cctech Digest, Vol 80, Issue 10 - test-drb@ccmp.vtda.org

11 May 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.)

 	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