Tapping question

[Rich2502Participant @rich2502]

Can i retap a 7/16 x 14 tpi hole to M12 and get some kind of useable thread ?

This is only the adjustment screw on a pair of welding clamps so needs to hold nothing. I don’t have any 7/16 bolts and to order 1 bolt is more than the tool is worth.

[Julie AnnParticipant @julieann]

It should produce a usable thread but only about 50% thread depth. Whether the thread is strong enough will depend upon your workshop gorilla.

Julie

[FulmenParticipant @fulmen]

7/16 should be 11.1mm, lets say 11.2 for good measure. That will give slightly less than 50% threads, but as long as it’s not subjected to huge loads it should work.

[DC31kParticipant @dc31k]

If you happened to have M12 x 1.5 or M12 x 1.0 taps and fasteners, that would also be a possibility.

[JasonBModerator @jasonb]

Or as it is for a welder fill the hole with weld and start again with a new hole to suit M12

[Howard LewisParticipant @howardlewis46836]

You could Loctite in a 7/16 x 14 tpi  stud, and then drill 10.2 mm and tap M 12 x 1.75.

The parent metal will protect the stud from tearing, and between the two, get a full depth thread.

This is the method used to convert a M 12 to 3/8 BSW for my drawbar!

This assumes that it is possible to hold the parent accurately both axially and centrally.

Howard

[Grizzly bearParticipant @grizzlybear]

Hi,

Weld a M12 nut onto it.

Nice one, Julie Ann.

[Bill PhinnParticipant @billphinn90025]

Presumably the 7/16” female thread on the clamp is in good condition or you wouldn’t be suggesting the ideal solution was a replacement 7/16” screw.

If that’s the case, it may be worth pointing out that all the 10” Irwin Vise-Grips I own use a 7/16” UNC adjuster screw. So, if you own any 10” Irwin Vise-Grips, try the screw in your welding clamp.

[Howard LewisParticipant @howardlewis46836]

At a pinch, if you have some hexagon bar, could you not make a replacement clamp screw?

Even if you do not have a 7/16 UNC Die, you could screw cut it (thread form 60 degrees, depth 0.04382″)

Howard

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I would do what JasonB has suggested.

Regards Nick.

[Author]

Posts