Despite the appearance of the parallel clamp, these types of clamp can make or break a projects. If glue sets, the clamp will not wait for a person to adjust the bars that may have flexed due to the weight of the workpiece. A good parallel clamp will evenly press against the workpiece, maintain the corners of the workpiece in a perfect 90 degree angle, and remain in place until the glue fully cures.
If a person has used good quality clamps, a person will never be satisfied with the performance of other, less costly clamps that may contribute to defective projects. Some of the best uses for parallel clamp are in projects that require large amounts of even pressure to be distributed to the workpiece, such as with large panels or doors. For these projects, the clamp need to be able to handle the even application of pressure to the workpiece, but also ensure that the clamp does not bow under the even application of the pressure.
Additionally, the jaws of the clamp need to be able to slide to accommodate the even application of the pressure to the workpiece. Because these clamps are not inexpensive, it is beneficial for a person to understand what separates good clamps from bad clamps. Thus, the following list will explain these differences.
Key Factors for Choosing Quality Parallel Clamps
1. Clamp Bars
The first of the factors to consider are the bars of the clamp. The bar should be made of metal and heavy-duty enough to resist any flexing that may occur when the clamp is used to even pressure to a workpiece. Bars that are at least 1.5 inches in width and 3/8 inches in thickness are the best for clamps that are to be used in any type of cabinet work.
Any clamp that has a bar that is thinner than this will bow under heavy pressure, which will result in the edges of the workpiece being glued down while the center of the workpiece may have a gap between the workpiece and the clamp. Thus, bowing of the clamp bar will result in a person abandoning the use of that clamp. Any clamp with a stout bar will remain stout throughout the glue-up process.
2. Jaw Design
In examining the second of the factors that contribute to quality clamps, the jaw design, a person should look at the jaws of the clamp. The best clamps has wide jaws that are approximately 2 inches in width by 3.5 inches in length. Additionally, the jaws may have removable plastic or rubber pads that will protect the workpiece from leaving black stains on the workpiece due to the reaction of the glue to the metal clamp.
The clamp should also have jaws that slide easily on the bar, but which lock in place when the clamp is pressed with even pressure on the screw. A clutch system on the clamp with a trigger will allow the clamp to be adjusted with one hand while the person is adjusting the workpiece with the other hand. The third of the factors to consider are the threads on the clamp screw.
3. Clamp Screw Threads
Coarse threads will allow for even pressure to be placed on the workpiece quickly, but the coarse threads will not have the fine control needed to place even pressure to delicate workpieces. Fine threads allow for even control of the pressure that is placed on a workpiece, but may take too long to open or close the clamp on a wide workpiece. Thus, quality clamps have multi-lead screws that allow for even pressure to be placed quickly with the screw, but then allow for fine control in the last few turns of the screw.
Additionally, the screw should have enough handle for the person to have leverage without using a cheater bar, but which will spin freely under moderate pressure on the handle. The fourth of the factors to consider is the size of the clamp. A clamp that is 24 inches in length may be sufficient for most cabinet work, but for people that build bookcases and tables of similar size, the person may desire longer clamps.
4. Clamp Size
Thirty-six inch and 48 inch clamps will provide the same even pressure as a pipe clamp of the same length. Thus, owning only long clamps will create difficulties when working with smaller workpieces. A person should own a set that includes both short and long clamps of both lengths.
In considering the weight and balance of the clamp, a person should desire a clamp that is heavy-duty in its construction, but balanced enough that it does not become too exhausting to utilize the clamp throughout the workday. Additionally, the movable jaw should remain in the position to which the person moves it, but should not droop towards the workpiece when the person releases the movable jaw. The drooping of the movable jaw will require the person to continually adjust the clamp, which may become frustrating during the glue-up of a workpiece.
5. Weight and Balance
Thus, a clamp that has holding power in the movable jaw is preferable to other clamps with less holding power. Another of the factors to consider is the even distribution of pressure from the clamp. The even distribution of pressure is what provides the clamp with its name: parallel clamp.
Pipe clamps and F clamps will typically rotate the workpiece when heavy even pressure is applied with the clamp. Thus, the clamp will often not allow workpieces to maintain their even corners. A true parallel clamp will not rotate the workpiece, even under heavy pressure.
6. Pressure Distribution
Thus, the pressure distribution of a clamp is a benefit that justifies the cost of such a clamp. An additional factor that a person should consider are the accessories for the clamp. Many clamp manufacturers will sell corner supports that are 90 degrees in length and that will allow clamps to be used with workpieces that require corners to be squared.
7. Clamp Accessories
Additionally, some makers will also sell extensions for the jaws that will allow the clamp to work well with workpieces that are wide but have narrow sides to the clamp. Additionally, the clamps will typically experience some buildup of glue that may harden on the clamp. This buildup can be removed by lightly wiping the clamp with a damp rag prior to the glue drying.
Additionally, a person can place a drop of light machine oil on the threads that connect the two jaws of the clamp to reduce any difficulties in the movement of the clamp. Avoid using the clamp as a vise for metal projects, however, as the hardened jaws will crack under that type of pressure. Another of the factors to consider are the number of clamps that a person should purchase.
8. Quantity of Clamps
To even pressure workpieces, a person should have at least one clamp every 6 to 8 inches along the length of the workpiece. Additionally, a few extra clamps are needed to allow for placement at angles in the workpiece. For example, kitchen cabinets may require eight to ten clamps of a variety of lengths.
Additionally, clamps should be purchased in pairs so that they can be used in opposing pairs. Thus, a half dozen clamps should be purchased initially, but more clamps can be bought as needed. These clamps will last for decades and will not need to be replaced.
An advantage to using a parallel clamp is that since the clamp stands on its own, a person can leave several workpieces on the workbench. Thus, the workpieces will not fall off of the bench when a person is not looking at them. Such stability during glue-ups will reduce the panic that a person may feel when attempting to glue a complicated workpiece.
Although a parallel clamp may not be the most glamorous of the woodworking tools, the clamp will determine whether the joint that took hours to cut will survive the clamping process. Once a person has experienced a workpiece that is perfectly flat from clamp to clamp, a person will understand the reason for woodworkers costs for quality clamps. The best clamps will allow the person using the clamp set to make the work stand out and be seen.
Thus, a person should purchase a few good clamps, take care of them, and the clamps will provide a return on the investment that was made in purchasing them.
