Ed Huntress wrote:
"David Billington" wrote in message
...
Ed Huntress wrote:
"Suga Moto Soy" wrote in message
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Jimmy Suarez wrote:
can somebody tell what kind of thread is this?
http://www.signaturehardware.com/product8636
it is for an old fashined door knob spindle,the thicknes is 9/32
square stock, and 20TPI,is there a nut or bolt made for this thing?
Thanx
I don't know what the thread is, but those things are so soft it
usually doesn't even matter. They'll mush in anything.
I can't believe this Jimmy, nobody can give you an answer,I thought
some great machinists are posting here.I heve seen this type of door
knobs in many houses built from the 1900s to 1940s.
Well, mine was built in 1924, but assuming it was a long-time
standard, the thread is 18 tpi (0.072" pitch) (Starrett thread gage)
and the major diameter of the threads is around 0.375" (Starrett
mike). The spindle is a little worn from old age and use, so I'll let
you guess at what nut might fit. It looks to me like a 3/8 x 18. I
don't believe that's a standard; UNC is 3.8 x 16 and UNF is 3/8 x 24.
I'd double-check that 20 tpi; it's close, but no cigar on the
spindles on my doorknobs.
I suggested 3/8" BSF which is 20 TPI but the OP doesn't seem to have
responded to any poster regarding their comments. If the OP is in the US
then BSF won't be that common unless they're next to gunner's motorbike
but for me my neighbour has quite a selection of BA, BSF, BSW, BSP, and
more recently UNF and UNC, and staggeringly a few metric, I also know a
guy that would have many such spindles from various periods so could
measure if required.
The period of manufacture would be of some use in pinning down standards
or not. I recently repaired a ceiling light, most likely of Dutch
manufacture in the 19th century, and the main thread holding it together
appeared to be M10.7 x 1.5. From the design with solid arms no provision
had been made for gas or electric so candles were the original light and
I reckon it dated from the first half of the 19th century. The 1.5 mm
thread pitch would be 17 TPI, which I have never seen anywhere , but
1.5mm pitch might make sense. IIRC at that date no real standards
existed, BSW coming in around the mid 19th century in the UK, so I
expect the threads were produced to suit in the factory which certainly
seems to be supported by the other mish-mash of threads else where in
the items. In the end I single point cut the main suspension rod thread
at one end to suit the female piece it mated with and the non-visible
end I fitted with a M10 helicoil.
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When I hear stories like that, I always wish I could be there when the
next handyman tries to repair the custom thread. g
It might be amusing but I doubt it will happen in my lifetime. If they
know something about the history of threads and the date of the piece
then they might realise why the threads are oddball to modern eyes. The
one that got helicoiled was only visible when the piece was dismantled
and the wrought iron suspension rod had rusted in and had to be machined
out so the thread insert was a good option. The one where I kept the odd
thread had a good female thread in a brass casting and would have been
visible on close inspection but not seen in the normal way as it was in
the top suspension eye . As the female thread was good and the casting
somewhat asymmetric it was easier to cut the thread to the odd
specification. Many of the other threads at the ends of the arms which
coupled the candle holders and drip trays to the arms looked more like a
deep Edison screws thread rather than a normal V form.
I don't know much about old screw forming techniques but the oddball
thread was larger than the rod it was on, like it was rolled rather than
cut, but I didn't think they did that in the early 19th century. Any
thoughts.
BTW the reason for the repair was that the light had fallen from the
ceiling. It seems a water leak had allowed water to collect in the
hollow brass ball at the bottom of the light unknown to the owners and
about 6 years after the leak the central suspension rod had rusted to
the point it gave up and the brass 2 tiered 12 light assembly fell to
the floor bending and breaking many of the arms. The bulk of the repair
was the work to straighten and repair the breaks. This is a similar light
http://www.lassco.co.uk/?id=58&tx_ev...5Buid%5D=13747
My ancient plumbing contains a few brass parts that I've had to
custom-thread, but I don't think it will all last before I have to
replace the whole works. I've already succumbed to plastic pipe in
place of oakum and lead on my cast-iron waste pipes. so the end is near.
The spindle on one of my tub faucets is a piece I turned from the
bronze propeller shaft of a 50' commercial fishing boat, with the
splines cut by cranking the feed handle on my lathe, with a lathe bit
clamped in my milling attachment.
That's why my wife calls me a cheapskate.