I've always wondered about industrial drill presses (such as many of the Clausing 15" and 20" units) that have a machined flat oil table, with drain gutter (trough) around the periphery, but no T-slots.
How is one supposed to clamp the work to a slotless table well enough to handle drilling a 1" hole in steel?
Drill jigs typically ride on a number of hardened and ground "feet" which allow the jig to slide around the table as the operator moves it to drill different holes in a part. T-slots would cause all kinds of problems with this movement.
============================= Back in the days when we were a manufacturing country, there were many drill presses like this. These were made to allow easy sliding of a drill fixture. The fixture was equipped with hardened steel drill bushings to locate the drill. The fixtures were generall quite large/heavy and more than ample to aboid being spun.
Typically these have several drill heads mounted on one table. the procedure is to slide the fixture under one drill head to drill one hole size, the next head to drill the next hole size etc.
In some cases, the drill bushings were removable and the 3rd or
4th drill head had a tapping attachment. The operator would drill all the holes possible, pop out the hardened bushings for the holes to be tapped, slide the fixture under the tapping head and tap the holes. FWIW -- a tapping head works in that it rotates the tap clockwise when the operator has pushed the tap against the part, and counter-clockwise when the operator (or the return spring) is pulling the tap out of the part.
Generally but not always the parts were made of die cast zinc or aluminum and the drills/taps were on the smaller side. [Did not drill 1 inch holes in steel]
A good drill press operator and a well tooled drill press were capable of incredible production.
In some cases the operators also changed the drills, to complete the part. In the 40s and 50s you could always spot the people that worked steady on these jobs because of the peculiar callus they had on their thumb and forefinger where they spun the chucks open/closed. Those people could tighten a drill chuck as tight by hand as I could with a chuck key (in about 1/100 the time). If you claimed to be a drill press operator, the foreman always wanted to see your calluses as part of the job interview.
Unka George (George McDuffee) ..................................................................... The arbitrary rule of a just and enlightened prince is always bad. His virtues are the most dangerous and the surest form of seduction: they lull a people imperceptibly into the habit of loving, respecting, and serving his successor, whoever that successor may be, no matter how wicked or stupid.
Denis Diderot (1713-84), French philosopher. Refutation of Helvétius (written 1773-76; first published 1875; repr. in Selected Writings, ed. by Lester G. Crocker, 1966).
Scully Jones made a tapered holder that would change drills on the fly. You would push up the collar while the spindle was running and the drill and inside straight/tapered tang holder would drop out, being held in by a set of three ball bearings that were released by the collar moving upward. You then slapped a new drill in and dropped the collar down. The collar would not spin while you were holding it.
I have an 18" Buffalo drill press that only has tee slots on the base. I've never even considered that the unit was missing anything. I use C-Clamps almost exclusively when drilling holes above about 3/16".
I used the base tee slots for the first time a month ago for a VERY specialized boring job. I've had the press for almost 30 years.