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Articles & Stories

The LT40 Sawmill History: Bed and Hydraulics Upgrades

Wednesday, November 30, 2022

The LT40 Sawmill History: Bed and Hydraulics Upgrades

The practical and convenient conversion of logs to timber depends on a strong and precise sawhead with an adequately selected sawmill blade and a reliable sawmill bed that lays the foundation for the entire machine. The sawmill bed equipped with efficient hydraulics allows the operator to rotate and level the log quickly while maintaining the safety and ergonomics of work. In addition, a mobile version of the sawmill will allow for the on-site conversion of logs just where the customer needs it.   

In the old days of heavy and static frame machines, the idea of mobile sawmilling did not exist, as the customer had to bring the logs to the sawmill and, in the end, take the material back home. Only with the advent of a lightweight and compact Wood-Mizer LT40 mobile sawmill could the conversion of logs to ready boards and cants take place in any chosen location, such as in the forest, on private property, or at a customer’s construction site. It was all possible with an innovative design of a portable sawmill built by two genius engineers from Indiana, USA – Don Laskowski and Dan Tekulve. They were the first to devise the idea of setting up a sawhead with a strong and thin sawmill blade on a long frame with two wheels. This is how the „revolution on two wheels” opened a new chapter for sawmilling companies and allowed ordinary people to process wood independently.           





Lightweight and portable design of the first LT40 sawmills 

The first machines in Europe in the early 1990s were mainly the LT30 and LT40 sawmills. These machines featured an identical sawhead, but the difference was the sawmill bed length – the LT30 sawmill could cut logs with a maximum length of 5,1 m, and the LT40 with 6,4 m.   

In those days, the LT40 sawmill impressed with its lightweight construction, suspension system, and overrun brake, but most importantly, it was a portable machine ready for towing behind a vehicle. The sawmill’s mere 1300 kg net weight allowed one man to detach it from the vehicle and pull it to a different place. In the Polish reality of the early 1990s, it often happened that the LT40 sawmill was towed across town with the popular Fiat 126p, known as the smallest car of those times. 
 
“One of the first machines in Poland was the Wood-Mizer LT40 Hydraulic sawmill equipped with a 24 HP gasoline engine and a bed with simple hydraulics, including the clamp, turner, log loading, and leveling. When we arrived with the LT40 at the sawmilling site, the villagers from the area came around to watch the new machine. They didn’t believe that the sawmill bed could hold the weight of a large poplar log,” recollects Dariusz Kujawa, Customer Service Manager with long-time experience in Wood-Mizer.




The LT40 sawmill frame upgrades 

The first frame of the LT40 sawmill looked rather delicate and consisted of six cross-sections, four static and two foldable ones. It used to be problematic for the users because before loading the log, they often needed to remember to fold them to secure them from damage. In 1996 the cross-sections were still foldable, but the frame was strengthened with extra support, and the 50x50 mm steel profile was replaced with the 100x100 mm one. The sawmill frame has not changed much over the years as it has always been built from good quality steel with 4-6 mm thick walls and uses the best-known manufacturing technology. 
 
In 1998 the LT40 sawmill had gone the so-called „metrification” process, which means that all imperial dimensions were converted to metric units, improving the manufacturing and servicing of the mill and decreasing its purchasing price in Europe. In addition, in the same year, the LT40 sawmill was upgraded with a unified AC power supply system, opening new possibilities for the designers to add a more efficient hydraulic pump and extend the sawmill bed with new hydraulic functions such as extra clamps, feed rollers or log-loading arms.  

In 2012, the manufacturing facility in Koło implemented a unique welding tool for welding the sawmill frame, which considerably increased the efficiency and precision of the manufacturing process. For many years the factory in Koło had been sourcing the sawmill frame with the feed rod welded onto the main beam from the Wood-Mizer facility in Indiana, USA. The production of this component is now possible in Poland.   



Central log clamp, side supports, and leveling 

In the first LT40 sawmills that arrived in Europe, the log loading mechanism could be either hydraulic or manual, depending on the sawmill’s equipment.   

The central clamp and side supports are essential elements of the sawmill bed, used for securing and stabilizing the log during sawing. The way the side supports work has stayed the same over the years. What has changed, though, is their shape, which had to be upgraded due to safety regulations. In portable sawmills, the activation mechanism of side supports also had to be modified.   

The central clamp used before 1996 worked on a single driver moved only horizontally and was equipped with a characteristic plate operated manually. It was raised in case of a larger log and dropped for smaller ones. Since 1996, the central clamp has been set on a 2-inch steel rod and moved both horizontally and vertically, allowing the operator to adjust the height and position of clamping conveniently. For a few years, the central clamp has also been offered with a double rod providing even more stability during cutting.    





The turner and the leveling system are essential in correctly positioning the log on the sawmill bed. The first LT40 sawmills in Europe featured a double-arm hydraulic claw turner. Until today, its mechanical design has not changed much, except for its generally strengthened construction and modified angle of the claws. Currently, the LT40 sawmill with STANDARD hydraulics is offered with a spike log turner. In contrast, a chain log turner is provided in the SUPER hydraulics version, allowing the user to rotate heavy logs in both directions.   

„The log leveling system from the early 1990s worked simply – it was activated hydraulically and released mechanically by unblocking the valve. In 1996, the first leveling rollers made preparing the log for sawing easier. The two rollers installed on both ends of the bed allowed the operator to move the log manually along the frame. At present, Wood-Mizer sawmills with hydraulics can be equipped with a driven roller which helps to position the log quickly and conveniently on a sawmill bed,” explains Robert Fret, Customer Service specialist. 




Bed extensions, angled bed rails, adjusted legs, and a “bumper” 

The first bed extensions for the LT40 sawmill that appeared on the European market were 3,6 m and 7,2 m long, respectively, the BX12 and BX24 types. In the following years, another two options were added to the offering, the extensions of 1,8 m and 0,5 m. In the older bed extension types, connecting the extension with the frame was problematic, which was improved in 1998. The currently applied connector is reliable and easy to use, which is meaningful for the operators of mobile sawmills. In portable LT40 sawmills, the bed extension which is most recommended is 0,5 m long because it is relatively lightweight and easy for transportation and assembly on a sawmilling site. For a long time, the bed extensions were offered without any hydraulics, which changed in 2005 after considering the suggestions from sawmill users.  

“The bed rails for holding the log on the bed were upgraded in 2019. Their shape and functionality were improved, turning them to the so-called “angled” bed rails. The previously used „flat” bed rails made the sawdust and bark gather under the log, disturbing the thickness measurements,” explains Dariusz Kujawa. The currently used angled bed rails prevent the debris from collecting under the log, which helps to increase the precision and efficiency of sawing. The transition from flat bed rails to angled ones was prompted by one of the users of Wood-Mizer sawmills. 

The first supports for stationary sawmills came around in 1992, but at that time, they did not allow any adjustments. It was problematic on the sites where the quality of the floor was relatively poor. Later, the stationary LT40 sawmill could be equipped with adjustable legs, with a 6-cm grade, helping the operators and service men to work quicker.  

The LT40 sawmill can also have a shock-absorbing roller, which reduces the impact of ready boards falling from a height. The shock absorber roller is a frequent accessory of large Wood-Mizer sawmills, e.g., LT70, WB2000, WM3000, and WM3500. The idea of the shock absorber roller also came from one of the Wood-Mizer sawmill users. 


 


Hydraulics options 

The first LT40 sawmills coming to Europe in the early 1990s were offered with essential hydraulic functions, including log loading, turner with side supports, central clamp, and leveling. Although the mechanism was powered with a DC pump coupled with a battery, the system worked properly and was functional. Unfortunately, the mechanism built on a DC power supply and a battery relied on the battery's efficiency – a less efficient battery also meant less efficient hydraulics. In 1996, the hydraulics of the LT40 sawmill was upgraded to the SUPER version, with two DC pumps powering the system. 

Another extensive and meaningful upgrade of the hydraulics took place in 1998, which introduced the option of a unified AC power supply to the hydraulics of the LT40. Today, customers can freely configure the hydraulics added to their sawmills, choosing only the functions they need most. 

“One of the more interesting options that the LT40 sawmill bed can get is the hold-down clamps, which move horizontally and vertically. With this function, the log is securely pressed against the bed, allowing for even higher cutting precision,” says Robert Fret.




Stationary and portable LT40 sawmill versions 

The first LT40 sawmills were only mobile since it was the primary technical assumption of the engineers from the USA. What is interesting – even the mobile versions had electric motors, and their users accepted carrying power supply wires wherever they traveled for sawmilling.  

„At the beginning of the 1990s, the first users of the mobile LT40 sawmill often removed the wheels and installed it on the supports to the floor so that they could work in a stationary way. The situation changed in 1992 when the stationary LT40 sawmill was introduced to the Wood-Mizer offering. The LT40 sawmill in the new version quickly became popular among users and won recognition on the European market and globally,” remembers Robert Fret.





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