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Cromemco JS-1 Joystick Replica

a little coaxing and it pulled in nicely. I also had to tap the screw holes 6-32 since, surprisingly, they weren't tapped. @Hugo Holden I noticed the same thing, the entire base was bowed a bit.

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Anyway it's all together now and boxed for shipping, but UPS closed at 3:00 today.
 
While we are on the topic of the Hardware, Hammond supplied four of a type of self threading 6-32 screw. The hole they force a thread into is 2.75 mm diameter.

I decided not to use them and instead I formed a 6-32 thread in those holes with a Roll Tap. This is very important, a standard Tap should not be used because it removes material. The Roll Tap, much like the screws Hammond provided, compress the material and it results in a much stronger thread, which is important as it is only aluminium.

Then I decided the case should have some rubber feet, however I virtually never use the stick on ones because the glue always melts and they move around or fall off. I used longer screws and some brass sleeves for them, so that when the screws tighten up the rubber foot is not excessively compressed. This avoids having to screw mount the rubber feet elsewhere on the base with extra holes.
 

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I have finished both of my units . It is always longer job when there are two of them.

(Thanks @nullvalue for the switches & buttons)

I wanted to use a tag board like the original, rather than a pcb, but the class B amplifier arrangement on the pcb did not lend itself well to a tag board, it needed more than the 10 tags.

Also I found I could help the connections to the Cherry switches by running a double sided 10mm tall section of pcb material slipped between the contacts, just etching one side of it, the other side being the earth bus, and using that to carry the 10k pullups and the 5V zener regulator, and make a stable place to connect the wires. Most of the wires I used are multi-colored Teflon insulation types, I prefer it because unlike PVC, the insulation doesn't shrink back with heat from the soldering iron.

So for my units I changed it to a class-A amp, somewhat power hungry, with a single 2N3053 transistor. It required a heat flag because the transistor heat dissipation is 1 Watt, I used the very attractive TO-5 Sylvania heat flags. And I had to design & wind the 32:8 Ohm impedance matching transformer to suit the 8 Ohm speaker.

I'm using standard style RS-232 serial cables that fit the D9 connector(whatever the correct nomenclature is), the ones I found on AU ebay were only a few dollars and the cable is 5mm outer diameter and is nice and soft/flexible.

It all worked out and the units are set up ready to go, that is after I figure out how to connect the cabling at the computer- D+7A pcb end, get my SOL-20 up and running again, restore the D+7A card, check and calibrate that before trying to run any Joystick operated software....
 

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djg said:
Same. Did a quick web search and couldn't find any sets at price for occasional use. May buy one of the size I need next time I'm working with material that would benefit. May be trickier to use without proper tooling.
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I thought maybe I'd get one for 6-32's - I do a lot of work (almost all) in aluminum. I'd be too scared to try this with a 4-40 and smaller because nothing sucks more than cracking a tap in your work. Although considering how thin the metal I'm likely to be tapping is with these maybe that's not so much an issue.

Here they are:
https://www.mcmaster.com/products/taps/flute-type~fluteless/

I also love press fit nuts - but in this case the hole is too close to the bend.
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DougM said:
I thought maybe I'd get one for 6-32's - I do a lot of work (almost all) in aluminum. I'd be too scared to try this with a 4-40 and smaller because nothing sucks more than cracking a tap in your work. Although considering how thin the metal I'm likely to be tapping is with these maybe that's not so much an issue.

Here they are:
https://www.mcmaster.com/products/taps/flute-type~fluteless/

I also love press fit nuts - but in this case the hole is too close to the bend.
View attachment 1279620View attachment 1279621
Click to expand...


Roll taps are good for aluminium panel work. If the Aluminium is over 2.5 thick it is about the limit. If the panel was say 3 to 4mm thick, you can combine a cutting tap to about 1/2 or more of it an finish with the roll to make a stronger thread that way. You'd never want to use the roll on things like extruded aluminium bar, the metal has to be able to spread a little. Steel panels up to around 1 to 1.5mm are ok with a roll tap too. I use 4-40 and 6-32 Roll taps all the time. Roll taps are far stronger and breakage resistant for any diameter because they don't have the large flutes. Like all these things, when you are used to them, you know when to use them and their limitations and if they are appropriate , or not and how much force you can apply for any size tap. As I mentioned, if you closely examine the screws that Hammond supplied, these work very much like a Roll tap. A roll tap can be difficult to start in some cases, and a an initial start with a cutting tap helps. And it pays to lubricate them.

I have those round press stainless steel nuts in 6-32 and 4-40, I buy them from PSME in the USA. I have used them on Hammond enclosures where they had done things like supplied self threading screws for the bottom cover. They can be pressed (pulled) into position with a screw and washer which is helpful when the access is tight, but they do require a close tolerance bur free hole. I normally create the hole by using increasing drill sizes in small steps to help those two issues.
 

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Hugo Holden said:
I buy them from PSME in the USA
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A Google of PSME does not return what I was expecting but I suspect you are talking about www.psmescale.com? They must have a paper catalog because their website sure doesn't have a lot of search functionality :) Or am I missing something?

One of the huge problems with McMaster is the cost of shipping. They were great when I was working and someone else was paying for shipping, but now that I'm retired and I need things on the cheap I have to significantly batch up my purchases to amortize shipping. It would be so nice if they had a slow cheap USPS option.

*on a totally separate note* here is the final DXF with the outline and joystick changes that I made for the final cut yesterday.
 

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DougM said:
One of the huge problems with McMaster is the cost of shipping.
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They also don't sell to anyone outside of the USA unless you are a government organisation or such. IMO they have probably the best product finding site I have ever seen - you can generally home in on something without resorting to a search box - if only other hardware stores had similar. Sadly I just can't buy any of it.
 
DougM said:
A Google of PSME does not return what I was expecting but I suspect you are talking about www.psmescale.com? They must have a paper catalog because their website sure doesn't have a lot of search functionality :) Or am I missing something?

One of the huge problems with McMaster is the cost of shipping. They were great when I was working and someone else was paying for shipping, but now that I'm retired and I need things on the cheap I have to significantly batch up my purchases to amortize shipping. It would be so nice if they had a slow cheap USPS option.

*on a totally separate note* here is the final DXF with the outline and joystick changes that I made for the final cut yesterday.
Click to expand...
Yes, precision scale model engineering. I have their paper catalogs, I have been buying stuff from them for over 20 years. It has been a while since my last order, I hope they they haven't changed their shipping policy to Australia. Never had any trouble buying things from them before. I have never used McMaster.
 
DougM said:
a little coaxing and it pulled in nicely. I also had to tap the screw holes 6-32 since, surprisingly, they weren't tapped. @Hugo Holden I noticed the same thing, the entire base was bowed a bit.

Anyway it's all together now and boxed for shipping, but UPS closed at 3:00 today.
Click to expand...

Thanks for squaring up the sides, these turned out terrific! Can't thank you enough for your help!
 
Hugo Holden said:
I have finished both of my units . It is always longer job when there are two of them.
Click to expand...

Wow these turned out amazing too, great job! I should have those PCB's next week sometime.

Hugo Holden said:
It all worked out and the units are set up ready to go, that is after I figure out how to connect the cabling at the computer- D+7A pcb end, get my SOL-20 up and running again, restore the D+7A card, check and calibrate that before trying to run any Joystick operated software....
Click to expand...
What are the chances we plug them in and they "just work"? :D
 
nullvalue said:
Wow these turned out amazing too, great job! I should have those PCB's next week sometime.


What are the chances we plug them in and they "just work"? :D
Click to expand...
I guess the D+7A boards could just work. But it appears on my board at least, sadly, they look like TI IC sockets. Notoriously unreliable unless the pins on the ICs and sockets are cleaned/treated. But all aged IC pins/sockets should be cleaned. And it could result in intermittent behavior or failure. So I think its better to fix them in the first place because if there is an issue it can take quite a while to track it down and the faults can come and go. Normally, with these sockets, if you extract the IC, you will see a grey or black line on the thin side of the IC pins at the socket contact points, where the dissimilar metals of the IC and socket claw have reacted and these are oxides, which are insulators.

I just looked at mine, they are luckily not the worst kind and they grab the IC pins across the flats, which is much better than the true TI type.
 
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