Products for bench top machinists | LittleMachineShop.com

Thread-Locking Insert 1/4"-20 Inside, 3/8"-16 Outside

Thread-Locking Insert 1/4"-20 Inside, 3/8"-16 Outside - Main image
$1.21 $1.95 In stock

These inserts reduce at 3/8"-16 threaded hole to a 1/4"-20 threaded hole.
Use them to bolt two 1-2-3 blocks together. Use them to reduce the hole in 7/16" or 1/2" T-slot nuts to 1/4"-20 thread.
These inserts use Loctite® adhesive to keep them in place. The adhesive reaches full strength after 72 hours.
Set the insert with a bolt and two nuts, or use a slotted screwdriver.

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (4.4 / 5 · 5 reviews)

Julian ★★★★★

Bought a pack to drop the thread on my T-slot nuts from 3/8"-16 down to 1/4"-20, and the reduction is exactly as specified. They thread in cleanly without any wobble, so I've already got two blocks locked together solidly.

Miles U. ★★★★★

Worked perfectly for bolting my 1-2-3 blocks together—the 3/8"-16 to 1/4"-20 reduction came out dead straight, no wobble. Threads cut cleanly and the insert seated flush without any burrs. Exactly what I needed to adapt those T-slot nuts too.

Michael O. ★★★★★

The external threads grabbed the 3/8"-16 hole without any wobble, and now my 1-2-3 blocks sit flush like they're meant to be one piece. It's a simple reducer, but it saves me from drilling a bigger hole every time.