Countersinks and Self-Sinking Screws

Countersink bit and self-countersinking screw recommendations. April 9, 2008

Our boxes are primarily melamine that we assemble with brads and #8 zip screws. I use a countersink with drill bit in the center to pre-drill all screw holes. I've used at least 5 different brands that don't seem to hold up. I've used Hitachi, Ryobi, Lee Valley (which were the best so far) and a couple of others. They all dull too quickly. Does anybody know of a commercial quality setup like this made for production?

Forum Responses
(Cabinetmaking Forum)
From contributor J:
Amana #55204. They last and last. Just don't side-load it at all while boring with the stock center bit. It snaps like a twig and then the carbide countersink hits it and blows up. $25 gone.

From contributor K:
I use drill bits and countersinks from WL Fuller. They make a nice assortment of bits and countersinks. I use a lot of #8 flat head wood screws in about 6 standard lengths and keep the bits and countersinks set up for each length all the time. I like the type "K" countersink on a fast twist drill bit. The fast twist has more flute to fill up with dust before it needs to be cleared so you often don't need to clear the dust at all for lengths up to 2" long. I also buy lengths of drill bits appropriate to the length of screw so that when I tighten the set screws of the countersink onto the bit, the set screw tightens on the solid shank and not into the flutes. If it does, the countersink tends to twist on the bit and change the drilling depth and can blow out the back of the work piece or cause the bit to break.

From contributor L:
Festool has one.

From contributor K:
Get better screws. I only countersink if I'm going to plug it.

From contributor N:
I have used Amana countersinks for years. I am an installer and find that these hold up really well. I have several and always have one sent off for sharpening. I also use Deerwood Screws that do not require a countersink for all pb style cabs.

From contributor T:
We also get Deerwood Screws W/NIBS. Self-countersinking, and now everyone in the shop has their own impact driver.

1 1/4", 2" and 2 1/2" in zinc.
1 1/2" and 3" in black oxide.
Harder to grab the wrong screw length.

From the original questioner:
Thanks for all the responses. I will definitely try some of these countersinks. The issue was brought up about the screws. I use #8 zip screws from Hafele. Good screws. Have #17 tip and nibs under head. I tried to use them without pre-drilling, but it seemed to bulge the melamine where it went in. It sounds like some of you don't pre-drill before screwing. Is this true? The countersinkng is something I found that helps the melamine not crack so much around the screw head. The use of impact drivers was brought up. What is the advantage? I have never used one except the hammer drill type for drilling into tile.

Contributor T, that is a great idea about the different color screws for the different lengths. I have both zinc and black, but have never thought about using them to help not grabbing the wrong length.

From contributor K:
We also use the Amana countersink. It's the best one I've found. We use a countersink despite using plywood for our boxes and having 5mm pilot holes predrilled. The screws simply perform better. You also asked about impact drivers. Impact drivers are not like the hammer drill you described. They are small, lightweight with incredible power. The impact driver has replaced the typical screw gun in my shop for cabinet assembly. I think it's one of those advancements that comes along every 20 years, something like the random orbit sander.

From the original questioner:
What brand of impact driver have you found works well for you?

From contributor K:
They all seem to work well. Between the ones I've bought for the shop, the ones guys have brought from home, and the ones my installers have, I've tried or held Makita, Bosch, Dewalt, and Hitachi. I like the 12 volt Makita best of all. It's small, light, fits the hand well, has a nice angle to the head, and has plenty of power for anything you'd want to do. Remember, a 12 volt impact driver will outperform even the biggest cordless drill when it comes to driving screws.