Intro
I am very pleased to introduce an article by someone who has been major figure in the packing and crating field for many years. I'm not going to attempt to spell out the full extent of his experience, but suffice it to say that on the East coast if you didn't train with Rick Yamada then chances are that you trained under someone who did. In my case I did both!
When I first approached Rick about writing something for the website I had no idea what he might want to write about.
When he told me his topic I couldn't have been more impressed. Like any master of a discipline the choice to focus on the fundamentals, the nuts and bolts as it were, demonstrates an important aspect of true professionalism.
Having an understanding of theory is important of course, but all of the ideas in the world can't act as a substitute for having a basic understanding of the tools and materials of the trade, and how they work (and sometimes don't). I can think of no one better to initiate this area of discussion than Rick Yamada. I will be right behind him submitting content on the website about my absolute favorite piece of hardware, following his lead. T. Ashley McGrew Publications Chair PACIN
My speciality for the past twenty five plus years has been high end, museum traveling exhibit crates and packing with all the bells and whistles. Accounts and pictures of these projects are popular and interesting, but I think the greater need, and the larger benefit, is to address some of the more common issues that we all in the world of museum packing and crating face on an everyday basis.
I am going to concentrate on a single component we all take for granted: the lid screw.
I venture to say that the majority of crates built for packing art have a lid that is sealed with screws, not bolt plates, lag bolts, or cam locks, but screws. I would further venture to say that a majority of those screws are drywall screws. I realize that, like any of the materials and hardware we use, the choice is largely a matter of what is cost effective, available, and functional.
A prime factor in the choice of any item of hardware is that it perform the task for which it is intended. No one piece of hardware is going to be ideal for every application, so the wider the range of options you have to draw from, the better chance you have to match the exact hardware solution for the task.
I want to present an argument for the consideration of the square drive, washer head screw as an alternative to the drywall screw as a crate lid attachment hardware.
The drywall screw has several variations. The most common is the flat bugle head, Phillips drive, straight shank, with either coarse or fine threads, depending on the materials being joined. (see picture below.)
As originally designed, the flat bugle head of the screw was meant to countersink itself down flush to the surface of the sheetrock or drywall panel. The slightly rounded edges of the Phillips indent meant that the driver would slip, or cam out in a high torque situation, thus preventing over tightening. Because the sheetrock panel is flat against the wall studs, the screws have to do little pulling of the panel. What holds the panel on the studs is the vertical shear force on the shanks of the screws. For installing sheets of drywall this is an ideal piece of hardware.
The issues involved in fastening a lid to a crate are different. In order to tightly attach the lid to the crate, the lid has to be pulled flat onto the walls of the crate. To accomplish this, the head of the screw has to resist sinking itself into the crate lid surface. A drywall screw, with its bugle head, will tend to drive itself into the surface of the lid, unlike when attaching sheetrock, where it sits flush to the surface. So as the screw head sinks into the crate lid, it is not necessarily pulling the lid tighter to the crate body. At the same time, the Phillips indent allows the driver to cam out, thus preventing the screw from being tightened past a certain point. A pilot hole through the crate lid helps the threads of the screw to bite more readily into the crate wall, but will not prevent the head from sinking.
Additionally, as the screw head sinks into the crate lid, it tends to tear wood fibers surrounding the entry hole. When it is time to remove the screw and open the crate, these fibers can make it difficult to determine if there is a screw in the hole at all.
A common solution to the head sinking tendency has been the addition of finishing washers to the screws ( see picture below).
This adds costs, not only the additional price of the washers themselves, but the additional step in the process means additional time. Also, the washers that do not remain on the crate lid after the screws are removed are most often crushed and unusable. Using flat washers only adds to the cost, as they are more expensive than the finishing washers and none will remain on the crate lid after the screws are removed.
An alternative to this screw and washer combination, the wafer head screw, came into limited use about twelve years ago (see picture below).
It was originally designed for the construction industry to attach wood lathe and metal framing to 20 to 25 gauge steel studs. It has a large and flat bearing surface under the screw head, which helps prevent the screw head from sinking into the crate lid, but it has several drawbacks. First, since it is only available with Phillips drive, it has the tendency to cam out under high torque like the bugle head screws.
Another drawback with the wafer head screw is the narrow threads. As they were never intended to be driven into wood, the threads are much narrower. Designed to be used with light steel fabrication, they do not have the grip of the wider wood threads on the course threaded drywall screw and tend to strip out easily in wood. Finally, a common problem when using these screws for sealing crate lids is that there is significant heat buildup when driving them into the crate wall. The heat concentrates just below the head, the screw shaft material often fails, and the head snaps off. This results in additional time to remove the broken screw shaft from the crate. The wafer heads were an improvement over the bugle head screw with the washer, and for awhile they were the best alternative available.
In summary , for sealing crate lids, the issues with using bugle head, drywall screws, are that the screw head tends to sink itself into the lid, and additionally cam out under high torque. The addition of finishing washers adds time and expense, and does not address the problem of camming out. The wafer head screw is an improvement, but not completely satisfactory due to narrow thread, head failure due to heat build up, and the cam out issue inherent with the Phillips drive
So, as an alternative to all the above, I want to advocate the square drive, washer head screw, which was developed in Canada in the early 20th century (see picture below).
Sometimes referred to as Robertsons, its drive mechanism is a square driver bit which fits tightly into a square recess in the screw head. This design eliminates cam out and allows much more torque to be applied from the driver to the screw. A round washer head provides a large, flat bearing area that resists sinking and pulls the crate lid tightly onto the crate wall. The number 10 size screw with a wood thread is able to pull closed and tightly most any crate lid. The difference in performance between the square drive screws and standard drywalls is significant.
While there is the issue of buying square bit drivers for the screws, quarter inch hex bits are available and fit existing drivers. Because there is still the need for drywall screws in overall crate construction, I am not advocating the discontinued use of the drywall screw. I find that time spent switching the bit heads is worth the additional capabilities the square drive screws offer. These screws are also available with a “combo head”, which enables them for a Phillips bit.
The square drive screws are also ideal to close and hold the side walls and the bottom of the crate in place. I have been using these screws for more than fifteen years and found them to be an ideal piece of hardware. While one screw type is not going to be appropriate in every situation, they cover such a wide range of tasks and functions, that I consider them an essential.
I’d like to open a discussion of expanding the standard range of crate hardware. I think once you try the square drive screws you will be convinced that they are worth adding to your shop inventory.
Rick Yamada
Surroundart
2914 V Street, NE
Washington, DC
Menu
Search topics by category