Hoping you wondrous Orchidians can help me again! I have recently
purchased a screwplate and tap set. The screwplate has two sets of
holes, threaded, which are in line with the engraved Gauge size (at
either side) The holes run from 20 down to 7. One row of threaded
holes in the screwplate has a small slit accompanied by a second
hole, then the second row of threaded holes do not have the
Why the slit - it would seem logical to assume that the slit is
some sort of expansion provision, or perhaps it is to allow the metal
being trimmed away to clear? Help!?
Why two sets of holes? Is the second hole perhaps a 'finishing’
What is the general rule (if there is one) as far as tolerances
go? i.e. what size wire is appropriate for what size hole? and also
what size chenier for what size tap I need to be able to make a thread
in chenier and then have a screw made of wire to suit.
Do I allow 0.5mm for the thread, 1.0mm? I hope that makes sense!
- In the past, I had a jeweller friend make some threaded
components for me and we had problems with the thread stripping. I
wondered if this was possibly due to incorrect tolerances having been
allowed (an engineering friend explained hat sometimes if a thread
was cut too deep the outer edge was fragile and therefore could strip
more easily). The other possible problem was perhaps metals that
were in differing states of hardness. My jeweller friend was using
manufactured chenier and annealed wire so I did postulate that
perhaps one surface being hard and the other surface being soft
might not be a good combination…
I’m sure there will be Orchidians with reams of experience so before
I go and stuff anything up…here’s hoping for some good advice
and thanking you in advance!
Queensland - Australia