Installing Metal inserts for threads in wood

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Forum topic by Mike Turner posted 11-22-2018 01:23 AM 1193 views 0 times favorited 6 replies Add to Favorites Watch
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Mike Turner

65 posts in 2760 days

11-22-2018 01:23 AM

I used some 5/16” and 3/8” metal inserts for threads on this project/jig not long ago. It was in soft wood.They worked out fine.

Now I need to put some 5/16”-18 in some oak on this same project.Ive tried drilling different sizes on the holes but I always pull the insert out when backing the guide bolt out…

Im using this method and it worked fine in the soft wood…

Im ready to finish this up. Help!!

-- Mike,North Carolina

6 replies so far

View Phil32's profile


840 posts in 508 days

#1 posted 11-22-2018 02:01 AM

It would seem that the drill size would be larger for hard wood like oak. It is also important to let the threads of the insert guide the process. Either the installation of the insert ran beyond the desired point or some other force tore the threads in the wood.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View knockknock's profile


473 posts in 2777 days

#2 posted 11-22-2018 02:12 AM

Besides tearing the threads (as Phil32 said). Are you backing out the jam nut and then the other nut, before backing out the drive screw (in hardwood the nuts can lock tight on the insert).

-- 👀 --

View waho6o9's profile


8812 posts in 3181 days

#3 posted 11-22-2018 02:41 AM

I would use a 5/16 bolt with a washer and impact the inserts in and then back out the bolt.

Practice on scraps and you’ll learn to finesse in the insert.

Proper pilot holes help a lot.


View pintodeluxe's profile


6033 posts in 3417 days

#4 posted 11-22-2018 03:55 AM

I use the type of threaded inserts that install with an Allen key. You can get them in tighter than the soft brass ones.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View AlaskaGuy's profile


5522 posts in 2913 days

#5 posted 11-22-2018 04:33 AM

I use the type of threaded inserts that install with an Allen key. You can get them in tighter than the soft brass ones.

- pintodeluxe


-- Alaskan's for Global warming!

View William Shelley's profile

William Shelley

609 posts in 2073 days

#6 posted 11-26-2018 02:46 PM

Oak? Just drill and tap the threads right into the wood. If you’re concerned about durability, then flood the hole with epoxy or CA glue, and chase the threads with the tap after the adhesive cures. Wood will hold machine screw threads remarkably well. Even soft woods like Pine can be tapped for bolts with coarse threads, like 3/8 and larger.

-- Woodworking from an engineer's perspective

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