I think it's going to work.
This is an early version I just got in yesterday.
That is a microscopic mount of bite at the top-right corner, but, it's
not zero, and I have managed to increase that a little since then, I
hope, but mostly I just realized, that may just not be that big of a deal.
Because 1, the bottom is trapped a little better, probably solidly good
enough, and that combines with 2, the straight lines on the ends of the
pcb, held inside the matching straight lines of the carrier, means the
pcb can't rotate or swing at all. So if one end of the pcb is
well-trapped, and the pcb can't rotate or swing, then the other end
isn't really going anywhere even if one of the corners isn't held as
well as I'd like.
https://photos.app.goo.gl/u2ATYQaP9BgJTNp87
https://photos.app.goo.gl/yor3tzNbatmRzuPw7
I have already tweaked it a bit from this, but this already would
probably work well enough, so I think it's going to work.
I just ordered these last night which are about 3 versions after the
pics above:
https://oshpark.com/shared_projects/693Ss1t7
http://shpws.me/Rqhy
The printer won't actually be able to print those little triangular
walls at the corners because they are way too thin, but it should at
least fill-in those corners a little like a webbed foot, and maybe raise
a little bit of a ridge along those corner edges to counter act how they
would normally get rounded off. That should help somewhat. I also
increased the thickness of the wedge shaped corner posts a little to
counteract how the printer seems to print it slightly under-size. And
made the end wall as thin as I can get away with, and the pcb as long as
possible to really fill the carrier. Between several tiny tiny nudges
like that, collectively it might all add up to working pretty well,
without needing either a big hole and pin, or those notches in all 4
corners, or any other kind of shape that eats into the available
real-estate of the pcb.
--
bkw
On 8/21/19 2:20 PM, Stephen Adolph wrote:
thanks Brian,
I'll take a close look and see what the extent of the changes would be
to adopt this.
cheers
Steve
On Mon, Aug 19, 2019 at 2:52 AM Brian K. White <[email protected]
<mailto:[email protected]>> wrote:
Steve,
I think I have a pcb & carrier that might work better for you.
I have to wait for the samples still, but here's what it looks like:
https://raw.githubusercontent.com/aljex/pcb2molex8878/cham/pcb2molex8878.png
On this one the pcb is a simple rectangle with no funky steps in the
corners, no polarity hole, and instead a simple chamfer on the
pin1 corner.
Dimensions are just 38mm x 16.2mm
For the chamfer, shorten two sides by 1.7mm
The carrier opening is 0.1mm bigger in both directions, so this is
the
actual pcb dimensions.
--
bkw
On 8/10/19 8:00 PM, Stephen Adolph wrote:
> Just the keys that fit the Molex. 2 on one end and one on the
other end.
>
> On Saturday, August 10, 2019, Brian K. White <[email protected]
<mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> What do you mean by stubs?
>
> The notches cut out of the corners?
>
> There needs to be something to hold the pcb from sliding
sideways.
> The pin actually would do that well enough on one end, but since
> the pin is far to one end, the other end would move too much (I
> think), and you don't want two pins. So that little bit of
> skinnier pcb trapped between those vertical edges at the ends is
> enough to do it.
> And I think I will simplify that to just be 45 degree angles at
> the corners instead of those little steps the way it is now.
> That job could be done some other way, not just that way. There
> could be a single notch in the middle of the ends, and matching
> ridge in the carrier, and no walls at the corners of the carrier
> and no notches in the corners of the pcb, for one possible
example.
>
> If you didn't already have a developed design with a lot of work
> already in it, and you were aiming to have all components on one
> side anyway for other reasons like manufacuring, then the
carrier
> would be both stronger and effortless to make if the parts were
> all on top instead of bottom. The pcb has to lay pretty close to
> the bottom of the socket and so there is not much room
between the
> pcb and the floor. Plus then you could have the hole for the
> polarity pin as long as you could make room between the traces.
> The pin doesn't extend above the pcb, so you can have chips over
> the hole, but not under it.
>
> --
> bkw
>
>
>
> On 8/10/19 6:58 PM, Stephen Adolph wrote:
>
> Thanks,
> Why do you have the stubs for the molex on this drawing? I
> would have thought that such things would be unneeded
with the
> carrier.
>
> I have to take a close look at length. I think it can work
> but with changes.
>
>
> On Saturday, August 10, 2019, Brian K. White
> <[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
> <mailto:[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>> wrote:
>
> Here is a messy pdf
> http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf
> <http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf>
>
<http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf
> <http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf>>
>
>
