Construction Boring Machines and Confirmat Screws

Tips on how to bore, countersink, and align cabinet parts for assembling with Confirmat screws. July 21, 2006

We are inching our way towards more efficient assembly and manufacturing. I'm fully embracing the 32mm system and need to upgrade our single fixed head Ritter line bore for a 2 head line bore machine. I notice many of these machines also do construction bore. The primary intention of the construction bore appears to be for doweled construction. I don't want to buy a case clamp and I'm wondering what kind of advice you all might have to offer regarding using the machine for end boring tops and deck and through boring ends for confirmat screws. Do you need to use a bit with a countersink in the through bore or can the confirmats be self countersinking?

Forum Responses
(Cabinetmaking Forum)
From contributor A:
This topic has come up quite often recently. You might want to do a search in the knowledge base under *confirmats*. We use confirmats and a construction boring machine, too. It is a good solution. Countersink is not necessary for melamine or plywood, but desirable for HPL. I am not familiar with 2 head machines that drill horizontally too.

From the original questioner:
There seem to be a lot of affordable line construction bore machines on the used market. Are there any recomendations out there? SCMI, Morbidelli, Vitap, etc.?

From contributor B:
I'm switching to confirmat screws, instead of a #8 self tapping, self countersinking,1-3/4" long screw. It's much heftier than what I've been using. I plan to use a 7/32" drill with a countersink collar. It works fine on melamine and particleboard. Plywood needs, in my experience, to have that first hole slightly larger to accommodate the smooth part of the confirmat.

From contributor A:
The top of the line is generally considered Ayen and Gannomat. Ayen drills from the top, Gannomat from the bottom. I prefer the bottom drilling. There are advantages for both. If you look at the Gannomat, I would avoid the Optima. It is a good, accurate machine, but the stops for drilling vertical holes allow for operator error. I have the Optima, but wish I would have gotten the Mentor. The guys at Gannomat are well versed in the strengths and weaknesses of the different types of machines.

Confirmats are metric. Try a 5mm for the threads and a 7mm for the shank. The shank is for alignment. Confirmats are considered to be a metal dowel and screw. Without the 7mm hole, you just have a screw.

From the original questioner:
We have been predrilling and using #8 zip-ax for years now, mostly on plywood. It still requires clamping the box together to achieve perfect alignment of edges, prior to drilling. If edges and faces are predrilled for something like the confirmat with such a meaty shank, then alignment will be right on without the one-armed-paper-hanger dance of getting things lined up before drilling

To contributor A: Do you find that to be the case that once parts are processed on the drill, alignment is a given?

From contributor A:
For the most part, yes. The alignment is only as accurate as the holes. But you have a little bit of adjustment. We snug the pieces together and then if we need to, tap the piece before we give it a final tighten. It's a great system. I also like the Fustabo screws. They have a high-low thread and a combi thread. You can use a pozi, a combi, or a #2 square drive.

From contributor C:
We've used confirmats for years, so based on our experience: *right on* alignment isn't always there but they do allow a little tweaking before final tightening. There are two different diameters of confirmat screws and several lengths, all metric. Check your Hafele catalog or online. Some brands have better nibs and will self countersink in melamine, some won't. To hold the parts in place before putting the confirmats in we have been using two old #2 Phillips screwdrivers that have been sharpened like awls. With them, you can hold or adjust the parts in alignment as you tighten the screws. Use Roo glue for melamine, yellow for plywood. We got a case clamp in a trade deal and have been using it with dowels for simple boxes; its faster than confirmats but not as versatile. On MDF you may have some separation of the core; if you commonly use MDF you may want to get a set of 5.2mm bits.

From contributor B:
Thanks for the comment that confirmats are metric, and that there are several sizes. You are right about the hole in the first piece must be larger than where the screw goes. That's a standard maxim for all butt joints with whatever kind of screw used.

To contributor C: Alignment is always an issue. I have found that the raw edge going against the flat edge in a butt joint must be dead on square, or the box won't line up, and hence, doors will be out of whack (I build frameless).