I built a big farm table out of a hickory tree that was in my yard before tornadoes came through Georgia in 2011. I cut it up took it to a sawmill and had it cut in the lumber. I’ll let it cure for many many years.I currently don’t have the top attached to the base but was wondering what type of threaded insert would I need to do this. The top is 2 inches thick out of dense hickory so it’s very heavy. Just looking online there are so many options for threaded inserts I’m not sure which ones are best for hardwood and weight.
GO VOLS
Replies
A continuous thread Brass or Stainless is what works best in hardwoods. The largest commonly available size would accept a ⅜" bolt.
With Hickory being probably the hardest of NA hardwoods I do recommend drilling the hole a step larger (1/64") than the recommended drill bit size. I also strongly recommend an insert tool be used in such dense wood.
This link may answer more questions:
https://www.ezlok.com/e-z-knife-inserts-for-hard-wood
I like to use them for a solid, knock down construction. If the inserts are on the underside of the top and the base has elongated holes for the screw to go through and allow for the top to contract and expand with changes in humidity, they make a solid attachment.
Unless you anticipate dismantling the table fairly frequently, I would question whether threaded inserts are necessary. I typically only use screws. Properly sized, they have adequate holding power unless the top is really prone to distortion.
If you do use threaded inserts, my favorite insertion tool is a bolt and nut of the same size as the internal threads. Screw the nut onto the bolt past enough threads to thread the insert on completely. Tighten the nut against the insert, and use a wrench (best is actually a T-handle and socket) to thread the insert in. When the insert is in where you want it, back the nut off the insert and remove the bolt. By the way, chamfering the hole will allow easier starting of the insert installation; it's hard to get it starting straight without the chamfer.
Be sure to test your hole size and chamfer on hickory scrap before you try it on the table top; you may need to drill the hole oversize to compensate for the density of the hickory. I would have an extra insert or two for this test process. I drill oversize a bit for hard maple as well. And stainless will probably stand up to the insertion stresses better than brass.
Thanks all!!
A little wax on the threads also helps.
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