L&B bandmill upgrades - Major improvement, low cost and impact

L&B bandmill upgrades

Major improvement, low cost and impact

BANDMILL GUIDE SYSTEM UPGRADES INCREASE SPEED, BOOST PRODUCTION

A stud mill cutting Douglas Fir and Hemlock in the Pacific Northwest recently upgraded its 1973 L&B bandmill with the latest in automatic saw guide systems. This upgrade occurred in conjunction with some significant custom work to relocate the bandmill motors out of the tightly confined space below the bandmill, to a more open area that could accommodate larger motors.

It was a major upgrade, and the mill took advantage of the downtime to do an upper sawguide conversion to further maximize guide precision and accuracy.

These workhorse L&B bandmills were typically designed with the motor housed beneath the wheel unit in a sloped sheeting area. This model usually runs 75-100 hp motors but the mill was running 125 hp motors, making the space underneath extra tight. Limited space and the amount of sawdust and chip debris from cutting wood, caused the motors to overheat too often. That inconvenience coupled with the fact that the mill wanted to further increase the motor size to 200 hp, so they could run faster on the larger pieces, caused them to reach out to us for a solution.

The solution involved moving the motor up out of the pit to provide easier access and reduce the risk of blowing the motor from suffocation. There is also more space available up top to accommodate larger size motors. The process involved removing the upper guard assembly and cutting a hole through the bandmill frame to install a motor base on top and a jack shaft underneath. A belt was then run down through the hole onto the jack shaft that drives the lower wheel.

“We were able to use cog belts instead of v-belts,” said Kyle Morgan who engineered the project, “which are smaller and can transmit a lot more torque. They also have less slippage on higher horsepower motors, making an overall tighter functioning system.”

Because the upper wheel guard on the original L&B bandmill wraps all the way around and connects to the base of the frame, new guards had to be installed to accommodate the motors. The single guard unit was split in two, creating an upper guard and a lower guard.

USNR took the opportunity to include a spare belt in the lower guard so the mill doesn’t have to drop the wheel just to change a belt. This saves a huge amount of time not having to realign the wheel, and a whole day of labor for the change-out. Kyle said, “Now they just remove the front plate off the lower belt guard to reveal hooks that seat a spare belt. This smart feature cuts the job in half.” Another small but significant convenience is all the belt sizes are the same length, so only one belt with one part-number is needed for all the belts that run between the motor, jack shaft, and band wheel.

Now they just remove the front plate off the lower belt guard to reveal hooks that seat a spare belt. This smart feature cuts the job in half.

BEFORE: The original configuration with the motors installed in a sloped sheeting area beneath the bandmill.

AFTER: The upgraded configuration with the motors mounted on top to accommodate larger motors and solve the overheating problem due to the tight confinement.

USNR’s standard guide system with linear rails, and guide package with pivot arms, will maximize guide precision and accuracy.

Kyle noted, “It was a major upgrade, and the mill took advantage of the downtime to do an upper sawguide conversion to further maximize guide precision and accuracy.” This involved upgrading to our standard guide system with linear rails. The mill also opted for the guide package with pivot arm. The pivot arm moves up and down, travelling on a linear bearing that provides additional precision and accuracy. The mill was able to reuse their existing linear positioners, and realize the maximum benefit of this conversion in terms of accuracy and precision.

Using linear positioners to drive the guide system enables the movements of the sawguide itself to be controlled by the PLC, which makes the system much more accurate and precise. It also allows for a saw blade deviation system to be added in the future if desired. This system tracks the movement of the blade on the wheels.

Many such projects are needed in the industry today but most don’t have the finances to support it. When mills work with manufacturers to find ways to improve equipment performance, solutions can be found that may permit them to run for another 10-15 years. USNR is proud to offer performance-enhancing upgrades with quick paybacks. Contact us to learn more about this, or other upgrades we offer.