We've just received some PCBs back from fab, and there's a problem. The
boards have an PC motherboard-style power connector which is to take a
significant current (10A or so). The footprint will take either a
straight-through or a right-angle connector, and was prototyped with the
straight-through version which have flat pins. The holes are
plated-through, and the plating is electrically necessary.

We need to use right-angled versions. The only R/A connector available has
square pins. Our holes are the same diameter, but round. D'oh.

So how might I go about making a large number of square pins fit in round
holes? There's hundreds of pins to do, and a PCB respin is awkward. It's a
tight enough fit that simply hammering it in isn't going to be a great idea,
and filing the holes out is a no-no because of the plating. Filing the pins
with a flat file is going to be hard work (especially since they're quite
close together and can't be removed from the connector).

I did wonder about getting a die to cut a thread on the end of each pin (ie
make it round), but 1mm diameter dies don't seem to be easily available. Is
there something similar around?

Any other ideas?

Thanks
Theo

HI Theo

I use diamond hole drills for glass-work.
They consist of a hollow tube, with diamonds bonded to the
'business end' of the tube.

Might it be possible to use one of these as a sort of 'auto-file' -
just to grind off the corners from your square pins ?

When used on glass, they need water-cooling -
don't know if they'd need that for metal-cutting.

Alternatively, can you find somebody who can drill a 1mm hole into the
end of a dremel-style mounted abrasive drum - that you can use to
re-form the end of the mains socket pins.

Don't know what the effect might be of removing material from the pins -
they might be plated to aid solderability, so you'd need to know that
whatever's under the plating will solder OK - also that you're not
affecting the current capacity of the socket (are there approvals
issues, perhaps ?)

Regards
Adrian

On 18/04/2011 18:32, Theo Markettos wrote:
We've just received some PCBs back from fab, and there's a problem. The
boards have an PC motherboard-style power connector which is to take a
significant current (10A or so). The footprint will take either a
straight-through or a right-angle connector, and was prototyped with the
straight-through version which have flat pins. The holes are
plated-through, and the plating is electrically necessary.

We need to use right-angled versions. The only R/A connector available has
square pins. Our holes are the same diameter, but round. D'oh.

So how might I go about making a large number of square pins fit in round
holes? There's hundreds of pins to do, and a PCB respin is awkward. It's a
tight enough fit that simply hammering it in isn't going to be a great idea,
and filing the holes out is a no-no because of the plating. Filing the pins
with a flat file is going to be hard work (especially since they're quite
close together and can't be removed from the connector).

I did wonder about getting a die to cut a thread on the end of each pin (ie
make it round), but 1mm diameter dies don't seem to be easily available. Is
there something similar around?

Any other ideas?

Thanks
Theo

On 18 Apr 2011 18:32:48 +0100 (BST), Theo Markettos
wrote:


We've just received some PCBs back from fab, and there's a problem. The
boards have an PC motherboard-style power connector which is to take a
significant current (10A or so). The footprint will take either a
straight-through or a right-angle connector, and was prototyped with the
straight-through version which have flat pins. The holes are
plated-through, and the plating is electrically necessary.

We need to use right-angled versions. The only R/A connector available has
square pins. Our holes are the same diameter, but round. D'oh.

So how might I go about making a large number of square pins fit in round
holes? There's hundreds of pins to do, and a PCB respin is awkward. It's a
tight enough fit that simply hammering it in isn't going to be a great idea,
and filing the holes out is a no-no because of the plating. Filing the pins
with a flat file is going to be hard work (especially since they're quite
close together and can't be removed from the connector).

I did wonder about getting a die to cut a thread on the end of each pin (ie
make it round), but 1mm diameter dies don't seem to be easily available. Is
there something similar around?

Any other ideas?

Thanks
Theo
How about drilling out the holes then soldering the connector pins on
both sides to remake the electrical connection of the plated hole - or
are these multilayer (ie not just double sided) pcbs?

On Mon, 18 Apr 2011 18:32:48 +0100, Theo Markettos wrote:
We need to use right-angled versions. The only R/A connector available
has square pins. Our holes are the same diameter, but round. D'oh.

Are there holes pre-drilled (I assume so) in the PCB for mounting the
connector body?

cheers

Jules

On Mon, 18 Apr 2011 18:32:48 +0100, Theo Markettos wrote:
We need to use right-angled versions. The only R/A connector available
has square pins. Our holes are the same diameter, but round. D'oh.

Are there holes pre-drilled (I assume so) in the PCB for mounting the
connector body?

cheers

Jules

Adrian Brentnall wrote:
I use diamond hole drills for glass-work.
They consist of a hollow tube, with diamonds bonded to the
'business end' of the tube.

Might it be possible to use one of these as a sort of 'auto-file' -
just to grind off the corners from your square pins ?

When used on glass, they need water-cooling -
don't know if they'd need that for metal-cutting.

Alternatively, can you find somebody who can drill a 1mm hole into the
end of a dremel-style mounted abrasive drum - that you can use to
re-form the end of the mains socket pins.

Hmmm... there's an idea. I could laser cut a small piece of glass to the
appropriate size with a hole in it, and then epoxy that in the end of a pen
or similar (tolerances between pins are quite tight, so the tool has to be
pointy). I'm only cutting copper, so it should be reasonably soft and
amenable to glass. However if this goes wrong it sounds like a recipe for
blood.

I'll see if there's any Dremel fittings lying around I can
abu^H^H^Hexperiment upon...

Don't know what the effect might be of removing material from the pins -
they might be plated to aid solderability, so you'd need to know that
whatever's under the plating will solder OK - also that you're not
affecting the current capacity of the socket (are there approvals
issues, perhaps ?)

No approvals issues, and taking off 0.4mm off the corners of the pins won't
do too much harm to the current capacity (the straight-through connectors
have smaller pins and the same current rating).

Now rummaging in the kitchen to find glass jars small enough to laser
cut...

Theo

Jules Richardson wrote:
On Mon, 18 Apr 2011 18:32:48 +0100, Theo Markettos wrote:
We need to use right-angled versions. The only R/A connector available
has square pins. Our holes are the same diameter, but round. D'oh.

Are there holes pre-drilled (I assume so) in the PCB for mounting the
connector body?

Yes, I assume they've come from a standard footprint as neither of the
connectors use them. Why?

Theo

DavidM wrote:
How about drilling out the holes then soldering the connector pins on
both sides to remake the electrical connection of the plated hole - or
are these multilayer (ie not just double sided) pcbs?

It's possible - it's only double sided, and there is access to the component
side pins on the R/A connector, though I don't know if I can get a fat
enough bit in to transfer sufficient heat. I'll try.

Theo

Theo Markettos wrote:
SNIP
Any other ideas?
Apart from looking for a different connector, which you couldn't find, but
may nonetheless exist somewhere at a price,
is there room for a tiny auxiliary or piggy-back adaptor board to take the
connector and wire links or pins to the main one?

On Mon, 18 Apr 2011 22:07:41 +0100, Theo Markettos wrote:
Are there holes pre-drilled (I assume so) in the PCB for mounting the
connector body?

Yes, I assume they've come from a standard footprint as neither of the
connectors use them. Why?

Oh... hmm. Well, I was wondering if you could solder round vertical pins
to the PCB, then solder a square-pinned connector to those - it'd hardly
be elegant, but better than re-doing a bunch of PCBs (and quick, too).

My concern would be mechanical strength, though (even if power cabling
was plugged in and supposedly never removed), so I really wouldn't trust
it unless there was also a way to physically anchor the connector to the
PCB.

As a second possiblity, maybe an off-board, in-line connector with short
flying leads to the PCB?

cheers

Jules

"Jules Richardson" wrote in message
...
On Mon, 18 Apr 2011 22:07:41 +0100, Theo Markettos wrote:
Are there holes pre-drilled (I assume so) in the PCB for mounting the
connector body?

Yes, I assume they've come from a standard footprint as neither of the
connectors use them. Why?

Oh... hmm. Well, I was wondering if you could solder round vertical pins
to the PCB, then solder a square-pinned connector to those - it'd hardly
be elegant, but better than re-doing a bunch of PCBs (and quick, too).

My concern would be mechanical strength, though (even if power cabling
was plugged in and supposedly never removed), so I really wouldn't trust
it unless there was also a way to physically anchor the connector to the
PCB.

As a second possiblity, maybe an off-board, in-line connector with short
flying leads to the PCB?


Just as an aside, the OP hasn't actually said what these PCBs are for..
if its military or medical stuff then most of the solutions proposed would
be unacceptable.
It should be noted that we used press fit connectors that had square(is)
pins and it may be the case that this is the case here, if so insertion
tools should be available to fit them.

If its a bit of consumer stuff then drilling it out and soldering both sides
appears to be pretty obvious if the pads are big enough to form a good joint
without the through plating.

Another possibility is to square the holes with a square pin in a press if
its just a small error.

What pitch are the pins? Could you modify a pair of suitable pliers by
drilling a hole in them to act as a crimp to change the pins from square
to round?

--
*If you try to fail, and succeed, which have you done?

Dave Plowman London SW
To e-mail, change noise into sound.

Theo Markettos wrote:
We've just received some PCBs back from fab, and there's a problem. The
boards have an PC motherboard-style power connector which is to take a
significant current (10A or so). The footprint will take either a
straight-through or a right-angle connector, and was prototyped with the
straight-through version which have flat pins. The holes are
plated-through, and the plating is electrically necessary.

We need to use right-angled versions. The only R/A connector available has
square pins. Our holes are the same diameter, but round. D'oh.

So how might I go about making a large number of square pins fit in round
holes? There's hundreds of pins to do, and a PCB respin is awkward. It's a
tight enough fit that simply hammering it in isn't going to be a great idea,
and filing the holes out is a no-no because of the plating. Filing the pins
with a flat file is going to be hard work (especially since they're quite
close together and can't be removed from the connector).

I did wonder about getting a die to cut a thread on the end of each pin (ie
make it round), but 1mm diameter dies don't seem to be easily available. Is
there something similar around?

Any other ideas?

Thanks
Theo
Make some sort of crimping device that forces the square pins round.
You may be able to modify heavy pliers or small bolt cutters by creating
flat meeting jaws and drilling a round hole of correct size in the
meeting faces.(if you can understand my ramblings)

F Murtz wrote:
Theo Markettos wrote:
We've just received some PCBs back from fab, and there's a problem. The
boards have an PC motherboard-style power connector which is to take a
significant current (10A or so). The footprint will take either a
straight-through or a right-angle connector, and was prototyped with the
straight-through version which have flat pins. The holes are
plated-through, and the plating is electrically necessary.

We need to use right-angled versions. The only R/A connector available
has
square pins. Our holes are the same diameter, but round. D'oh.

So how might I go about making a large number of square pins fit in round
holes? There's hundreds of pins to do, and a PCB respin is awkward.
It's a
tight enough fit that simply hammering it in isn't going to be a great
idea,
and filing the holes out is a no-no because of the plating. Filing the
pins
with a flat file is going to be hard work (especially since they're quite
close together and can't be removed from the connector).

I did wonder about getting a die to cut a thread on the end of each
pin (ie
make it round), but 1mm diameter dies don't seem to be easily
available. Is
there something similar around?

Any other ideas?

Thanks
Theo
Make some sort of crimping device that forces the square pins round.
You may be able to modify heavy pliers or small bolt cutters by creating
flat meeting jaws and drilling a round hole of correct size in the
meeting faces.(if you can understand my ramblings)
OOPS did not see the same idea proposed earlier.

"Dave Plowman (News)" wrote:
What pitch are the pins? Could you modify a pair of suitable pliers by
drilling a hole in them to act as a crimp to change the pins from square
to round?

That sounds like a good idea. Or at least mangling the pins with pliers
sufficiently might work. Pins are 1.14mm square on 4.2mm pitch.

For now I've soldered them by pushing in the pins as far as they'll go, then
putting solder paste in the other side of the hole. Heat the solder paste
and it surrounds the pin and drops through to the inaccessible component
side of the pad (paste has a lot more flux than solder wire, and is a bit
more mobile). Then fill up the hole with wire solder.

It's electrically good and isn't mechanically too bad. It'll probably do
the job until we can respin the boards.

Theo

In article ,
Theo Markettos wrote:
"Dave Plowman (News)" wrote:
What pitch are the pins? Could you modify a pair of suitable pliers by
drilling a hole in them to act as a crimp to change the pins from
square to round?

That sounds like a good idea. Or at least mangling the pins with pliers
sufficiently might work. Pins are 1.14mm square on 4.2mm pitch.

I'd say that's wide enough to get strong enough square nosed pliers in.
You might need a tungsten drill, though.

--
*A clear conscience is usually the sign of a bad memory *

Dave Plowman London SW
To e-mail, change noise into sound.