A rip saw is a wood saw that is specially designed for making a rip cut, or a cut made parallel to the direction of the wood grain, as opposed to a crosscut, a cut made perpendicular, or across the wood grain.
Many companies use straight line rip saws for ripping random width material. Straight lines are very versatile in that they allow the operator to rip virtually any combination that’s needed from his cutlist.
They also have the benefit of providing an excellent glue-line quality rip. A glue line cut means that the cut is perfectly straight and free of saw marks, allowing the part to go straight to the assembly glue up table without further processing. This is possible due to the groove in the chain that the saw blade runs through as the material is transported through the saw. This groove provides support to both sides of the blade, making the rip quality superior to any other ripping method.
Straight line ripping also provides the ability to rip random width material for use in glued up panels. In doing so, the operator can rip fixed widths and panel lay ups can be ripped as random widths for gluing into panels. This guarantees the maximum possible yield on each random width board.
Straight line rip saws give the operator the flexibility to rip around wane and defects in his material. For example, if there is a knot in the smallest width needed in the cut list, being able to rip around the knot ensures the smallest amount of waste at the crosscut saw.
TigerStop makes a straight line rip fence called the TigerFence SLR featured above
One of the issues with straight line rip saws is that of production. If you want to make three strips out of a board, it will require the operator to pass the board through the saw four times. As a result, if you need to rip more than 5,000 board feet in 8 hours, you may need to have multiple straight lines. This is not all bad as having multiple saws gives fault tolerance should one go down and provide flexibility in that you can rip multiple species at the same time.
So, while straight line rips offer superior flexibility and glue joint quality, the problem still remains that they rely on the operator to make all the decisions, as well as keep track of how much lineal footage has been ripped and where the ripped material goes after ripping.
Rip optimizing has come a long way in the last 10 years. There are several good systems available on the market today. Most of these employ the use of movable blade gang rip saws. There are much larger systems capable of ripping the largest quantities of material and their prices range from hundreds of thousands of dollars up to half a million dollars.
If those numbers are out of your price range, worry not, there are optimizing systems available for your existing straight line rip saw at fractions of the cost. These systems allow the operator to define the board width, usually using a laser array system, and optimize the entire board for both fixed width rips as well as random widths for glue up.
TigerStop makes a rip optimizing saw system called the TigerRip 1000 featured above.
Typically, a servo controlled fence is used on a straight line rip saw. This allows the operator to place the board against the fence and feed it into the rip saw. This greatly improves accuracy and allows the operator to focus on aggressively cutting around wane and defects.
Optimizing in this manner allows the operator to focus on feeding the system and ensures that the maximum mathematical yield will be obtained. There is no concern about over or under ripping, as the system will rip the lineal footage required and stop.
Inkjet printing is available on most systems and will print on each ripped strip, the width or the next process (i.e. Moulder 2). This eliminates the logistical issues of determining where the ripped material needs to go. Inkjet printing also gives you the ability to batch multiple jobs of the same species and thickness and still determine what job each ripped strips goes to. More width combination equals more opportunity for yield.
When looking for a rip optimizer you should consider the below:
1) The amount of production you will need daily.
2) Whether or not your system can be used by unskilled employees. The system should allow anyone to be placed at the ripping cell, regardless of experience, without adverse effects on yield.
3) Whether your system will allow you to rip only what you need, when you need it.
4) How you will identify ripped strips and determine where they go next.
By: Mike Anderson