12mm thread chaser

[britman]

Anyone have a good source for a 12mm spark plug thread chaser that doesn't cost an arm and leg?

[britman]

I found a 12 mm bolt with 125 pitch at True Value Hardware. With some careful work with a cut wheel I put three channels in the threads for grease to collect the crude and it worked like a charm. Plugs go in smooth and tight. Cost for the bolt a little over three bucks.

[e3steve]

Had I not been away for my birthday ~ your day of posting ~ that would've been my suggestion; I did the same thing, but with 4 grooves, using a Dremel edge-disc.

Your attack on the problem is the heart of a forum like ours here, giving us all an uplift and the enthusiasm to solve problems with a little lateral thinking.

This type of screw was (is?) commonplace back in the early 70s in (UK) vehicle production, whereby the leading 2 or 3 turns of thread were removed, leaving merely a 'lead-in' location stub; there was a wedge-shaped groove circumventing 90º of the screw and reducing to nothing at about 30% of the threadlength. These 'modifications' were pre-plating/passivation process, and the reason was to allow the leading part of the thread to clean out paint from the prepared bodywork's captive nuts.