Threaded insert installer

[Gordon Stump]

I do hundreds of those brass knife type threaded inserts. I adapted a concept I found online years ago and made a jig for my needs. It works really great. I countersink the hole slightly to avoid raising the wood at the start. I fought installing these inserts straight and square for years. The shouldered allen drive bit is driven with a cordless drill with a clutch. Once the head of the hardened shouldered bolt hits the top of the jig the clutch is engaged. There is a steel sleeve to protect the hole in the wood. I leave space below the installed insert by drilling the hole deeper than is required. If the insert bottoms out sometimes it just rips the wood threads. Since I wrestled installing the inserts quickly and accurately for years I thought maybe this might be useful. The wood is 8/4. I suppose the wider the better depending on your needs.

Cheers,
Gordoninserts.JPG

[Tom M King]

Thanks for this! I use them to make the window stops easily removable in old houses to simplify, and encourage future work on sash by being able to take them out without damaging anything with prying. Getting them straight, and square has always been a problem in the old window jambs. Small, straight slot, plain steel machine screw heads are not noticeable enough, even in museum houses, to be objectionable, and well worth it.

[Gordon Stump]

Great. This jig is perfect for on site work.

[Tom M King]

I made a jig, with hardened drill bit guides, to drill all the holes in the same height window jambs the same, so the stops would be hard to mix up, but have always had a hard time getting the inserts in as square as I would like. Did you use the standard insert driving bits to make that jig?

[Gordon Stump]

The inserts are threaded on to the shoulder bolt thread. The nut and the threads actually drive the insert into the wood. A fairly strong spring pushes the insert down and the cordless drill also pushes down. My work is with hardwood so it takes lots of torque to do this.

[Tom M King]

Some of the commercial driver bits work similar, without the spring. Did you machine the part? I've bought die springs for various things before, so expect a spring wouldn't be hard to find.

All the old jambs I would use it on are Heart Pine (Southern Long Leaf) over 200 years old. The wood density, and even grain size, and orientation varies with each individual piece a Lot, which is what make is so hard to get them in square. Ideally, I'd like to have a tap that matches the threads on the inserts , and prethread the holes with a jig for the tap.

edited to add: I found this video, and believe it might work. Very similar to your design. I'll try it the next chance I get.
https://www.youtube.com/watch?v=EszFoi7c_Y8

The tip that someone added in the comments section, below that video, to put the insert in with slot down, to help tapping the threads, may be worth modifying a little too.

Thanks again for posting this thread. I hadn't spent enough time thinking about, or researching how to solve that problem.

[Gordon Stump]

I bought a hardened shoulder bolt from Bolt Depot. 1/4" x 3" 10-24. I use a 10.5 mm or 13/32" HSS brad point bits. They are plenty tight. I have never had a product come back due to a problem threaded insert after 20 years.

[Tom M King]

Thanks again! I'll be using #6's, but all useful information.

[Tom M King]

I've found another thing to try too. There are stainless steel inserts, designed to be used in metal, that use standard tap size threads on the outside. I'm still thinking that may be the best way in the old, large grained Heart Pine jambs. I may go up to no. 8's. I'll try both, and see how it goes, but the to do list is long before I even get to this.

https://www.newmantools.com/ez/stainless.htm