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On Wed, 21 Jun 2023 16:06:13 -0000 (UTC), Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
snip
[2] I wonder if there are any strong non-conductive screws. It
wouldn\'t matter if they had zero clearance to the next board in the
crate. Nylon would be too wimpy to scrunch down my mosfets.
Amazon bought out Small Parts Inc some years back, and still sells things
like Delrin screws, way cheaper than elsewhere.
Dunno if itÂs all NOS or if theyÂre still making them.
.<http://dmp-ortho.com/products-catalog/acetal-screws/
Acetal is very slippery, so it may be difficult to prevent such a
screw from working loose.
But acetal does not creep under steady load.
Joe Gwinn
It also doesnât get brittle when it dries out.
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 21 Jun 2023 16:06:13 -0000 (UTC), Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
snip
[2] I wonder if there are any strong non-conductive screws. It
wouldn\'t matter if they had zero clearance to the next board in the
crate. Nylon would be too wimpy to scrunch down my mosfets.
Amazon bought out Small Parts Inc some years back, and still sells things
like Delrin screws, way cheaper than elsewhere.
Dunno if itÂs all NOS or if theyÂre still making them.
.<http://dmp-ortho.com/products-catalog/acetal-screws/
Acetal is very slippery, so it may be difficult to prevent such a
screw from working loose.
But acetal does not creep under steady load.
Joe Gwinn
It also doesnât get brittle when it dries out.
On Wed, 21 Jun 2023 21:43:31 +1000, Chris Jones
lugn...@spam.yahoo.com> wrote:
On 20/06/2023 1:49 am, John Larkin wrote:
[1] Don\'t you hate it when a cafe table has four legs and it tilts all
over the place and spills your coffee?
[2] I wonder if there are any strong non-conductive screws. It
wouldn\'t matter if they had zero clearance to the next board in the
crate. Nylon would be too wimpy to scrunch down my mosfets.
On Wednesday, June 21, 2023 at 7:44:24?AM UTC-7, John Larkin wrote:
On Wed, 21 Jun 2023 21:43:31 +1000, Chris Jones
lugn...@spam.yahoo.com> wrote:
On 20/06/2023 1:49 am, John Larkin wrote:
[1] Don\'t you hate it when a cafe table has four legs and it tilts all
over the place and spills your coffee?
If it\'s a circular table, rotate it until all four legs contact at the same time.
[2] I wonder if there are any strong non-conductive screws. It
wouldn\'t matter if they had zero clearance to the next board in the
crate. Nylon would be too wimpy to scrunch down my mosfets.
Nah; what you want is to scale heat losses down as much as device sizes
have been scaled down. The microfabricators have convinced you that
the high power stuff SHOULD be small. Critters smaller than mice
are generally cold-blooded because they can\'t maintain thermal gradients,
because high power metabolisms don\'t work when small.
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 21 Jun 2023 16:06:13 -0000 (UTC), Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
snip
[2] I wonder if there are any strong non-conductive screws. It
wouldn\'t matter if they had zero clearance to the next board in the
crate. Nylon would be too wimpy to scrunch down my mosfets.
Amazon bought out Small Parts Inc some years back, and still sells things
like Delrin screws, way cheaper than elsewhere.
Dunno if it?s all NOS or if they?re still making them.
.<http://dmp-ortho.com/products-catalog/acetal-screws/
Acetal is very slippery, so it may be difficult to prevent such a
screw from working loose.
But acetal does not creep under steady load.
Joe Gwinn
It also doesnt get brittle when it dries out.
On Wed, 21 Jun 2023 15:11:47 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:
[1] Don\'t you hate it when a cafe table has four legs and it tilts all
over the place and spills your coffee?
If it\'s a circular table, rotate it until all four legs contact at the same time.
That obviously doesn\'t work all the time.
On Wednesday, June 21, 2023 at 4:10:12?PM UTC-7, John Larkin wrote:
On Wed, 21 Jun 2023 15:11:47 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:
[1] Don\'t you hate it when a cafe table has four legs and it tilts all
over the place and spills your coffee?
If it\'s a circular table, rotate it until all four legs contact at the same time.
That obviously doesn\'t work all the time.
If the legs are the same length, but the floor is warped, it does.
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joeg...@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joeg...@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chri...@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down..
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Is it the hope that this screw into the copper heat sink be
non-metallic?
It might be simpler to use a steel screw into copper, insulated from
the fet package.
Or press-fit a delrin plug into a roughened hole in the copper, and
run the metal screw into an undersize blind hole in the delrin plug.
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Is it the hope that this screw into the copper heat sink be
non-metallic?
It might be simpler to use a steel screw into copper, insulated from
the fet package.
Or press-fit a delrin plug into a roughened hole in the copper, and
run the metal screw into an undersize blind hole in the delrin plug.
Joe Gwinn
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Card cage:
https://www.dropbox.com/s/gr57bhafemypi63/P940_box_9.jpg?dl=0
Bottom of board, with fets scrunched down to the CPU cooler.
https://www.dropbox.com/scl/fi/gsbc9o7cwc0o3rwfbrhr4/K199_Fets_Pusher.jpg?dl=0&rlkey=fzp5oylmb7ounxjhozu6k8j26
That hardware is cute but too tall, hence the idea of using four
flathead screws and countersinking the mosfets.
On 24/06/2023 9:20 pm, John Larkin wrote:
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Card cage:
https://www.dropbox.com/s/gr57bhafemypi63/P940_box_9.jpg?dl=0
Bottom of board, with fets scrunched down to the CPU cooler.
https://www.dropbox.com/scl/fi/gsbc9o7cwc0o3rwfbrhr4/K199_Fets_Pusher.jpg?dl=0&rlkey=fzp5oylmb7ounxjhozu6k8j26
That hardware is cute but too tall, hence the idea of using four
flathead screws and countersinking the mosfets.
What if you countersink the washer?
If instead of a washer you use a plate with recesses machined into it
for the TO-247s, the un-machined parts would stiffen it. Also more than
one screw would vastly decrease the required stiffness.
You could glue or (otherwise secure) a piece of thin FR4 over the whole
thing to provide durable insulation from the next card.
If you have sufficient clearance on the other side of the card, then you
could put some washers between the heatsink and your board, which would
give more clearance on the side with the mosfet pusher.
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joeg...@comcast.net
wrote:
Is it the hope that this screw into the copper heat sink be
non-metallic?
My concern is that the transistor mounting screws could short to the
solder side of the adjacent board in the card cage, and I\'m tight on
spacing. If I don\'t c\'sink the fets and use a plastic screw, it
becomes a spacer, not a short! Zero clerance to the next board is no
problem.
On Sat, 24 Jun 2023 21:38:20 +1000, Chris Jones
lugnut808@spam.yahoo.com> wrote:
On 24/06/2023 9:20 pm, John Larkin wrote:
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Card cage:
https://www.dropbox.com/s/gr57bhafemypi63/P940_box_9.jpg?dl=0
Bottom of board, with fets scrunched down to the CPU cooler.
https://www.dropbox.com/scl/fi/gsbc9o7cwc0o3rwfbrhr4/K199_Fets_Pusher.jpg?dl=0&rlkey=fzp5oylmb7ounxjhozu6k8j26
That hardware is cute but too tall, hence the idea of using four
flathead screws and countersinking the mosfets.
What if you countersink the washer?
There\'s a neoprene washer under the metal one, so it\'s still kinda
high. And I\'d still have metal about to touch the next board.
But that idea suggests something: Use a giant plastic washer for the
pusher, something that flexes a bit and avoids the 4-leg-table issue,
c\'sink that, and use a plastic screw.
Interesting idea.
If instead of a washer you use a plate with recesses machined into it
for the TO-247s, the un-machined parts would stiffen it. Also more than
one screw would vastly decrease the required stiffness.
You could glue or (otherwise secure) a piece of thin FR4 over the whole
thing to provide durable insulation from the next card.
If you have sufficient clearance on the other side of the card, then you
could put some washers between the heatsink and your board, which would
give more clearance on the side with the mosfet pusher.
On Sat, 24 Jun 2023 08:10:16 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Sat, 24 Jun 2023 21:38:20 +1000, Chris Jones
lugnut808@spam.yahoo.com> wrote:
On 24/06/2023 9:20 pm, John Larkin wrote:
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Thu, 22 Jun 2023 07:56:35 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Thu, 22 Jun 2023 10:52:57 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 09:33:56 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:
On Tue, 20 Jun 2023 03:46:47 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:
On Mon, 19 Jun 2023 18:57:31 -0700 (PDT), Chris <chris.863@live.com
wrote:
On Tuesday, 20 June 2023 at 01:50:16 UTC+10, John Larkin wrote:
Has anyone done this? I need to get the mounting screw height down.
I guess I\'ll have to try it.
Rivets?
Rework would be difficult, and a rivet adds height too.
The reason to not just epoxy the fets down would be the rework issue.
And the mess, although there are some instant-set thermally conductive
super-glue things.
Aluminum solid rivets with a 100-degree cone angle are also available.
Set with an arbor press to avoid shock.
.<https://www.mcmaster.com/96685A149/
An afterthought: Solid rivets expand when set, and it\'s not clear
that the semiconductor package can handle the resulting radial stress.
Joe Gwinn
I plan to blind tap four holes into the copper CPU cooler. There\'s not
much thickness until the tap would hit fins. I don\'t know how a rivet
would anchor into the cooler, and replacing a fet would be nasty.
Yeah. Can\'t say that I am able to visualize the arrangement. So I
was pointing out possibly relevant options, fasteners with 100-degree
cone heads.
Card cage:
https://www.dropbox.com/s/gr57bhafemypi63/P940_box_9.jpg?dl=0
Bottom of board, with fets scrunched down to the CPU cooler.
https://www.dropbox.com/scl/fi/gsbc9o7cwc0o3rwfbrhr4/K199_Fets_Pusher.jpg?dl=0&rlkey=fzp5oylmb7ounxjhozu6k8j26
That hardware is cute but too tall, hence the idea of using four
flathead screws and countersinking the mosfets.
What if you countersink the washer?
There\'s a neoprene washer under the metal one, so it\'s still kinda
high. And I\'d still have metal about to touch the next board.
But that idea suggests something: Use a giant plastic washer for the
pusher, something that flexes a bit and avoids the 4-leg-table issue,
c\'sink that, and use a plastic screw.
Interesting idea.
If instead of a washer you use a plate with recesses machined into it
for the TO-247s, the un-machined parts would stiffen it. Also more than
one screw would vastly decrease the required stiffness.
You could glue or (otherwise secure) a piece of thin FR4 over the whole
thing to provide durable insulation from the next card.
If you have sufficient clearance on the other side of the card, then you
could put some washers between the heatsink and your board, which would
give more clearance on the side with the mosfet pusher.
Delrin might work for that big washer. In the space between the FET
packages there is added depth available, enough that an ordinary
flat-head steel screw would fit, and could be screwed directly into
the copper heat sink, perhaps with a heli-coil (pure copper is pretty
soft, so an insert may be necessary).
Joe Gwinn
On Saturday, June 24, 2023 at 4:21:09?AM UTC-7, John Larkin wrote:
On Fri, 23 Jun 2023 18:12:33 -0400, Joe Gwinn <joeg...@comcast.net
wrote:
Is it the hope that this screw into the copper heat sink be
non-metallic?
My concern is that the transistor mounting screws could short to the
solder side of the adjacent board in the card cage, and I\'m tight on
spacing. If I don\'t c\'sink the fets and use a plastic screw, it
becomes a spacer, not a short! Zero clerance to the next board is no
problem.
Shorting is only a problem where the \'next board\' is too close? Can you
put a few strategically placed holes in that \'next board\' so that a sticking-up
screwhead avoids contact by going into a void?