deskthority

Since the common KPD8923 people harvest trackpoints from are pretty much unobtainium in Germany I was looking for an alternative. Broken Thinkpads regularly pop up on Ebay and often go for less than ten bucks. The trackpoints in these are too short to mount them in between keys, though.
Turns out that can be fixed easily using another part from the Thinkpad.

I took one of these little "pillars" (technical term, anyone?) and glued it to the the trackpoint. Then I needed to do some filing to get a fitting tip. And voilà, a larger trackpoint. This was just an experiment because I wasn't very confident that the glue would actually hold but it turned out just fine. I used a two component epoxy glue.

ToDo:
1. Figure out the right length. I just used whatever the length of that plastic piece was.
2. Test it in actual use to see if the longer lever has an impact on the feeling. Maybe they used a different firmware with higher sensitivity on the short trackpoints. Nothing that couldn't be fixed in software of course.
3. Check thickness. My extension is bigger than the lever on a KPD8923 so it might be harder to get it inbetween keys. No reason not to use thinner plastic though. I just wanted to try out if it works in principle first.

Note: When you guys go salvaging make sure to check for old laptops with trackpoints. We really should have a pointing device in every keyboard.

nice, what is your strategy to get the correct pinout?

Extra note:
Before you go crazy buying old notebooks on Ebay I have to warn you of these: This is the trackpoint from a 2626 Thinkpad. It has no controller!
It is probably useable but nowhere near as easily as the others (which you can hook up to ps/2 with only two resistors).

EDIT: If you harvest any trackpoints please let me know! Let's try to collect some model numbers with respective trackpoint type.

CeeSA wrote:nice, what is your strategy to get the correct pinout?

The datasheet for that controller is available online (that's the exact chip I have but the pinouts are usually the same) and there are some more resources here. (recently reposted by hasu: http://deskthority.net/workshop-f7/my-d ... 34-30.html ) including this. If you look at the middle right it shows you how to connect it to ps/2.

NOTE:
If anybody wants....we can get the KPD8923 from ebay or wherever, I can remove the trackpoints, and ship to you. It may take 2 weeks turn around on my end.

I'm in the U.S.

Hey IN! Thanks for the offer! Can't find anything on the KPD9023. Was that a typo?

SORRY!
KPD8923 I spend a lot of my time using my phone so I have a few typos.

I have a Black KPD8923 to sell at $45 plus shipping (bummer), should be able to get a little cheaper on ebay though I think.

KPD8923 like this one.

I might take you up on that.

Just be careful on ebay since IIRC that same model comes in black or white with and WITHOUT trackpoint.

Just got redirected to this thread again...

The term for the 'pillar' is called a 'stand off'

I'll keep my eyes open for a possible bulk purchase of KPD8923. Now I wish I had gotten more than the 10 a couple years ago...but who knew?

Good to have options...it would be nice to expand this thread with some part numbers.