The sides or blade of a Speed Slot Hole Saw are made from bimetal material, a narrow strip of HSS (high-speed steel) edge-wire welded to a wider high carbon steel backer. The teeth are cut into the HSS, which is hard and resists wear better than high carbon steel. These are rolls of the carbon steel backing material before it’s attached to the HSS. It’s mind blowing to see how many towers of steel coil are stacked around the factory.
Lenox makes its own bimetal material. This high carbon steel backer will be fed into an electron beam welder and joined to the HSS edge-wire.
The edge-wire passes through straightening rollers before being fed into an electron beam welding machine.
As they enter the welder the edge-wire and backer pass over a “box” containing an electromagnet. The magnet captures stray metal filings that could cause problems if they got inside the welder. Note the old-school toggle switch on the electromagnet (which looks like something I could build in my garage).
Here you can see the edge-wire and backer lined up before they enter the electron beam welding machine.
One of many electron beam welders in the facility, this particular machine was designed in the 1960’s and has been in use ever since. Unlike regular welders, this machine uses an electron beam in excess of 7,000 degrees to fuse the two types of metal. Lenox has some newer equipment for this process, but I was not allowed to photograph it because they don’t want competitors to see it.
Here is the band after it has been welded. Bimetal material may not look like much but that HSS edge makes all the difference when it comes to making hole saws (and recip blades) that will stay sharp for a very long time.
The steel gets coiled again as it comes off of the welder. It is then transported to the next operation, the tooth cutting machine.
Cutter heads such as these are used to cut teeth in the band material for hole saw, recip saw, and band saw blades. You see these things all over the factory, as they are frequently changed out.
Multiple strips of bimetal material enter the machine on the left, where they will be stacked tight before having teeth cut into them by the type of cutter head shown in the previous slide. They essentially gang-cut the things. Talk about fast!
After the teeth are cut into them the bimetal strips exit the machine and rolled into individual coils.
This coil of bi-metal material, has been placed on a reel and is about to be fed into the machine that sets the teeth.
This is one of the machines Lenox uses to set teeth; it can set about 4 inches of teeth at a time. The strip goes in flat and comes out with the teeth set to the correct kerf width.
As soon as the teeth are set the stock enters a machine that punches the blanks that will be turned into hole saws—the longer the blank the larger the diameter. I was not allowed to photograph the punching process. As you can see, the blades come out of the machine with the cutouts and stamped lettering already done.
Here’s what the pieces look like after the sides have been formed but before the forged end piece is welded on. I was not allowed to photograph the operation in which the blank is formed into a curve—which is too bad because it was my favorite part of the process. I agreed not to describe it in detail, but can say it involves more than heating and bending.
This “rotisserie” holds a stack of the forged steel plates (the flat end that connects to the arbor) that will be welded onto blades. They are stacked in this manner so a robotic arm can pick them up, position them, and hand them to the robot that does the welding.
The robot grabs a plate & inserts it into the coiled blade. Another robot grabs the infant hole saw and brings it to the welding robot.The robot grabs a plate & inserts it into the coiled blade. Another robot grabs the infant hole saw and brings it to the welding robot.
I would have loved to stick my camera in there and catch the welding process—but peeking was not allowed. I am sure you can imagine what is taking place behind the curtain.
The next step is heat treating—which takes place in large vat-like furnaces where temperatures exceed 2,000 degrees. It takes many many hours to heat treat the pieces. The hole saws go in bright (like the piece on the right) and come out a dull grey color (like the one on the left).
After heat treating the hole saws are sent to a machine that paints them an applies (prints) the company logo. One of the unique things about Lenox is that they only paint the outside of the hole saw. The inside is raw steel—which reduces friction and the likelihood of gumming during use.
These finished hole saws have been stacked and are awaiting shipping. The shelves that contain them seem to go on for miles.
In this area of the plant hole saws and recip blades are tested on a variety of materials—and against competitors’ products. The fellow in the dark jacket was on the tour with me and is using a hole saw to drill a piece of stainless steel.
The nearest saw is from Lenox and was able to drill twice as many hole Uni-Strut as a competitors saw, and it still has teeth left!
Lee “Hackman” Breton came back for the 100 year anniversary event. He surprised me by cutting through a door so fast I was unable to catch a photo. He’s more or less retired now but you can see him in his prime in the video on the main page of this story. Hackman has cut more things in half than probably any man alive: railroad cars, planes, tanker trucks, armored cars, and something like 500 autos.