Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead (I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex spacers.
Initially it seemed ok, but with a small amount of leverage the spacers came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave

I gluing 2 pieces of metal together there a 3 things to remember;

#1 surface area
If you can use a 1" sq plate with a hole in the corner instead of the
standoff it will have 20 times the glue joint area.

#2 tooth
Rough up the joint surface with 80 grit sandpaper, it increases the
surface area and randomizes the shear angle so it will not pop off easily.

#3 Chemical coupling
Epoxies work best when they are able to chemically bond with the metal.
This is tough on aluminum because the oxide surface on aluminum is almost
completely inert and will form immediately on exposure to air. The solution
is to put a drop of epoxy on the area to be glued and rough the surface of
both pieces to be glued with sand paper through the epoxy. This protects the
surface from exposure to air. Then, wipe off the dirty with epoxy with a DRY
paper towel and apply some fresh clean epoxy and bond as usual.

Paul K. Dickman

Dave Marsh wrote in message ...
Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes
in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one
of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of
idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead
(I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex
spacers.
Initially it seemed ok, but with a small amount of leverage the spacers
came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave

"Paul K. Dickman" wrote in message
...
I gluing 2 pieces of metal together there a 3 things to remember;

#1 surface area
If you can use a 1" sq plate with a hole in the corner instead of the
standoff it will have 20 times the glue joint area.

#2 tooth
Rough up the joint surface with 80 grit sandpaper, it increases the
surface area and randomizes the shear angle so it will not pop off easily.

#3 Chemical coupling
Epoxies work best when they are able to chemically bond with the
metal.
This is tough on aluminum because the oxide surface on aluminum is almost
completely inert and will form immediately on exposure to air. The
solution
is to put a drop of epoxy on the area to be glued and rough the surface of
both pieces to be glued with sand paper through the epoxy. This protects
the
surface from exposure to air. Then, wipe off the dirty with epoxy with a
DRY
paper towel and apply some fresh clean epoxy and bond as usual.

Paul K. Dickman

Dave Marsh wrote in message ...
snip

So far I've tried an epoxy ("plastic steel" by Draper) with the hex
spacers.
Initially it seemed ok, but with a small amount of leverage the spacers
came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also
been
advised that curing the epoxy will improve the adhesion - does this make
a
big difference?

Many thanks,

Dave


Many thanks Paul. That all sounds like very solid (sic) advice. I did sand
down the surface of the aluminum but not in the way you described. I will
try that next time. The plate idea is a good one, so I'm thinking of putting
a short countersunk machine screw through a small plate (unfortunately it
will have to be more like 3/5" square due to lack of room) and then gluing
the plate to the front panel. I can then screw a spacer on to the screw.

Dave

Dave Marsh wrote in message ...

Many thanks Paul. That all sounds like very solid (sic) advice. I did sand
down the surface of the aluminum but not in the way you described. I will
try that next time. The plate idea is a good one, so I'm thinking of
putting
a short countersunk machine screw through a small plate (unfortunately it
will have to be more like 3/5" square due to lack of room) and then gluing
the plate to the front panel. I can then screw a spacer on to the screw.

Dave

Screw the spacer to the plate before you glue it down. It'll be a lot easier
to get tight.

Paul K. Dickman

On Wed, 9 Jun 2004 15:28:17 +0100, "Dave Marsh"
wrote:

Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead (I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex spacers.
Initially it seemed ok, but with a small amount of leverage the spacers came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave


Dave,
If you can, cut a plate the same size as the pcb. Drill and c'sink for
the screws you want to use. Use short screws and thread a spacer onto
them. Then, wet both surfaces to be bonded with epoxy and use a wire
brush to rough up the surfaces through the epoxy. Or, use loctite 330
adhesive. You can get this as a kit for about $20.00. And it sticks
very well. Even on oily surfaces. I have personal experience with both
methods.
Eric

"Eric R Snow" wrote in message
...
On Wed, 9 Jun 2004 15:28:17 +0100, "Dave Marsh"
wrote:

Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB
contains
the push buttons that protrude through holes in the front panel.

snip

Dave,
If you can, cut a plate the same size as the pcb. Drill and c'sink for
the screws you want to use. Use short screws and thread a spacer onto
them. Then, wet both surfaces to be bonded with epoxy and use a wire
brush to rough up the surfaces through the epoxy. Or, use loctite 330
adhesive. You can get this as a kit for about $20.00. And it sticks
very well. Even on oily surfaces. I have personal experience with both
methods.
Eric

Many thanks Eric. That sounds like great advice. I'm going to give it a try
asap.

Dave

"Dave Marsh" wrote in message ...
Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead (I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex spacers.
Initially it seemed ok, but with a small amount of leverage the spacers came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave

I used Tracon 2151 epoxy for aluminum applications a lot. Its CTE is
quite decently matched to aluminum, which helps a lot if the assembly
sees temperature variations, etc.--C. Hale

Penn Engineering, makers of Pem Nuts, makes just the product you need.
They are called concealed head studs.
You take an end mill and make a counter bore part way thru your panel. Then
you press this stud in. Viola! instant stud with no head or hole visible on
the outside.

http://www.pennfast.com/fastening_pr...pdf/chdata.pdf

Erich



"Dave Marsh" wrote in message
...
Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes
in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one
of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of
idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead
(I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex
spacers.
Initially it seemed ok, but with a small amount of leverage the spacers
came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also
been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave

Many thanks for the link Erich. I'll take a close look at those.

Dave

"Kathy and Erich Coiner" wrote in message
...
Penn Engineering, makers of Pem Nuts, makes just the product you need.
They are called concealed head studs.
You take an end mill and make a counter bore part way thru your panel.
Then
you press this stud in. Viola! instant stud with no head or hole visible
on
the outside.

http://www.pennfast.com/fastening_pr...pdf/chdata.pdf

Erich



"Dave Marsh" wrote in message
...
Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06"
thick)
anodized aluminum front panel for an electronics project. The PCB
contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put
holes
in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses
one
of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the
aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of
idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead
(I'm
thinking the contact are of a screwhead will be greater than that of a
hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be
zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex
spacers.
Initially it seemed ok, but with a small amount of leverage the spacers
came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also
been
advised that curing the epoxy will improve the adhesion - does this make
a
big difference?

Many thanks,

Dave

"CHale" wrote in message
om...
"Dave Marsh" wrote in message
...
Hi,

snip
My idea so far is to glue 4 metal hex spacers to the back of the
aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of
idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead
(I'm
thinking the contact are of a screwhead will be greater than that of a
hex
spacer with its central thread hole).

So far I've tried an epoxy ("plastic steel" by Draper) with the hex
spacers.
Initially it seemed ok, but with a small amount of leverage the spacers
came
away.


I used Tracon 2151 epoxy for aluminum applications a lot. Its CTE is
quite decently matched to aluminum, which helps a lot if the assembly
sees temperature variations, etc.--C. Hale

Many thanks for the epoxy recommendation. I will give that a try. TBH when I
have done testing to breaking point, there is always epoxy left on the
aluminum, but never on the screwheads/spacers. So it seems to me that the
epoxy is having most difficulty adhering to the nickel plated brass
(spacers), or the zinc/stainless steel (screws).

Someone elsewhere suggested anodized aluminum spacers. Maybe they would
stick more firmly? (if I can find a source for them).

Dave

On Wed, 9 Jun 2004 15:28:17 +0100, "Dave Marsh"
vaguely proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

Ideas:

(1) If you placed a panel behind the front panel, stuck to the front
panel and made of something eminently glueable, you get a huge area of
contact on the front panel aluminium, and an easily-glued surface
behind it. On such a large area, even contact cement would hold.

I am thinking of some of the "super cardboard" fibreboards etc, gasket
material etc.

OR

(2) If you can place the circuit board closer than 1/4" to the panel
that holds it (say 1/8") then you can adhere a standoff panel to the
front panel with plenty of area, and bolt the cctbd to the backing
panel.

(3) Place spacers _behind_ the cctbd, so that there is no pressure on
the panel, except that carried by the back wall of the enclosure or
columns from the bottom.

(4) Re-design the project box as many would. Countersink the front
"working" panel by pressure, to allow csunk screws. Place a
prettypanel in front of that, label and all, held by the edges of the
box (if it's one of those slotted things), or again simply held on by
contact.

Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead (I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex spacers.
Initially it seemed ok, but with a small amount of leverage the spacers came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave



************************************************** *****

Sometimes in a workplace you find snot on the wall of
the toilet cubicles. You feel "What sort of twisted
child would do this?"....the internet seems full of
them. It's very sad

"Old Nick" wrote in message
...
On Wed, 9 Jun 2004 15:28:17 +0100, "Dave Marsh"
vaguely proposed a theory
......and in reply I say!:
remove ns from my header address to reply via email

Ideas:

(1) If you placed a panel behind the front panel, stuck to the front
panel and made of something eminently glueable, you get a huge area of
contact on the front panel aluminium, and an easily-glued surface
behind it. On such a large area, even contact cement would hold.

I am thinking of some of the "super cardboard" fibreboards etc, gasket
material etc.

That sounds a very good idea, thanks.

OR

(2) If you can place the circuit board closer than 1/4" to the panel
that holds it (say 1/8") then you can adhere a standoff panel to the
front panel with plenty of area, and bolt the cctbd to the backing
panel.

(3) Place spacers _behind_ the cctbd, so that there is no pressure on
the panel, except that carried by the back wall of the enclosure or
columns from the bottom.

(4) Re-design the project box as many would. Countersink the front
"working" panel by pressure, to allow csunk screws. Place a
prettypanel in front of that, label and all, held by the edges of the
box (if it's one of those slotted things), or again simply held on by
contact.


For the next design I will definitely rethink it - Many thanks for your
suggestions Nick.

Dave

On Thu, 10 Jun 2004 15:31:03 +0100, "Dave Marsh"
vaguely proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

Think behind the panel you hide behind G
************************************************** *****

Sometimes in a workplace you find snot on the wall of
the toilet cubicles. You feel "What sort of twisted
child would do this?"....the internet seems full of
them. It's very sad

On Thu, 10 Jun 2004 15:31:03 +0100, "Dave Marsh"
vaguely proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

BTW. Like the accountant, I trot out that "If only" theory that I
_should have_ applied to my last effort....G

Signed....boundary umpire....who _sometimes_ got to apply the learning
from the last match.

HIH...and all that.

************************************************** *****

Sometimes in a workplace you find snot on the wall of
the toilet cubicles. You feel "What sort of twisted
child would do this?"....the internet seems full of
them. It's very sad

Dave Marsh wrote in message
...
Hi,

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes
in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one
of
the buttons.


How is your front panel held on?

It must be connected to the back somehow - even if it is glued to a chassis
then what I'd do would be mount the pcb to whatever the panel mounts to.

I'm thinking you have a box or something with a pretty front panel - well,
mount the pcb to the back of the box on some sort of standoff.

I'd rather have dumb users (are ther any other kinds?) push on a structure
that is solid than pull on one that is glued.

Dave,

Using glue for your application is messy and unreliable. For your
application, as someone mentioned, use:
http://www.pennfast.com/fastening_pr...pdf/chdata.pdf

I have used these at work for electronic enclosures. Give me the
height and screw size and I can probably send you some studs free. I
just drill and press in using a vise. (Sorry, I can't make that offer
to everyone)

Ed Ferguson

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06" thick)
anodized aluminum front panel for an electronics project. The PCB contains
the push buttons that protrude through holes in the front panel.

The PCB has M3 holes drilled for fastening purposes but I can't put holes in
the front panel for appearance sake. I need to fasten the PCB strongly
enough so there is no danger of it coming loose when the user presses one of
the buttons.

My idea so far is to glue 4 metal hex spacers to the back of the aluminum
panel. I can then bolt the PCB to that. Alternaitevely the same kind of idea
but glue the flat heads of 4 countersunk M3 screws to the panel instead (I'm
thinking the contact are of a screwhead will be greater than that of a hex
spacer with its central thread hole).

The hex spacers are made of nickel-plated brass. The screws could be zinc
plated or stainless steel.

So far I've tried an epoxy ("plastic steel" by Draper) with the hex spacers.
Initially it seemed ok, but with a small amount of leverage the spacers came
away.

Could someone please suggest whether I would get better adhesion on the
anodized aluminum with the zinc screws, stainless steel screws or the
nickel-plated hex spacers? What epoxies would you recommend? I've also been
advised that curing the epoxy will improve the adhesion - does this make a
big difference?

Many thanks,

Dave

Hi Ed,

Thanks for your advice and the very kind offer. I'm after M3 studs height
6mm (panel is 0.06" thick). I'm in the UK and I'm guessing you are in the
US? I can get a bag of 50 Penn self-clinching nuts (not studs, but they
would be ok) from Rapid Electronics over here for ~$4, so that might be
easier and save you overseas postage. But thanks again.

Dave


"Ed" wrote in message
om...
Dave,

Using glue for your application is messy and unreliable. For your
application, as someone mentioned, use:
http://www.pennfast.com/fastening_pr...pdf/chdata.pdf

I have used these at work for electronic enclosures. Give me the
height and screw size and I can probably send you some studs free. I
just drill and press in using a vise. (Sorry, I can't make that offer
to everyone)

Ed Ferguson

I need to space off a PCB by 0.25" behind a small (4" x 1" x 0.06"
thick)
anodized aluminum front panel for an electronics project. The PCB
contains
the push buttons that protrude through holes in the front panel.

snip

Dave

On Fri, 11 Jun 2004 15:28:15 +0100, "Dave Marsh"
vaguely proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

self-clinching nuts

oooohhh!
************************************************** *****

Sometimes in a workplace you find snot on the wall of
the toilet cubicles. You feel "What sort of twisted
child would do this?"....the internet seems full of
them. It's very sad

On Sat, 12 Jun 2004 11:57:18 +0800, Old Nick
wrote:

On Fri, 11 Jun 2004 15:28:15 +0100, "Dave Marsh"
vaguely proposed a theory
......and in reply I say!:
remove ns from my header address to reply via email

self-clinching nuts

oooohhh!


That is the result of viewing Hillary Clinton nude.
************************************************* ******

Sometimes in a workplace you find snot on the wall of
the toilet cubicles. You feel "What sort of twisted
child would do this?"....the internet seems full of
them. It's very sad

That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell