Since I have not been able to find a decent 3D drawing of the Jupiter
ACE housing I created this myself in DesignSpark Mechanical.
Since I do not own one to take measurements from I collected as much
photos as possible, preferably from the sides and top. The only fixed
measures I had were those of the PCB, so I used that as the basis. Then
I used placed the photos on different layers and scaled the 3D model
until it fits the images.
What I overlooked in the first place was that the housing of the ACE
is significantly larger than that of a ZX-80, which I previously printed
successfully. So I had to split the model into printable parts.
And once assembled, the top section looks a lot like the original.
Since, as mentioned in the Intro, I will probably never own a real Jupiter ACE I decided to go for the next best thing,which is building a replica. This has been done before, and the super accurate replication of the original PCB by Grant Searle is probably the best example. The schematics were redrawn later by Bodo Wenzel in ORCAD, and a modified version was made by Isidro Nuñez Blanco De Arenas.
Both builds were done 2003-2006 ( which shows if you look at the design
of their websites), and things have changed a bit since then. PCB
manufacturing is much cheaper now, and it's also easier to create custom
plastic parts. Because what's lacking in all these rebuilds is the
actual housing, which to me is a huge part of the charm of this machine.
And using a 3D printer it cannot be too hard to replicate this.
The Housing
To my surprise there are also no 3D models available , apart from the 'mini Jupiter ACE', which obviously it too inaccurate to use as a basis for a real housing.
So I started out to do this myself, using my favourite 3D modelling software: 'DesignSpark Mechanical'
(DSM). I used Grant's PCB layout, made it into a .png image and
imported that into DSM. Since the drawing includes millimetre marks on
the edge it was easy to scale it to exactly 100%.
The Keys
That's
a hard one. Getting a custom made rubber key-mat is beyond my financial
capacity so that's not an option. I'll try to make them using my 3D
printer. The main problem here is to get the text on the keys. I
considered printing this on adhesive film and just stick it on top of
the key. Then I thought I could also print the keys in white, with the
text sticking out. Then if I spray painted them black and sand the top
it would reveal the text again.
Looks great in my 3D software !. But how would it turn out in reality ?
The PCB
Though
it's possible to create the exact PCB replica using Grant Searle's PCB
foils, that is not what I wanted. I did want to make some minor changes
on the EPROM and RAM connections, and use standard mini switches for the
keyboard. Also if the PCBs have to be made by a cheap Chinese shop,
it's essential to have Gerber files. So, all in all a good incentive to
replicate the schematics again, but now in KiCad.
For years KiCad has been a bit troublesome to use, but over the last
few years it has improved significantly and is now a serious EDA
package. It's free, open source and multi-platform so it is becoming the
de-facto standard for all open-source hardware projects.
