I’m making a jig out of MDF. I have a piece of MDF with a lengthwise dado that will accept another piece of MDF. I want to attach the second piece of MDF to the first with counter-sunk screws. I put a 1/8th” bit in drill press, set the first piece of MDF on top of a piece of scrap to avoid tearout and tried to drill through the bottom of the dado. I did this so I could make sure the holes were centered in the dado. I planned to come back and drill the counter-sinks from the other side. When I drill the hole starts off easily, but stops abruptly like I’ve hit something very hard. I tried a second drill bit and I had the same result.
Thanks,
Zach
Replies
The outer layers of MDF are a little harder than the center, I think, but "stops abruptly" does seem anomalous.
I think the next thing I would try is drilling a pilot hole with a smaller bit and higher RPM, then enlarging it to your preferred size. If that doesn't work, try a brad point bit.
I understand why you're starting the holes from the dado side, but just as an experiment, you might try drilling a piece starting on the outside.
Brad points (dull ones) punch a disk out of the bottom of the work.
That disk stops all cutting, press harder and you'll burn up the bit.
Ergo, stop the drill remove the disk and get on with it. Twist or plexi drills do not produce the disks but don't cut as well in MDF either. Nuthin's easy.
ROuters
I just tried it without the scrap piece underneath and it worked like a champ.
"Routerman" is correct, brad point, "spade" bit & "Bullet Bits", all have that same effect.
John
Zach,
MDF will quickly clog up the cutting surface of a twist drill bit, especially a smaller diameter one (e.g. 1/8"). Your bit is unable to eject the drilled material - the build up literally clogs up the flutes to the point that the bit can't cut any more. Just back the bit all the way out of the hole, let the waste eject from the flutes, and finish drilling the hole. You should find that the remaining depth of the hole drills with ease.
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Zach
Ditto Jackie Chan (Dan). I have drilled thousands of holes in MDF with a twist drill bit. As long as you back out and let the waste eject, no problems. BTW, the 1/8" bit you mentioned is what I use on MDF for #8 Spax screws.
sarge..jt
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