little uneven:





I applied a few more layers. The spray paint can advised for me to give 10-15 minutes between layers, but I left it about 20. But then... disaster! I wasn't careful enough and I allowed my plate to get cardboard from the box stuck to it as it dried overnight:



I sanded this off again and then re-primed and painted the affected area. A cereal-bar based support allowed me increased precision with no cardboard residue on the next run:



After letting the paint dry and sit overnight and for most of today, I tried mounting it in the case:



Not bad! It looks and feels great with some switches mounted in it, just to test the fit and to make sure that I hadn't gone overboard with the paint and ruined the fit:



One final shot:



Looks like Problem #1 is now dealt with. Next problem: switches...

I'd like to use SKCM Blues in this build, but unfortunately I only have about 20 of them. Anyone looking to get rid of any?

Edit: Maybe the next step should be retr0briting the nasty spacebar or case...