Confirmat screws -- getting started

      A discussion on drilling holes for confirmat screws dives deeper into screw and dowel construction. July 3, 2001

If I were to transition to confirmat screws for carcass construction, what would I need to drill the pilot holes? I read that it takes a special step drill. Anything else to watch out for? I will be starting my first Euro style project and would like to use butt joints and confirmats. Any advice concerning assembly using butt joints? (We normally build ff cabs, using dados, glue and screws.)

Forum Responses
From contributor L:
If you want to get the benefits of systemic manufacturing at a basic level, take it off the bench and put the critical work onto equipment. Consistency and reliability come from holding tolerance, and tolerance comes from properly machined parts.

At your transistional phase, I'd suggest you purchase a "mini-fix" jig. Bush it to suit the diameter of the confirmat specification, and bore your horizontal members accordingly. Use either a drill press or your line borer (you can hand drill) to bore the vertical members. Although I prefer the larger diameter confirmats, you can use the ones with a 5mm shank. You can then use your line borer to drill through the vertical member at the desired location.

Tip for dual purpose line borers: Use 70mm length drills in the construction spindles to avoid removing all the other drills.

Does anyone make a step drill with a counterbore for confirmats? What would be perfect would be a long 6mm spear-point drill with a 7mm drill collar. This way I could drill both the through-holes for the ends and the horizontal holes with the same set-up on the same construction drill, just by varying the depth of cut. The drills need to have regular 10mm shanks. Any ideas?

From contributor L:
Have you tried the confirmats with "nibs" under the head? One guy I know bores with a bottom boring bit and lets it blow out the backside enough to provide a home for the screw head. Seems reasonable to me.

Yes, such a bit is available from several suppliers of the screws, Hafele, Hettich, etc. and some toolmakers. I believe Reliable in San Bernardino, California makes both carbide and H.S.S. step drills. That's right about the NIBS for the countersink. Each "step" produced on the bit increases the cost. S & G Specialty Fasteners makes a confirmat type with nibs and a point to help line up the holes/assembly.

In a perfect world I would look for a countersink as well! Right now I drill 6mm for the horizontals on one machine and 7mm for the through holes on another machine. I can add countersinks to the 7mm machine to take care of recessing the heads. I drill a lot of pre-finished maple for cabinet sides and blowing through with a bradpoint just makes a big mess.

So the perfect bit would have a 6mm spearpoint section 40mm long, a 7mm section that was 20mm long (we bore mainly 18mm stuff) and, of course, a 10mm countersink with a 10mm shaft.

From contributor L:
Since we're fantasizing, I've thought about having 10mm HSS drills ground to the proper diameters.

An alternative assembly screw which I have been using for about 15 years now is the 50mm x 11 gauge Titus funnel-headed screw. To drill the pilot holes and make way for the funnel head, I just use a standard machinist's drill bit with one of those Fuller countersinks on it. No stop collar required since they just get all jammed up with dust and eyeball accuracy works fine anyway.

I made some comparison tests with confirmat vs Titus--make a joint and then break it. Both worked fine. The particleboard is the weak link with either screw. I like the Titus because the drill setup is simple and cheap. Five Bessey corner clamps, an electric drill and driver and away you go.

Hafele makes a drill setup called Zentrix part 001.22.510. Get the drill as well and get the steel bits. The carbides are too fragile for homies with hand tools. The system works great if you want to use the screws and drill your holes by hand.

What's a mini-fix jig? Where can I see such a beast?


From contributor L:
These discussions always include the use of smaller diameter screws, and how they hold as well as the confirmats. Yes, the PB core breaks before the screw. The tricky part of the equation is the center core where the screw is "biting" is the weakest portion of the panel. The diameter of the confirmats replace the "pucky" center core. The larger confirmats reach even closer to the "fine" layers.

Another consideration? The smaller diameter can function like the sharp edge of a blade to shear through the panel. Which edge cuts quicker, the sharp face or back of the head on the ax?

Confirmats are a substitute for the case clamp and adhesive. Confirmats function as dowels to reference and locate the parts with consistent accuracy.

I think one thing to remember with confirmat screws is, as with all screws, the key is the pilot hole. This allows the screw to bite evenly all around its diameter without splitting the core apart. The larger the screw the more area it has to bite.

Courmatt can provide you with a carbide 2 or 3 step drill for the confirmat screws. We have sold a variety of different lengths on the countersink. Both right hand and left hand rotations are available.

I had a discussion the other day with a fellow cabinetmaker about which way is faster in the construction of cabinets, confirmat screws or dowels and a case clamp. He felt that the clamp and dowels were faster and I feel that confirmat screws are faster. What do you all think?

From contributor L:
That would depend on the equipment involved. Generally speaking, dowel construction assembles much faster than confirmats. I've consistently clamped a case a minute, hanging the doors and inserting the drawers "in the clamp". So for volume, I'll always take dowel construction or mechanical fastener over manually driven confirmats.

That's a good point. The Euro system was developed for speed and consistency, while using un-skilled and willing labor, and forced the improvement of machines. To accommodate the machine functions, dowels became more widely used. The result was fewer "turning" parts and more "knock-in" parts.

Thus the Euro hinge is inserted using plastic dowels. Most shops are now equipped with a hinge machine for the purpose. The Euro slide can be inserted using plastic dowels and cases are assembled using inserted wood or plastic dowels. Drawer boxes are doweled and even 45 plastic dowels are available for mitered corners.

The assembly screw is a very good and viable assembly method, but really it's a bridge from manual to machine assembly. As stated above, while assembling a cabinet, you're not turning an assembly screw, you're hanging doors. That is a simple explanation of "production" or efficiency.

To contributor L: You said that you have clamped a box a minute. That sure beats my confirmat screws. After the box leaves the clamp, how do you keep the box square until the glue sets up? I need to speed up my production and am looking at different means to accomplish this.

From contributor L:
A case clamp is useless to square cabinets. It presses together the parts it is given. In "my world", cabinets are squared in the machine department. A minute in the clamp with the proper adhesive can be sufficient if the tail line is setup correctly.

Many times, cases are clamped for long periods in an attempt to overcome the hydraulic effect of high viscosity adhesive, overlength dowels or improperly machined components.

I'm just getting started with dowel construction (case clamp and SCMI double row line borer will be delivered next week) and I wonder if it is better to use pre-glued dowels or glue capsules. I plan on pre-finishing the carcasses before assembly. Also, is it necessary or beneficial to use an additional adhesive along the butt joint or not? I'm building tall, free-standing entertainment center type units.

From contributor L:
The operative words are "free-standing", another kettle of fish from installed cabinets. You have to retain integrity of the joints while allowing for the perils of uninstalled casework. You must also provide for multiple openings, moldings and the critical nature of pocket doors.

You didn't mention the type of dowel insertion you will use, but I think you'll rest easier with a "glue as you go" process in tandem with a true furniture cleat block. I wouldn't rely on dowels alone to build this type of case.

You don't need the headaches associated with adhesive in the butts, besides the finish prevents it from attaching itself to the wood.

I wouldn't rely on a back panel to "hold" the case square. In high-end audio, an easily removed back is a sales benefit. PE the case to include vertical members tied to horizontals to achieve a square case. Think of the keel on a sailboat.

Do it right the first time, overbuild your mockups, and "backup" from there. There's no reason to cut a corner in construction, especially when dealing with this type of product.

Most of us here are not interested in turning out 500 boxes a day. If turning out giant volumes is your goal, one can hardly argue that dowels are the way. However, there is an associated cost involved. To do what you guys are talking about "in volume" you will need either multiple dedicated manual boring machines, or a P2P. With either of them you will also need some sort of automated dowel insertion. You will need a saw and software to drive this thing.

On the very cheap end you're going to have 85-90K in a small P2P, another 50K in a saw, 6-7K in a dowel gun, 5-8K in a clamp. You will also easily spend 30K on software. You guys know as well as I do that the machines I'm talking about here are not able to produce the volume you're talking about, but it does give us a reference for the sake of argument--say 180K for an entry level doweling setup.

The other side of this: with a couple of 12K boring machines you will have a nice setup for using confirmats/European assembly screws. You can get in a decent slider for 30K, so for 54K you can have a good setup for doing smaller volumes.

My point here is if you're making a buck turning screws, what enticement is there to go into business with your local banker? Higher volume? Does higher volume really translate to more profits in this industry? Especially in a small shop, which is how I'm looking at this. I ain't even going to go into how I fit the saw, P2P, clamp, dowel inserter into my 24'x24' garage:)

If you're making a buck turning screws, do it. If you want to make a buck and a quarter maybe the banker doesn't look so ugly. You are also right that increased production doesn't in and of itself make you more money. But dowels will allow more and more efficient box construction. Dowels are really pretty well accepted when you look around the shop at the applications and potential applications. Those facts don't dispute the viability of an assembly screw. The dowels do feed the need for speed.

You're absolutely right about the challenges of a free-standing unit as opposed to an installed cabinet, but most mass-produced entertainment centers that I have seen are dowel constructed or KD.

The key to the strength IS in the design using vertical pieces as stiffeners. I want to get the best glue joint possible using dowels and was wondering if using pre-glued dowels has any advantages or disadvantages over glue capsules. I do not have a dowel inserter but I think it may be a wise investment.

From contributor L:
Nothing wrong at all with confirmat construction--it's a moneymaker. Confirmats or mini-fixes take the place of a case clamp and most of the adhesive. Confirmats are a form of dowel, at least in the way it functions. In smaller batches, and with limited square footage, this is likely the preferred path, especially if there is an eye towards growth.

Growth requiring semi or unskilled labor could be time to re-examine the dowel issue. At this point, a fully doweled case can begin to make sense.

One of the reasons I am high on confirmat construction is the changeover to fully doweled cases is so simple. It is simple because the cases are constructed just like I would with a fully doweled case.

In confirmat or mini-fix cases, I use dowels, typically glued, in my rails, rather than two confirmats. On runs of a hundred or so, I'll usually pop a couple of dry dowels into the full depth horizontal members to aid the assembler in alignment.

Increase the numbers, and I'll replace the confirmats with glued dowels. I liken this to planned growth instead of being pushed into reinvention in the heat of battle.

For equipment, the semi-automatics can deliver a large quantity of high quality components. The P2P can quickly hit its peak. Can't a dedicated horizontal borer/doweler, a double line borer and a construction borer be had for about the price of a P2P? And these machines are always "in demand" in a growing operation.

We don't need to always optimize our speed of operation, since we only make money on the performance of the total operation.

I posted something like this in debates with the true 32 team. The reason I recently bought a horizontal boring machine, clamp and inserter was for my eventual road to a point to point. One of the biggest obstacles is the learning curve and the acceptability in any shop of new technology. I never wanted to buy a point to point without a shooter and a clamp because what I'd have is basically a really expensive way to drill holes for screws. The fastest machine in the shop will only be the bottleneck until you have established a flow of equal times for different processes or cancelled out times for extended processes by doing something that is not affected by the bottleneck while the bottleneck is doing it's thing.

I know this sounds confusing, but here's an example. While cabinet parts requiring finish are in the spray room and drying, you could be working on drilling pre-finished doors or putting tracks onto pre-finished and pre-assembled drawer boxes.

Another example: use the point to point only for the cabinet sides (if you don't use partitions), keep your existing horizontal boring machine set up only for end drilling on floors, tops, stretchers, and kicks. As was said, you could actually upgrade from your horizontal borer to a borer/inserter for about 20,000 more. You can do 1 side every 30-45 seconds on a point to point, but you can do two horizontal rails drilled and inserted if upgraded to this machine in 1/3 the time. In fact, a point to point is a real bottleneck maker if you decide to use it for every part. This assembly speed is only attainable with a dowel method, not staples and screws or blind dados. It's a constraint of the machinery available to process parts at this speed. They simply want to drill and shoot dowels, not confirmats or staples and screws.

This is expensive stuff, and it's true that you wouldn't be able to produce hundreds per day with a point to point. The method you choose must relate to your entire mode of doing business--that means gross, personnel, budget, machinery and communications.

From contributor R:
I went from dado and screw construction to manual dedicated boring machines with a hand held dowel shooter to a point to point and a horizontal drill/inserter, which is probably where I'll stop. I gained significant throughput at every increase in machinery capability. I never went through the butt joint with staple and screw phase that I have been reading about, because I never thought it would be adequate and it seemed like inferior construction--I have learned different from my reading here and on True 32, but not enough to go back.

The point to point has made a significant positive difference in our casework production, (partly because it simply helps to force a new level of rationality on the process). But the point to point has truly revolutionized production of most of the other things we make besides boxes, and that is where it is really earning its keep. It is also bringing in a steady flow of highly profitable piecework from other businesses who haven't made the technological commitment but who need the results.

The underlying message here seems to be growth, but for what reason? There is a stigma that if you are bigger, you're making more money, and the two don't necessarily go hand in hand.

In our FF shop, we had 10 people running the finish department in two shifts. I nearly ended up in the hospital with stress fatigue, and we were loosing money hand over fist. There were several factors working in that situation, but I can now do with 1.5 people nearly what I was doing with 10, we make a profit, and my stress level is nearly 0.

My point is that I am making money at what I'm doing, so why should I want to add the complexities of doweling into the mix? I don't want 15 people in my shop. I only need to depend on 2 guys to show up for work. I just don't care to be big for the sake of being big. I see the headaches my brother goes through trying to get and keep employees in his shop and I don't need it.

To contributor R: is your entire system up and running yet? Are you labeling at the saw, and using barcodes at the P2P and Hdrill/inserter? How long to get this thing going and all the associated hiccups ironed out? What has happened to the bottom line? How long to learn, set up, and implement the software?

From contributor R:
Yes, it is working now, labeling and optimizing at the saw, and using barcodes at the P2P (my inserter is not CNC). We installed the software in January and were getting good cutting lists downloaded to the saw right away, but it took until the end of February to iron out various hiccups in the barcoding. This compares favorably with our experience with Woodwrite Systems 10 years ago (now defunct), Cabnetware 8 years ago, and IMOS 2 years ago. I hope we're done experimenting with software- it feels like it.

It's too soon to say how the bottom line is affected, but throughput is already improved. Our worst bottleneck has been in the office, getting work from the returned submittal stage out to the shop to start processing, and Microvellum is already cutting this time radically. Fold in the accuracy of cutting lists, the ease and efficiency of cutting well-optimized parts and the speed of barcoding at the p2p and I think it will pay off very quickly. I couldn't say how life would be if we had never started with dowel construction back then, but our evolution from manual to automated has been a success. I think that with the right tools, doweling actually simplifies things, but the cost of the tools is prodigious. The shop almost looks like my vision of what I wanted when I started- quick, clean, quality. Now we've just got to learn to relax!

I may be a very lucky businessman but I have a payroll of 34 and no current employee headaches. When I bought the business all the problem people quickly left (10 of them are currently working for one of my competitors!) and the remaining group is dependable and working hard. I am trying to create some common goals, both financial and otherwise, and we are working together as a group for the first time in 10 years. An intangible benefit of the technology move has been the change of work and attendant excitement for at least 5 of my employees who might have otherwise been deadening in their careers--these guys are supercharged right now and carrying others with their energy. Learning new things is a great motivator.

I don't have any interest in being big for the sake of being big, either. We were the biggest in our state for several years and the bigger we got, the less money we made, to the point of near collapse. I like the size we are because it enables us to take on the projects that no one else can. I'd really like to shrink a bit because I feel exposed to a downturn in the economy, and I don't especially like to work as hard as we do currently. But I really enjoy the challenges we face and I am gratified that realizing my personal set of goals is also providing a good and rewarding living for a whole lot of other people and their families. If I stop liking my employees, I guess I'll stop liking the business and stop wanting to enable them to get where they want to go. So far I'm getting what I want out of the whole thing.

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