How many confirmats?
Determining how many fasteners to use per joint in frameless cabinetry. April 2, 2002
Question
How many confirmats do you use on a typical 24" base per joint? Also a 20" base, 15" upper and 12" upper.
I primarily build face frame with dados, but when we build frameless, we use confirmats and on finished ends use the blum kd fittings.
Forum Responses
From contributor P:
Per joint, 4 in 24", 3 in 20", 3 in 15", 2in 12". And to top it off, a little dab of hot melt on each hole before applying the screws keeps the case steady while installing it in the jig. This may also depend on how you are building your bases, since they are different than wall mount cabinets, and you may want to add dowels to the floor panels.
From contributor R:
I thought you were supposed to do them the same as dowels: 1 each within an inch of each end and then every 6 inches.
From contributor P:
It winds up that way on the floor panels when you use the dowels, and they also help in lining up for the screws. On the wall mounted cabinets, which are usually 12"deep, 2 - 2 1/4" per joint with hot glue is a permanent bond.
From the AWI Quality Standards, Section 400, page 153:
"The use of steel "European" assembly screws is added to the 7th edition as acceptable for all grades of work. The illustrated screw is to be used a minimum of 37mm from each end, with subsequent screws spaced a minimum of 128 mm on center. Glue is not required with this system."
The illustrated screw is 50mm long with an 8mm diameter shank. Clearance hole is 8mm diameter and pilot hole for threaded portion is 5mm diameter.
You are correct about the AWI specs. Just one thing - where does one find a European assembly screw with an 8mm diameter shank? I brought this issue up with one of the members of the committee that writes this stuff for AWI. He was completely dumbfounded - he had no idea what was even available.
The Hettich Directa and others were all 8mm until Hafele introduced the 7mm, to gain a price advantage most likely. As the screws found more acceptance and became more widely available, the prices were driven lower. Now Hettich offers the smaller Directa 2 that is 7mm and for that matter a Directa 3 that is even smaller. I would guess that German manufacturers, including Hettich, could make an 8mm available from an inventory somewhere in the world. The underlying reason for 8mm was to be consistent with wood dowels in the same case for drilling of the assembly holes. Nothing solved with the AWI spec mentioned here but there may be a way if absolutely necessary.
If by hot melt you mean the typical EVA adhesive, it's not structural - if you are using PUR, it is. We use Roo glue or its equivalent. It is structural and allows the panels to fit tightly together. We use 6/24", 4/12" of the 7mm x 50mm. Check to be sure the pilot hole size you use is not too tight and causing the panel to split. 5mm is sometimes a bit too tight, especially in MDF. 5.2mm bits work better there.
From contributor R:
It figures that the AWI is on a different wavelength. It seems logical to me that the 7 mm is preferable anyway, especially if you use 5/8" (17 mm) case goods because your screw to edge distance is a hair less. This wouldn't matter most of the time but it might depending on your hanging method or how big a Miss Piggy you put on top of the cab.
From contributor A:
The only way to make the AWI spacing work on a 12" upper is to use only 2 confirmats in the joint.
12"= roughly 305mm
305- min. 37 from edge=268
268- min.128 to next con.=140
140- min.128 to next con.= 12
Not enough cabinet left to be 37mm from the other edge unless you build 13" uppers. Who thinks this stuff up?
One interesting thing to note: Based on AWI, a cabinet which is 4' deep could also be made with only three Confirmats! Notice it says "with subsequent screws spaced a minimum of 128 mm on center", which is still open to interpretation. An informal pole here at “Confirmat Central” (Häfele) found an almost universal agreement that up to 18” or so two is sufficient, and on 24” three to four max on each joint. If glue is used on the joint, three is the quantity of choice.
From contributor R:
I have never read the AWI specs but I would interpret "37 mm (1-1/2") from each end and a minimum of 128 (5") on center" to mean no more than 37 from each end and no more than 128 on center. This translates into 5 for a regular base, 4 for an 18" cab, and 3 for a 12" upper.
From contributor A:
The above quote from AWI was word for word. A minimum (not less than) 37mm from each end, with subsequent screws spaced a minimum (not less than) 128 mm on center. It is right that there is no maximum on center called out in the AWI standards.
