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impossible stud

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  impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-19 20:51 -0700
    Re: impossible stud Perry <Perry@null.com> - 2018-04-20 12:41 +0800
      Re: impossible stud Perry <Perry@null.com> - 2018-04-20 12:47 +0800
      Re: impossible stud TTman <kraken.sankey@gmail.com> - 2018-04-20 11:13 +0100
      Re: impossible stud George Herold <gherold@teachspin.com> - 2018-04-20 06:10 -0700
        Re: impossible stud gnuarm.deletethisbit@gmail.com - 2018-04-20 22:29 -0700
    Re: impossible stud "Tim Williams" <tiwill@seventransistorlabs.com> - 2018-04-20 02:07 -0500
      Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-20 07:14 -0700
    Re: impossible stud Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2018-04-20 08:41 +0100
      Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-20 07:22 -0700
        Re: impossible stud tabbypurr@gmail.com - 2018-04-20 07:38 -0700
          Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-20 08:29 -0700
            Re: impossible stud "Carl Ijames" <carl.ijames@NOverizon.net> - 2018-04-20 11:50 -0400
              Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-20 09:41 -0700
                Re: impossible stud "Carl Ijames" <carl.ijames@NOverizon.net> - 2018-04-20 14:05 -0400
                Re: impossible stud whit3rd <whit3rd@gmail.com> - 2018-04-20 12:39 -0700
                  Re: impossible stud John Larkin <jjlarkin@highland_snip_technology.com> - 2018-04-20 16:44 -0700
                    Re: impossible stud George Herold <gherold@teachspin.com> - 2018-04-20 16:54 -0700
                      Re: impossible stud John Larkin <jjlarkin@highland_snip_technology.com> - 2018-04-20 17:41 -0700
                        Re: impossible stud George Herold <gherold@teachspin.com> - 2018-04-20 18:55 -0700
              Re: impossible stud Jeff Liebermann <jeffl@cruzio.com> - 2018-04-20 10:26 -0700
                Re: impossible stud John Larkin <jjlarkin@highland_snip_technology.com> - 2018-04-20 12:16 -0700
                  Re: impossible stud Jeff Liebermann <jeffl@cruzio.com> - 2018-04-20 17:52 -0700
                  Re: impossible stud piglet <erichpwagner@hotmail.com> - 2018-04-21 10:45 +0100
                    Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-21 07:53 -0700
                      Re: impossible stud Joseph Gwinn <joegwinn@comcast.net> - 2018-04-21 15:00 -0400
                        Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-21 15:23 -0700
                          Re: impossible stud Joseph Gwinn <joegwinn@comcast.net> - 2018-04-22 12:39 -0400
                            Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-22 10:19 -0700
                              Re: impossible stud Joseph Gwinn <joegwinn@comcast.net> - 2018-04-24 10:07 -0400
                                Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-24 07:58 -0700
                                  Re: impossible stud Joseph Gwinn <joegwinn@comcast.net> - 2018-04-24 22:38 -0400
                                    Re: impossible stud John Larkin <jjlarkin@highland_snip_technology.com> - 2018-04-25 10:31 -0700
                                  Re: impossible stud gnuarm.deletethisbit@gmail.com - 2018-04-25 14:44 -0700
                      Re: impossible stud Joe Chisolm <jchisolm6@earthlink.net> - 2018-04-21 14:44 -0500
                      Re: impossible stud whit3rd <whit3rd@gmail.com> - 2018-04-21 14:11 -0700
                  Re: impossible stud tabbypurr@gmail.com - 2018-04-21 03:18 -0700
                    Re: impossible stud tabbypurr@gmail.com - 2018-04-21 03:34 -0700
            Re: impossible stud Joseph Gwinn <joegwinn@comcast.net> - 2018-04-20 12:41 -0400
            Re: impossible stud "Tim Williams" <tiwill@seventransistorlabs.com> - 2018-04-20 20:35 -0500
            Re: impossible stud bill.sloman@ieee.org - 2018-04-20 19:00 -0700
    Re: impossible stud Jasen Betts <jasen@xnet.co.nz> - 2018-04-20 08:12 +0000
      Re: impossible stud Mike Perkins <spam@spam.com> - 2018-04-20 10:26 +0100
        Re: impossible stud "dcaster@krl.org" <dcaster@krl.org> - 2018-04-20 07:09 -0700
      Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-20 07:23 -0700
    Re: impossible stud Jeff Liebermann <jeffl@cruzio.com> - 2018-04-20 10:13 -0700
    Re: impossible stud Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-04-20 14:17 -0700
    Re: impossible stud Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2018-04-20 15:08 -0700
      Re: impossible stud John Larkin <jjlarkin@highland_snip_technology.com> - 2018-04-20 16:48 -0700
        Re: impossible stud Joe Chisolm <jchisolm6@earthlink.net> - 2018-04-20 23:17 -0500
    Re: impossible stud "Tim Williams" <tiwill@seventransistorlabs.com> - 2018-04-20 20:20 -0500
    Re: impossible stud mickgeyver <alan.yeager.2013@gmail.com> - 2018-04-20 18:41 -0700
    Re: impossible stud Robert Baer <robertbaer@localnet.com> - 2018-04-21 00:53 -0700
    Re: impossible stud Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-04-21 13:06 -0700
      Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-21 15:29 -0700
        Re: impossible stud Lasse Langwadt Christensen <langwadt@fonz.dk> - 2018-04-21 15:46 -0700
    Re: impossible stud Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2018-04-24 09:10 -0400
      Re: impossible stud John Larkin <jjlarkin@highlandtechnology.com> - 2018-04-24 06:55 -0700
        Re: impossible stud Joe Chisolm <jchisolm6@earthlink.net> - 2018-04-24 11:00 -0500

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#502995 — impossible stud

I want a lot of these:

https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1

It probably doesn't exist. Maybe a Swiss screw machine company could
make us a bucket full of these.

Six of these would press into a small PCB, which could then be bolted
onto the bottom of a bigger PCB.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#502998

On 20-Apr-18 11:51 AM, John Larkin wrote:
> I want a lot of these:
> 
> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
> 
> It probably doesn't exist. Maybe a Swiss screw machine company could
> make us a bucket full of these.
> 
> Six of these would press into a small PCB, which could then be bolted
> onto the bottom of a bigger PCB.
> 
> 


I guess you've already looked at what these guys offer?

<https://www.pemnet.com/fastening-products/fasteners-for-mounting-into-printed-circuit-boards-2/>

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#502999

On 20-Apr-18 12:41 PM, Perry wrote:
> On 20-Apr-18 11:51 AM, John Larkin wrote:
>> I want a lot of these:
>>
>> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>>
>> It probably doesn't exist. Maybe a Swiss screw machine company could
>> make us a bucket full of these.
>>
>> Six of these would press into a small PCB, which could then be bolted
>> onto the bottom of a bigger PCB.
>>
>>
> 
> 
> I guess you've already looked at what these guys offer?
> 
> <https://www.pemnet.com/fastening-products/fasteners-for-mounting-into-printed-circuit-boards-2/> 
> 

In particular the broaching studs.

With the one you have drawn the PTH has to take all the force, the 
broaching studs put the force into the PCB.

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#503011

On 20/04/2018 05:41, Perry wrote:
> On 20-Apr-18 11:51 AM, John Larkin wrote:
>> I want a lot of these:
>>
>> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>>
>> It probably doesn't exist. Maybe a Swiss screw machine company could
>> make us a bucket full of these.
>>
>> Six of these would press into a small PCB, which could then be bolted
>> onto the bottom of a bigger PCB.
>>
>>
> 
> 
> I guess you've already looked at what these guys offer?
> 
> <https://www.pemnet.com/fastening-products/fasteners-for-mounting-into-printed-circuit-boards-2/> 
> 
Standard mil spec type of fixing in sm pcb. not sure about 032 though....

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

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#503014

On Friday, April 20, 2018 at 12:42:07 AM UTC-4, Perry wrote:
> On 20-Apr-18 11:51 AM, John Larkin wrote:
> > I want a lot of these:
> > 
> > https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
> > 
> > It probably doesn't exist. Maybe a Swiss screw machine company could
> > make us a bucket full of these.
> > 
> > Six of these would press into a small PCB, which could then be bolted
> > onto the bottom of a bigger PCB.
> > 
> > 
> 
> 
> I guess you've already looked at what these guys offer?
> 
> <https://www.pemnet.com/fastening-products/fasteners-for-mounting-into-printed-circuit-boards-2/>

Right, I've got one place where we press fit pem nuts into pcb.  
(4-40) If they made one that was 2-56 you could have someone make
threaded rod with two threads.  

Geogre H. 

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#503068

On Friday, April 20, 2018 at 9:10:49 AM UTC-4, George Herold wrote:
> On Friday, April 20, 2018 at 12:42:07 AM UTC-4, Perry wrote:
> > On 20-Apr-18 11:51 AM, John Larkin wrote:
> > > I want a lot of these:
> > > 
> > > https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
> > > 
> > > It probably doesn't exist. Maybe a Swiss screw machine company could
> > > make us a bucket full of these.
> > > 
> > > Six of these would press into a small PCB, which could then be bolted
> > > onto the bottom of a bigger PCB.
> > > 
> > > 
> > 
> > 
> > I guess you've already looked at what these guys offer?
> > 
> > <https://www.pemnet.com/fastening-products/fasteners-for-mounting-into-printed-circuit-boards-2/>
> 
> Right, I've got one place where we press fit pem nuts into pcb.  
> (4-40) If they made one that was 2-56 you could have someone make
> threaded rod with two threads.  
> 
> Geogre H.

How well do they work?  Years ago one of the large connector/wiring companies made a press in pin for IDC wiring (like wirewrap but quarter inch tall pins instead of inch and a half).  It was rather tricky to get the thing inserted without pushing out the via barrel.  One PCB fab house I visited said the only way to get a final hole diameter that would meet the tolerance requirement was to drill after plating.  Even then they said it would be tricky to meet the spec.  These parts were "interference" fit with a complaint pin meaning the pin was fatter than the hole, but had a degree of springiness to the width which would allow it to fit very tightly.  The knurled fitting works by reshaping the metal it is being pressed into.  Can this work very well with PCB material?  

From the PEM product page for a broaching PCB fastener...

Broaching and broach/flare types are designed for unplated mounting hole applications. If used in plated mounting holes, the stresses involved 
can damage the plating, push out the plating entirely, or break any traces inside the board that might be connected to the plated hole. When 
installing into non-plated mounting holes there may even be issues with delamination, measeling or crazing in some instance

I think they are saying this mounting type doesn't always work well. 

Rick C.

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#503004

Screws?  Press-ins?  Your manufacturing people are going to be screeching 
when they discover you could've designed a thing with snap type standoffs 
instead!

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/

"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message 
news:umoidd15080nk6v6c67nuff55b6523qfd4@4ax.com...
>I want a lot of these:
>
> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>
> It probably doesn't exist. Maybe a Swiss screw machine company could
> make us a bucket full of these.
>
> Six of these would press into a small PCB, which could then be bolted
> onto the bottom of a bigger PCB.
>
>
> -- 
>
> John Larkin         Highland Technology, Inc
>
> lunatic fringe electronics
> 

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#503018

On Fri, 20 Apr 2018 02:07:01 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>Screws?  Press-ins?  Your manufacturing people are going to be screeching 
>when they discover you could've designed a thing with snap type standoffs 
>instead!
>
>Tim

It's going to be a gigantic improvement over Rev A.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#503006

On 20/04/2018 04:51, John Larkin wrote:
> I want a lot of these:
> 
> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
> 
> It probably doesn't exist. Maybe a Swiss screw machine company could
> make us a bucket full of these.

Not quite what you asked for but how about getting some threaded bar and 
turning down to the other size and using a nut to make the collar.
Or don't turn it down at all and use a larger countersunk screw.

If you did it in copper or brass then they could be soldered in to the 
daughter board and so wouldn't need to be a tight press fit.
> 
> Six of these would press into a small PCB, which could then be bolted
> onto the bottom of a bigger PCB.

Does it really need 6 of these supports? I don't envy production putting 
it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?

-- 
Regards,
Martin Brown

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#503019

On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
<'''newspam'''@nezumi.demon.co.uk> wrote:

>On 20/04/2018 04:51, John Larkin wrote:
>> I want a lot of these:
>> 
>> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>> 
>> It probably doesn't exist. Maybe a Swiss screw machine company could
>> make us a bucket full of these.
>
>Not quite what you asked for but how about getting some threaded bar and 
>turning down to the other size and using a nut to make the collar.
>Or don't turn it down at all and use a larger countersunk screw.
>
>If you did it in copper or brass then they could be soldered in to the 
>daughter board and so wouldn't need to be a tight press fit.

Yes, one option would be to delete the knurl and solder one end. I
want the botton of the baby board to be essentially planar, but a
little solder bump would probably be OK.

>> 
>> Six of these would press into a small PCB, which could then be bolted
>> onto the bottom of a bigger PCB.
>
>Does it really need 6 of these supports? I don't envy production putting 
>it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?

They are electrical connections too. I need six connections between
boards. The baby board is about 0.5" on a side.

https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#503022

On Friday, 20 April 2018 15:22:28 UTC+1, John Larkin  wrote:
> On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
> <'''newspam'''@nezumi.demon.co.uk> wrote:
> >On 20/04/2018 04:51, John Larkin wrote:
> >> I want a lot of these:
> >> 
> >> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
> >> 
> >> It probably doesn't exist. Maybe a Swiss screw machine company could
> >> make us a bucket full of these.
> >
> >Not quite what you asked for but how about getting some threaded bar and 
> >turning down to the other size and using a nut to make the collar.
> >Or don't turn it down at all and use a larger countersunk screw.
> >
> >If you did it in copper or brass then they could be soldered in to the 
> >daughter board and so wouldn't need to be a tight press fit.
> 
> Yes, one option would be to delete the knurl and solder one end. I
> want the botton of the baby board to be essentially planar, but a
> little solder bump would probably be OK.
> 
> >> 
> >> Six of these would press into a small PCB, which could then be bolted
> >> onto the bottom of a bigger PCB.
> >
> >Does it really need 6 of these supports? I don't envy production putting 
> >it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
> 
> They are electrical connections too. I need six connections between
> boards. The baby board is about 0.5" on a side.
> 
> https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1

I'd hate to rely on solder for a mechanical connection. I know consumer stuff does it routinely, but we've all seen the reliability problems that result.


NT

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#503025

On Fri, 20 Apr 2018 07:38:42 -0700 (PDT), tabbypurr@gmail.com wrote:

>On Friday, 20 April 2018 15:22:28 UTC+1, John Larkin  wrote:
>> On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
>> <'''newspam'''@nezumi.demon.co.uk> wrote:
>> >On 20/04/2018 04:51, John Larkin wrote:
>> >> I want a lot of these:
>> >> 
>> >> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>> >> 
>> >> It probably doesn't exist. Maybe a Swiss screw machine company could
>> >> make us a bucket full of these.
>> >
>> >Not quite what you asked for but how about getting some threaded bar and 
>> >turning down to the other size and using a nut to make the collar.
>> >Or don't turn it down at all and use a larger countersunk screw.
>> >
>> >If you did it in copper or brass then they could be soldered in to the 
>> >daughter board and so wouldn't need to be a tight press fit.
>> 
>> Yes, one option would be to delete the knurl and solder one end. I
>> want the botton of the baby board to be essentially planar, but a
>> little solder bump would probably be OK.
>> 
>> >> 
>> >> Six of these would press into a small PCB, which could then be bolted
>> >> onto the bottom of a bigger PCB.
>> >
>> >Does it really need 6 of these supports? I don't envy production putting 
>> >it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
>> 
>> They are electrical connections too. I need six connections between
>> boards. The baby board is about 0.5" on a side.
>> 
>> https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1
>
>I'd hate to rely on solder for a mechanical connection. I know consumer stuff does it routinely, but we've all seen the reliability problems that result.
>
>
>NT

The old Radio Amateur's Handbook admonished against using solder as
mechanical support. Then Tektronix did it everywhere in their old tube
scopes.

Paul Revere soldered the handles onto teapots. Who is going to argue
with Paul Revere?


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#503026

On Fri, 20 Apr 2018 07:38:42 -0700 (PDT), tabbypurr@gmail.com wrote:

>On Friday, 20 April 2018 15:22:28 UTC+1, John Larkin  wrote:
>> On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
>> <'''newspam'''@nezumi.demon.co.uk> wrote:
>> >On 20/04/2018 04:51, John Larkin wrote:
>> >> I want a lot of these:
>> >>
>> >> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>> >>
>> >> It probably doesn't exist. Maybe a Swiss screw machine company could
>> >> make us a bucket full of these.
>> >
>> >Not quite what you asked for but how about getting some threaded bar and
>> >turning down to the other size and using a nut to make the collar.
>> >Or don't turn it down at all and use a larger countersunk screw.
>> >
>> >If you did it in copper or brass then they could be soldered in to the
>> >daughter board and so wouldn't need to be a tight press fit.
>>
>> Yes, one option would be to delete the knurl and solder one end. I
>> want the botton of the baby board to be essentially planar, but a
>> little solder bump would probably be OK.
>>
>> >>
>> >> Six of these would press into a small PCB, which could then be bolted
>> >> onto the bottom of a bigger PCB.
>> >
>> >Does it really need 6 of these supports? I don't envy production putting
>> >it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
>>
>> They are electrical connections too. I need six connections between
>> boards. The baby board is about 0.5" on a side.
>>
>> https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1
>
>I'd hate to rely on solder for a mechanical connection. I know consumer 
>stuff does it routinely, but we've all seen the reliability problems that 
>result.
>
>
>NT

The screw head would probably stick up too far for you if a bump of solder 
is your limit, but you could put a 0-80 x 1/4" screw through the baby board 
and tighten down a nut with a drop of blue loctite to hold it.  That takes 
the place of the knurling and pressing and machined end of your stud, then 
insert through your main board and put on six more nuts.  If these 6 screws 
are all within a 3/8" square then little height differences might be enough 
to put in some significant bending stresses, causing cracks or bad 
connections over time.  Hmm, browsing at www.mcmcaster.com there are a 
couple of head styles that are 0.032-0.037" tall, and they have brass and 
stainless steel.

-- 
Regards,
Carl Ijames

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#503029

On Fri, 20 Apr 2018 11:50:21 -0400, "Carl Ijames"
<carl.ijames@NOverizon.net> wrote:

>On Fri, 20 Apr 2018 07:38:42 -0700 (PDT), tabbypurr@gmail.com wrote:
>
>>On Friday, 20 April 2018 15:22:28 UTC+1, John Larkin  wrote:
>>> On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
>>> <'''newspam'''@nezumi.demon.co.uk> wrote:
>>> >On 20/04/2018 04:51, John Larkin wrote:
>>> >> I want a lot of these:
>>> >>
>>> >> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>>> >>
>>> >> It probably doesn't exist. Maybe a Swiss screw machine company could
>>> >> make us a bucket full of these.
>>> >
>>> >Not quite what you asked for but how about getting some threaded bar and
>>> >turning down to the other size and using a nut to make the collar.
>>> >Or don't turn it down at all and use a larger countersunk screw.
>>> >
>>> >If you did it in copper or brass then they could be soldered in to the
>>> >daughter board and so wouldn't need to be a tight press fit.
>>>
>>> Yes, one option would be to delete the knurl and solder one end. I
>>> want the botton of the baby board to be essentially planar, but a
>>> little solder bump would probably be OK.
>>>
>>> >>
>>> >> Six of these would press into a small PCB, which could then be bolted
>>> >> onto the bottom of a bigger PCB.
>>> >
>>> >Does it really need 6 of these supports? I don't envy production putting
>>> >it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
>>>
>>> They are electrical connections too. I need six connections between
>>> boards. The baby board is about 0.5" on a side.
>>>
>>> https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1
>>
>>I'd hate to rely on solder for a mechanical connection. I know consumer 
>>stuff does it routinely, but we've all seen the reliability problems that 
>>result.
>>
>>
>>NT
>
>The screw head would probably stick up too far for you if a bump of solder 
>is your limit, but you could put a 0-80 x 1/4" screw through the baby board 
>and tighten down a nut with a drop of blue loctite to hold it.  That takes 
>the place of the knurling and pressing and machined end of your stud, then 
>insert through your main board and put on six more nuts.  If these 6 screws 
>are all within a 3/8" square then little height differences might be enough 
>to put in some significant bending stresses, causing cracks or bad 
>connections over time.  Hmm, browsing at www.mcmcaster.com there are a 
>couple of head styles that are 0.032-0.037" tall, and they have brass and 
>stainless steel.

I guess I could just smash the boards together with six nuts and
bolts. That's inelegant but easy. I'd have the screw heads poking out
the bottom of the baby board, so I'd have to live with that. I would
want low screw head height.

The parts on the baby board will get hot. The baby board pushes
against a silicone gap-pad that conducts heat into an aluminum
baseplate. Some of the gap-pad material is very compliant, about like
chewing gum, so would flow around the screw heads and make a decent
thermal interface. I could use thermally conductive putty, but that's
messy.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#503034

"John Larkin"  wrote in message 
news:jg5kdddookkqqkamj6enuq2idvkfcn6lrk@4ax.com...

On Fri, 20 Apr 2018 11:50:21 -0400, "Carl Ijames"
<carl.ijames@NOverizon.net> wrote:

>On Fri, 20 Apr 2018 07:38:42 -0700 (PDT), tabbypurr@gmail.com wrote:
>
>>On Friday, 20 April 2018 15:22:28 UTC+1, John Larkin  wrote:
>>> On Fri, 20 Apr 2018 08:41:23 +0100, Martin Brown
>>> <'''newspam'''@nezumi.demon.co.uk> wrote:
>>> >On 20/04/2018 04:51, John Larkin wrote:
>>> >> I want a lot of these:
>>> >>
>>> >> https://www.dropbox.com/s/dmj4vff7mnldrcs/Impossible_Stud.JPG?raw=1
>>> >>
>>> >> It probably doesn't exist. Maybe a Swiss screw machine company could
>>> >> make us a bucket full of these.
>>> >
>>> >Not quite what you asked for but how about getting some threaded bar 
>>> >and
>>> >turning down to the other size and using a nut to make the collar.
>>> >Or don't turn it down at all and use a larger countersunk screw.
>>> >
>>> >If you did it in copper or brass then they could be soldered in to the
>>> >daughter board and so wouldn't need to be a tight press fit.
>>>
>>> Yes, one option would be to delete the knurl and solder one end. I
>>> want the botton of the baby board to be essentially planar, but a
>>> little solder bump would probably be OK.
>>>
>>> >>
>>> >> Six of these would press into a small PCB, which could then be bolted
>>> >> onto the bottom of a bigger PCB.
>>> >
>>> >Does it really need 6 of these supports? I don't envy production 
>>> >putting
>>> >it together. Wouldn't 3 or 4 thicker ones be much easier to assemble?
>>>
>>> They are electrical connections too. I need six connections between
>>> boards. The baby board is about 0.5" on a side.
>>>
>>> https://www.dropbox.com/s/dsjwdnize4ig2gx/Impossible_App.JPG?raw=1
>>
>>I'd hate to rely on solder for a mechanical connection. I know consumer
>>stuff does it routinely, but we've all seen the reliability problems that
>>result.
>>
>>
>>NT
>
>The screw head would probably stick up too far for you if a bump of solder
>is your limit, but you could put a 0-80 x 1/4" screw through the baby board
>and tighten down a nut with a drop of blue loctite to hold it.  That takes
>the place of the knurling and pressing and machined end of your stud, then
>insert through your main board and put on six more nuts.  If these 6 screws
>are all within a 3/8" square then little height differences might be enough
>to put in some significant bending stresses, causing cracks or bad
>connections over time.  Hmm, browsing at www.mcmcaster.com there are a
>couple of head styles that are 0.032-0.037" tall, and they have brass and
>stainless steel.

I guess I could just smash the boards together with six nuts and
bolts. That's inelegant but easy. I'd have the screw heads poking out
the bottom of the baby board, so I'd have to live with that. I would
want low screw head height.

The parts on the baby board will get hot. The baby board pushes
against a silicone gap-pad that conducts heat into an aluminum
baseplate. Some of the gap-pad material is very compliant, about like
chewing gum, so would flow around the screw heads and make a decent
thermal interface. I could use thermally conductive putty, but that's
messy.

John Larkin         Highland Technology, Inc

lunatic fringe electronics
===================================================================

I thought you wanted an air gap between the boards, that's why I suggested 
two nuts (and it retains the screw and makes assembly easier).  You could 
counterbore the screw head side of the baby board to sink the screw head up 
to about half the thickness of the board, which would probably make it 
basically smooth for your gap-pad.  Or you could just put a header row of 
through-hole pins with spacers in the main board with matching holes in the 
baby board and solder the baby board down.  Assembly would be easy, R&R for 
service not so much :-).  If the two boards can touch without shorting, put 
six pads on the main board and six vias on the baby board large enough to 
get a soldering iron tip all the way through to touch the main board and 
solder the baby board down.  Like a plug weld, only with solder, and you 
don't really need to fill the via.  Remove with a heat gun to melt all six 
at once.

-- 
Regards,
Carl Ijames

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#503036

On Friday, April 20, 2018 at 9:41:21 AM UTC-7, John Larkin wrote:

> I guess I could just smash the boards together with six nuts and
> bolts. That's inelegant but easy. 

Anything with small loose parts is an assembly irritation, and
a did-it-get-loose maintenance issue.

If you go instead with some plastic snap-in standoffs, the baby board can
have six pogo pins for its electrical connection, or if plating is
pricey, just put landing spots on the (small) baby board and pogo pins
in motherboard.

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#503046

On Fri, 20 Apr 2018 12:39:18 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Friday, April 20, 2018 at 9:41:21 AM UTC-7, John Larkin wrote:
>
>> I guess I could just smash the boards together with six nuts and
>> bolts. That's inelegant but easy. 
>
>Anything with small loose parts is an assembly irritation, and
>a did-it-get-loose maintenance issue.
>
>If you go instead with some plastic snap-in standoffs, the baby board can
>have six pogo pins for its electrical connection, or if plating is
>pricey, just put landing spots on the (small) baby board and pogo pins
>in motherboard.

The snap-ins would take too much room. We considered pins on the baby
board and pin sockets on the main board, also a hassle.

Currents and speeds are high for pogos.

If I make the holes in the baby board a tad smaller than the screw
size, the screws will thread into the plated holes a bit and become
essentially captive. That makes assembly a little less messy.




-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

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#503049

On Friday, April 20, 2018 at 7:44:14 PM UTC-4, John Larkin wrote:
> On Fri, 20 Apr 2018 12:39:18 -0700 (PDT), whit3rd <whit3rd@gmail.com>
> wrote:
> 
> >On Friday, April 20, 2018 at 9:41:21 AM UTC-7, John Larkin wrote:
> >
> >> I guess I could just smash the boards together with six nuts and
> >> bolts. That's inelegant but easy. 
> >
> >Anything with small loose parts is an assembly irritation, and
> >a did-it-get-loose maintenance issue.
> >
> >If you go instead with some plastic snap-in standoffs, the baby board can
> >have six pogo pins for its electrical connection, or if plating is
> >pricey, just put landing spots on the (small) baby board and pogo pins
> >in motherboard.
> 
> The snap-ins would take too much room. We considered pins on the baby
> board and pin sockets on the main board, also a hassle.
> 
> Currents and speeds are high for pogos.
> 
> If I make the holes in the baby board a tad smaller than the screw
> size, the screws will thread into the plated holes a bit and become
> essentially captive. That makes assembly a little less messy.
> 
I'm mostly confused about what you want to do.  Is the 
thermal conductivity of the connections important?  If there's 
not enough room for some header.  Then some mechanical mount for 
stability, and hand solder in bus wire through plated holes. (?)

(with a loop on top so it doesn't fall through, how many are you making?)


George H.   
> 
> 
> 
> -- 
> 
> John Larkin         Highland Technology, Inc
> picosecond timing   precision measurement 
> 
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com

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#503050

On Fri, 20 Apr 2018 16:54:09 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>On Friday, April 20, 2018 at 7:44:14 PM UTC-4, John Larkin wrote:
>> On Fri, 20 Apr 2018 12:39:18 -0700 (PDT), whit3rd <whit3rd@gmail.com>
>> wrote:
>> 
>> >On Friday, April 20, 2018 at 9:41:21 AM UTC-7, John Larkin wrote:
>> >
>> >> I guess I could just smash the boards together with six nuts and
>> >> bolts. That's inelegant but easy. 
>> >
>> >Anything with small loose parts is an assembly irritation, and
>> >a did-it-get-loose maintenance issue.
>> >
>> >If you go instead with some plastic snap-in standoffs, the baby board can
>> >have six pogo pins for its electrical connection, or if plating is
>> >pricey, just put landing spots on the (small) baby board and pogo pins
>> >in motherboard.
>> 
>> The snap-ins would take too much room. We considered pins on the baby
>> board and pin sockets on the main board, also a hassle.
>> 
>> Currents and speeds are high for pogos.
>> 
>> If I make the holes in the baby board a tad smaller than the screw
>> size, the screws will thread into the plated holes a bit and become
>> essentially captive. That makes assembly a little less messy.
>> 
>I'm mostly confused about what you want to do.

Me too! Design usually starts that way.


>  Is the 
>thermal conductivity of the connections important?

The baby board will get hot, so I may as well dump some heat into the
main board. But the main heat transfer path is baby board to gap pad
to baseplate.


>  If there's 
>not enough room for some header.  Then some mechanical mount for 
>stability, and hand solder in bus wire through plated holes. (?)

The baby board is 0.47" square, has parts, has six big connections to
the main board. Tight. Hand soldering (and desoldering!) would be
messy.

>
>(with a loop on top so it doesn't fall through, how many are you making?)

Just a few now, until we determine if the world wants it. We have one
potential customer who might.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

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#503059

On Friday, April 20, 2018 at 8:41:25 PM UTC-4, John Larkin wrote:
> On Fri, 20 Apr 2018 16:54:09 -0700 (PDT), George Herold
> <gherold@teachspin.com> wrote:
> 
> >On Friday, April 20, 2018 at 7:44:14 PM UTC-4, John Larkin wrote:
> >> On Fri, 20 Apr 2018 12:39:18 -0700 (PDT), whit3rd <whit3rd@gmail.com>
> >> wrote:
> >> 
> >> >On Friday, April 20, 2018 at 9:41:21 AM UTC-7, John Larkin wrote:
> >> >
> >> >> I guess I could just smash the boards together with six nuts and
> >> >> bolts. That's inelegant but easy. 
> >> >
> >> >Anything with small loose parts is an assembly irritation, and
> >> >a did-it-get-loose maintenance issue.
> >> >
> >> >If you go instead with some plastic snap-in standoffs, the baby board can
> >> >have six pogo pins for its electrical connection, or if plating is
> >> >pricey, just put landing spots on the (small) baby board and pogo pins
> >> >in motherboard.
> >> 
> >> The snap-ins would take too much room. We considered pins on the baby
> >> board and pin sockets on the main board, also a hassle.
> >> 
> >> Currents and speeds are high for pogos.
> >> 
> >> If I make the holes in the baby board a tad smaller than the screw
> >> size, the screws will thread into the plated holes a bit and become
> >> essentially captive. That makes assembly a little less messy.
> >> 
> >I'm mostly confused about what you want to do.
> 
> Me too! Design usually starts that way.
> 
> 
> >  Is the 
> >thermal conductivity of the connections important?
> 
> The baby board will get hot, so I may as well dump some heat into the
> main board. But the main heat transfer path is baby board to gap pad
> to baseplate.
> 
> 
> >  If there's 
> >not enough room for some header.  Then some mechanical mount for 
> >stability, and hand solder in bus wire through plated holes. (?)
> 
> The baby board is 0.47" square, has parts, has six big connections to
> the main board. Tight. Hand soldering (and desoldering!) would be
> messy.
Is there some edge you have access too?  Then you could solder 
some bus header there... and clip the wire to take it apart.  
I saw some 2-56 pem nuts upstream can you fit two 
of those for support? Maybe the thermal conductivity of 
pem nuts is not so good.    

George H. 
> 
> >
> >(with a loop on top so it doesn't fall through, how many are you making?)
> 
> Just a few now, until we determine if the world wants it. We have one
> potential customer who might.
> 
> 
> -- 
> 
> John Larkin         Highland Technology, Inc
> picosecond timing   precision measurement 
> 
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com

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