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geekhack Community => Keyboards => Topic started by: zooksman on Tue, 11 April 2017, 19:47:58

Title: How to replace a Model F spring?
Post by: zooksman on Tue, 11 April 2017, 19:47:58
I got a Model F XT in its original box recently on a pretty good deal. But I noticed that the spring under the 8 key on the numpad is bent. It registers as being pressed continuously or sometimes not at all. The switch doesn't click, feels almost linear. My plan was to just switch the spring with a less consequential key, but I can't seem to remove the thing. The chopstick method doesnt seem to work, it won't grip the spring since it wont go in far enough. Any ideas on how to fix it bar disassembling the whole thing? If thats what it takes I'll do it. Also, any idea on where to get a replacement? Thanks.
Title: Re: How to replace a Model F spring?
Post by: OldIsNew on Tue, 11 April 2017, 21:54:25
Have you whittled down the end of the chopstick/skewer so that it fits better? I've had no problems replacing F XT springs with Ripster's method once the skewer fits properly. Link: http://imgur.com/a/6bnzW.

Also orihalcon has springs and barrels for sale on ebay: http://www.ebay.com/itm/IBM-Model-F-XT-Keyboard-Part-1x-Spring-Hammer-and-Barrel-Set-/272068789903?hash=item3f5890468f:g:hxIAAOSwbdpWZMHt
Title: Re: How to replace a Model F spring?
Post by: E TwentyNine on Wed, 12 April 2017, 04:27:49
It is not Ripster's method, it is Sandy's.  (Sandy55)

When removing, if you give it a bit of a twist it should come out.   I hadn't used a chopstick when removing, just got a grip on the tip of the spring, a slight pull and a twist.

Title: Re: How to replace a Model F spring?
Post by: Snowdog993 on Wed, 12 April 2017, 18:43:32
Any ideas on how to fix it bar disassembling the whole thing? If thats what it takes I'll do it. Also, any idea on where to get a replacement? Thanks.

I believe you can still order buckling springs from Unicomp. Just order the Model M "pivot plate and spring assembly", get some extras too.  You never know when you need the springs. (Of course the Model M hammers are useless for a Model F, but the springs are.)
http://www.pckeyboard.com/page/product/PVPLASM
Hope this helps!
Title: Re: How to replace a Model F spring?
Post by: zooksman on Wed, 12 April 2017, 19:13:25
Well I managed to get them out by just twisting and pulling, but now I can't get the damn things back in. The skewer just hits the peg when I push in and turn and I can't get the spring to lock in. Nothing seems to work. Also I have a spare model m, are those springs compatible with this board?
Title: Re: How to replace a Model F spring?
Post by: zooksman on Wed, 12 April 2017, 19:22:49
Doh. I was turning it the wrong direction, so I managed to get it back in. Still wondering about those model m springs though
Title: Re: How to replace a Model F spring?
Post by: Snowdog993 on Fri, 14 April 2017, 08:21:17
Doh. I was turning it the wrong direction, so I managed to get it back in. Still wondering about those model m springs though
Yes.
Title: Re: How to replace a Model F spring?
Post by: rowdy on Tue, 20 June 2017, 22:11:15
Did anyone ever work out what the differences between M and F springs are?
Title: Re: How to replace a Model F spring?
Post by: fohat.digs on Wed, 21 June 2017, 16:40:54
I think the consensus is that they feel about the same, with the F being marginally lighter.
Title: Re: How to replace a Model F spring?
Post by: rowdy on Sun, 25 June 2017, 22:16:23
The F spring seems a little longer with more coils (closer together).

The different flipper size might compensate for that - need a tighter spring to flip the F flipper perhaps.
Title: Re: How to replace a Model F spring?
Post by: fohat.digs on Mon, 26 June 2017, 18:27:13
The Model F pivot plate does not need to actually "do" anything except rock downwards and momentarily change the capacitance between contacts.

The "foot" of the Model M actually presses down on one membrane to cause it to deflect downwards and make electrical contact with the matching dot below it.
Title: Re: How to replace a Model F spring?
Post by: rowdy on Mon, 26 June 2017, 22:12:01
The Model F pivot plate does not need to actually "do" anything except rock downwards and momentarily change the capacitance between contacts.

The "foot" of the Model M actually presses down on one membrane to cause it to deflect downwards and make electrical contact with the matching dot below it.

Interesting.

So really you'd need a heavier spring in the M to better move the flipper.