Driving threaded inserts

[Myles Moran]

I'm working on driving threaded inserts into hickory table legs to be used to secure the legs to the table. I bought the ez-lok 1/4-20 303 stainless inserts for hardwood and the associated driving tool. I drilled out the holes with a 3/8 forsner and then reamed them to the 25/64 (what the manufacturer recommends) with a twist drill. I started them in the drill press turning the chuck by hand as I pushed the quill down. They all started just fine in the holes. I then used my impact driver to try and drive them home. The first leg went in perfectly. The second leg I ended up breaking the slots on the threaded insert and had to carefully back it out so I could replace it. I then noticed that the driving tool was a pretty beat up, like the impact had done a number on it (are these tools meant to be run with an impact?). I'm now waiting on replacement parts to ship from rockler - 2 driving tools and some more inserts so hopefully I can get them all driven. Are there any tips to getting these things to drive home successfully? Its been years since I last used a threaded insert, and I had forgotten about putting wax on them before driving them, so I will definitely be doing that. I'm debating if I should upsize the holes to 13/32 since this hickory is tough stuff, or at least in the legs that are giving me trouble - they drove in smoothly into the first leg and were really fighting on the second leg before they broke. Anything else I should be doing?

[Lee Schierer]

Try coating the exterior threads of the inserts with bees wax, they go in much easier. However since hickory is so tough, they may not work.

[Ed Aumiller]

Definitely do not use impact driver.
Do each one by hand SLOWLY...
If your tool allows, put in 1/2 turn, then back out 1/4 turn, repeat...

Good luck.. Hickory is very hard....

[Paul F Franklin]

Another way to drive them that would avoid the issue with the slots getting messed up is to cut the head off an appropriate size bolt and chuck it in your driver. Then spin a nut on the threads followed by the insert. Thread the insert on most of the way, then tighten the nut down onto the insert. Use this to set the insert. I would definitely wax the threads, and if it is still a real hard go then I would go a wee bit bigger on the hole diameter.

[Jamie Buxton]

Yes, wax helps a lot. Good aim helps too. Aim the insert straight in the hole. It does not straighten itself out like a regular screw does. And Lee Valley sells a terrific driver: https://www.leevalley.com/en-us/shop/tools/hand-tools/screwdrivers/bits/70791-1-4-20-insert-nut-driver?item=50J0351

[Dan Friedrichs]

Another way to drive them that would avoid the issue with the slots getting messed up is to cut the head off an appropriate size bolt and chuck it in your driver. Then spin a nut on the threads followed by the insert. Thread the insert on most of the way, then tighten the nut down onto the insert. Use this to set the insert. I would definitely wax the threads, and if it is still a real hard go then I would go a wee bit bigger on the hole diameter.

+1, or just use a bolt threaded all the way down into the insert and drive the bolt with a ratchet, etc. The EZ-Lok driver is very easy to mess up inserts (or the driver, itself).

[Robert Hayward]

I used those exact inserts a couple months ago rebuilding and old cast iron garden bench. The wood used was Ipe and it proved to be impossible to drive the inserts without splitting the wood or buggering the insert. I tried drilling larger holes and then the inserts would not hold well enough. Ended up drilling and tapping like I was putting the inserts into metal. The external thread was a 7/16-14. Amazon had the tap here the next day.

[Myles Moran]

Thanks for the ideas. As far as the wax, would the paste wax I use for my tools be good enough or should I go try and find some beeswax?

[Dave Cav]

Another way to drive them that would avoid the issue with the slots getting messed up is to cut the head off an appropriate size bolt and chuck it in your driver. Then spin a nut on the threads followed by the insert. Thread the insert on most of the way, then tighten the nut down onto the insert. Use this to set the insert. I would definitely wax the threads, and if it is still a real hard go then I would go a wee bit bigger on the hole diameter.

This. In my experience, the slotted drivers are worthless in hardwood. Also, experiment with some scrap with various size holes to find the best combination of dirvability and holdability.

[Jim Becker]

The best tip I ever got for threaded inserts in hardwood came from one of the guitar builders that I follow on YouTube...use inserts designed for steel in drilled and tapped holes. You start with a regular tap and then use a bottoming tap to finish. PVA glue before threading them in completes the job very nicely.

[Jeff Bartley]

The inserts from McMaster Carr are way better than what you find at the hardware store. They sell a decent insert tool as well.

[Lee Schierer]

Thanks for the ideas. As far as the wax, would the paste wax I use for my tools be good enough or should I go try and find some beeswax?

Paste wax should work, don't be shy about using a liberal amount.

[al ladd]

This is a situation where a brushless motor drill makes a difference, allowing high torque at slow speed. If you're doing a lot of these make this: https://www.youtube.com/watch?v=EszFoi7c_Y8&t=275s
I find I can use the much cheaper cast metal ones meant for soft wood in hardwood with proper installation. These have flanges, and if the application allows mounting from the rear the flange provides extra security against the insert pulling out.

[johnny means]

Ditch that tool. Get yourself one of these tools. Cut off the handle and chuck it in a drill. Drive the inserts in slotted end first because that end likes to break. I've spent entire work days doing nothing but driving hundreds of inserts like this and almost zero failures. Between the end of the insert and threads, it spreads the load over lot more material.