Counter-Boring for Cabinet Assembly

Is there any way to speed up the process of drilling pilot holes for screw assembly of cabinets? July 28, 2007

I'm looking for suggestions on a quicker way to drill pilot holes for screws in end panels. Currently I assemble the cabinet with staples, then drill a countersink/pilot hole for each screw. I'm considering buying a single row line bore, replacing the bits, and using it as a dedicated machine to drill these holes before assembly. Any suggestions would be appreciated.

Forum Responses
(Cabinetmaking Forum)
From contributor S:
With the right screw you can eliminate having to drill a pilot hole altogether. CHS carries a screw that I use and with the countersink nibs and type 17 tip, it works fine in all sheet goods except the cheapest big box store 5/8 melamine.

From contributor H:
Same for me. Flat head #8 Robertson with nibs. Never pre-drill. Stay at least 1" from end of panel. Trainees always pre-drill with a carbide Amana countersink till they get used to the centerline of the panel. Some never pick it up and are dismissed.

From the original questioner:
Thanks. I use a similar screw and still prefer the pilot holes.

From contributor F:
If you are driving a screw through one panel face and into the edge of another panel and you prefer to use a pilot hole and counter sink the head, I don't think there are any machines that will do that job. Not cheap machines anyway.

The only way I know of to speed that operation up is to learn to sharpen your drill bits and countersinks and keep them sharp. That is much faster than using dull ones.

Other than that, also use a drill motor with some real power, not slow underpowered cordless type drills. Also, learn when you need to back the drill bit out to clear the cuttings.

A small 3/8" right angle corded drill motor is usually pretty comfortable for that type of operation. I am sure these new self-tapping screws are pretty good but I prefer the sureness of knowing I am not just forcing a screw into the material.

From contributor R:
I would have to assume that you are using melamine. The quickest way is to make a template and drill all the holes while the panels are on the flat. You might want to consider moving to pre-finished plywood or outsource your cutting and boring to a CNC shop. The cost difference between the labor to drill the holes and the plywood would be close to even.

From contributor F:
The problem with that scenario is that all you could be drilling with your template and flat laid parts is the clearance hole and countersink. You still need the pilot hole in the connecting part... That's the one that is same diameter as the screw shank minus the threads.

It is faster to hold the two parts together with a couple of staples... Then drill the screw holes with clearance, pilot and countersink machining all in one bit. Or use self tapping screws.

From contributor S:
Before I started using type 17 screws, I would also drill a pilot hole with a Smart Bit used for countersinking on deck boards. It drilled a 1.25" deep pilot hole with a #6 or #8 countersink.

From contributor A:
I can't imagine that you will save any money using a machine to drill those holes. You will have to drill in the side of the panels as well as in the ends of the tops/bottoms. You might as well switch entirely to doweling or Confirmat fasteners. How much time can it possibly take to drill pilot holes? Keep in mind that you are drilling through both parts at the same time. Stick with the pilot drill.

From contributor F:
Can someone tell me if Confirmats are the same thing as "screws with nibs"?

From contributor S:
No, confirmat screws are basically a 5 or 7mm steel dowel with threads and require a hole drilled with a special stepped drill bit. Screws with nibs are a basic assembly screw with a wood cutting tip and 4 small nibs on the underside of the head that countersink the head and do not require pre-drilling.

From contributor L:
We pre-drill the end of our cases with a 7mm v shaped pointed bit and the ends of decks and case shelves with a 5mm brad point. This is done on our ptp. It makes assembly a breeze. The special bit is stepped and you can buy them with a spring loaded guide from Hafele.

To the original questioner: We tried what you are asking with a Delta manual line borer. Used 5mm on the end panels. You need to change the bits to a 5mm panel drilling pointed bit. This will give you the ability to run through the mel without too much blowout. Worked great. I quickly upgraded to a ptp.

Have you looked into used construction borers? I know someone who bought a couple for 4k. One is set up for case/panel ends, the other case shelves... Uses 2 8mm bits and 2 5mm bits spaced at 64mm (? - not real sure) at right side and left side respectively, 4 dowels per box, 4 confirmats per box. The interval setup allows to leave everything in place and not move anything between walls and base pieces.

I am actually looking for used ones also. Although I have a ptp, it has gone down and man it is a mess when it does, and clients want their cabs.

I am looking to set up the const borers, the line borer (have it), and an old hinger that I can swivel head around for hinge hole plates placement. The above system is a low dollar backup.

I used the nail/pre-drill system for 10 years and hated every minute of it, but I have a suggestion that got me through - get the nib/auger pointed screws as listed and pre-drill with 1/8 bit no counter, nail the cases together with 1 1/2 nails and build in runs of four. Built 185 cases this way - the drawers were hell.

Another suggestion: we notch our cab backs in at 1", leaving a 3/4" offset for cleat. We pocket these in and sometimes just nail them in for bases. This really helps and takes some of the frustration out of squaring up the boxes.