Thursday, February 23, 2012

V3.8 - Drill Press: Speeds and Capacities

My, my. We’re just moving right along with our information about Drill Presses.
At some point we’re going to get into ‘what to look for when buying a DP’. I’m sure that will help anyone who is contemplating adding a new machine to their shop.
For now, let’s get back to our rundown.

Where’d we leave off? Oh yes, we were at the chuck and the next nearest thing to talk about is the spindle. The ‘spindle’ is usually driven by a stepped-cone pulley or pulleys that are connected by a v-belt to a similar pulley on a motor. The ‘motor’ is bolted to a plate that is located at the rear of the head casting at the rear of the column. The average range of speeds of the typical DP is 250rpm to about 3000rpm. Delta used to manufacturer a ‘super hi-speed’ Drill Press. It was so named because the bit speed was around 10,000rpm. The motor only turned at 3450rpm, but because of the belt ratio, it could really turn ‘n burn. It seems that jewelers loved it. Since the motor shaft stands vertically, a sealed ball bearing motor is best suited for a Drill Press. For average work, a one-quarter or three-quarter horsepower motor usually meets most requirements.

The capacity, or ‘size’ of a Drill Press is determined by the distance from the center of the drill bit to the front of the column - then doubled. For instance, a 12-inch Drill Press can drill to the center of a 12-inch diameter circle, but the distance from the center of the bit to the front of the column is only 6 inches. This is how all Drill Presses are measured. One of the most versatile Drill Presses was the “Ram Radial” Drill Press. This was an industrial Drill Press that was used a lot, during the Second World War, in airplane factories. The head had a long appendage fastened to its back and that casting rolled inside a ball bearing track. What this allowed was that the head could be moved backwards and forwards almost 3 feet. I’m working off memory but as I recall this press could drill to the center of a 72-inch circle, or down to about an 8-inch circle…and any and all points in between. It was such a popular concept, but one that most home shop guys could not afford, that back in the 1970’s, Rockwell International created a home shop version that could drill to the center of a 32-inch circle. It could also slide in and out, just like its bigger brother, which enabled it to be just as versatile.

Next week we’ll outline a few tips to keep in mind when you’re out shopping for your new Drill Press.

Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can do to help you.

1 comment:

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