PBT Spacebar for Topre

[Hypersphere]

There seems to be no source for PBT spacebars for Topre-switch keyboards, such as the Realforce 87u or HHKB. The keycap sets for these boards are all PBT, except that the spacebars are ABS. Does anyone here know of a source for PBT spacebars for Topre?

[absyrd]

There are none.

They are all ABS so they aren't as warped and will work properly on the switch.

[strict]

http://geekhack.org/index.php?topic=63970

[oscillik]

I believe there is another reason why Topre spacebars aren't PBT - because when removing the spacebar, the keycap stem may break if it were PBT.

There have already been a few reports on here from people who have accidentally broken stems on just normal alpha and modifier keys, simply because they didn't use a keycap puller / didn't use enough care when pulling the keycap.

Since the only real way to remove the spacebar from a Topre board is to essentially use brute force with your thumbs / use two keycap pullers (which wouldn't yield an even force), a PBT spacebar would likely have it's keycap stem break during keycap removal. ABS is a bit more forgiving.

That's just a theory, though.

As far as I know there aren't any Topre PBT spacebars available.

[Puddsy]

I believe there is another reason why Topre spacebars aren't PBT - because when removing the spacebar, the keycap stem may break if it were PBT.

There have already been a few reports on here from people who have accidentally broken stems on just normal alpha and modifier keys, simply because they didn't use a keycap puller / didn't use enough care when pulling the keycap.

Since the only real way to remove the spacebar from a Topre board is to essentially use brute force with your thumbs / use two keycap pullers (which wouldn't yield an even force), a PBT spacebar would likely have it's keycap stem break during keycap removal. ABS is a bit more forgiving.

That's just a theory, though.

As far as I know there aren't any Topre PBT spacebars available.

I never thought of this.

This actually sounds fairly plausible.

I'd run some tests if I had extra Topre space bars kicking around.

[Hypersphere]

One reason spacebars tend not to be made from PBT is that the cooling process is a bit tricky and the spacebar can warp. Nevertheless, IBM made PBT spacebars for years with no apparent problems, and some of their spacebars were very long.

There are also some PBT sets for Cherry mx stems that include PBT spacebars -- I have some of these sets from geek_feng and Imsto.

It is quite possible to remove spacebars from RF or HHKB boards. The trick is to remove the neighboring Alt keycaps on the RF or the adjacent OS keycaps on the HHKB to make room for lifting the spacebar straight up from both ends simultaneously. I think that a PBT spacebar could be removed in this manner without breaking the stabilizers or main switch.

Would it be possible to interest a company such as Signature Plastics in making Topre PBT spacebars? Group buy via Massdrop? What about 3D printing from Shapeways?

[oscillik]

One reason spacebars tend not to be made from PBT is that the cooling process is a bit tricky and the spacebar can warp. Nevertheless, IBM made PBT spacebars for years with no apparent problems, and some of their spacebars were very long.

There are also some PBT sets for Cherry mx stems that include PBT spacebars -- I have some of these sets from geek_feng and Imsto.

It is quite possible to remove spacebars from RF or HHKB boards. The trick is to remove the neighboring Alt keycaps on the RF or the adjacent OS keycaps on the HHKB to make room for lifting the spacebar straight up from both ends simultaneously. I think that a PBT spacebar could be removed in this manner without breaking the stabilizers or main switch.

Would it be possible to interest a company such as Signature Plastics in making Topre PBT spacebars? Group buy via Massdrop? What about 3D printing from Shapeways?

I know that PBT spacebars exist - I have two right here, from the Leopold 1.5mm thick PBT keycap set. Both of them are also perfect, no warps at all. I think this may be due to the fact that they're so thick, whereas the Topre PBT keycaps are thinner in comparison and would likely warp much easier.

I also know that it is quite possible to remove the ABS spacebar from Topre boards, but as you've already alluded to, it is tricky - requiring the Meta keycaps to be removed so you can lift the spacebar using your thumbs. It's much more prone to an error in applying force than using a keycap puller for a single alpha / mod key. However, I believe that doing this if the spacebar were PBT would cause the keycap stem to break, due to PBT being a much more brittle plastic. I'm not talking about the stabilisers or main switch getting broken, I'm talking about the stem on the spacebar itself.

[Puddsy]

I actually got mine off without getting the meta keys off.

There were some not-nice noises, though.

[Hypersphere]

As I mentioned, all the keycaps on vintage IBM Model M and Model F keyboards are PBT, including the spacebars. I have removed and reinstalled many of these spacebars and never broken the stems or the stabilizer wire holders. The PBT certainly seemed tough, so I don't think fragility is an issue. For some reason(s), Topre decided not to make their spacebars from PBT. Nevertheless, I think that those who have Topre-switch keyboards would be interested in having PBT spacebars for them, mainly to avoid spacebar "shine" that occurs with ABS spacebars.