Thread: mdf Holes

I hope I'm not telling you how to suck eggs.
Use a sacrificial piece of MDF behind or under the piece that you are drilling. With MDF, drill must be sharp and don't force the drill through the work.
This should work, but try it out first on some scrap. If possible, clamp the sacrificial piece to the back of your work.
Good luck.

I read somewhere to use brad point bits on melamine to get a clean entry hole, because it scores the outside of the hole, this will probably do the same on MDF.

A forstner bit with Toyboys suggestion of a sacrificial block tightly clamped on the back.

Originally Posted by

A forstner bit with Toyboys suggestion of a sacrificial block tightly clamped on the back.

Yep and yep - Or if inconvenient, drill a tiny pilot and drill from both sides.

Small holes ... brad point bit; larger, as suggests.

If you don't need to finesse them, round end of a ball-pein hammer.

Ditto all the above.
Even the ball pein.

Remarkable! we all think alike, therefore we all have great minds!

Originally Posted by BobL

Yep and yep - Or if inconvenient, drill a tiny pilot and drill from both sides.

That is the way I do them if both sides of the hole are critical.

Dunno 'bout great minds. Innergrance x N just equals consensus ;-}

Al, yep, sometimes brute force is the only way to break through.

But to bring some finesse back into the picture, Tool, whatever you use remember that MDF is a pox and an abomination as far as wood goes. Cutting produces dust rather than shavings so play around with speed as well as force to get the best result. Make sure you start with sharp bits and note that it doesn't take much to dull them.

Don't forget: "Fools seldom differ."

I prefer a spade bit until the tip breaks through t'other side, then flip it over to finish the 'ole. For smaller holes, I go with a backing piece and an ordinary twist drill. (As far as I am concerned, if the customer wants precision they can at least supply decent wood to work with!)

I could sell you some mdf holes if you like via virtual download

Originally Posted by rsser

Cutting produces dust rather than shavings so play around with speed as well as force to get the best result.

That's another reason to use a forstner bit on a slow speed - this makes much more shavings than dust.

Dear Tool,

To control your tearout on exit, try drilling a pilot hole with a smaller bit first. Failing this, a piece of sacrificial backing timber behind where you're drilling through would definitely prevent the exit problem.

As regards your entry problems, could your drill bit perhaps be blunt, or could the cutting angles be a little out (as in, have you recently tried to sharpen it manually?). Otherwise, have a close look to see if your chuck wandering a little off axis...

Cheers,
Batpig.

Originally Posted by Batpig

To control your tearout on exit, try drilling a pilot hole with a smaller bit first. Failing this, a piece of sacrificial backing timber behind where you're drilling through would definitely prevent the exit problem.

I have tried pilot holes with mdf and have found that it seems to grab the drill bit and almost "pull" it through the hole making it difficult to get it out again. Mind you, this was with thick (12mm) mdf. For 6 mm mdf sheeting I don't bother with pilot holes but do put the old sacrificial piece underneath, or behind, to stop the hole blowing out.