Vacuum forming dongles

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Chr$
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Vacuum forming dongles

Post by Chr$ »

I got a vacuum forming machine (a small model aimed dentists). Plastic sheets 130x130mm fit inside and that's just about enough to practice replicating some original ROM dongle/kludges, which are of course vacuum formed in the first place.

Making the master from the inside of a real dongle was quite a bit of work. I thought I could just pour some plaster in the original and let it set but it wouldn't come out without breaking it. So it's made of plaster, epoxy putty and glue and involved lots of shaping, filing, grinding, sanding etc. It has a plastic base to add strength made from an old floppy disk. It's not perfect but is very close to the original and the original ROM PCB certainly fits inside as it should. It's not quite as thick as an original but I'm still perfecting my vacuum forming skills. I used sheets of ABS - no idea what the original plastic was. I need to also make up the base part.
20220622_213350.jpg
Pic above shows one before cutting out.
20220622_213424.jpg
Mould at the top (or whatever the technical term is for the 'master' used in conjunction with vacuum forming), a real dongle under it and a copy on the right.

Unfortunately it's not big enough to create a housing for my Q68.


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aalea
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Re: Vacuum forming dongles

Post by aalea »

Looks awesome!.
Because I clone some time ago the PCB of the cartridge (here: https://github.com/alvaroalea/QL_Rom_Cartridge not sure if is OK, because I do it from pictures of internet)
I also tried to do the case, I have Mold Press from We R Memory Keepers that I think is about the size of yours, but i was not able to get anything, all my test were horrible and bad, I do not know it the plastic was to thick or what, but...

Are you planning to sell it? I will be interesed in 3 or 4 of this.


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Re: Vacuum forming dongles

Post by Chr$ »

aalea wrote:Looks awesome!.
Because I clone some time ago the PCB of the cartridge (here: https://github.com/alvaroalea/QL_Rom_Cartridge not sure if is OK, because I do it from pictures of internet)
I also tried to do the case, I have Mold Press from We R Memory Keepers that I think is about the size of yours, but i was not able to get anything, all my test were horrible and bad, I do not know it the plastic was to thick or what, but...

Are you planning to sell it? I will be interesed in 3 or 4 of this.
I wish I'd known there were KiCads for a copy of the original PCB as I recently made up (with help) another PCB of the same footprint, but with the whole ROM space on it in 1x 27C512. Started from scratch but was able to measure my original so hopefully that part is right. There is a bottom vacuum formed piece too but I haven't replicated those yet. In fact the top part copy is not perfect, there are some areas where the plastic is too thin. I'm waiting for new ABS sheets and I will try to get it right. I'll post here, happy to sell some.


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Ask me about felt pads - I can cut them to size and they have proved excellent for mdv data recovery.
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Re: Vacuum forming dongles

Post by Chr$ »

If you want to check your PCB size specs:

The original board is 84mm long by 38mm wide.

The circular cut-outs are 8mm diameter at the widest part (the edge of the PCB) and are 5mm deep into the PCB, therefore the distance at the narrowest part of the PCB from one cut out to the cut out on the other side is 28mm. The highest part of the circular cut-outs are 5mm from the upper edge of the board (this is actually slightly different on both sides - it's a little wonky).

The slot-key gap at the bottom is 9mm long and 2mm wide. From the edges of the PCB to the centres of the nearest through-holes for the EPROM footprints is about 1.5mm. From the bottom slot edge of the board to the closest EPROM through-hole is 34mm.

Pins 4 & 5 (and also 10 & 11) of the 74LS00 straddle the centre of the PCB and the 74LS00 pins closest to the top edge are 2.8mm from the edge (measured from the centre of the holes).


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aalea
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Re: Vacuum forming dongles

Post by aalea »

OK, not bad, my error is about 1mm in some places, I put the dimensions in red over the mine, is correct?
QL_Cart.png


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Re: Vacuum forming dongles

Post by Chr$ »

Yes that looks right.

I notice on the 3D model of the plastic upper part, it should be higher, actually about 21mm in height (they are quite chunky). This is probably to allow enough space for the EPROM(S) to be socketed.


https://QXL.WIN
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Ask me about felt pads - I can cut them to size and they have proved excellent for mdv data recovery.
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