On Tuesday, 25 April 2017 22:07:06 UTC+1, dennis@home wrote:
On 25/04/2017 13:32, tabbypurr wrote:

no, but vinyl decks do want a very stiff shelf

Why?

anything less is prone to vibrate.

They fit rubber feet to make them flexible.

Preventing feedback is done by a series of hard heavy & soft damping materials.
Heavy platter, stiff metal deck
on soft springs
on a heavy very firm wooden case
slightly squashy rubber feet
very hard shelf

Anything less might or might not work, but often is far from ideal. I managed to get an old Pioneer PL12D working well by sitting it on stone - it had no deck to cabinet squishy layer. The paving slab mentioned is another effective way to stop vibration.


NT

In article ,
wrote:
Preventing feedback is done by a series of hard heavy & soft damping
materials. Heavy platter, stiff metal deck on soft springs on a heavy
very firm wooden case slightly squashy rubber feet very hard shelf

What sort of feedback are you trying to stop? Acoustic feedback from the
speakers also requires a decent cover to the turntable.

--
*Bills travel through the mail at twice the speed of cheques *

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

Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold fairly
weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between MDF,
plywood, veneered chipboard, solid timber or something else, would any
particular material be preferable? 22 inches isn't much of a span, is
it? And appearance isn't really a factor.

Many thanks.
To get the relative performance of different materials look up "sagulator"

If you decide MDF will be adequate for your loading, go for MRMDF which
will resist the absorption of atmospheric moisture. It also gives a much
superior painted finish.

As others have said simple front edge lipping adds little stiffness.
However a deeper batten fixed to the underside of the rear edge between
the shelf supports can make a useful contribution to stiffness.

On 25/04/2017 11:51, Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold fairly
weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between MDF,
plywood, veneered chipboard, solid timber or something else, would any
particular material be preferable? 22 inches isn't much of a span, is
it? And appearance isn't really a factor.

If the shelf is of reasonable depth (say 10" or more) then I find 18mm
WBP ply with a softwood lipping works well. (you can make the lipping
thicker than the shelf so it under hangs the front if you want extra
stiffness or a more substantial look to the shelf). I would not use MDF
for shelves, since that tends to sag under its own weight if unsupported.

I built this coming up to three years ago:

http://wiki.diyfaq.org.uk/index.php/..._shelf_unit s

and the ply shelves have shown no visible sag in that time, in spite of
some quite heavy loads on them.

In fact I have just temporarily dismantled that to decorate that room,
and had to unload all the stuff from it. The piles of books and DVDs
from the top section alone were quite surprising:

http://wiki.diyfaq.org.uk/index.php/File:BookPile.jpg
(the videos were in one of the cupboards rather than on the shelves)

http://wiki.diyfaq.org.uk/index.php/FileVDPile.jpg

--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
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Thanks, John.

On 25/04/2017 11:51, Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold fairly
weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between MDF,
plywood, veneered chipboard, solid timber or something else, would any
particular material be preferable? 22 inches isn't much of a span, is
it? And appearance isn't really a factor.

Many thanks.
Whatever you use, it's tendency to sag can be hugely improved by gluing
a length of wood to the underside at a convenient point.

Bert Coules wrote

I have to erect some shelves: 22 inches wide, supported at
the ends by heavy-duty bookcase-type uprights and brackets.
This is to hold fairly weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice
between MDF, plywood, veneered chipboard, solid timber or
something else, would any particular material be preferable?

Solid timber doesn't flex as much, but 22" isnt enough span to matter.

22 inches isn't much of a span, is it?

True.

And appearance isn't really a factor.

On 25/04/2017 11:51, Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold fairly
weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between MDF,
plywood, veneered chipboard, solid timber or something else, would any
particular material be preferable? 22 inches isn't much of a span, is
it? And appearance isn't really a factor.

Many thanks.

Cut the tops of these up, they are remarkably stiff for their weight.


http://www.ikea.com/gb/en/products/t...-art-20011408/

You can see how stiff they are at http://printtable.com/

"dennis@home" wrote:

Cut the tops of these up, they are remarkably stiff for their weight.

Are those tops solid? The price is remarkable.

Bert

On 25/04/2017 22:29, Bert Coules wrote:
"dennis@home" wrote:

Cut the tops of these up, they are remarkably stiff for their weight.

Are those tops solid? The price is remarkable.

Bert

No, they are like doors with a honeycomb core.
Very stiff for their weight.
The whole table is about 2-3 kg.
They happen to be just about the right width for the shelves @550mm.

dennis@home wrote:

No, they are like doors with a honeycomb core.
Very stiff for their weight.
The whole table is about 2-3 kg.
They happen to be just about the right width for the shelves @550mm.

Thanks very much. They're definitely worth a look, for future use.

On 25/04/2017 22:00, dennis@home wrote:
On 25/04/2017 11:51, Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold
fairly weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between
MDF, plywood, veneered chipboard, solid timber or something else,
would any particular material be preferable? 22 inches isn't much of
a span, is it? And appearance isn't really a factor.

Many thanks.

Cut the tops of these up, they are remarkably stiff for their weight.


http://www.ikea.com/gb/en/products/t...-art-20011408/


You can see how stiff they are at http://printtable.com/


Google "lack rack" for plenty of examples of use as equipment mounts.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 25/04/2017 22:00, dennis@home wrote:
On 25/04/2017 11:51, Bert Coules wrote:
I have to erect some shelves: 22 inches wide, supported at the ends by
heavy-duty bookcase-type uprights and brackets. This is to hold
fairly weighty audio-video equipment.

Given an equal thickness (18mm? 20mm? More?) and a choice between
MDF, plywood, veneered chipboard, solid timber or something else,
would any particular material be preferable? 22 inches isn't much of
a span, is it? And appearance isn't really a factor.

Many thanks.

Cut the tops of these up, they are remarkably stiff for their weight.


http://www.ikea.com/gb/en/products/t...-art-20011408/



Or these:

http://www.ikea.com/gb/en/products/storage-furniture/wall-shelves/persby-wall-shelf-white-art-10191264/

The form of mounting isn't the last word in strength, though - I'd say
15kg is optimistic.




--
Cheers, Rob

On 26/04/17 01:48, RJH wrote:
On 25/04/2017 22:00, dennis@home wrote:

http://www.ikea.com/gb/en/products/storage-furniture/wall-shelves/persby-wall-shelf-white-art-10191264/


The form of mounting isn't the last word in strength, though - I'd say
15kg is optimistic.


IME The legs are made of cheese. Drive bolts through for mounting, say
19" rack things, but tapping screws in it? - er, nope.

--
Adrian C

On 26/04/17 18:17, Adrian Caspersz wrote:
IME The legs are made of cheese. Drive bolts through for mounting, say
19" rack things, but tapping screws in it? - er, nope.

Opps, that comment was aimed at the LACK tables.

--
Adrian C

On 26/04/2017 18:18, Adrian Caspersz wrote:
On 26/04/17 18:17, Adrian Caspersz wrote:
IME The legs are made of cheese. Drive bolts through for mounting, say
19" rack things, but tapping screws in it? - er, nope.

Opps, that comment was aimed at the LACK tables.


All the lack rack mods appear to use the unit underneath to provide support.
I doubt if you could just mount much halfway up like in a proper rack.

Many thanks to everyone for the new replies - too many to respond to
individually, so please forgive this general note.

I'm going to go with 18mm ply: I can get more than enough shelves out of a
single 8x4 sheet. And I'll probably put a cosmetic strip along the only
visible edge (though I have seen varnished ply edges which didn't look
unattractive).

That Lack table is a nice find, so thanks for that.

I have those concealed fitting shelves elsewhere in the house, but I
wouldn't put anything of any great weight on one. They can't be used for
this present job anyway, because I'll only have fixings available at the
ends.

I'm grateful for all the responses and ideas.

Bert

"Bert Coules" Wrote in message:
Many thanks to everyone for the new replies - too many to respond to
individually, so please forgive this general note.

I'm going to go with 18mm ply: I can get more than enough shelves out of a
single 8x4 sheet. And I'll probably put a cosmetic strip along the only
visible edge (though I have seen varnished ply edges which didn't look
unattractive).

Although that won't be made from cheap ply, which is what you'll
be getting, which will have some voids in the layers, colour
differences, distortions in the plies etc.

One can try to fill & sand etc then varnish, but cheap D moulding
hardwood lengths glued on the fronts works & is quicker IMHO.


--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

"Bert Coules" Wrote in message:
Many thanks to everyone for the new replies - too many to respond to
individually, so please forgive this general note.

I'm going to go with 18mm ply: I can get more than enough shelves out of a
single 8x4 sheet. And I'll probably put a cosmetic strip along the only
visible edge (though I have seen varnished ply edges which didn't look
unattractive).

That Lack table is a nice find, so thanks for that.

I have those concealed fitting shelves elsewhere in the house, but I
wouldn't put anything of any great weight on one. They can't be used for
this present job anyway, because I'll only have fixings available at the
ends.

I took that proposal to be that you would purchase some & cut them
down to use as shelves supported at the ends...? As an
alternative to raw ply/whatever?

Iirc they come in various "flavours" & are ready finished.

I had to trim one a few years ago & the honeycomb structure (like
a cheap interior door) was a bit tricky to cut with a panel saw
as the two surfaces (top & bottom) of the shelf are ~2 inches
apart & tended to drag the saw off line, as well as splinter the
finish. If I did it now I'd use a veneer saw working from both
sides alternately & hope my marking up was good enough :-)


--
Jim K


----Android NewsGroup Reader----
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Jim,

Thanks for the explanation. Yes, the shelf I have is certainly well put
together, though I did find that the dedicated hidden fixings weren't strong
enough to bear even a moderate weight without sagging; I had to add more
conventional brackets to support a small-screen TV.

Bert