Welcome to IES-STA.com

	This site features our newest Windows based version of our Saw Tension Analyzer Many customers requested improvements that were just not feasible with the original Linux based version, and we wanted to improve the system performance, as well as add some unique features. We have upgraded to a Windows PC based version with a USB multifunction Digital Acquisition Device that supports 14-Bit, 48 kS/s signal processing for the ultimate in frequency response. Using proprietary Fast Fourier Transforms, we can capture the resonant frequencies of the sawblade and display them graphically onscreen. By storing this data, and ringing another sawblade, we can compare the resonant frequency response of the 2 blades. This allows us to tell if the target saw blade matches the tension profile of the original saw blade, or is over, or under tensioned
So exactly what is it, and how does it work? Our Saw Tension Analyzer is essentially a very simple and accurate way to graphically display the actual tension in a sawblade. We do this by “ringing” out the blade and recording its resonant frequencies. We analyze this information through use of some sophisticated software algorithms, and display this information onscreen. We can store thousands of different sawblades, and their tension profiles. The main use of our STA is to compare a master or embedded blade with another blade to determine if they have the same amount of tension. In a gang saw application especially, you want all the blades in the gang box to have the same tension profiles. It’s amazingly simple to verify the tension profile of a blade, and takes only a few seconds to accomplish. For training new filers, this device has proven indispensible. New filers generally compare every blade they put up to an embedded master. They quickly learn how to touch up the blade, and eventually they check every other and then more random blades as their experience increases. Even seasoned filers find the STA a huge benefit in their ability to produce a consistent product. Progressive manufactures, or suppliers of saw blades have an STA to allow them to produce saws for their customers that match the exact tension profiles desired before shipping them to the mills.
	In order for any type of saw to cut efficiently, a saw blade must be properly tensioned to allow it to “Stand Up” in the saw box. Trained Millwrights do this by hammering, or rolling tension into the saw to allow it to perform optimally. Sadly, saw filing is becoming a lost art, and good filers are very hard to find. They are even harder to replace. Mills are actually closing down today because they can’t find enough skilled filers to continue. Some mills resort to having their suppliers provide properly tensioned saws. This works well in some cases, in others, where the supplier can’t properly tension a saw it works poorly, at best. Our STA makes it easy for even a novice to tell if a saw is properly tensioned.
To achieve the maximum recovery from a saw log, you need to produce the minimum kerf that you can reliably run your saws at. Many mills, unable to properly tension their saws are running .120” plate saws with .030” kerf per side and because the saws are poorly tuned they snake through the cut, increasing the ideal kerf as much as 20%. This yields an actual kerf width of .216” for each blade in the gang box. Several Mills using our Saw Tension Analyzers have been able to switch to .090” plate saws. With the STA, they can properly tension their saws are able to run .090” plate saws with as little as .020” kerf with little or no snaking, yielding a kerf of only .130” for each blade in the gang box. This is a reduction of .086” in kerf. In many mills this results in several million dollars per year in additional recovery. When you consider the benefits of reduced kerf, and better performance, a Saw Tension Analyzer makes a lot of sense and typical performance improvements alone often pay for the system in a couple months. One of the leading benefits, however is that it makes it much simpler to train a new filer. For experienced filers it gives them an ideal tool to help millwrights and mill managers ascertain the root cause of a problem when A board target can’t be met, or is erratic. Often time the saw filer gets a bad rap. With board target issues people generally assume the cause of the problem to be the last thing that touches the wood, which was the saw. This makes it the filers problem. By being able to prove and document that the saws are properly tuned, it allows mill management to search deeper, often finding alignment issues as the root cause, not the sawblades themselves.
	Why do we even need Tension in a sawblade? When you consider a bandsaw, as shown to the left; cutting into a saw log, each tooth generates a measurable amount of force as it shears through the wood fiber. The more teeth in the cut, the greater the total force applied. The resistance to this force tends to stretch the tooth side of the sawblade. Left uncorrected, the blade will develop a ripple that causes it to snake through the wood, increasing the amount of material removed in the kerf, and causing poor cutting performance and yield. To compensate for this we stretch the backside of the sawblade so that in the cut it runs flat and true. A Round Saw, as shown to the right functions the same as the bandsaw, wrapped around a center. It generates the saw force at the rim that causes it to want to stretch and snake through the wood. Similar to a bandsaw, we hammer, or roll tension near the center of the blade to allow it to stand up and run true as it cuts through the wood.
	Most round saw blades are tensioned either by hammering or through the use of stretcher rolls. The tensioning stresses induced by hammering depend on the elastic compliance of the anvil. The hammering surface of the anvil is slightly crowned, which creates a sweet spot at the very center of the anvil. When tensioning the saw, it must be positioned so that each hammer blow strikes the saw plate directly over the sweet spot. If the saw is not hammered over the sweet spot, it will create a bump in the saw, instead of the intended tensioning stress. Hammer tensioning is quickly becoming a lost art, as it is very difficult to train a new filer without some way to quantify their performance.
	As a result, many mills are moving to stretcher rolls to provide the required tension with greater consistency and uniform results. The two crowned rolls squeeze the metal sideways towards the rim and center of the saw. This creates tensioning stresses in the rolled area.
	As shown in the illustration to the left in A, a properly tensioned saw will stand up when turning at its desired speed, yielding the optimal performance and minimum kerf. If the saw has too much tension as in B, it will have excessive dish, and heat up at the center of the saw. The saw will cut with excessive kerf and reduce the plank size coming out of the edger from the desired size. If the saw has too little tension as in C, the rim is in compression and will heat up possibly causing failure of the babbit pad mounted to the saw guide and catastrophic failure. Figure D shows the results of a saw with uneven tension. It snakes wildly as it cuts through the wood generating a wide and erratic kerf that makes it almost impossible to consistently achieve a desired board target.
Interestingly, one of the greatest uses of our STA has come from mills that purchase sawblades “allegedly” pre tensioned to match the mills desired profile. Experience has shown that many times these blades are improperly tensioned causing poor performance from the outset. One of the neat features of owning a Saw Tension Analyzer is that certain saw blade manufacturers already utilize our STA’s in their facilities. You can ring out a saw at a remote mill, and save that tension profile to a USB device. You can then email that tension profile to the manufacturer who can then adjust their tension rolls to reproduce a sawblade that will match exactly your desired tension profile. This saves you a lot of time and labor $$$ at the mill site.
	Verifying the actual tension in a sawblade has always been an esoteric exercise. It is most often done visually by using a light and a gauge to determine the presence or absence of light or shadow between the blade being checked and a gauge. Give 4 filers the same blade to check, and most often you will get 4 different results. There is no reasonable way to document whether or not the tension matches a master blade, or does not. Some really tuned filers can actually ring out a blade and determine through the pitch it rings at whether the blade matches a master or not. These folks are an incredible gift, and rarely realize the method that they use to tune their blades.
*There is a much better way to measure tension in a saw blade…*

Using our Saw Tension Analyzer lets you instantly compare a sawblade being “put up” to an embedded master. Consider it as a very simple to use Go / No Go guage. The display visually shows you when the saw tension is in range, or matches the master blade; or if it is over or under tensioned. It makes it much simpler to touch up blades to the proper tension, which yields the optimal performance the blades are capable of delivering. It’s also the ideal way to quickly verify that blades from an outside supplier are properly tensioned before putting them in service. Excellent references are available from some of the most experienced filers in the industry. Please contact us at the contact info above for further information, or a demonstration of the Saw Tension Analyzer.

There is a much better way to measure tension in a saw blade…