Silver Brazing Your Own Band Saw Blades
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Silver Brazing Your Own BAND SAW BLADES B Y J O H N W ILSO N Save money and get better results by making your own blades. was on the road teaching a woodwork- Silver alloys such as N50 or Easy-Flo 3 about 50 cents a foot. Coils of .025" x 1⁄4" x Iing course recently when my band saw blade are examples available today that contain 6-tooth blade is about 70 cents a foot. Olson broke. Not carrying a spare meant buying a cadmium. Used for decades, we now know doesn’t mention the availability or price of replacement locally. that the cadmium in them creates a health the coils on its web site or in its catalogs; you It had been 20 years since I began silver risk. Cadmium-free alloy such as BRAZE 505 need to call them. brazing my own band saw blades, and I had (visit LucasMilhaupt.com for a brazing book In researching the article I asked folks in forgotten what a broken band saw blade means you can download) contains 50 percent sil- the band saw blade industry about this. Their for woodworkers who don’t. First, there is the ver, 20 percent copper, 28 percent zinc and answer was that their customers had been inconvenience of stopping operations while 2 percent nickel. dissatisfied with the results of their shop- shopping for the blade. Second is the cost. Just as with soft soldering, a suitable paste made blades. The solution, I suggest, is better Third is the disappointment in the poor qual- flux is needed to ensure joint surfaces that information. ity of the weld on the band. are free from oxidation. Both silver alloy and My store-bought blade got me through my flux are available in convenient quantities Steps in Making Up Blades immediate need, but it soon broke. All these from catalog stores. While the conventional Here is how you go about saving money and factors are improved by making your own propane torch is used for both soldering and gaining independence by making your own band saw blades. brazing, the temperature range for silver braz- band saw blades. What must be the best-kept secret in the ing is much higher: 1,200˚F to 1,600˚F. 1. Buy a coil of your favorite band saw blade band saw market is worth your time to learn. from a supplier. Dependence on pre-dimensioned blades can 2. Obtain a “refill kit” for splicing your be a thing of the past. What you need to know “You can make up your blade that contains silver alloy and flux from and the tools you use and the materials to a catalog store. make your own are all readily available. No own band saw blades 3. Make a jig for holding the ends of the special machinery, no elaborate instruction, in 10 minutes using blade as shown on page 65, or buy one. no obscure source of supply. 4. Cut your band to length (add 1⁄4" for You can make up your own band saw nothing more than a the scarf joint). blades in 10 minutes using nothing more than 5. Scarf both ends of the band on a belt a propane torch and a holding jig. Buy the propane torch and sander to prepare them for joining. same band blade material you are currently 6. Align the blade in the jig, add flux and using from the same supplier and you’ll save a holding jig.” a premeasured wafer of silver alloy into the 50 percent to 70 percent. And you’ll get back scarf joint. to work doing what you came to do in the first 7. Heat the joint cherry red with a pro- place – working wood in your shop. Band Saw Blade Stock in the Coil pane torch. If the ingredients for brazing are simple and 8. Anneal the blade with several passes Silver Brazing vs. easily obtained, what about the band saw blade of the torch to remove brittleness on either Resistance Welding material itself? side of the joint. There are two methods for splicing band saw Olson Saw Co., a major supplier of band 9. File the joint smooth. blades: resistance welding and silver brazing. saw blades, will sell blade stock in the coil Let’s take these steps one at a time. The In welded blades, the ends to be joined are cut directly to you. Most common types of blades sources of supply at the end of this article square and electric current supplies the heat are available, and at significant savings. You will help you locate the blades and materials to arc weld the butt joint. Silver brazing joins also can find other sources for band saw blades you need. Silver alloy sells for $25 to $40 per using a fill material of silver alloy. The surface in coil form on the Internet (even at the auc- ounce, and flux is $6 in a 4-ounce jar. Both area of the joint is increased by scarfing the tion site eBay.com) or through other suppliers. quantities are more than you will need, so it ends back about 3⁄16". The heat for joining the Other major blade manufacturers, such as makes sense to buy a “refill kit” from a cata- ends is from a common propane torch. Starrett, Lenox and Sandvik, provide blades log store. What is significant to getting good Silver brazing is not the same as soft solder- in coil form. A large and user-friendly source is results is knowing about what is called “rib- ing used in copper plumbing fittings. While MSC Industrial Supply Co. (mscdirect.com), bon solder.” This is .003" thick by 1⁄4" or 1⁄2" both processes use solder, flux and torch heat, which carries Starrett and Morse brands. (Key- wide. A page of this magazine is .003" thick brazing is done at a higher temperature, and word search on the site for a list and price of to give you an idea of how thin this is. Cut it there is more strength in the band when the different types.) with paper scissors and make confetti-sized filler material is silver alloy. It is, in fact, as For example, Olson sells .014" x 1⁄4" x 6- squares as a pre-measured unit for use. For a strong as the metal itself. tooth blades for fine work in a 100' coil for 1⁄4" blade a piece that is 1⁄4" x 3⁄16" is plenty. OPenING PHOTO BY AL PARRISH; ILLUSTRATION BY MARY JAne FAVORIte popularwoodworking.com ■ 63 Cut your band 1⁄4" longer to allow for the overlap at Align the two ends of the sawblade in your jig. Sight across the blade and use a screw- 1 the joint. Here we’re using a belt sander to bevel one 2 driver to tap the ends into position. end of the band to create the scarf joint. Place silver alloy in rib- 3 bon form between the two scarfed ends of the blade (above). Add flux to the joint using a small shop scrap (right). Use a propane torch to heat the joint to Remove the brittleness from the band by heating the The final step is to file off the 4 a cherry red. 5 joint using successively less and less heat. Back up the 6 burrs at the joint and remove the torch on each pass. glass-like residue left by the flux. 4 ■ Popular Woodworking June 2008 #10 x 1" pan 1⁄2" screws 1⁄2" Cut a dozen such pieces and place them in the flux jar where they are ready for use along with 1⁄ the flux. Note: Flux contains zinc chloride and 2 2" needs to be used with caution. Use a scrap of wood to pick out the pre- 1 measured silver alloy square along with a dab 6" 6" ⁄2" 21⁄2" of flux. This is a more convenient and accurate way than using wire solder common in plumb- 16" ing work. The refill kits differ in this regard. ELEVATION PROFILE Woodcraft sells its joint kit for $34.99 with a HOLDING JIG 10" length of wire silver solder and the refill kit for $9.99 with the same length of wire. Lee Valley Tool’s splice kit sells for $32.40 and has are held in place by the blade ends. anneal it to restore the weld joint to the same a 71⁄2" length of 1⁄4" ribbon solder, while the It is now time to turn on your torch. Silver metallurgical hardness and strength as the refill kit at $18.90 gives you a larger jar of flux alloy flows at about 1,200˚F, and the joint will rest of the band. This is done by reheating it and 38" of ribbon silver solder. This will do be heated cherry red in the 1,600˚F range. to an annealing temperature and then cool- 150 splices. I rate this a good buy. When it is fully hot the joint appears to ing it slowly.” When discussing silver brazing, The holder for the band joint is easily made have a molten shimmer to it. It takes less than however, there is no mention of annealing from 1⁄2"-thick hardwood. It will hold the two a minute to heat. The joint is now brazed, but after heating the joint with the torch to flow ends for brazing and gives you the opportunity an important step remains: annealing.