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Hi All,

I have been looking for the description of the "universal" thread on a
chimney/drain rod?

I guess it's about 18mm diameter with a 3 mm pitch, but would like to
know exactly. I know it not standard metric whitworth UNF etc. Does
anyone know where I may get a tap+die for this thread?

I have a mortar problem in a chinmey and have a "hammer" but need to
thread it for the rods.

I've look everywhere without success.

Regards

Steve

[Matty F]

wrote:
Hi All,

I have been looking for the description of the "universal" thread on a
chimney/drain rod?

I guess it's about 18mm diameter with a 3 mm pitch, but would like to
know exactly. I know it not standard metric whitworth UNF etc. Does
anyone know where I may get a tap+die for this thread?

It doesn't seem to match anything standard.
Here's some threads from 15mm to 20mm:

Type Size Dia" TPI Dia mm Pitch mm

MF 15 0.591 25.40 15 1
UNEF 5/8 0.625 24 15.88 1.06
UNF 5/8 0.625 18 15.88 1.41
BSF 5/8 0.625 14 15.88 1.81
BSW 5/8 0.625 11 15.88 2.31
UNC 5/8 0.625 11 15.88 2.31
MF 16 0.630 16.93 16 1.5
M 16 0.630 12.70 16 2
MF 17 0.669 25.40 17 1
UNEF 11/16 0.6875 24 17.46 1.06
BSF 11/16 0.6875 14 17.46 1.81
BSW 11/16 0.6875 11 17.46 2.31
MF 18 0.709 16.93 18 1.5
M 18 0.709 10.16 18 2.5
UNEF 3/4 0.75 20 19.05 1.27
UNF 3/4 0.75 16 19.05 1.59
BSF 3/4 0.75 12 19.05 2.12
BSW 3/4 0.75 10 19.05 2.54
UNC 3/4 0.75 10 19.05 2.54
MF 20 0.787 25.40 20 1
MF 20 0.787 16.93 20 1.5
M 20 0.787 10.16 20 2.5
UNEF 13/16 0.8125 20 20.64 1.27
BSW 13/16 0.8125 10 20.64 2.54

[Tony Williams]

In article . com,
wrote:

I have been looking for the description of the "universal" thread
on a chimney/drain rod?

I guess it's about 18mm diameter with a 3 mm pitch, but would
like to know exactly. I know it not standard metric whitworth
UNF etc. Does anyone know where I may get a tap+die for this
thread?

I have a mortar problem in a chinmey and have a "hammer" but need
to thread it for the rods.

Why not sacrifice a rod and convert it to a
hammer, either temporarily or permanently.

--
Tony Williams.