Maurice wrote:
On Tue, 16 Aug 2016 14:33:48 +0000, Tim+ wrote:

you're going to have to hoik it out with something poked down the screw
holes. A J-shaped key sounds ideal.

Seems I need to take another look at 'J' keys.

The penny drops!


As the bolt hole is 1/4" dia, would need to find a J key that will go
down
that and be the right diameter to permit 'hooking' underneath.
So when the hook of the J key emerges from the lower end of the bolt
hole,
what is the trick for engaging the hook on the underside of the cover?

It's called "poking it in and wiggling it until it jams".


It may well be that the lower end of the bolt hole abuts the threaded
flange
into which the bolt screws, so there would be no way the hook could find
a
grip.

Obvious (to me anyway), you're not going to insert it into the threaded
parts of the hole.

From looking at the pictures of the new lid posted previously the screws
pass through a square section hole before reaching the threaded hole in the
lower flange. Just poke the J key through the hole and jam it up against
the side of the square section of tube.

That's why I didn't pursue 'J' keys (or 'T; keys or 'D' keys).

And that's why I suspect - as I postulated earlier - something like an
expanding rawlplug might do the trick, by clamping within the bolt hole,
but
for all I know the bolt hole may be just a gap in the infill below which
the
receiving threaded flange sits, rather than a hole in a solid that could
cope
with the pressure of an expanding plug.

Still awaiting reply from www.manholecovers.co.uk w.r.t. their product:

"All trays manufactured locked with 4 galvanised
steel screws as standard. When unlocked screw holes act as lifting
eyes."

as to HOW the screw holes act as 'lifting eyes'...

I think I've covered that.


Failing all else, I shall have to leave the situation as is, so that
if/when the drain unblocking guy next comes he will be able to remove the
bolts (which he failed to do on his first visit)...

Many thanks to all who have responded - much appreciated!

Perhaps there is still time to find a solution to 'take gold'...


Given the minimal price of lifting keys on eBay, just buy some and try
them.

Tim

--
Trolls AND TROLL FEEDERS all go in my kill file