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I'd like to attach a 1 1/8" thick table made of beech to a metal frame.

The metal frame normally attaches to a particle board top through 3/8" holes. An outer piece of plastic is first inserted into the particle board through the hole in the frame, and a thin plastic pin exerts pressure to create a lock.

attach frame

How can I attach a metal frame with pre-drilled 3/8" holes to a hardwood table top? I'd like not to drill matching 3/8" holes in the wood, and use hardware to do the coupling instead. Just using wood screws with a flange will require that I rely on tightening to keep the top from sliding sideways.

Update

Potential Solutions:

  1. Use a wood screw and a washer. To avoid sliding the screws must then be tightened hard, perhaps more than the wood can handle for long.
  2. Drill a 3/8" hole and use the same plug-and-pin technique. The large hole is needed to secure a frame to particle board, but it's an unsavoury solution for real wood because it introduces an unnecessary weakness.
  3. Use a wood screw, a washer, and some kind of jacket. The cylindrical jacket would be 3/8" on the outside, exactly the same depth (height) as the frame, and have a hole that matches the wood screw. What is such a jacket called at the hardware store?
  4. Thanks to WoodAirGrille's thoughts, "all I need" is to drill a hole through a wood plug, but that's beyond my ability.
  • What's your objection to using the original technique? It seems appropriate to me. You could also use 3/8 inch coarse thread machine screws in a similar fashion. – isherwood Mar 31 '18 at 14:15
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    What do you mean "using wood screws... will require... tightening to keep the top from sliding sideways". I am trying to understand why wood screws would not be perfect for this application. – Jimmy Fix-it Mar 31 '18 at 14:47
  • @isherwood It would be nice not to damage and weaken the board by drilling six large holes. Surely there must be a way using screws of much smaller diameter. – Calaf Mar 31 '18 at 14:54
  • @JimmyFix-it Two weeks or two years after attaching the base to the board, it will be necessary to retighten. Avoiding that the board slides sideways will rely on the friction between the head of the wood screw and the metal frame. I'd like to insert instead some kind of filling that prevents sideway-sliding, an adapter between a large bored hole and a thin screw. What is such a thing called? – Calaf Mar 31 '18 at 14:57
  • Most would call that a bushing, essentially a sleeve with specific I.D. and O.D. You could get nylon spacers 3/8"O.D. and 3/16" I.D. (#10 screws are 3/16") with length matching the height of the tubular frame, but I feel that you are over-engineering this. Preventing the top from sliding doesn't just "rely on the friction between the head of the wood screw and the metal frame"; you will also have friction on the whole area where tho top contacts the frame. I would just carefully mark each, drill pilot holes, and use wood screws with fender washers. Glue it too, if you want. – Jimmy Fix-it Mar 31 '18 at 15:04
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If I understand correctly, your concern is that the 3/8" holes in the frame would require a pretty large diameter screw in order to have a snug fit when you screw down the table top. Since you are dealing with Beech instead of particleboard, you want to use traditional screws instead of the pressure plugs. If this is correct, I can offer the following thoughts:

Using the frame as a template, it is reasonable to drill 3/8" Holes in the top and use the pressure plugs that came with it.

You could buy a large 3/8 diameter screw or lag bolt. Just be sure to pre-drill you pilot hole large enough so you don't crack the top.

You can drill pilot holes in the top and screw it down with bugle head wood screws. (AKA flat head screws, AKA flush head screws, AKA countersink screws) The cone shape of the head of the screw will center the screw in the hole and prevent the smaller shaft of the screw from wiggling around inside the larger diameter hole.

You could cut off the bottom part of the plastic pressure plug so that the length is the same as the thickness of the frame. You could then insert the plug in the frame, drill your pilot holes, and use the plug as a spacer inside the 3/8" hole to keep you screws from wiggling around.

In any case, be sure you use a good quality, high strength screw. A cheap screw (drywall screws especially) may snap off when you are tightening them in beech.

Hope that is helpful, good luck with your project!

  • A "lag shield" is what I had been referring to as a "jacket". Thanks! But I'm not clear. I'll look for a lag shield that matches the diameter of the hole in the frame, but it's very unlikely I'll also find one that matches the height/depth of the frame. With a wood screw and a washer I've now prevented sideways sliding, but the tabletop will be loose: If I lift it, it will be some distance (1/4"?) before it grabs the frame. – Calaf Mar 31 '18 at 15:24

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