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I got these fasteners with table legs that I bought for a formica table top. I get that I need to embed the outer part with the big thread into the table, and then use an Allen key to fasten the bolts into that.

But how do I get the outer part into the wood? Do I drill a little hole and just screw it in?

  • 3
    For reference, these are known as "threaded inserts". Websearching that term will find info about how to use them effectively. Their largest advantage over just driving screws directly is that the metal-to-metal connection can be disassembled and reassembled repeatedly without significant wear. T-nuts are a similar fastener which is installed from the opposite side of a piece rather than being screwed into the face; they can add some strength as well but are unattractive and so used only when the back side will not be seen.
    – keshlam
    Commented Jan 6, 2017 at 16:40

4 Answers 4


If you have a micrometer, measure the outside diameter of the entry point in the barrel (illustration below)

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If you don't, measure with a tape measure that will do increments of 1/32". Next, measure the depth of the barrel, and mark that depth on a drill bit that is sized to the entry point of the barrel (plus a few mm to cover the depth of the screw that goes into said barrel). Now, simply drill into the material and then screw the barrels in.

  • 3
    Since this answer was accepted, I will note that the other answers below also contain some important notes. @Harper smartly advises to first test the setting of these barrels in some scrap wood, and isherwood's comment that these are likely insufficient to securely affix table legs should also be noted.
    – Beems
    Commented Jan 6, 2017 at 16:10
  • 1
    You should edit your answer to put such additional information in your answer, not just a comment. Give credit to the source, but answers are not intended to just be static when you know they can be improved. The answer should be as good as you can make it. Obviously, there is a difference between incorporating ideas (with credit) and wholesale copying of content.
    – Makyen
    Commented Jan 6, 2017 at 20:16
  • Many may find it more effective to directly compare their available drill bits against the part than to measure (especially with something as crude as a tape) - that's more useful if you are contemplating buying a drill bit for this purpose, or need to fetch the drillbit from another room or supply counter and can't take the part there. Commented Jan 6, 2017 at 20:24
  • 1
    Calipers are probably a better measuring tool for this kind of thing then a micrometer. Micrometers are a specialized tool, and getting precision from them greater then you can get from a good pair of dial or digital calipers takes some skill.
    – Fake Name
    Commented Jan 7, 2017 at 7:12
  • 1
    To select a drill bit, hold the butt end of a possible bit up against the narrow end of the fitting, and compare sized. The bit needs to be a hair larger in diameter. Also note that the fitting is likely slightly tapered, and so you need to eyeball it such that the bit is still large enough at the flange end of the fitting. But as other said, I would not use these to hold legs on anything substantial, unless there are at least 4 per leg, or the material you're driving them into is quite resistant to splitting.
    – Hot Licks
    Commented Jan 7, 2017 at 14:01

You need to pre-drill a large but shallow hole of the correct depth, and use the bit size recommended by the manufacturer for the material you are setting those into. Too small and you'll crack the wood/whatever. Too big and they won't hold. It matters.

You might want to try on some scrap first.

Did the supplier provide these nuts full knowing that you're going into formica? Or is this a generic kit?

  • I've never used those, but if they're going to be subjected to stress from holding in table legs, I'd also be tempted to use some wood glue or construction adhesive on the nuts. If it's a strong enough hold it may not really add much, but I don't think it would hurt at all.
    – gregmac
    Commented Jan 6, 2017 at 18:54

You'll need to drill holes for the sleeves the same size as the shaft, then thread them in using an Allen wrench that fits the larger sleeve socket. They're essentially screws themselves.

I'd have expected that the hardware kit specified a bit size. Check the packaging, and check the hardware itself for markings.

On a side note, I wouldn't trust just those to secure table legs. You'll almost certainly want some diagonal bracing or brackets to distribute the load and prevent tearout from torque stress. Post photos of the entire project for more specific help.

  • Depends how many there are, and their layout and spacing. Commented Jan 6, 2017 at 16:25
  • Good point about bracing -- tho' the OP may well have table legs w/ braces attached. He didn't tell us very much. Commented Jan 6, 2017 at 16:25

Here is an illustration how to use these screws: https://www.rampa.com/cgi-bin/rampashopen.pl?id=2019&lang=

Lookup the correct diameter for your material in the data sheet before you drill the hole.

Assembling recommendation by a manufacturer:


ps: I am not sure, if we may copy the pictures here. If yes, feel free to do so.

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