Romford deluxe crank pins

[Roger Sunderland]

Hi All

 

A quick question if I may. What drill size do coupling rods have to be drilled out to to take the collars on Romford deluxe crank pins?

 

Have looked loads but cannot find the answer.

[Nile]

1mm

[cctransuk]

1mm

 

Nope.

 

1.5mm., then opened out with a broach to 1.6mm. for clearance for the top-hat threaded securing bushes.

 

1.0mm. is for the bog-standard Romford / Markits plain crankpins.

 

1.6mm. can be VERY tight in some etched coupling rods.

 

Regards,

John Isherwood.

[Nile]

These must be extra super-deluxe crankpins. The ones I have look just like the standard ones, but most of the pin is threaded for a 14BA nut. No bushes, just a nut. The non-threaded part measured 0.91mm.

Edited August 15, 2018 by Nile

[cctransuk]

These must be extra-deluxe crankpins. The ones I have look just like the standard ones, but most of the pin is threaded for a 14BA nut. No bushes, just a nut. The non-threaded part measured 0.91mm.

 

Nile,

 

 

The Super Deluxe ones that I have are threaded the full length of the pin, and come with top-hat shaped threaded bushes.

 

The smaller diameter part of the bush is 1.5 - 1.6mm. diameter to fit through the rod, and the larger diameter retains the rod and is slotted on its edges to fit the Romford screwdriver.

 

The bushes are screwed down tight against the flange of the crankpin, and the surplus threaded pin is cut and filed flush to the bush; no soldering is required.

 

There would appear to be at least two lengths of bushes - short for single etch rods, and longer for double laminated rods.

 

The downside it that some etched rods are too slim to take the larger bush diameter of 1.5 - 1.6mm.

 

Regards,

John Isherwood.

[Roger Sunderland]

Nile,

 

MCRNKPD.jpg

 

The Super Deluxe ones that I have are threaded the full length of the pin, and come with top-hat shaped threaded bushes.

 

The smaller diameter part of the bush is 1.5 - 1.6mm. diameter to fit through the rod, and the larger diameter retains the rod and is slotted on its edges to fit the Romford screwdriver.

 

The bushes are screwed down tight against the flange of the crankpin, and the surplus threaded pin is cut and filed flush to the bush; no soldering is required.

 

There would appear to be at least two lengths of bushes - short for single etch rods, and longer for double laminated rods.

 

The downside it that some etched rods are too slim to take the larger bush diameter of 1.5 - 1.6mm.

 

Regards,

John Isherwood.

 

Many thanks John. I've drilled out the rods to 1.6 already BUT it is still a VERY tight fit and if the crank pins are not 100% at right angles to the wheels (I'm using Scalelink not Romfords) then there is no room for error. I don't have a 1.7 drill and am a bit reluctant to go up to 1.8 in case it's too sloppy.

[RexAshton]

Many thanks John. I've drilled out the rods to 1.6 already BUT it is still a VERY tight fit and if the crank pins are not 100% at right angles to the wheels (I'm using Scalelink not Romfords) then there is no room for error. I don't have a 1.7 drill and am a bit reluctant to go up to 1.8 in case it's too sloppy.

You're probably better using fine cutting broaches for the final fitting. If you haven't got access to them try the end of a fine round file. Rotate the file anti-clockwise in the hole so it doesn't bite into the metal. You'll need to work carefully and gently open the hole from both sides. Take your time and check often and the inventor of the putting on file hasn't been born yet :)

[cctransuk]

You're probably better using fine cutting broaches for the final fitting. If you haven't got access to them try the end of a fine round file. Rotate the file anti-clockwise in the hole so it doesn't bite into the metal. You'll need to work carefully and gently open the hole from both sides. Take your time and check often and the inventor of the putting on file hasn't been born yet :)

 

I would strongly recommend that you purchase a set of cutting broaches - do an ebay search on "cutting broaches set".

 

You don't need anything too expensive - this looks OK :-

 

https://www.ebay.co.uk/itm/SET-OF-10-CLOCK-CUTTING-BROACHES-SET-0-9-4mm-FOR-BUSHING-SERVICE-REPAIRS/360554497317?hash=item53f2b90525:g:BboAAMXQ~6VQ5svn

 

Regards,

John Isherwood.

[Roger Sunderland]

Many thanks for the tips. Cutting broaches it is then.