repair of Model F casing

[berserkfan]

Hello Fellow Geekhackers


I recently bought a Model F-122 from someone. It came with the casing cracked in the bottom right, a nasty mark several inches right across the bottom of the numpad which unfortunately I use a lot of. IE I am sure to rest my wrist there in future. Now I’d like to ask if anyone has any idea how I can repair the casing. I expect to use this keyboard intensively, so I really don’t want a prominent crack.

I am open to solutions that involve covering the area with some kind of padding or material. The wristrests that I buy are standard length and not enough for a terminal keyboard, so I could make the best use of a bad situation and fashion some kind of foam guard. Since I’ve never done that before, would appreciate any advice.

I believe the seller is an honest person, so I’m not keen to file claims or ask seller for a partial refund. I haven't inspected the keyboard fully (just got it shipped to me today), but the casing is totally loose and not holding together properly so there may be more damage.

[fohat.digs]

It has been my experience that the vast majority of F-122 cases arrive broken.

My reinforced epoxy repair, as detailed in my guide, has worked moderately well for me, particularly in situations like yours. But it is not foolproof. Attached is a photo of the keyboard I am using now, with a repair that might be much like yours (this one is at least a year and a half old).

Although rootwyrm has a differing opinion, I am convinced that the F plastic composition is different. I believe that it is much harder and more brittle than the plastic used in the Ms, which is tougher, and, it seems to me, does not have a hard smooth inner layer and a textured "skin" layer like the Fs. Also, the design of the F-122 gives it weak front corners.

If you can keep the repair out of tension, it might hold pretty well, like mine, but if it is torqued or "sprung" you are less likely to succeed.

[Obakemono]

Jumhhh, maybe sugru?

http://sugru.com

Other thing that come to my mind, acetone + plastics scraps, you disolve them and ones it dries is like the original plastic (i can't find a link now)

Found it: http://hackaday.com/2011/12/16/welding-and-casting-abs/
http://www.protoparadigm.com/blog/2011/12/abs-glue-weld-cast-texture-and-more/

Or, some modeling clay, people doing mods on handled consoles use them to shape the case, you can see it here (down on the thread)

http://forums.benheck.com/viewtopic.php?f=5&t=34774

[fohat.digs]

Other thing that come to my mind, acetone + plastics scraps, you disolve them and ones it dries is like the original plastic

Interesting!

I may have to try this, but I still think that a really good epoxy like JB Weld will prove to be a stronger long-term fix.

One advantage to this system, assuming that you use beige shavings to add body to your slurry, is that the "glue" will match the original material.

[Justblair]

I have never repaired a keyboard, but I have repaired many other plastics.  If you have a plastic that melts in acetone then you can make plastic cement.  However, you need a decent amount of plastic to make a strong bond. 

My suggestion is that you make a cement, you don't rely on it for providing strength.  I would either bond another material to the inside of the plastic using an epoxy.  Or alternatively if you run a generous bead of hot glue on the inside that can add a flexible yet solid support for the broken part.

A combination of the two might be best.  From the interior of the keyboard, steal a little plastic from the supports.  Put them into an empty nail varnish jar and add a tiny amount of acetone.  (Assuming that the model F is dissolvable in acetone?)

Leave it for 24 hours and check for consistancy.  I like around slightly runner than cream cheese too runny you can leave the cap off for a bit, too stiff add a tiny bit more acetone.  Use a paint brush to paint the plastic into the crack and then close the gap.  Clamp it in position, but don't force it tight.  You want the crack to fill, but not to stress the part... Leave it clamped for 24 hours and then while still clamped add some support to the back.  Either epoxy or hot glue.  You will usually get a better bond if you rough the smooth plastic.  A disposable nail file is good for this.  You can cut it down with scissors if it is too wide to get into the area you need to roughen up.  If you do, give the rough plastic a good clean to remove loose material.

Acetone can be found in hairdressing supply businessess.  Be wary of buying it in normal chemists, it often contains additives to make it a bit more skin friendly.  A proper chemical supplier will provide better acetone.  If your fingertips go kinda milky white on contact with it it is the good stuff.

[invariance]

What about using fibre glass on the inside of the case?
Suppose it would depend on how well it bonds to the plastic.....

[fohat.digs]

What about using fibre glass on the inside of the case?
Suppose it would depend on how well it bonds to the plastic.....

Your repair would probably work great, especially if you embedded a reinforcing fabric, but would be a lot more trouble than ordinary epoxy.

Keeping the parts aligned together under proper pressure is tricky, hence the wire/turnbuckle/rubber band affair in my guide.

The "other" problem is that the Model F case has a hard inner plastic layer with a textured "skin" layer that will flake off. Any sort of sanding or grinding on the outside causes a difference in texture that is hard to re-create.

[ch_123]

Just to one-up what others have said, the plastic casing on the 122-key Fs are notoriously fragile. Unless they packed the keyboard really carefully, it will arrive with cracks or with things broken off.

[dgreekstallion]

I have some sugru coming in to fix my IBM Model F. I temporarily fixed the corner crack with Gorilla Tape layered over painter's tape as an attempt to keep the frame strong whilst preventing the Gorilla Tape from ruining the paint job!

[h2gofast]

Just to one-up what others have said, the plastic casing on the 122-key Fs are notoriously fragile. Unless they packed the keyboard really carefully, it will arrive with cracks or with things broken off.

I might have to disagree with this.  This is anecdotal, but  I have shipped a few in usps game boxes without any reported cracks and the only one I had with a cracks arrived to me in that condition.  The rest are holding up well.  There is one with cracks in the coating but the plastic underneath is fine. 

[fohat.digs]

Just to one-up what others have said, the plastic casing on the 122-key Fs are notoriously fragile. Unless they packed the keyboard really carefully, it will arrive with cracks or with things broken off.

I might have to disagree with this.  This is anecdotal, but  I have shipped a few in usps game boxes without any reported cracks and the only one I had with a cracks arrived to me in that condition.  The rest are holding up well.  There is one with cracks in the coating but the plastic underneath is fine. 

At least 7 of these have passed through my hands and I believe that "notoriously fragile" is a very accurate description.

Clearly, there are certain places (bottom front corners) that are both weak and subject to torsion if the package is dropped.

The vast majority of my F-122s have been broken, before or after, but honestly I cannot remember ANY other keyboard case EVER arriving broken.

[ch_123]

I guess there are plenty of variables with these things, and obviously there are people will get lucky and those who will get unlucky. I think, nonetheless, that the fact that there have been so many who have had these issues suggests that a lot of care needs to be taken.

I noticed quite a lot of flex in the case of mine. Particularly if I press down on the area between the top of the alphanumeric pad and the F-key block.

The notorious part comes from being involved in one of the original group buys for these things, and the amount of breakages that were reported after transit in a UPS box with a reasonable amount of packaging.

[h2gofast]

All valid data points but these things weigh a ton.  Model F for fat, the bigger they come the harder they fall
A Model M's case can better support the weight of itself when dropped, but a model F, not so much.  I think if both fell off the desk, the F just weighs too much not to break something.   But if I dropped something on the Model F, it probably wouldn't do much.  But who knows, I'm not willing to test the theory.
My guess is that the packing wasn't adequate enough or someone shipped multiple F's  in the same box.  And aside from that, there's almost 30 years of variables on these.

Has anyone tried to put Model F internals in a Model M case?
 

[fohat.digs]

Has anyone tried to put Model F internals in a Model M case?

A very small number of the very very early M-122s seem to use the same case top shell as the F-122.

If I can ever find one for cheap I will try it out. I feel certain that it will work, with perhaps a bit of Dremel work required.

Chances are that they used the same harder more brittle plastic, if it came out of the same molds.

[h2gofast]

Has anyone tried to put Model F internals in a Model M case?

A very small number of the very very early M-122s seem to use the same case top shell as the F-122.

If I can ever find one for cheap I will try it out. I feel certain that it will work, with perhaps a bit of Dremel work required.

Chances are that they used the same harder more brittle plastic, if it came out of the same molds.

I bet I have one of the early M 122's.  What do you consider cheap?  As long as you're in CONUS the shippings only 17 bucks.

[dgreekstallion]

Hello Fellow Geekhackers


I recently bought a Model F-122 from someone. It came with the casing cracked in the bottom right, a nasty mark several inches right across the bottom of the numpad which unfortunately I use a lot of. IE I am sure to rest my wrist there in future. Now I’d like to ask if anyone has any idea how I can repair the casing. I expect to use this keyboard intensively, so I really don’t want a prominent crack.

I am open to solutions that involve covering the area with some kind of padding or material. The wristrests that I buy are standard length and not enough for a terminal keyboard, so I could make the best use of a bad situation and fashion some kind of foam guard. Since I’ve never done that before, would appreciate any advice.

I believe the seller is an honest person, so I’m not keen to file claims or ask seller for a partial refund. I haven't inspected the keyboard fully (just got it shipped to me today), but the casing is totally loose and not holding together properly so there may be more damage.

How is your repair coming along? Got any ideas to test out?

[wcass]

yeah, i have an F in an M case. <searching through my old posts ...>
http://geekhack.org/index.php?topic=45089

lots of pictures

[dgreekstallion]

yeah, i have an F in an M case. <searching through my old posts ...>
http://geekhack.org/index.php?topic=45089

lots of pictures

This is pretty amazing. Thanks for the information.

I just finished the "band-aid" repair of my Model F's case. See my picture...

[berserkfan]

Thanks everyone. Sorry I have been so busy. But Obakemono’s suggestion seems a truly awesome solution, unless Model F casing is not made of ABS. (It seems too rigid for ABS.)

I am having a far more serious problem with the F now and I think it is unsolvable.  Model F is producing unreliable keypresses. It doesn’t seem consistent, but I haven’t tested it enough – some HID codes are NOT coming through.

It seems to be an analogue of my other problem, with a Model F XT that simply refuses to work even though all keys feel ‘normal’ and make that plinky sound. Check out my thread.
http://geekhack.org/index.php?topic=48505.0 If you can help me solve that, you should be able to help me solve this.

6.20am here. My Friday night/ Sat morning ruined. Going to sleep now. I have only a one day window to work on things this weekend, sigh.

[dgreekstallion]

Thanks everyone. Sorry I have been so busy. But Obakemono’s suggestion seems a truly awesome solution, unless Model F casing is not made of ABS. (It seems too rigid for ABS.)

I am having a far more serious problem with the F now and I think it is unsolvable.  Model F is producing unreliable keypresses. It doesn’t seem consistent, but I haven’t tested it enough – some HID codes are NOT coming through.

It seems to be an analogue of my other problem, with a Model F XT that simply refuses to work even though all keys feel ‘normal’ and make that plinky sound. Check out my thread.
http://geekhack.org/index.php?topic=48505.0 If you can help me solve that, you should be able to help me solve this.

6.20am here. My Friday night/ Sat morning ruined. Going to sleep now. I have only a one day window to work on things this weekend, sigh.

I checked out your thread, interesting.

Also, I will post up my Model F case repair soon; I think I have gone ape****, as I put over 15 coats of paint on it.

[ch_123]

As with the XT, I'd suspect the issue may be with your adapter. The electronics in the Model Fs are pretty rugged, so two keyboards with the same problems might suggest that the problem is elsewhere.

[berserkfan]

I have another XT that works ie not XT adapter problem.
For F122, I have two Terminals (M122) that work. So it's also not adapter problem.
These are two separate adapters using two different teensies. I made different adapters so that I can attach ps2 and 240 degree DIN to them respectively.

I have spent god knows how much money and time on this hobby and it is turning into a total pain. Model F? F!!!!

As with the XT, I'd suspect the issue may be with your adapter. The electronics in the Model Fs are pretty rugged, so two keyboards with the same problems might suggest that the problem is elsewhere.

[larrymoencurly]

Apparently 2 different types of plastic were used for IBM keyboards.  The Model M was made from ABS or a blend of ABS & PVC, while the 84-key model F was made from polycarbonate.  Both plastics can be solvent welded, but if something goes wrong with a polycarbonate solvent weld, it can't be done again because the solvent changes the plastic to something resembling aspirin.  OTOH polycarbonate can be heat welded really well with a soldering iron.  I built up the crack repair, sanded, and applied automotive touch-up paint (lacquer), but I wouldn't be surprised if Krylon Fusion worked even better.

[dgreekstallion]

Apparently 2 different types of plastic were used for IBM keyboards.  The Model M was made from ABS or a blend of ABS & PVC, while the 84-key model F was made from polycarbonate.  Both plastics can be solvent welded, but if something goes wrong with a polycarbonate solvent weld, it can't be done again because the solvent changes the plastic to something resembling aspirin.  OTOH polycarbonate can be heat welded really well with a soldering iron.  I built up the crack repair, sanded, and applied automotive touch-up paint (lacquer), but I wouldn't be surprised if Krylon Fusion worked even better.

Good information right here. Thanks.

And yeah, the Krylon Fusion worked well for my Model F Repair, along with some JB Plastic Weld.