[GreenKeys] Model 15 keycap removal

[Bill Strangfeld]

Here are more notes on M15 keycap removal.  The keycap lever has a round platform that the keycap mounts on.  That platform has tabs at about 11 o’clock and 5 o’clock.  The keycap itself has retaining indents at 12 and 6 o’clock.  All references are as viewed from above.

 

If the keycap is removed with a quarter-turn clockwise, the keycap indents travel in the arcs of 12 to 3 and 6 to 9 o’clock so they do not touch the indents at 11 and 5 o’clock.  But if it is turned CCW, the keycap indents travel in 12-9 and 6-3 o’clock arcs so they hit the tabs at 11 and 5 o’clock and may get bent leading to a sloppy fit.  That’s why removal worked better for me with a quarter-turn clockwise.  This is easier to understand with actual parts in front of you.

 

Installation is the opposite, of course.  It worked best to start with the keycap positioned so it is rotated a quarter turn clockwise and then turn it CCW to install.

 

These notes are based on a sample of one WW2 era TG-7, the military version of the M15.  Other machines may differ.

 

From: drlegendre . [mailto:drlegendre at gmail.com] 
Sent: Thursday, October 22, 2015 1:09 PM
To: Bill Strangfeld <bstrang at iac.net>
Cc: nagle at animats.com; Green Keys <greenkeys at mailman.qth.net>
Subject: Re: Model 15 keycap removal

 

You may well be correct, about the direction being CW. 

 

When my M15 arrived, it had a couple of loose caps, and a couple more that were simply crooked. The crooked ones were all off slightly CCW and I found that turning them CW felt right - and they seemed to snug down. Likewise the loose caps, they were about 1/4 turn CCW and it was easy to push down and turn CW to secure them. 

 

I came away from it with the sense that CCW was the way it should be done, but that's only based on this one machine. Fwiw, all of the caps seem to stay put just fine. Next time I work with it, I will definitely pay closer attention to how the mating features are stamped. 

 

On Thu, Oct 22, 2015 at 11:48 AM, Bill Strangfeld <bstrang at iac.net <mailto:bstrang at iac.net> > wrote:

I just experimented with removing some keycaps on an old model 15.  Results
were better by turning them a quarter-turn clockwise to remove than by
turning them counter-clockwise.  Turning them counter-clockwise consistently
made them loose when they were reinstalled.

When I reinstalled the ones that I turned clockwise to remove, they were as
tight as before removal.

But when turned CCW to remove, there apparently is interference between the
two retaining indents on the bottom of the keycap and two small tabs on the
round part of the keyboard lever, where the keycap fits.  It looks like this
bends the keycap indents and makes the keycap fit loose and sloppy.  Those
indents might be bent back to tighten the fit but it is a delicate job.  It
is all too easy to tear the thin metal and ruin the keycap.

This was a small sample and your results may differ.

Bill


On 10/21/2015 08:11 PM, drlegendre . wrote> @John Nagle
>
> As to removing the keycaps, I think it's as easy as quarter-turn CCW
> (of the metal base) and remove by pulling straight upward?

    Ah, thanks.  The keycaps were just stuck.  I've been able to replace
most of the missing keytops from spares.



 

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