How to reduce the size of a bore in steel to accommodate screw threads

metalsteel

I want to somehow get an M5 insert into a 7.5mm diameter hole in solid steel. (The hole has already been drilled with 7.5mm DeWalt cobalt-tipped drill bit.)

Is there such a thing as a threaded insert that is suitably constructed to be able to go into solid steel? Some have external threads, some have that rough/raised diamond pattern on the exterior instead. I'm not sure what might work. How about something I could hammer in, if the insert's diameter is finely tuned to be just above 7.5mm?

Here are some threaded inserts "for metal and plastic". I have no idea if something like this may work, or how to insert it properly.

Any advice is much appreciated. Thanks

Best Answer

Sounds like you're asking for a drop-in solution for an existing hole and screw size. That's a tall order. I doubt you'll find it, but if you can stand a bit of DIY here are a few options...

  1. A Helicoil (repair coil) normally requires existing threads, but you could epoxy it into place. I'm not sure an M5 will fit your hole, though. You'd want to run your screw in and out before the epoxy sets to clear any squeeze-out.

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  1. A threaded sleeve or bushing could work, but again you'll probably need to epoxy it and possibly drill larger.

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  1. Tap it for a larger screw. You haven't said what you're mounting, but it may accommodate a thicker screw with or without slight modification. An M8 might work well with the existing hole.

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