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Please note: I see some other very similar questions but the recommended answers all suggest using glue in some form. I can't use glue as part of this solution!


I have a workbench that, on the end cap, has an upside down screw that keeps a piece of wood (on my bench) fastened to an MDF board. The problem is that I've had to move the workbench many times over the years, and each time I do, I need to unscrew and rescrew this upside down screw, and the residual wear-and-tear has started to strip both the wooden and MDF screw holes.

So now, I can pretty much just push the screw into place, and its not really doing its job, and the two pieces of wood come apart easily.

What can I do to make the screw "stick" and properly secure the two pieces of wood together?

I absolutely have to keep the existing MDF board in place; I cannot replace it. I do not want to use any type of glue as that would be permanent. And I am open to using a thicker "gauge" screw but I'm worried this might cause the board and MDF to crack or break apart and, besides, I'm not sure if there are any other woodworking tricks this community could teach me here that would solve the problem without needing new hardware! Thanks in advance!

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    You've made a couple assumptions that have me scratching my head. First, how will repairing the hole be a "permanent" attachment? Then, why would a larger screw crack your workpiece? MDF is very resilient and you should pilot properly anyway (if needed--sounds like it's not). Plus, if the screw supports some weight or load now, the MDF can't be that flimsy. The bottom line is that your question isn't very clear. – isherwood Aug 31 '20 at 14:57
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    A photo or two would really help. I have several ideas but I'm not sure they're appropriate with just your vague description. – isherwood Aug 31 '20 at 15:02
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One non-glue option that comes to mind is a threaded insert, specifically one suited for MDF. I did a quick search for "threaded insert for MDF" which returned many. One promising link is EZ-LOK Soft Wood Inserts as it references MDF among other types of wood.

Two versions are noted in the linked page, providing a metal foundation for the removable screw.

hex drive insert

The above image from the web site shows a hex drive insert. One drills the appropriate size hole for the insert and uses a common allen wrench/hex key to insert the insert.

I've used this type with good results, but not on MDF.

The second listed is a press-in style:

press-in insert

This one has text that states it minimizes splintering and splitting. I've had no experience, but it looks promising.

The site has links for drill sizes as well as providing information for various lengths. You may also find other products of a similar nature which perform the same task.

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  • I can see those working well, but they'd need to be used in conjunction with a "hanger bolt", which has machine threads on half and wood threads on the other. – isherwood Aug 31 '20 at 15:17
  • Thanks @fred (+1) -- are my concerns about using a thicker screw warranted, even if I drilled a slightly larger pilot? – hotmeatballsoup Aug 31 '20 at 15:43
  • No reference was made to require a machine thread for the bolt. If that's accurate, no hanger bolt needed, but if a machine bolt is required, your suggestion is certainly valid. – fred_dot_u Aug 31 '20 at 15:43
  • @hotmeatballsoup, the insert will prevent splitting. You need only to select the insert to match the size of bolt/screw used. Note also isherwood's reference to machine threads or screw threads, unspecified in the question. "Screw" is a term often used interchangeably between both types. – fred_dot_u Aug 31 '20 at 15:45
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Use a glue/wood mix to fill the hole and let it harden.

Then you can drill it and use the existing screw as it should be used to hold the part in place.

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    Thanks @Solar Mike (+1), but I don't think you read the question. The title mentions WITHOUT glue. The disclaimer at the top of the question mentions no glue. And I even state it a 3rd time in the last paragraph. – hotmeatballsoup Aug 31 '20 at 14:51
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    @hotmeatballsoup and I don't think you understood my answer. The glue will not permanently attach the part to your desk, which is what you mentioned as the real issue. – Solar Mike Aug 31 '20 at 14:52
  • Thanks @Solar Mike (+1 again) -- are my concerns about using a thicker screw warranted, even if I drilled a slightly larger pilot? – hotmeatballsoup Aug 31 '20 at 15:43
  • MDF will split if you screw into the edges, if you screw into the face it does not easily split. – Jasen Sep 1 '20 at 13:41
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Expanding on fred_dot_u's answer...

Threaded insert is an excellent choice for this application. To make the fix as robust as possible, two details to keep in mind:

  • If you have a choice between a threaded insert that takes a machine screw (similar to a Helicoil) vs one that takes a wood screw (similar to Wall Driller drywall anchors), get the one that accepts a machine screw. Those threads will hold up far better to future unscrewing and rescrewing.
  • The screw-in insert is far more likely to stay firmly in place over the long term than the press-in one. For best results, I would suggest that you smear a thin layer of glue (I'd probably use slow-setting epoxy) on the outside of the insert; then drive the insert into the MDF; wipe off any excess glue and wait. After the glue is fully cured, put the board in place and screw it down.

This solution will give you a very sturdy threaded metal hole like a regular nut, installed very permanently in the MDF. You can then remove and reinstall the machine screw into the insert as many times as you want without worrying about your insert eventually wiggling its way loose and stripping that hole. It will not result in the board being glued to the desk so you can't remove it.

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  • Excellent points. The epoxy makes the insert permanent, but doesn't make whatever is screwed into it permanent. (To head of the possibility of concern by the OP over the use of glue.) – FreeMan Mar 24 at 13:57

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