Fosdick 3 Foot Radial Arm Drill

Radial Arm Drill
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Radial Arm Drill
Radial Arm Drill
Radial Arm Drill
Radial Arm Drill
Shop made Drilling Table
Radial Arm Drill
Speed numbers cast on Tumbler box
Radial Arm Drill
tumbler gears
Radial Arm Drill
Speed tag
Radial Arm Drill
3 position back gear shifter
Radial Arm Drill
Radial Arm Drill
Setting the Table in Place
Radial Arm Drill
A vise for the arm drill
Radial Arm Drill
5 hp motor Drive
Radial Arm Drill
Gearbox less shifter & Countershaft
Radial Arm Drill
Ready to Work
Radial Arm Drill
First Project
Radial Arm Drill
Some broken Axle Stud bolts get drilled out
Radial Arm Drill

Fosdick Mfg. Co., appears to have been a fairly prolific maker of Radial Arm drills in the first half of the 20th Century. I've often seen gang drills with their name on it as well. One notable thing about the early arm drills is that a lot of folks in Cincinnati made them under numerous brand names and they pretty much all look alike. Indeed this one was mistaken for an American until, I got close enough to it to read the tag.

The heritage of this design is based on the lineshaft. Before the electrification of machine shops, they were universally powered by an overhead lineshaft turned by some central power source. The critical patents that made the Radial arm drill convenient were issued in the 1890's. The feature that makes them all look alike is the method of raising and lowering the arm. The input to it in this case is not a line shaft but rather an electric motor, as after World war I, the industry quickly shifted to electric power as it was available and vastly more convenient than trying to power everything off a flat belt from a line shaft. As the line shaft contemplated a single power source, it had to be on a stationary part of the drill. As with many of these drills---this one likely dates to the 1920's---, behind the column is a 'tumbler box'. It is a 5 speed open gear transmission with a sliding shifter that can be shifted under power. It's just a drill press version of a 'quick change' box used on lathes to select a threading

Once the power gets through the transmission box the output shaft goes inside the column to a bevel gear, and goes up a rotating shaft and comes out on the top of the column. There are several gears on top the column to create an offset and then the main drive is a rotating keyed shaft that goes down the outside of the column. If you look at the second photo, the power shaft is the shaft on the 'motor' side of the column. It intersects with a bevel gear box which is aligned with the arm. This gear box can slide up and down on a sliding key and the arm is raised or lowered, and it will swing with the arm as well since both the upper and lower bearings of the shaft are on parts that swing left and right with the arm. Indeed the arm will rotate (swing) in any position around the column. The only caution on doing this is that the based needs to be bolted down because the drill can get off balance and tip over under some conditions. The output from the sliding bevel gear is yet another horizontal shaft with a sliding keyway also visible in the second photo. It delivers power to the drill head which can slide to and from the column down the arm. It has a hand wheel which turns against a rack on the arm to move it in and out.

Once in the drill head there are three more gear choices or back gears managed by a lever on the back of the head. The back gears set a hi,med,low range which is fine tuned to the desired speed by the tumbler shifter at at the base of the column. The quill takes, I believe a #5 Morse taper, and the speed tag includes speeds for HSS drill bits ranging from 5/8ths bits to 3 inch bits. Not surprisingly 3" is the maximum size that is used for the #5 Morse taper. A power feed is a feature of the drill and power feed settings are provided on the tag as well (photo 6).

As for raising and lowering the arm, there is a screw on the arm side of the column (see photo 2). This screw is activated by the control lever on the control side of the drill. You loosen the clamps that hold the arm and engage the drive which is gearing up on top the column (a subject of the 1895 patent by a guy by the name of Anton Mill) -- presumably after whom the Milling machine was named. That gearing can be engaged easily under power and the arm moves nicely up or down.

If you find an arm drill made in the 2nd half of the 20th century, the big difference is that it will have electric motors all over it--a different motor for every function instead of one motor and a lot of complex shafting and gear boxes.

I would estimate that the drill weighs around 3500 lbs. I have a shop made table for it that is about 16" high. It is made of two sections of 15" H-beam with a slotted top of 1" steel welded on top. Provision is made for bolting it to the T-slots on the base. The table can become an issue if you are drilling on something high. This drill only has about 2 feet of vertical travel on the arm. The quill has about 12 inches of travel. It appears that the end of the quill with the arm down will reach only to within about 12" of the floor. This implies that to use this drill successfully you either need a table, or drill bits at least 12 inches long.

This is known as a '3 foot arm drill' because the Quill will travel on the arm out to a position 3 feet from the column. The actual travel of the arm is less than that as the quill won't go closer than 8 or 9 inches from the column. It's a nice little drill, but you do need to understand its limitations. The arm can move in and out a little over 2 feet, up and down 2 feet and swing 360 degrees on the column. When you consider that a drill of this type was often used in production context with the arm swung off to the side with the work to be drilled pulled past the drill on a cart you can understand the limitations of a small arm drill which likely explains why many arm drills are quite a bit larger.

For example our 60 inch radial arm drill has about 4 feet of traverse on the arm and a much taller column allowing it to move up and down around 4 feet. Such drills take up a lot of space, but if you are going to do drive by drilling you can see the advantage. It's also something to remember if you ever are around one. Many models are made with a fairly narrow base to accommodate drive by drilling, and as a consequence they aren't very stable and need to be bolted to the floor to keep them from overbalancing when the arm is off to the side.

The Shifting Box

To the rear of the drill is a 6 speed gear box. Lathe folks will recognize it as a 'Quick change' box on steroids. Many drills of this vintage were designed for being powered with a flat belt from a line shaft and I suspect this one was as well. It has however been converted to run with a 5 hp. motor that sits on a shop made bracket on top of the shifter box. The shifter is of an open gear type and can be shifted under power.

As with a lathe quick change, the handle is attached to a gear that slides on a sliding keyed counter shaft which is also the input shaft. There is a second gear in the handle which I call the drive gear. You slide the handle right or left and lower it to engage the drive gear with one of the gears you can see in the cone of gears on the output shaft. The largest gear on the output shaft produces the slowest speed (almost). You will note that I said it was a 6 speed box, but if you look carefully you will note that there are only 5 cluster gears and 5 engagement slots. The 6th speed is obtained by lifting the handle up and propping it up with a little flip bracket on the left. There is a planatary drive which operates when the handle is not engaged at all (which lets the cluster gear turn free). The 'shifter handle up' (on the box) provides a modestly lower speed than using the largest cluster gear.

One of the issues that I had when I acquired this drill is that it wouldn't shift as the handle would not slide on the keyed shaft. It was a bit of frustration, but I finally figured out that if I replaced the key I could solve the problem. This took a bit of doing but the gear box can be dismantled. The main countershaft is also the input shaft with the belt pully on it. It is held in with a flange held with a tapered pin on the column end. The bearing behind the pully is pressed in the end of the casing. We put in a full length key (about 8 inches long) in the shaft. It can't get out so it stays there happy, and the handle with the tumbler gear can be slid back and forth to engage the selected speed.

The 6 speed shifter box combines with a 3 speed set of back gears located up on the drill head to provide a total of 18 speeds between 25 and 400 RPM's. The speed chart provides drilling feeds and speeds for drill bits 5/8th's in diameter to 3", the latter being the maximum standard size for #5 Morse taper drill bits which happens to be the quill size as well.

The last photo shows its very first drilling job. A remodel on the cutting head of our feller buncher was needed as the spare parts we had didn't quite fit. The drill was quite happy with the task.

- - Updated 12/31/2012
- - Updated 11/13/2010
- - Updated 09/16/2010
- - Updated 4/24/2010