Garvin Plain Milling Machines were made for many years, in a variety of sizes, and the selection shown on these pages is typical of the firm's products during the early part of the twentieth century.
A new machine, the No. 14A, was added to the line in 1906 and this miller, together with the No. 16A, was provided with power feed and automatic trips and reversing feeds in all directions; newly developed square "ways" and a taper-gib strip for the saddle to knee adjustment were also introduced.
Garvin developed a patented and rather novel "Direct, Constant and Positive Feed" system, where the slower rates of feed to the table were driven from the end of the milling spindle and the faster from the belt-drive countershaft; this system (which the makers claimed relived the spindle belt of 80% of the load) was only fitted to the larger machines, the Nos. 14, 14A and 16A.
In the same year the spindle cones on the three largest millers were widened and the numerical ratio of the "back-gearing" increased - both small modifications resulted in a claimed doubling of the machines' previous cutting power.
On the Nos. 13 and 131/2 millers, the table-feed cones were made interchangeable - which not only increased the feed rate by a factor of three, but doubled the number feeds to 24.
The tables, (except that on the No. 16A) were fitted with a large oil pan, with finished top edges, designed to keep coolant and chips from spreading over the machine and to increase the working surface of the table slightly.
All models were fitted with table-feed screws having what the makers described as quick-pitch threads (-.e double-start) that gave one inch of travel per turn - handy for production work but not so useful when aiming for a precise setting. However, a side benefit of this specification - claimed the makers - was that the screws would not "start back" if the table feed was tripped out when taking a cut.
Power was applied to the table-feed screws by a bronze or hardened-steel worm gear acting directly on the screw, with the assembly running continuously in oil. The table feed screw was fitted with one fixed and one adjustable nut - which meant that backlash could be removed entirely - and provided with a zeroing micrometer dial - making the task of setting spacing work for rack cutting and locating holes (as in jig boring) rather easier than with a fixed dial.
The knees of all machines were made as stiff as possible, using a system patented on February 9th., 1904, where both the top and sides were completely enclosed - and so did not need sliding cover plates to protect the telescoping vertical-feed screws and the multi-thread, worm-and-gear knee-elevating mechanism. The extra stiff knee also made a better support for any arbor support braces it might have been required to carry..