cctech Digest, Vol 80, Issue 10
mark at matlockfamily.com
Tue May 11 12:29:55 CDT 2021
Date: Mon, 10 May 2021 10:15:34 -0700
> From: Vincent Slyngstad <vincent.slyngstad at gmail.com>
> To: cctalk at classiccmp.org
> Subject: Re: QBUS/UNIBUS card handles
> Message-ID: <826ef016-3060-e690-de81-8209479712e9 at gmail.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> On 5/10/2021 9:25 AM, Fritz Mueller via cctalk wrote:
>>> On May 10, 2021, at 7:14 AM, Joshua Rice via cctalk <cctalk at classiccmp.org> wrote:
>>> I would assume it would be trivial to do an injection-moulded run of these handles...
>> They might also be ideal for silicone mold / resin cast, for smaller/home production runs?
> Resin casting will work, but it's messy, etc. I haven't had any trouble
> with the toughness of 3D printed handles. Honestly, I often attach them
> with a pair of small zip-ties instead of rivets, and they are still
> plenty strong. The usual caveats about 3D printing apply -- just don't
> print it so that the layers will be torn apart when you pull on it!
> Maybe you PDP-11 guys are more used to hex cards, or something? I did
> have some PCB made where the card fingers tended to bind, but that's
> best addressed with some careful filing and a tweak of the CAD files for
> the next run :-). (The CAD files on so-much-stuff have long been
> tweaked for a good fit to the connector blocks.)
I recently had Shapeways 3D print some of your card handles in Nylon 12.
They call Nylon 12 “versatile plastic” on their web site and they use a laser sintering
process for fabrication. I used the card handles on my QBone and UniBone boards
which makes them MUCH easier to insert and pull. The Nylon 12 seems to be
quite tough and I used 3mm x 6mm long screws to fasten them. Shapeways
charged $5.00 each plus shipping to make them.
Thanks for the great 3D design!
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