A bit on band saw blades. Band saws are one of the more common power tools in the blacksmith shop. A high quality blade will make a cheap saw perform much better and make a good band saw perform like a dream. Many of us have a cheap 4' x 6" horizontal/vertical band saw. I have three. I have a fine tooth on one, a much courser tooth blade on the second and the third gets mostly worn out blades as it is strictly a vertical saw, set on a bench and used for cutting curves.
So why you ask do I use mostly worn out blades to cut curves? Because cutting curves dulls one side of the teeth. If you use a nice new sharp blade to cut curves it will want to cut curves when used as a cut off saw and you do not get square cuts.
Lets talk about teeth per inch versus stock thickness. A good rule to follow is to never have less then 3 teeth in the cut. IE a 1" thick piece could use a 3 tooth per inch, and a 1/2" thick could use a 6 tooth per inch and a 1/4" thick could use a 12 tooth per inch. Most folks don't have that many selections of blades. I try to keep a 28 tooth wavy pattern in one saw and a 9-14 tooth variable spaced in the other. The 28 tooth is good for stock down to 0.107 thickness. The 9-14 variable is great on stuff.214" and thicker. If you need to cheat a little you can use very light pressure and often get away with thinner stock then the 3 tooth rule says, but it is also easy to misjudge the pressure and strip a few teeth and then the blade is scrap.
Lets talk about blade materials. Blade teeth have to be harder then the stock being cut. They also have to stay hard when heated by cutting and hold that sharpness. Most of the 4" x 6" saws come with a carbon steel blade. Meaning high carbon and so the teeth are heat treated and the main blade body is not to allow flexibility to allow the blade to wrap around the saw wheels without snapping. These blades are short lived. I use a blade with M-42 tool steel teeth and a flexible back. Several brands are available. I have had the best life and durability from Lennox Diemaster II blades. In these tool steel tooth/flex back blades, the weld is super critical and I have had other blades suffer weld failure quickly, but get reliable blade welds and long life as well as very fast cutting from this brand. Been using them since about 1984 both at work and in my home shop.Starrett are also very good. The welds are made in a different system then the regular blade welders one see on the big shop band saws. These are best bought factory welded. Yes you can buy both carbon steel and hard tooth blades at the big box store. Yes they will cut some. I have found that with care, a Lennox Diemaster II blade will out cut a plain carbon steel blade at least 10;1, and maybe 15:1. The big box store hard tooth blades, seem to fail the welds in short order, even the name brands.
So what defines "With care" ? Follow the 3 tooth in the cut rule. When you put on a new blade, reduce the feed pressure for a few cuts. Don't cut hard stuff. Hard stuff that CAN be cut, but reduces life will produce blue chips. The blue is from the heat. Producing blue chips means you needed lubricant or you should have used an abrasive cut off saw, or you just accept lower life of the blade.
There are many solid stick lubricants that are used for drilling-tapping and sawing. These work well on the little 4" x 6" saws and are not messy like flood coolant. One has to apply often to keep the blade cool and lubed.
Besides stripping off teeth from too thin a material, the next quickest way to ruin a blade is to let the stock shift in the vise. That kinks the blade. The kink will often fail by snapping soon after the damage. Make sure you stock is very secure in the vise.
So you messed up and took a tooth or two off a still sharp blade? you can snap the blade to lengths for you hacksaw, and drill that flexible back and have some really excellent hack saw blades. Takes a little sting out of ruining a $28 blade to recycle it into maybe 6 or so hack saw blades.
Written by Jeff Reinhardt