Stanley tote tap set ...

[mikey78]

I would be wary of brazing the hole, you could distort or crack the cast iron.
Pete

I'm wary too ...

Have a read of this thread, especially the pdfs linked to by Swagman.
It's not the sort of BSW coarse threads that were in common use in the UK up to about 20 years ago, so would not be found in old stock from your local ironmongers or garage.

I quickly read the pdf, but didn't really find answer.
Please keep in mind I speak Italian so (because of the language) I might have missed, in those long pages the point . . .

why not may your own tap using a tote screw? it only needs a flute cutting in. you could then make a brass insert, drill out the old and replace using soft solder or epoxy.

This is an option if I can't find a tap !!!

 

[ED65]

I was told by a machinist that cast iron and epoxy have different strenght and, of course, different elastic module ...

That's true, but only a theoretical problem. The difference in strength and properties between the base metal and the epoxy repair doesn't appear to matter in practice.

Metal-filled epoxies are significantly harder and tougher than aluminium and some of its common alloys but are used extensively to repair stripped threads in them. What's more, epoxies can be used to deliberately form strong threading in softer materials such as weak metals, wood and even plastics.

remaining metal thread in the hole and not epoxy thread to faight against the pulling action (hope it is clear )

The brittle nature of cast iron by itself might make the usual method of repairing a thread not be suitable. Plus on top of that the hole is going to be rusty and dirty, so you'd need to do something to ensure the epoxy was able to grip onto fresh metal.

The best way would be to grind out the hole slightly, this is better than drilling because you'd end up with more texture for the epoxy to cling to. The hole could be slightly undercut while doing this for additional hold, or a few small shallow holes can be drilled at various angles for the epoxy to creep into and form anchors.

 

[Phil Pascoe]

If the top thread is fine, why not just clean the hole and the bottom thread and just JB Weld the rod in? How often do you anticipate taking it out again?

 

[mikey78]

why not may your own tap using a tote screw? it only needs a flute cutting in. you could then make a brass insert, drill out the old and replace using soft solder or epoxy.

HI novocaine this is pretty much my second option (the first being epoxy alone without any insert ),
just a question , you said "soft solder", can you explain it better :wink: ?
Thankyou

 

[mikey78]

If the top thread is fine, why not just clean the hole and the bottom thread and just JB Weld the rod in? How often do you anticipate taking it out again?

Maybe I'll never take it apart again but, this solution is not for me ... thankyou anyway !!!

 

[mikey78]

From what I've read untill now the correct tap looks like a #12 - 20,
someone else says 7/32 - 20 withworth, but at the moment the more I read this last option is getting increasingly less likely.
If the correct tap is designed only by this : "#12-20" and in looking for this size tap I don't miss any other information (pitch, etc, etc ) there could be a little chance I find it in europe ...
Otherwise I need to buy it the other side of the pond !!!

 

[mikey78]

Other side of the pond ...
But now I have a tap and die set !!!

 

[Racers]

Excellent, but where did you get it from just in case other people want one, or can we borrow yours? :wink:

Pete

 

[mikey78]

"St. james tool bay" or "victornet.com" ( the first one being a lot cheaper than the second ).
... borrow ??? No problem :mrgreen:

 

[CHJ]

Whatever thread is used, rather than 'filling' or otherwise trying to build up the stripped thread I would drill out an oversize blind hole and fit a threaded bush.
(Knurled outer for a interference fit, pressed in with good epoxy.)

(custom made riv-nut style bush)

Avoids trying to tap a shallow blind hole