Threaded Inserts - Interchangeable?

[onocoffee]

Was looking at using threaded inserts to attach a table top to a metal base. The top is made of hardwood (walnut, cherry, maple). Was perusing the Woodcraft website and noticed that there are two types (softwood, hardwood). One uses brass inserts, the other uses flanged. Can they be used interchangeably?

 

[rvieceli]

@onocoffee i use a lot of threaded inserts in my work. Bases are all hardwood. I always use the brass inserts.

The brass inserts have a knife edge on the outside threads which makes it easier to screw into hardwood. Generally the flanged inserts for softwood have a thicker and blunter outside threads which makes them easy for softer wood but more difficult for hardwood IMHO.

EZ LOK is the big name in threaded inserts. They make several sizes and market kits with an insert tool. I made in insert tool by cutting the head of a longer machine screw and using double nuts on the threads.

My process:

I use a drill press to drill the appropriate size hole. It needs to vertical. Remember to make it deep enough to allow for extra space at the end. Using a zero flute countersink I chamfer the hole. I’ll pop my insert tool into the drill press chuck and start the insert. Without changing the set up I’ll use a wrench to continue to sink the insert.

I like to sink the a bit below the surface so I use a socket head screw that has a head slightly smaller than the insert diameter in to screw it in more with a small impact driver.

I buy my inserts in bulk from ZORO (zoro.com) the ZORO select brand is actually EZ LOK inserts in bulk pack.

Ron

 

[Steve1]

I find Rampa inserts the best for hard woods. They are steel. Lee Valley or many other places sell them.
Not positive if all the sizes are the same OD, but in the sizes I use, they suggest 10mm pilot drill in softwoods, 10.5mm pilot drill in hardwoods.
I put a small chamfer on the hole and the flange sits below flush.

I made a small jig to ensure the insert goes in straight.
You can tell it is made of scrap, but it works. (One day I will make a nice jig)
Some of the Rampa inserts have a 3-start thread, with the idea that it is sitting on 3 points, so tends to go in straight, but I normally use the jig, to guarantee it goes in straight.

Not sure why you would want to mix insert types, but I don't see any problem with that.

 

[Cheese]

I've used E-Z Lok inserts in both hardwood & softwood installations, they work well...making sure the guide hole is perpendicular to the surface and properly chamfered is paramount.

I've also "cut" threads into hardwood if the stress levels are low in the final application. For those installations, I'll use a pilot drill that's a smaller diameter than normal and the fastener threads in very snugly. I liken the process as similar to using Threadfloer taps in metal.

https://infinitytools.com/products/infinity-tools-wood-tap

 

[Packard]

I rarely use threaded inserts in wood. Mostly if the screw has to be removed and replaced frequently. The last time I used them was to make a height adjustment for my router insert in a shop made router table.