Reparing MDF with screws pulled out

[Lee Ludden]

I have an extension table that is basically made of coated MDF about 1" thick. There is a steel plate mounted to the bottom of it with four 3/4" screws. Someone has pulled this plate mostly off, the MDF around the screws is broken in some decent size chucks.

I need to repair this small section so I can remount the plate. I am thinking of routing out the entire area about 1/2 or 3/4 deep and cutting a replacement piece to fit in there and gluing it back in. Would I be better off using 3/4 plywood for this section? Or some other solution. The total area I'd be replacing is about 6" x 6".

Thanks

[Steve knight]

that will work. or fill all the holes and missing spots with epoxy let cure and drill the holes and screw the part in again.

[Joe Chritz]

You can also use plugs or dowels and just drill a hole and fill it.

MDF isn't known for its screw holding ability anyway.

Joe

[Prashun Patel]

I have a vise mounted to the bottom of my mdf-topped bench.
I drilled countersunk holes in the top, then used a bolt and a 3/4" washer to secure the undermounted hardware. You can either plug the holes with sections of a dowel, fill with sawdust and epoxy, or put a replaceable piece of 1/4" hardboard over the entire top like I did.

[glenn bradley]

Depends on how big the tearout is around the screw area. I prefer the routed out area replaced with the plywood plate idea but, dowels could also work.

[Myk Rian]

Sheet metal screws work better for MDF as opposed to wood screws.
As mentioned, dowel pieces work, or you could buy some threaded inserts that screw in, with internal threads for a machine screw.
http://www.rockler.com/product.cfm?page=362&filter=threaded%20inserts

[Greg Portland]

or fill all the holes and missing spots with epoxy let cure and drill the holes and screw the part in again.I have done this in the past and it works very well (using West Systems). Be sure to get the 'thickener' additive which is very fine flakes that will allow you to turn the syrupy epoxy into peanut butter consistency. This makes filling holes much easier (to leaking out). Once dry, sand everything smooth.