Identical in concept to all thread tapping machines with sensitive control and the feed and a reverse facility, the one made by David Dowling could be had in two forms - the Model C for mounting on a bench the Model P as a self-contained floor-standing unit.
Like the similar English-made  S and DE tappers from Engineering Products Ltd, (branded Apex and Oldak) and the machines by Herke, the Dowling was intended for smaller work. The maximum capacity in mild steel was 1/4" Whit (6 mm) and in brass 5/16" Whit (8 mm). The maximum clearance from the chuck to the round, 7.5" (190 mm) diameter table, was 6" (152 mm), the maximum travel of the spindle 1.4375" (37 mm) and the spindle centre line to the inside face of the column (the throat) 7.125" ( 181 mm).
Bored with a No. 1 Morse taper, the spindle had forward speeds of 375, 700, 1240 and 2330 r.p.m. and in reverse of 430, 800, 1435 and 2695 r.p.m. Power came from a 1.4 h.p. motor, a friction clutch, mounted on ball bearings, transmitting the drive.
An adjustable depth stop was provided as standard with what the makers described as a "follower attachment" being available at extra cost, this being used when tapping soft materials and fitted with leadscrews of the same pitch as the thread being cut.
The Model C needed a bench space of 22.5" x 13" (571 mm x 330 mm), stood 30.5" high (775 mm) and weighed approximately 89 kg.
Although essentially the same machine, with the same tapping capacity, the Model P had a larger rectangular table 13" x 9" (330 mm x 228 mm), an increased chuck to table clearance of 16" (406 mm) and a motor of double the power. Fitted with a head-mounted control lever as standard, the Model P could also be fitted, at extra cost, with a foot pedal.
The Model P needed a floor space of 26" x 16" (660 mm x 406 mm) stood 65" (1651 mm) high and weighed approximately 161 kg.