12-08-2017, 08:49 AM
(This post was last modified: 12-08-2017, 09:10 AM by Steve Hainsworth.)
Hi
I must apologise to Ian Williams as the thread is actually 1-1/4" Conduit (electrical ) thread -16 TPI.
Standard Whitworth Form 55 Degrees -depth of thread .040 " ( Forty thousandths of one inch)
The thing to look for is a conduit blanking plug in brass.
I will look into availability and if hard to get make a few hundred in brass if there is demand.
Cheers Steve Hainsworth
Forgot to mention. To get the old ones out (destructive ) They are cast iron and quite brittle
Drill a 5mm pilot hole as close to center as possible-right through.(but not into the cylinder walls!)
Open out to 8 then 13 (as big as a battery drill will go ) Don't drill too fast as they will blunt your drills.
Using a hacksaw blade (18TPI ) in a pad saw handle carefully cut from the center out til you hit the major Dia of the thread.
Make the cut opposite to form a cut both sides.repeat process at 90 degrees so you have the plug quartered.
A few judicious taps with a chisel or pin punch will collapse the pieces inwards so yo can extract them with a magnet or rod.
I have done this to 3 blocks recently with no damage to the block thread. Clean the threads up with an internal thread file.
Cheers Steve Hainsworth.
I must apologise to Ian Williams as the thread is actually 1-1/4" Conduit (electrical ) thread -16 TPI.
Standard Whitworth Form 55 Degrees -depth of thread .040 " ( Forty thousandths of one inch)
The thing to look for is a conduit blanking plug in brass.
I will look into availability and if hard to get make a few hundred in brass if there is demand.
Cheers Steve Hainsworth
Forgot to mention. To get the old ones out (destructive ) They are cast iron and quite brittle
Drill a 5mm pilot hole as close to center as possible-right through.(but not into the cylinder walls!)
Open out to 8 then 13 (as big as a battery drill will go ) Don't drill too fast as they will blunt your drills.
Using a hacksaw blade (18TPI ) in a pad saw handle carefully cut from the center out til you hit the major Dia of the thread.
Make the cut opposite to form a cut both sides.repeat process at 90 degrees so you have the plug quartered.
A few judicious taps with a chisel or pin punch will collapse the pieces inwards so yo can extract them with a magnet or rod.
I have done this to 3 blocks recently with no damage to the block thread. Clean the threads up with an internal thread file.
Cheers Steve Hainsworth.