In article 1c5692a4-cdea-43cf-9c70-
,
says...
Finer pitch than the main thread, so it locks the board against the
screw head, but still allows them to be tightened down onto the joist.

Can anyone remember who it was who made frame-fixing screws that had
ribs under the head which bit into to the wood so you could screw them
in and out? They were great - you could screw the frame to the
brickwork, then jack it in and out until all was plumb and square - then
foam it to lock it.

Did our back door like that and wish I could find them again.

Might have been Fischer - but I can't seem to find them again.

--
Skipweasel - never knowingly understood.