|January through June 1998 - Issue No. 152|
Technology Enhances Armstrong No. 4 and 6 Band Saw Sharpeners
By Scott Emmert
|Affordable upgrades like the frequency drive will improve performance on your band saw sharpener with sharper, more accurately ground saws. Contact Armstrong for information on a built-in wheel shaping/truing device.|
| Saw filers
are always looking for ways to improve the quality of their saws. Many saw filers have
discovered that switching to finer grit wheels improves the sharpness of the cutting edge
and the smoothness of the total grind area.
Finer grit (80 grit and finer) saw grinding wheels often require a very light grind to prevent burning the saw. For that reason, many saw filers have replaced old conventional saw grinders with new full flood sharpeners equipped with variable speed motors such as the Armstrong PRO-Filer. Not all mills are ready to invest at that level. Even a sawmill on a tight budget can install frequency drives and micro groove flat belts on their sharpeners. This inexpensive technology is proving to be an investment with a fast pay back.
Frequency drives, or phase converters, have been around for years. Like all technology, frequency drives continue to improve in performance while becoming more affordable. Installing a frequency drive unit on the main gear head drive of the No. 4 or 6 sharpener produces many exciting options for improved performance. The main benefit is the ability to control the grind speed. When a saw is reswaged, the amount of stock removed is greater than for a saw that just needs sharpening only.
Similarly, Stellite tipped saws require substantial stock removal when freshly retipped. This heavy stock removal usually causes the corner of the grinding wheel to wear at normal grind speeds. A frequency drive allows the grind speed to be slowed on the first round of sharpening so the wheel cuts rather than breaking down under the extreme grind pressures. Many saw filers report improved grinding wheel life and a reduced chance of dubbing the point off the tooth. In fact, filers contend that a frequency drive coupled with a StrongArm II power clamp, is the only acceptable way to sharpen Stellite tipped band saws.
When shopping for frequency drives look for the following features:
A frequency drive big enough to run a No. 4 or No. 6 sharpener ranges in price from US$500 to $1000, depending on features.
In addition to frequency drives, the installation of a micro groove flat belt with sheaves on the grinding wheel spindle and motor can make a big difference in grind quality. Micro groove belts are thinner and wider than standard V-belts producing a greater contact area which reduces belt slippage. This allows the grinding wheel to remove stock more efficiently.
Bending V-belts around small diameter pulleys quickly develops deep cracks which in turn induces excessive vibration that can cause premature spindle bearing failure or possible burning of the saw when grinding. Due to the guards around the belt, this cracking often goes undetected. Micro groove flat belts are thinner and therefore dont develop the deep cracks from bending stress like V-belts. Therefore, they produce very little vibration. Most filers report significant improvements in grind quality after installing this inexpensive technology.
The combination of frequency drives and micro groove flat belts greatly enhances the performance of a No. 4 or 6 band saw sharpener. These investments are definitely worth taking a look at. Belt conversion kits with the proper sheave diameters are available from Armstrong or your Armstrong Stocking Distributor/ Service Center.
A special thanks to Scott Emmert for contributing this article. Scott is an independent filing consultant and can be reached for training or troubleshooting at:
Armstrong does not supply phase inverters. Check with your electrician or power transmission supplier for a recommendation.