The Advantages of Construction Boring and Dowel Assembly

January 29, 2010

Reprinted with permission from Tritec, importer and distributor of Gannomat machines.

If you are constantly thinking this about your cabinet business: ďI donít have anything but a few hand tools and I can walk away anytime,Ē you might as well quit reading right here. This article is for people who want to be successful and are looking for a better way to manufacture cabinets.

Letís assume some things:

1. Your monthly fixed costs donít change.

2. Your number of workers stays the same.

3. Your workers and you are busy all day.

4. Most jobs are under a deadline.

5. You are making some money building cabinets, but would like to improve profits.

6. Your philosophy is, "Iím in business to grow and be successful."

You may be using one of the following cabinet construction methods:

1. screws/staples

2. dado/blind

3. Confirmats, or equivalent

4. pocket screws

All of the construction methods above can be sped up by adding sophisticated equipment. Question is, what improvement would there be in using expensive equipment when the final product still has to be bench assembled?

Letís eliminate the above construction techniques one by one for their obvious weaknesses.

1. Screws/staples - It would be hard and expensive to automate this process. The holding power of screws and/or staples is questionable, especially in melamine board, be it particle or MDF. Blowouts from screws and staples can shrink profits fast. Bench assembly is required.

2. Dado Ė If done with a sophisticated router, itís a wonderful ďold timeĒ construction method. But assembly requires skilled workers to assemble the parts without gaps showing, and what do you assemble with - screws, staples? This is without a doubt the slowest method. It requires a number of bench workers to complete many finished cabinets.

3. Confirmats - This requires a sophisticated machine with both horizontal and vertical drilling capacity, and the screws themselves are expensive. Keeping alignment without dowels to register and align is close to impossible.

Confirmats were introduced by a hardware company back in the 1970ís. For some RTA applications they are okay, but for productivity they canít match dowel construction for the simple reason that cabinets must be bench assembled.

*Note: Using the above three methods, screw ends or staples will show, which means cabinets with finished ends have to go through another

4. Pocket screws Ė The biggest problem is aligning parts correctly. Like Confirmats, to register and align parts you may want to consider using dowels. Bench assembly required here too.

*Note: All of the above methods use bench assembly, and squaring cabinets for unskilled assemblers can be a problem. Itís also easy to rack cabinets. Either of these problems will cause loss of time all the way through installation.*

Which brings us to dowel construction. Dowels have been part of assembly forever, whether with chairs, cabinets, or frames. The reason is this: dowel construction is extremely strong. Dowels are also inexpensive and there is a lot of machinery available to insert and assemble with dowels.

Here are some advantages of dowel construction. Once parts are machined, dowel assembly forces the assembler to put the work piece together the correct way. There are no screws peeking out and no misaligned parts. To speed assembly, a case clamp should be used.

Eliminating bench assembly means while the cabinet is setting up in the clamp, the back can be installed on the clamp-squared work piece. While glue is setting up the next cabinet can be pre-assembled and readied for when the preceding cabinet comes out of the clamp. 3 to 5 minutes of clamp time is required for initial setup of glue, depending on temperatures and glue used.

So whatís the difference between bench assembly and case clamp dowel assembly?

1. Bench assembly requires a more skilled worker.

2. Complexity is reduced dramatically.

3. A worker using a case clamp is actually working on one and a half cabinets at a time. Case goes into clamp, back is applied, next cabinet is readied for the clamp.

4. Depending on material requirements, there is no extra step required for finished ends.

5. Uniformity of cabinet assembly quality is much improved. Flaws are eliminated that crop up in bench assembly.

What does it take to set up a good dowel construction operation? It takes three machines to complete dowel boring successfully (assuming you have a saw that can cut squarely, and an edgebander):

1. An accurate dowel boring machine.

2. A machine to insert the dowels into the parts. (Start with a pistol type automatic glue and dowel inserter).

3. A case clamp to clamp cabinets with enough clamping pressure to close all joints tightly, and of course square the cabinet. Some of these tools are available for cents on the dollar. My only suggestion is buy a new glue and dowel inserter with electronic - not pneumatic - control.

Do your homework on the machinery you plan on buying. A little more money on a monthly lease for better equipment is worth it.

This article is not meant to be a time study. There are so many variables that go into cabinet milling and assembly and this is true for dowel construction too. On the other hand, there are many success stories from companies that have used dowel construction techniques. I will be glad to put you in touch with any of the people behind these success stories.

Finally, dowel construction is a uniform process. Ask any efficiency expert how important uniformity is to overall efficiency, and Iím sure they will say itís number one on the list.

Reprinted with permission from Tritec, importer and distributor of Gannomat machines.