How to ‘Time’ or ‘Clock’ Your Screw Heads
First a warning: Don’t read this blog entry if you already obsess too much over the details of your furniture. This entry could only make things worse.
Years ago, a high-end finish carpenter infected me with a disease for which there is no cure: clocking your screw heads. What is “clocking” – sometimes called “timing?” This is when you get the slots in all your screw heads to line up, either horizontally or vertically.
This carpenter pointed it out to me on a job he was working on. When he installed switchplates or hardware on cabinets, he always clocked the slots and said it was a mark of good workmanship. Since that day I have always looked out for clocked screws on furniture and cabinetry and have clocked my own screw slots when they are visible.
It’s a fairly uncommon feature on furniture, though it is common in other trades. I’ve met gunsmiths who clock all the screws on high-end firearms. I’ve also seen it on nice astronomy equipment.
So how do you do it?
Well there are lots of methods – enough to write a 10-page article on. When you are driving machinist’s screws into metal you might even use special screws designed for this. The head of the screw comes too tall for the hole. So you drive it in and mark where you want the slot to go. Then you remove the screw, file the head flush and cut a new slot with a hacksaw.
There are also ways to clock screws by machining the underside of the screw head.
In woodworking, you don’t need to go to those extremes to clock your screws. The way I do it is fast. It adds only a few minutes to installing a piece of hardware. But before I show you how, let me stress that this is not something I recommend you necessarily do in your furniture. I get obsessed about hardware and I might have mild OCD. That said, here goes.
1. Do all this before you color your hardware (if you are going to color it). This process can remove some of the color from your screw countersinks.
2. One method that some people recommend is to drive the screw, then remove it and just drive it again. This method doesn’t work well for me. I don’t want to cross-thread the wood and potentially weaken the screw’s grip.
3. So what I do is to drive in the screw and note how far off the slot is from vertical. Then I remove the screw.
4. Sometimes I will take a countersink and twist it by hand to remove a little bit of metal in the screw’s recess. This is fast and it works well – it usually takes four or five twists to adjust a screw by a quarter-turn. I actually don’t prefer this method, however, even though it is fast. I’d rather adjust the screw (which is disposable), than the hinge (which is expensive).
5. So what I do is wrap the threads of the screw in some masking tape and chuck the tape into my drill press or a cordless drill clamped to my benchtop. I set the drill on fast speed and spin it. Then I take a triangular saw file and touch it to the underside of the screw head. This turns the underbelly of the screw head down a bit. It takes only about 5 seconds of filing to make a difference. Then I unwrap the screw and drive it in.
By the way, I’m not alone in my obsession. Toolmaker Colen Clenton clocks the heads in his beautiful squares. He uses square-drive screws and clocks them to look like diamonds. Nice. There probably should be an encounter group for people like us. I’ll bring the doughnuts.
— Christopher Schwarz
P.S. I know there are still other methods for clocking screws that use epoxy. But I’ve done enough damage today already to your supply of valuable shop time. And if you think I am compulsive, then you should read James Krenov’s masterpiece “A Cabinetmaker’s Notebook.” Krenov was the king of details and opened my eyes to many things important to the craft.