Using Dowels and Confirmats Together

A cabinetmaker gets advice on an assembly method that would combine Confirmat screws and dowels. September 27, 2008

Our shop has just purchased a construction/line bore that we are going to dedicate to dowel boring. Is it possible to add four confirmats to the assembly for clamping purposes? We do not have a case clamp yet. The cabinets are frameless, laminate, WI boxes.

Forum Responses
(Cabinetmaking Forum)
From contributor R:
You would need a 5 mm bit for the pilot holes and a 7 for three through-holes if the length of bit's were correct I would say it's possible, but why not just use cofirmats and skip the dowels?

From the original questioner:
The object with the dowel construction is to make the boxes easier to assemble. No alignment issues for the assembly person to be responsible for accuracy. Finished ends with WI will have to be all dowels, as applied panels are not acceptable. We are just setting up the machine, and I am waiting of a few parts from Italy before I can start my test runs. For most of the boxes, I can use some confirmats, but like I said, I want these to go together like legos. No thinking for the assemblers (even when itís me) to help eliminate mistakes. So we bought a machine to try dowels, but we donít have the case clamp yet.

From contributor M:
Confirmats are like a combination of dowels and screws. The 7mm shank aligns the parts while the screw holds it in place. I think you under estimate these things. Your alignment will be as accurate as your holes. When you go to assemble, snug them up. Let the nibs touch the outside part. Then tap into alignment if necessary, and sink the head a bit.

If you are using the construction boring machine to drill all your holes, you may be a ways off from needing a case clamp. Use the confirmats everywhere you can. Screw them and you are done. When you have exposed ends make sure to use dowels. Bessey K body clamps have worked great for us.

Case clamps work best when you can put four or more carcasses at a time. Otherwise you are spending too much time clamping, waiting, and unclamping. Case clamps are effective when you are doing institutional work where many cabinets are the same size. Also, try European Tooling for your bits. Good quality and great prices.

From contributor R:
After doweling, why not add a few pocket holes to clamp the bow while the glue dries? A few seconds on a castle machine and youíre done.

From contributor H:
Use the dowels and skip the confirmats, thatís what I recommend. Yes, your construction machine can use two sets of bits (5mm-7mm) or a step-drill but both require changing something. You would use dowels, just one set of bits and a direction change.

Confirmats cost more than simple self-drilling screws which would do the same job. Confirmats are dandy for knock-down use or some application that requires extra strength. If you do decide to use them, just don't use the hex heads which are prone to strip.

From contributor P:
In addition to changing bits, you'd need to reset the drilling stroke twice - first for the through holes, then for the pilot. Dowelled-only with pre-glued dowels works great for me - no space for a case clamp, but Jorgensen bar clamps do a fine job of assembly.

From contributor M:
To contributor H: I think you miss the point with confirmats. They are not knock down, they are RTA. Confirmats have nibs that help them resist backing out. These are not for countersinking.

"Confirmats cost more than simple self-drilling screws which would do the same job." Confirmats are dowels and screws. Confirmats are very accurate, and provide alignment. Assembly screws are much smaller and provide nothing for alignment, when it comes to changing the drill depth, you don't have to change between the 7's and the 5's. We drill our 5's at 35mm (which is actually 30 in the horizontal position). When the head is set in the vertical position, we would leave the setting the same. It is a drill through and needs at least 20mm for the tip to barely penetrate. Another 10 and it is clearly through. Ours is a Gannomat. I am not sure if others gain 5 when switched to the horizontal. And, for the record, we machine out parts on a router and horizontal drill on the construction boring machine.

From contributor P:
I realize it's not a big deal to switch the machine each time, but just one more step, and one more thing to screw up. I'm not averse to throwing in a few 2" screws to take the place of clamping, and for me it's quicker than changing the machine over - mine doesn't have QC chucks so I have to unscrew every bit.

From contributor H:
To contributor M: The way I read the OP, the question was to add confirmats with dowels. Yes, they (confirmats) are dowels. My thought, why duplicate that when the intent was to "clamp" the assembly? There, regular screws with the dowels to align would be cheaper, in fact it is what I use with 8mm dowels.

I once used confirmats and I do remember the terms knock-down and RTA being mixed usage (way back when) but Iím not sure now. The step drill sold for them does countersink the rim.

I'm using prefinished maple ply for everything we do. I'd suggest adding three through-bore 5mm bits in the system when using PBs to prevent screw splits and make placement neat.

From contributor M:
Confirmats 37 from ends, 128 oc, dowels 1 per 75 mm (64 oc in your case). European screw heads cannot be exposed on any grade.

Dowels and confirmats are redundant. Why would you do this? (I understand Contributor Hís point, but he is not pre-drilling). If you drill for confirmats, you don't need dowels - confirmats align like dowels. If you are doweling because it is an exposed end, you cannot have exposed fasteners, so why drill for confirmats?

From contributor U:
I use confirmats. One problem: the heads can easily strip and then I'm stuck with a screw that doesn't want to go in or back out. I think the screws are too soft of a metal.