I needed to make a box to house a delicate measuring probe for my CNC lathe,
and had to hand an offcut of 12 mm 7 ply from B&Q the bulk of which had made
a new counter top for a tool cabinet.

Usual approach, make the box as one entity pinning and gluing the top and
bottom to the already fixed sides making a sealed box, sand all faces to a
good finish, then saw apart making a lid and base that you can guarantee
will match each other even if very slightly out of square.

Worked very well until we get to the sanding stage where I find I've been
heavy handed and sanded through the top ply - surely NOT - 11.45 mm thick
(measured) 7 ply each ply should be about 1.6 mm thick - no way have I
sanded 1.6 mm!

.. . so I did an experiment with a scrap of the ply, and sanded until I got
the same effect then measured how much I had removed. Answer a bit less than
SIX thou so what's going on ????

It seems that it's NOT 7 ply but 9 ply, the two outer 'plys' being only 6
thou thick and basically just a colour layer that is paper thin.

.. . .what junk is being foisted onto us these days !!!!


Andrew

On Sunday, 12 May 2019 14:58:20 UTC+1, Andrew Mawson wrote:
I needed to make a box to house a delicate measuring probe for my CNC lathe,
and had to hand an offcut of 12 mm 7 ply from B&Q the bulk of which had made
a new counter top for a tool cabinet.

Usual approach, make the box as one entity pinning and gluing the top and
bottom to the already fixed sides making a sealed box, sand all faces to a
good finish, then saw apart making a lid and base that you can guarantee
will match each other even if very slightly out of square.

Worked very well until we get to the sanding stage where I find I've been
heavy handed and sanded through the top ply - surely NOT - 11.45 mm thick
(measured) 7 ply each ply should be about 1.6 mm thick - no way have I
sanded 1.6 mm!

. . so I did an experiment with a scrap of the ply, and sanded until I got
the same effect then measured how much I had removed. Answer a bit less than
SIX thou so what's going on ????

It seems that it's NOT 7 ply but 9 ply, the two outer 'plys' being only 6
thou thick and basically just a colour layer that is paper thin.

. . .what junk is being foisted onto us these days !!!!


Andrew

you bought it.

"Andrew Mawson" Wrote in
message:
I needed to make a box to house a delicate measuring probe for my CNC lathe,
and had to hand an offcut of 12 mm 7 ply from B&Q the bulk of which had made
a new counter top for a tool cabinet.

Usual approach, make the box as one entity pinning and gluing the top and
bottom to the already fixed sides making a sealed box, sand all faces to a
good finish, then saw apart making a lid and base that you can guarantee
will match each other even if very slightly out of square.

Worked very well until we get to the sanding stage where I find I've been
heavy handed and sanded through the top ply - surely NOT - 11.45 mm thick
(measured) 7 ply each ply should be about 1.6 mm thick - no way have I
sanded 1.6 mm!

. . so I did an experiment with a scrap of the ply, and sanded until I got
the same effect then measured how much I had removed. Answer a bit less than
SIX thou so what's going on ????

It seems that it's NOT 7 ply but 9 ply, the two outer 'plys' being only 6
thou thick and basically just a colour layer that is paper thin.

. . .what junk is being foisted onto us these days !!!!


Andrew




"Far Eastern"...
--
Jim K


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In message , Andrew Mawson
writes
It seems that it's NOT 7 ply but 9 ply, the two outer 'plys' being only
6 thou thick and basically just a colour layer that is paper thin.

Even 30 years ago when I needed quantities of decent marine ply, I had
to trawl round the wood yards, inspecting samples carefully. I was often
in the position of being told that they were waiting for some ship to
come in for the next decent batch.

I think there were about 4 yards to visit, and who got to know me.

B & Q was not one of them.
--
Bill

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