Woodworker's Journal 1994-18-3, страница 16

In The Shop

Continual

PROBLEM #8: Blade Irregularities

Many folks bin a new band saw blade, mount it in the saw. turn Ihe saw on. and assume that something is wrong with their saw if the blade does not track properly. Surprise, the problem may be with the blade itself, and not the saw.

SOLUTION:

Inspect the hlade carefully, especially at the weld. Bumps on the back edge of the hlade w ill cause the blade to jump as it passes the guides. This can produce rough cuts and even damage the thrust bearing. Poorly made blades can show misalignment at the weld, and even kinks, either of which can result in tracking problems. Grind or file away any irregularities. II the problem can't be corrected, replace with a new blade.

PROBLEM #9: Tracking narrow blades

Many folks have reported difficulty in tracking '/s in. or '/lis in. w ide blades on smaller—especially low-cost benchtop—band saw s. The likely cause of the problem is that these saws are simply not made lo ihe same quality specifications as more expensive. professional model saws.

Cutting performance can be enhanced by grinding the corners off the back edge of band saw blades Blades that have been rounded in this wav can make tighter turns because the corners aren't there to get hung up in the kerf, Rounfrbacked blades are also less hkeiy to damage thrust bearings. To round the back of a blade, set a sharpening stone on the saw table and carefully slide it against the back side of the moving blade This operation will produce sparks, so be sure to wear eye protection and make sure there is no dost in or around the saw that could be ignited by sparks fI once saw a table saw catch on fire because someone cut metal on it with an abrasive blade without first cleaning the sawdust out of it I

SOLUTION:

To bring your saw up to snuff, first follow all the above noted suggested fives, from balancing wheels lo setting proper tracking. If every thing is perfectly aligned and balanced, and il there are no inherent problems with the blade itself, then a narrow blade should track. However, if there is any built-in play in some of the critical parts, due to lower-quality bearings, poor castings, or whatever, or if the problem is with the blade, all your fine-tuning may still not be enough.

One final trick you may want to try is buy ing a new set of tires, specifically for use with the narrow blade. It's hardly practical to change tires every time y ou change blades, but tires can acquire a "memory" that makes them work best on certain size blades. If the new tire trick doesn't solve your narrow blade tracking woes, ihen maybe it's time for a better saw.

Guides and Guide Stock

In theory , straight cuts could be made on a band saw w ithout the blade even touching the guideblocks, whose primary purpose is to help blades resist twisting. Metal guideblocks should never pinch the saw blade. The gap between the blade and guide-blocks should be around .004 in. You can set this gap b\ folding a dollar bill < which just happens to be .(X)4 in. thick i around the hlade and adjusting the guideblocks so they're against the bill ihig. B). When the bill is removed, the gaps will be correct.

Some saws come equipped with ball bearing guides <Photo 71. These provide belter support because they can be set right up against the sides of the blade. The performance of saw s with metal guideblocks can be improved by retrofitting them w ith ball bearing guides. These can be purchased from Carter Products Company (see Sources). A cheaper and easier way to improve the performance of your saw is lo replace its metal guide-blocks w ith Cool Blocks. These graphite-impregnated phenolic resin blocks are self-lubricating and can be sei right up against the sides of blades. They 're available at most good tool stores, or from mail-order companies (see Sources). If a blade's teeih are allowed to rub against the guideblocks or bearings, both hlade and guides will be ruined. Guideblocks and bearings can be shifted forward and backward in the saw. They should be set so the sit '/tvi in. back from the bottom of the blade gullet i l-'ig. B). This position maximizes cutting control without damaging blade or guides.

Setting the Thrust Hearings

Novices frequently set thrust bearings righi up against the backs

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