In article ,
Iain Churches wrote:
My personal choice for a top plate is laser cut stainless steel, 4mm.
Just get the au-pair to flick her feather duster over it once a week,
and it will stay pristine for ever.

Provided you don't touch it. ;-)

--
*I didn't fight my way to the top of the food chain to be a vegetarian.

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

"Dave Plowman (News)" wrote in message
...
In article ,
Iain Churches wrote:

My personal choice for a top plate is laser cut stainless steel, 4mm.
Just get the au-pair to flick her feather duster over it once a week,
and it will stay pristine for ever.

Provided you don't touch it. ;-)

I keep a pair of white silk gloves by the side of my amp.
I thought everyone did:-)

Iain

Jim said:
However as Iain has pointed out, note that the anodising produces an
*insulating* layer on the surface. So mask off any areas which you need
to ensure remain conducting for ground contacts, etc - or be prepared
to
abrade them clean of anodising afterwards.

Hello Jim. Thanks for your views here. For a finished product it does
point to anodised. I wasn't aware it wasn't conductive, so that's worth
knowing. I'm assuming that I should cut out main holes before
anodisation - holes for tube sockets and XLRs for instance. But then I
should drill holes holding the top plate to the chassis after
anodisation so the screws make contact with the aluminium. This sounds
logical doesn't it?

Iain: My personal choice for a top plate is laser cut stainless steel,
4mm.

I considered that but that is HARD! I don't fancy working on 4mm
stainless - don't you find that it blunts your hole saws and drill
bits???

Using a hole saw in my drill press on 4mm alu is time consuming enough
when the diameter gets to 30mm and above (even 25mm takes a little
time) - I can't imagine what it's like on stainless. Andy

"Jim Lesurf" wrote in message
...

However as Iain has pointed out, note that the anodising produces an
*insulating* layer on the surface. So mask off any areas which you need to
ensure remain conducting for ground contacts, etc - or be prepared to
abrade them clean of anodising afterwards.



Jim. This point was brought home to me when looking at the construction
of a pre-production audio workstation, just recently.

The chassis (four of them) were of slab construction,
6mm anodised aluminium. In the lower right hand corner of
each plate was a tapped 4mm hole, with a bright steel machine screw
a tag, with serrated washer, and a ground wire going direct to
the chassis star ground.

Iain.

In article .com, Andy
Evans wrote:
I'm assuming that I should cut out main holes before
anodisation - holes for tube sockets and XLRs for instance. But then I
should drill holes holding the top plate to the chassis after
anodisation so the screws make contact with the aluminium. This sounds
logical doesn't it?

Drilling holes after anodising will only ensure that the insides of the
holes are clean, and there is no guarantee of contact here. You need a
small area of the flat surface around the hole to be clear, so that
washers, nuts and screwheads make contact. There's probably a special
rebate drill that can do this neatly, otherwise it might be enough to use
those spiky washers that bite through the surface oxide. Don't forget to
file away the oxide around the edges of the top plate, and the parts of
the chassis with which it makes contact.

Rod.

Andy Evans wrote:

I'm assuming that I should cut out main holes before
anodisation - holes for tube sockets and XLRs for instance.

Yes.


But then I
should drill holes holding the top plate to the chassis after
anodisation so the screws make contact with the aluminium. This sounds
logical doesn't it?

You could drill the holes before anodising, and tap them afterwards. That
way, if there are any mishaps during the drilling, you aren't adding the
price of anodisng to the scrap box. (The taps should cut through the
anodised surface insde the holes without difficulty, BTW.)

AAMOI, how do you drill? Do you centre-punch and drill, or do you use a
centre drill to start and then do the hole? Do you clamp the piece before
drilling?


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com

"Wally" wrote in message
. ..
Andy Evans wrote:

I'm assuming that I should cut out main holes before
anodisation - holes for tube sockets and XLRs for instance.

Yes.


But then I
should drill holes holding the top plate to the chassis after
anodisation so the screws make contact with the aluminium. This sounds
logical doesn't it?

You could drill the holes before anodising, and tap them afterwards. That
way, if there are any mishaps during the drilling, you aren't adding the
price of anodisng to the scrap box. (The taps should cut through the
anodised surface insde the holes without difficulty, BTW.)

It is much better practice to drill and tap before anodising,
and then fit plastic machine screws into these threads, to keep
tjem clean.

Then you do not need to put your anodised panel under the
drill press any more. I have learned this the hard way:-)

Iain

Roderick Stewart wrote:

Drilling holes after anodising will only ensure that the insides of
the holes are clean, and there is no guarantee of contact here. You
need a small area of the flat surface around the hole to be clear, so
that washers, nuts and screwheads make contact.

Ah, I assumed the holes were being tapped.


There's probably a
special rebate drill that can do this neatly,

A milling cutter called a slot drill will produce a flat-bottomed hole. If
well centred, it could put a tidy shallow rebate around a drilled hole.


otherwise it might be
enough to use those spiky washers that bite through the surface
oxide.

I'd scrape/sand off the anodising from a small area inside, and fit an earth
point with a serrated washer and tag.


Don't forget to file away the oxide around the edges of the
top plate, and the parts of the chassis with which it makes contact.

Not so keen on that - the filed edges could tarnish and acquire resistance.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com

Iain Churches wrote:

It is much better practice to drill and tap before anodising,
and then fit plastic machine screws into these threads, to keep
tjem clean.

Like little grub screws? Fine if you have them handy, I suppose...


Then you do not need to put your anodised panel under the
drill press any more. I have learned this the hard way:-)

If you've drilled it before anodising, then it shouldn't need to go back
under the drill - provided you can spin a tap in a straight line. :-)


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com