Choosing a Joinery System for Knock-Down Cabinets

Cabinetmakers discuss alternative setups and systems for creating knockdown cabinet packages. September 23, 2013

Question (WOODWEB Member) :
We do a lot of retail fixtures and as freight costs go up we are looking for more economical ways to ship our fixtures. That brings us to building our cabinets for Knock Down or "KD" assembly.

We currently have been exploring the Rafix system. It's nice that you don't have to do horizontal boring for the lock and cam, but it's still warranted if you want to include dowels with the system. We've been doing this by hand since we can't do horizontal boring with our Skill FT and don't have a horizontal boring machine.

We have been exploring the idea of using a biscuit machine to "flush up" the corners of our fixtures rather than dowels and we came across the Lamello P System. We were curious if anybody has had success or failures with this system. Also if there is a more preferable system out there, I would appreciate the wisdom.

Forum Responses
(CNC Forum)
From contributor D:
I recently went from a beam saw and PTP to a nested base machine. We lost our horizontal drilling capabilities. We now produce a better cabinet. We use Cabinet Vision and have it set up for our cabinets to utilize a blind dado/mortis and tenon assembly. On unfinished ends we use 2" assembly screws and on finished ends we use a flush mount Hafela Rafix. We also utilize a 3/4" back on the cabinet. Many people freak out when they hear that, but for the material we use the price for 1/4" and 3/4" is close to the same price, and when you nest it all together, we use less sheets total so itís a good deal. All necessary machining is completed on the CNC, with no secondary machining. For cabinets, it takes us between 6-10 minutes per sheet to machine. We then edgeband and assemble, so there is minimal handling.

From contributor M:
I have gone all over the map with this issue. I think I have tried every system out there at least once. My advice is to buy a manual horizontal boring machine. It will only require set up once. Pick a pattern and use it on everything. My pattern worked on base, wall, tall and vanity depth cabinets as well as my three standard sizes of drawer boxes and nailers and drawer stretchers. I use Cabinet Vision and created an "intelejoint" that matches the boring machine and used it on every joint.

I found a manual boring machine is faster by a factor of ten than a CNC doweler or anything else I tried. I know Lean dictates reduced handling and all that, but it literally takes ten extra seconds per boring operation. I pull the part off the nested table, take five steps to the boring machine step on the pedal, then turn around and put the part in the rack for wrapping with its sibling parts for shipping. There is no extra handling, the part has to be removed and put in the rack anyway (unless you have an automated unloading and sorting robot). The only extra time is the few seconds the boring machine takes to bore the holes, and that happens faster than the router can cut a dado at a 400 IPM feed rate.

I ended up ditching the Rafix and going back to confirmat/dowels. My installers and resellers preferred the simplicity of the confirmats and I prefer the price! The confirmats are only used to hold the case together while the glue sets on the dowels. Most of my resellers did not use glue at all if it was part of a cabinetry run along the wall. No complaints at all. I had a lot of complaints with the Rafix and other cam systems. The exposed head of the confirmat was not an issue because we always use finished panels. If the design required hidden fasteners we just used dowels and clamped for five minutes while we hot-glue the backs. If it was to be assembled by others we used the cam system of their choice.

A manual boring machine costs 3,000 new and 1,000 used. If that is not fast enough look at a dowel insert machine. Again the manual multi head drill/insert machines are much faster than the CNC versions with moving heads. Not to mention they are more reliable and have almost no maintenance.

Dado construction is fine if you are assembling your own cabinets, but if you are sending them out to other installers you are taking a risk that they will screw it up. Also the joinery fit is always a pain requiring the operator to check new batches of panels with calipers and modifying the settings to tweak the fit.

Beyond my solution you are looking at dado joinery or screws and butt joints. Dados sound great if you are a smaller shop using plywood, but a large shop with mixed product lines that use melamine, plywood and other odd stuff. Situations where other, possibly untrained, people are assembling your cabinets dowels and screws are best.

From the original questioner:
We currently do create dados for in-house assembly, and you are correct in having to adjust the tool diameter frequently otherwise, those dados just don't fit anymore. Although I like the Confirmat system, we don't use partible board a whole lot. We typically use MDF with HPL the majority of the time for our fixtures. I think the end result is to spend the money on a horizontal boring machine and use the Rafix system. Can anyone recommend some good brand names for used equipment? My budget is $1,000-$1,500 dollars max! I know you get what you pay for, but the up-front cost of a nicer machine isn't justified since our production has diminished.

From contributor C:
I bought a used Lobo construction drill for $1500 or so and have run the heck out of it. We just locked it into the horizontal position and that's where it stays. It took some dialing in, but at the end of the day it has saved us a lot of time. It's one of those purchases I wished I would have bought sooner.