3D Printing Service

[Curto]

One more observation. With everything in the case, the 'feet' of the cage raise everything too high for my card set. Some of the ribbon cable 'clips' are too high to put the cover on when engages. Going to go to the shortest standoff I can and trim the bottom of the cage pieces to make fit.

[Wayne Parham]

I've worked through the details of mounting an improved card cage for the 9-slot backplane. Use the STL files attached below to create your right and left sides. Everything mounts using the existing holes in the cabinet, so no drilling is needed.

• Altair_8800_Card_Guides.zip

  STL files for card guides

  (216.56 KiB) Downloaded 1484 times

The card cage leaves plenty of room for the components on the backpanel, should you choose to use them. You might have to lean a capacitor over or use small LEDs, but everything will fit if you're mindful during construction.

Room to mount components on the backpanel PCB

To install the card cage and backpanel, you'll need the following hardware:

(18) M3x20 countersunk screws
(8) M3x10 threaded spacers
(12) M3 nuts
(4) star washers for M3 screws
(20) M3x6 screws (might want more for your power supply)

All 18 holes in the card cage / backpanel assembly use M3x20 countersunk screws. This keeps the screw head flush with the card cage so there's no interference with any circuit boards.

Use M3x20 countersunk screws to attach the card guides

[Wayne Parham]

Underneath, use M3 nuts on slots 1, 2, 3, 5, 7 and 8. Use an M3x10 threaded spacer on slots 4, 6 and 9 and also use them on the outboard (IMSAI) holes nearest slot 1. Mount those outboard spacers with M3x6 screws and put a star-washer underneath the screw head. This will bite into the ground pad and provide good grounding.

Mounting hardware on the backplane solder side

Underneath the cabinet, line up the holes with the threaded spacers and mount the board with M3x6 screws. The easiest way to do this is to get the assembly into position and thread one screw into place. Don't worry about the other holes - if the assembly rotates away, it's of no concern as long as you get one screw in. Then once you've done that, use the screw as a pivot to rotate the assembly into position to thread the remaining screws. Use a star washer under the outboard (IMSAI) screws to bite through the paint to ensure a good ground connection.

Bottom of cabinet, showing screws needed to mount the backpanel and card cage assembly

[Wayne Parham]

Here's what the backpanel and card cage assembly looks like when mounted in the cabinet:

Backpanel and card cage assembly mounted in cabinet

And here's a photo of an installed board, showing ejector alignment with the top of the cage:

Board ejectors align with top of card cage

[Curto]

Wow! Great job! I really like it. I think I will get a set printed!

[BillO]

Yes, very nice indeed. I elected to go without a card cage for now. I may use wood if I do decide to install one. As it is the computer is pretty much sessile.

[Curto]

Wayne's design fixed all of the discrepancies of the "Perko" set. I had a set printed and they look great. Thanks Wayne

BTW: I don't own a 3D printer but have found very good service and rates at treatstock.com

[CodeCage]

I should look before I leap! My complaint below about logging in was directed at the original files. These redone by Wayne look AWESOME, and I don't have to login to another site to get them. Just download here. THANKS Wayne! Now I don't have to design my own. How about the card eject STL file?

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And why do I have to create an account to download 3D print files? I have too many things to log into as it is.

Guess I'll design something myself, and if I do you will be welcome to them without having to waste away your time walking through so many screens just to download a file!

[Wayne Parham]

For ejectors, I bought Bivar CP-06 WE, available at all the popular suppliers, e.g. Digikey, Mouser, Newark, etc. You'll also need 3/32" x 1/4" pins, which are also easy to find. I prefer solid stainless steel pins to rolled for this application, but either will work just fine.

[Neukam]

Wayne, I have a few minor fitment issues that I'd like to address. Would you mind sharing the cad file?