Thread: Splitting MDF

Use a pilot hole bigger than the shank of the screw, but less than the threads of the screw. 3.5mm pilot hole is what I normally use on 8g and 10g screws.

Agreed. There is a goldilocks zone. You want the inner shank of the screw to be the perfect fit for the drill hole. That way only the sharp spiral of the screw is grabbing the MDF.

Too loose and the threads won't bite.

If you need to fix the split MDF, pre-clamp it closed (hard) and put a few drops of super thin CA on the split. The MDF will suck it up and glue it closed hard. Easy way to fix a flub

You could drill the end grain out larger, and glue in a wood dowel.

What the others have said. You really only need the hole to be ½mm smaller than the threads for them to grab. If you want more strength then put some glue in the screw hole first. If you need even more strength then use proper timber.

If I can reach the area where the screw is going, I place a clamp over this area before inserting the screw. This causes the screw to bite into the MDF rather than just pushing it apart.
But as others have said, make sure you get your pilot hole sized correctly first and use screws with good sharp points on the flutes.

The problem may be that the screws are too thick a guage. I like to use long thread particle board screws. You may have to play around with different guaged screws to suit the project.

Also, if you're too close to the ends, a pilot hole won't help you. I try keep screws about 50mm from the ends; you could probably go down to 40mm, but not much less.

Originally Posted by elanjacobs

Also, if you're too close to the ends, a pilot hole won't help you.

Good thing to point out Elan. It should be remembered that MDF is much closer to cardboard than timber (really), and behaves as such.

Thanks for your time. It's working well now.

Regards,

KB

Thanks woodPixel - but what is CA?

Regards,

KevinB

Thanks for your time and efforts everyone.

I've taken it all onboard for another MDF job this weekend.

Good luck and best wishes,

KevinB

CA=CyanoAcrylate (sp?) aka SuperGlue

Originally Posted by FenceFurniture

.... that MDF is much closer to cardboard than timber (really), and behaves as such.

I've never tried to screw cardboard together

Especially end-grain cardboard.

Thanks Fence; the penny drops.

Regards,
KevinB