Nut sizes imperial measurements, disorientation!

[Howard LewisParticipant @howardlewis46836]

Drain Rod threads appear to be Whit form, 7/8 or 3/4" ( From poor memory A While since i made an "unstopper" using broom handle and the rubber disc, for our daughter )

Howard

[Nigel Graham 2Participant @nigelgraham2]

Yes: Drain Rod Threads are 7tpi BSW form! I can't recall the diameter without going and dragging them out to measure, but I don't think it's as large as 7/8" .

How do I know?

I made parts for a pump for a caving application, with a drain-rod section as its piston-rod / handle. It starts a siphon to drain a short "sump", a pool totally filling the passage with water, like a sink-trap.

I turned a brash bush with male thread, to fit the plastic piston that works in a short length of 150mm PVC drain-pipe. Calculating the wheels for an EW lathe with 20-65 X 5T change-wheels, two-stage only and 1/8" lead screw, was interesting.

'

I used that lathe too as a 2-axis dividing-head for drilling about 130 holes in a plastic tube for the pump's inlet strainer: using a hole through a brass block in the tool-post, to guide the bit in a small battery-drill. Workpiece between centres.

Fibre-tip pen marks on the 60T change-wheel on the spindle as angle indicator sighted against a headstock feature on the headstock as their "pointer"; similar but separately on the lead-screw for lengths. Guide-block against the work as angular brake, normal saddle lock for lengths.

[bernard towersParticipant @bernardtowers37738]

Drinks bottle threads?

[Bdog507Participant @bdog507]

Good evening all.

The thread I had in mind is the Schrader valve thread. Invented by a German in the USA…..Says it all really!

Cheers.

Stewart.

[JasonBModerator @jasonb]

Is it Unique though as there are several different sizes of the Vg thread form and the common tyre size Vg8 is just a 60deg 32tpi thread

I would have said threads like Edison, plastic bottle and glass bottle forms are fare more unique in shape though again have several size options

Edited By JasonB on 27/02/2023 19:26:28

[Bdog507Participant @bdog507]

Good evening all.

As far as I know there's nothing else that uses it. Bloody Yanks!

Indeed bottle threads are very unique in form, and there are considerable variations. Think how many times a day bottles get unscrewed vs how many tyres are pumped up. I wouldn't like to be the chap who had to count them!

Cheers.

Stewart.

[Nigel Graham 2Participant @nigelgraham2]

My candidate thread in all our homes and probably operated by more people than is the tyre-valve thread, is that used on glass jam-jars:

A rounded-top, flat-bottom profile, multiple-start breech-thread; i.e.perhaps 4-start but cut through to give a quarter-turn action for a female thread that is no more than tabs!

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