cctech Digest, Vol 80, Issue 10

[Mark Matlock]

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.)
> 
> 	Vince

Vince,
    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!

Best Regards,
Mark