Hardinge BB4
Like all small Hardinge millers the BB4 was superbly made from top-quality materials and finished to a high standard. Although a relatively small machine, with a table having a working surface just 12" long by 33/16" wide and without an overarm support for its cutters, the hardened and ground pre-loaded ball-bearing 4C collet spindle was driven by 3 V belts - an arrangement that must have provided a more-than-adequate surplus of grip over metal-removing ability. The maximum collet size was 3/4" and the 8 spindle speeds, driven from a 2-speed motor under-slung within the standard  sheet-metal cabinet stand, ranged from 180 to 3000 rpm.
The table, with hand-scraped ways and positive locks, was almost identical to that fitted to the earlier MD3/MD4 being the same 12 inches long but, at 33/16", just 1/16 of an inch narrower. Unfortunately the table travel was slightly reduced on all three axes with a longitudinal movement of 5", traverse of 31/8" and vertical of 5".
By the time this machine became available the Hardinge habit of supplying an indexing head and tailstock with each miller as standard had stopped and these useful items were confined to the expensive Accessory List.
The chip tray was a generous 24" x 29" and the plan space required to house the miller was, allowing for the opening of the cabinet's collet and tool-storage doors, 39" x 38".

Hardinge TM UM Miller
Made from the mid 1930s until the late 1950s the best known and most common of the Hardinge miller range, the TM UM, was a carefully-designed, heavily-constructed machine intended to be strong and accurate enough for both production and toolroom work. The table had a working area of 203/4" x 61/2" with a longitudinal travel of 14" (11 =1/2" with power feed) a traverse feed of 51/2" and a vertical movement of 131/4". The optional table power-drive attachment gave rates of travel from 1/8" to 13" per minute and was unusual in providing a total of 32 different feeds. All the gibs strips were of the proper taper type giving better support and allowing more precise adjustment. A thoughtful touch was the ability to disengage the transverse handwheel engagement; once released by sliding a collar towards the micrometer dial the operator could walk around the machine without fear of nudging the handle and upsetting the position of the table. The double nuts for longitudinal and traverse feed screws were adjustable for backlash and the 3"-diameter micrometer dials were larger than other Hardinge millers with, for the first time, parallel engraved surfaces instead of the bevelled ones used previously.
The spindle, carrying a 5C collet nose and hardened and ground like all those fitted to Hardinge machine tools, ran in pre-loaded, grease-packed-for life ball bearings and had 8 speeds from 110 to 1850 rpm. The two speed motor was held on a pivoting plate within the sheet metal cabinet stand and used a 4-step V-belt pulley to transmit power to a 2-step V belt countershaft with the drive then taken vertically upwards, via 2 V belts, to the spindle. Motor-speed switching was controlled by the usual Hardinge method of two concentrically mounted levers, one selecting high and low speeds and stop, the other forward and reverse with a second, separate, stop function.
The cutter arbor, in 7/8" or 1" sizes, was ground on its end in the form of a 5C collet and held into the spindle by a draw bar equipped with a ball-thrust bearing; it was supported by a drop bracket containing a precision ball race whilst the solid steel 2"-diameter overarm was ground and lapped to be a perfect fit within the main casting.
Although not supplied as standard, provision was made to retro-fit a coolant system with all the necessary holes drilled and then sealed with plugs to stop dirt entering. Oil cups were provided to lubricate the longitudinal and traverse feed nuts and the table and carriage slides - in the latter case lines scribed on the table and carriage had to be lined up before oiling to allow the lubricant to reach its correct destination.