|American Tool Works Drill|
|Drill At work|
|Use small bits where required|
There are drills on the market and then there are drills. The twist drill bit dates to the mid 19th century. Specifically, Stephen Morse developed the idea of creating a twisted drill consisting of two parallel spiral grooves with a straight cutting edge. Prior to this, drills were made from a flat piece that was pointed and sharp. He began manufacturing drills in October of 1861 with a small shop. His original patent, No. 38119, is dated April 7, 1863. Morse is a name in drill bits that we associate with the "Morse taper" which is a specification of a taper used to hold larger bits in the quill, but Morse was also the patent holder for the very concept of a twist drill.
The value of this invention which is beyond recognition in the development of machinery. The twist drill is a highly efficient way to cut metal, and unlike the spade bits preceding it, will uniformly drill holes that are round. The main change in drilling technology since the Morse patent is the replacement in the 20th century of the carbon steel bits with High Speed steel (HSS) material. HSS has been around for lathe cutters and drilling applications since the beginning of the 20th century. It is an alloy which is much more resistant to softening when heated meaning that it is usable for machining at higher speeds than 19th century steels.
HSS is quite expensive, and particularly large drill bits use a lot of it so even up to recent years HSS has not fully displaced carbon steel on the larger drill bit sizes simply because of the cost. Large drill bits (over 1") are very spendy items (or at least were until the Chinese flooded the market), and in buying second hand bits (which we often do beause of cost) one needs to look carefully to see if they are HSS bits or not.
I'm estimating that this Radial Arm Drill by the American Tool works dates to the 1920's. It is very similar in appearance to the ATW catolog drills appearing in the ATW catalog of a decade earlier on my website at "http://atw.vannatta.com" but for the fact that the table is a different shape. It also has a lot of zerk grease fittings on it, which while they could be retrofits, didn't show up on pre World war I machinery.
The grease fitting in general is credited to Arthur Gulburg in 1916, who with his father created the Alemite brand name, and produced the Alemite button head grease fittings beginning in 1922. In 1924, the Allyne-Zerk Company of Cleveland, Ohio was purchased by Alemite, and the Zerk line of lubrication fittings and hand grease guns was added to the Alemite line. The Zerk design, named after Oscar Zerk, used a fitting much smaller than the Alemite pin-type and did not lock the hose coupler or hand gun and fitting together. Instead, the seal between them was maintained by the pressure of a pushing action when the operator applied the coupler to the fitting. This became known as a push-type system, and thus we have the Zerk fitting still in use today.
While clearly this drill could have been manufactured with 'grease cups' and then retrofitted, it has a couple of oil cups. and if the retrofitters were redoing it, I can't see why they would have left a couple of oil cups and changed everything else which makes me suspect that the machine is post 1924.
Modern radial arm drills have electric motors all over them, but the design here is from the line shaft era, and the power comes from an 7.5 hp electric motor sitting on the floor on the back corner of the drill which is belt fed to an open gear 'quick change' box similar to the lathe quick change boxes located on the back corner as you look at the first photo. The arm can be raised and lowered under power, and of course the quill is turned under power, and an adjustable rate power feed for the quill is provided.
The power drive goes in the bottom of the column and up the center of the column allowing the arm to be swung (manually) in any position. clamps are provided to keep it from swinging. Of the two rods seen outside the column on the right side the front one is a screw to raise or lower the arm, while the rear one is a sliding key shaft that turns the bevil gears that turn the horizontal sliding key shaft that runs laterally down the arm.
The drill head takes it's power from this sliding key shaft and is otherwise self contained, and can be cranked on down a rack with a wheel. Radial Arm Drills are rated in size by the length of travel on the arm. This Drill is a 60" drill because the arm will move in and out 60" or 5 feet. The quill has a couple feet of travel, and the arm can be positioned anywhere up and down the column. The Quill will not yaw or roll so it is necessary to rotate the work to accommodate the fact that the drill is only going to drill straight down. Sometimes you see drills with tilt tables to accommodate angle drilling.
Controls on the drill head do include, of course, the big crank to lower the quill which holds a Morse taper #5 hole in the end of it. If you pull the quill control slightly it engages a clutch for the feed as an alternative to hand cranking it. The feed can be a hand feed via the handwheel on the right, or a power feed if you set a dog clutch the other way. The power feed rate is adjustable via two star wheels (one you can see and the other is behind the quill knob). The lever below the arm in front is a forward, stop reverse lever for the quill. The hand wheel at an odd angle on the left turns racks the head in and out on the arm, and the lever on the upper left shifts a 3 speed shifter in the head (presumably the back gears).
The arm clamps and the arm up/down control lever are on the column off the picture. Also off the picture is an 8 speed shifter box which is an open gear sliding shifter that looks like an overgrown lathe quickchange box.