today I figured it's time for a follow-up video on my HP 86
now if you're not familiar with the back story on my HP 86
about six months ago I replaced all of the original key stems
with brand new 3d printed replacements
I detailed the entire disassembly design testing and final installation process
in a two-part series about 6 months ago now for the most part these 3d printed
keys have held up pretty well and I haven't really had any problems with
them well until recently that is now if you haven't seen the original two videos
which you might want to check out because it was a really cool process the
original key stems have a problem where after time the plastic gets brittle and
it starts to crack in the sides this would cause the keys to stick when you
press them down all the way so what I did is create a 3d printed replacement
piece for this and that one shouldn't split because the way that the layers
are printed and it has this really large top lip so it should be extra strong
well at the very end before I decided on the final design I'd made one more
choice I had altered the pieces so they could be easily removed from the stem
because the original parts cannot be removed due to the flat side on the
latch mechanism and you have to desolder the entire keyboard and it is a massive
painful long process to get the key stems out if you have the original ones
in so my new parts were meant to be removable from the front but over time
there is proven to be some pros and cons with that on the one hand I can now work
on this keyboard without having to desolder all of it but on the other hand
the little nub here that holds the key stem in place has failed on a couple of
the keys and they just get popped out by the spring so today we're gonna take a
look at updating the design with a new model and replacing all of the key stems
that I have in here right now alright so there are two changes I want
to make to the design here one of them's pretty obvious I'm gonna make the bite a
little bit bigger for the tabs that hold the key stem in place so let's go ahead
and do that first and the other thing I want to do is
actually inside the keycap so if we look down in there we'll see that I have this
kind of octagon shape cut out of everything but along the edges of the
inside there is this line here and that was part of how I solve the holes
printing in these sidewalls of the key stem so that is kind of required well
the entire piece in the middle here is printed without supports and it's kind
of unreliable so what I want to do is take that inner wall and make it just a
little bit taller and what that will do is make the printer have to print a
separate line of plastic before it gets to these parts that are bridged and that
isn't really technically bridged it's just kind of an overhang but this will
give something for the bridged pieces to be put on to so it'll work out to be a
little bit stronger every single one of these that I printed last time actually
had some stringing pieces inside of here and I had to file all of them by hand
before I could put them in the keyboard and it was an absolute nightmare so I
really want to avoid having to do that again and that should do it because this
will just make sure everything goes where it needs to be all right so I'm
gonna go ahead and set slicer to just print a hundred of these that's a lot
and yeah should be ready to go one of the important things with how these are
printed I don't think I covered this too well in the last one last videos I
should say is how these are actually done so I have my settings pretty
carefully chosen over here so that the outer wall of the stem is just one line
of plastic I know I mentioned that but it has to be like that the whole way
through and then here's where we have the outer wall and the inner wall but
this part here we can see there is a couple beads of plastic now before it
gets to the bridging so that's gonna help that a ton but yeah so the whole
thing it's really it needs to be done in a particular way so they have to be
printed upside down it's it's rather complicated these the settings have to
be just right for these to actually work these things are barely 3d printable it
you're really working within the maximum restrictions
of what you can print with this part but yeah I think that's it so yeah I'm gonna
go ahead and let that print run overnight
[cracking sounds as the parts release]
all right so some of these
turned out just fine and others clearly did not I'm not a hundred percent sure
what happened there if we look at the octolapse as the print is going towards
the end of it the whole printer kind of shifts and I'm not really sure what
caused that but after that a bunch of the key stems from the back kind of just
disappear so I'm thinking that that caused the erroneous prints here now I
did just do a lot of work on my 3d printer I just replaced the bed leveling
sensor with a touch version and I had to redo a lot of the wiring for that so I
just went ahead and redid all of the wiring as a safety precaution so I I may
not have it fully dialed back in yet but it was pretty close but anyway I'm gonna
have to reprint some of these I printed a hundred but I need ninety one and I
lost more than what it looks like here so I'm gonna have to go and get some
more printing all right the print is going along nicely on the twelve new key
stems and while that's going I'm gonna go ahead and start pulling out all of
the keys so I can get those new stems in
all right so that's all of the keys out but you may have noticed that there were
a couple of black ones in there and these are new designs but I was testing
them out and they really don't want to come out ooh yeah see now that's
starting lift up there so yeah I think these new ones really aren't going to be
removable after they're put in there well at least maybe not without great effort
that one feels like it might release I don't know
but being removable isn't terribly important so I'm not that up there we go
that one who came out okay so that's good
that's actually the same design as the ones that are currently being put in so
this one has a bite that's a bit bigger than these do actually so that's why
that one's just not gonna cooperate at all I don't think it's going to want to
give me oh that's less than desirable I may have to take that one out now mmm
fun I wanted to avoid doing that because I'm afraid that this top you know what
I'm just gonna leave that one um I'll put this on the key that goes there so
it spaces it out correctly but I don't want to take this one out or try and rip
this out in case the layers separate and then I'm left with a part of the key
stem in there because then I will have to desolder the entire keyboard again
and I don't want to do that so I'm gonna leave that in broken I don't care
the rest of the stems are still printing so while that's going on I'm going to
start removing the stems from the keys themselves
all right the new key stems just finished being printed so it's time to
start getting them in here yep I am going to be using the Installer tool
like I did last time it just makes it so much less likely to damage the contacts
inside of here and I assume I'm not going to get away
with no finishing on these parts so I have a file ready to go as well
well great it does look like I am going to have to
sand every single one of these fun okay the amount of time to do this is on the
magnitude of hours not minutes so you're just gonna have to miss this part
because I'm not gonna record three hours of footage or whatever it takes me to do
this okay this is one pretty hate machine later and I've got 27 keys in
here now not including the one that was already in there and I figured I would
show you exactly what I have to do with how these failed because I actually had
to psych myself up to do this video this time because I had to do this last time
as well and remembered how much it sucked so here's what I'm actually
having to do to get these in okay here we have one of the printed key stems all
the layers are nice and smooth across it's consistent going down the sides
there's no real apparent problems unless I flip it over which case you can see
that side looks a bit gnarly now what's going on here is when it's moving from
part to part on every single one of these it's leaving a bead along two
corners one at the bottom and one at the top now
when you print one of these you don't have that problem because the extruder
goes from one layer and then just move slightly up and goes immediately to the
next layer but when you're printing multiples of these it has to keep
jumping back and forth between the pieces and the extruder will retract a
little bit of plastic and put it back down at least I have to or else the
stringing here gets even worse on this print so it's just it's a really big
problem we are trying to print multiples of these and I was afraid this was going
to happen I was really really hoping it wouldn't happen with this plastic or
this would be minimal or I'd tweaked my settings it happened so so be it now
this problem is actually why I ultimately never sold these even though
I said I was considering it it would just take too much time to be able to
sand every single one of these before I send them out or it would be too big of
a burden to expect someone who purchased these from me to be able to sand them
themselves so just yeah that that's not meant to be
so here's what I have to do for every single one of these I have to take it
look at it see that it is just those two sides that are really that bad these
sides can sometimes be blotted with the little specks that can form but most the
time they're good and from here I just have to file it down until the corner is
smooth enough that it's not going to catch inside the slot it's not fun takes
forever I have to do this for all of the keys the whole print on that printer
computer at least two corners on every single one of them I know once it looks
like it's good I inspect it one can use a little bit more on that side
all right then when I think it's good it's time to actually put it in the
computer which is a hair-raising enough process by itself so I have to feed the
install tool in there take my sanded part and a spring put the spring on
first and then align the sanded part although now I can
look in there I can see a couple little strings in there so what I'm gonna have
to do is take the other one of these kind of just break those free from
inside so they can't catch him between the contacts there we go
that looks better now I can align this on the correct side feed it down and now
I get to find out if I sanded it enough and in this case I did so that's the
entire process that I have to do for every single key on here yeah this sucks
oh that's the last one which means that once again all of the stems in the
keyboard are 3d printed now I just have to go back and put all the key caps in
I don't really need to test them before I put the key caps in to see if they work
because well pretty easy to see that they work if the two metal contacts
inside touch after you depress the key they're good to go and every single one
of these keys you can see the two contacts touching so they should all be
working just fine all right so now I'll just start getting the key caps on
okay so I'm almost all done the majority of the keys here are nice and happy there's
just six here that are sticking I'll have to pull those out and file them
some more huh you want to know something funny I forgot that after
whatever the last video it was that I worked on a keyboard actually bought key
pullers so yeah I guess I can use these to try and get these out yeah that's
slightly easier so yeah I just got to remember to actually use these in the
future because wow yeah that makes a big difference and there we have it the
three remaining keys all fixed and as you can see on screen I went through and
tested every single one of the keys and they're all working so the keyboard is
back to being good as new ish I mean see the keys aren't super level just because
of how the 3d printing is kind of uneven but
it doesn't really matter so you know I'd take this over the keys that originally
just stuck down and wouldn't come back up any day so you know this has its
drawbacks it's not for everyone but it's worth doing if you really want to use
one of these or any other computer that has the Stackpole or high-tech switches
it's such a shame you can't just pull the original key stems out through the
top I mean the real problem is the lip on there you can see how that's just
totally flat makes it just impossible to do that it's just annoying because one
individually printed key stem looks like this and printed in batch looks like
this clearly this one's a sloppy nightmare compared to this one and
that's why you have to file off these rough corners that develop and
individually printed one it just goes layer to layer one after another and the
whole thing looks very good I mean there's a little bit of you know
inconsistency on the other side but still it's way better than that one
these don't have to have anything done to them when they're printed
individually they just fit right in the whole problem is because of those
retraction lines that develop on the sides of the stem during printing
multiples perhaps a belt bed printer would work very well for this because
you could just print one after another and have them fall off the edge of the
belt I'm even almost considering trying to put a plow on my extruder and see if
I could print one of these at a time and then just Ram it off and then print
another one these take about seven minutes to print each and it would just
be too much effort to sit there and every seven minutes have to remove one
of these for ninety one of these you might be able to fit ten of them on a
build plate and have them print individually one at a time but really
the extruder, the whole mechanism for the hot end is just too big to be
able to really print these one at a time on the print bed maybe if you had a just
a Bowden extruder so you had only the hot end on there it could work but I
don't know I don't have that so I haven't been able to experiment with
that now for me it doesn't really matter how much effort it's going to take to
work on the keyboard or any other part for this computer because this is one of
my favorite vintage computers I have so whatever effort I need to put in to
keep it going I am going to do and that's pretty much it for repairing the
keyboard so let's check out a cool thing you can do with this computer now as I
said in the first video for this little series on the keyboard this is perhaps
the most proprietary computer I own the disk drive has a unique interface the
monitor has over scanning or under scanning actually to fit more
information on the display the CPU is totally proprietary for HP I believe the
code name is Capricorn and there's a interesting story in there involving
Steve Wozniak and kind of the seeds that created Apple but that's for another day
one of the things about the CPU being totally proprietary is that it was very
difficult to convince developers to write software for this computer so most
software was created and published by HP for this computer including games this
is actually for the 85 which is a 40 column version of this the games don't
run quite well but close but everything went through HP to get on here and there
are very few examples of third-party software that will actually run on this
one example here would be Visicalc though so if you wanted to program
software directly for this computer it was quite the burdensome task however HP
recognized this limitation and came up with an interesting solution the CP/M
system cartridge now what's actually inside of this is a complete z80
computer kind of weird huh now you can connect this into the back and then you
can use the z80 contained within this cartridge to run CP/M so let's go ahead
and try that out I'll go ahead and put the CP/M system cartridge in the slot
just above the memory expansion alright now that these CP/M cartridges in there
I'll go ahead and put the CP/M disk into the drive connected to interface 0 and
fire up the computer
and there we have it CP/M running off of the z80 cartridge
plugged into the back of the computer
pretty cool huh now this all gets more complicated from
here because the CP/M formatted disks for this computer are totally different than
the HP basic formatted disks and you can't use the same files between them
there are transfer programs to allow you to migrate the files from one operating
system to the other and I do have some of those but haven't tried them all that
much so I can't really say how well that works but it's the whole thing's really
weird with the CP/M system in here though that would give you the option to go to
a store and get a regular boxed CP/M application and be able to run it on
your HP 86 so it was a really cool feature to add this didn't really help
this thing gain any market share though even though it's a really
interesting feature perhaps they should have gone with an 8086 cartridge to
allow you to run Microsoft DOS instead that might have gotten them some more
headway but anyway it's an interesting look at the HP and my keyboard repair I
hope you guys enjoyed that and I'll see you next time
hmm that's kind of strange
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