The Craftsman 6" x 18" (3.5" centre height) backgeared, screwcutting miniature lathe (101.21200, 101.21400, 101.21***) was made by the Atlas Corporation in Kalamazoo, Michigan, for Sears, Roebuck & Co. and was styled to closely resemble its larger brothers, the 10-inch Atlas and almost identical 12-inch Craftsman lathes. The maker's numbers used on these machines included: 101.20140, 101.2048, 101.2048F, 101.2120, 101.2140, 101.M1518 (mica undercut version for electric repair-shop use) and the very early (and rather different) Type 101.07300 and 101.0730* etc)  with an integral countershaft. The lathe was available in a "Craftsman" version from late 1936 until the early 1970s and was, despite its modest price, a very well specified lathe with, on the original "round style" Mk. 1 versions, a remarkable 16 speeds between approximately 54 and 3225 rpm.
The catalog specification for the lathe included a backgeared headstock spindle fitted with a 60-hole plunger indexing device, a 17/32" hole and a 1" diameter 10 pitch NF thread, running in plain bronze bearings contained within a headstock casting that had a prominent frontal bulge. The same model badged by the makers under the Atlas brand was fitted with Timken taper rollers and had a much smoother, flatter front to the headstock. Despite this move to "cheapen" the Craftsman version the same excellent speed range of was claimed for the plain-bearing model as for the "genuine article". The countershaft of the standard lathe was a separate unit that bolted to the bench behind and was fitted with both a motor platform and a neatly-designed swing head to adjust the belt tension.  A stand was offered in the form of cast-iron legs joined by a substantial timber top with sufficient room to mount the maker's countershaft and motor assembly.
Although the Atlas-specification roller-bearing headstock was a much more expensive proposition than the plain-bearing Craftsman version, during the 1940s and 1950s some Craftsmen 6-inch lathes were sold with what amounted to an Atlas headstock - a result, perhaps, of shortages of plain-bearing units or an experiment in marketing - the clue being that the Atlas and Craftsman casting were slightly different. However, by 1959, the Craftsman was being listed with Timken roller bearings as standard - though one can imagine the pleasant surprise of earlier Craftsman customers as they unpacked their machines to discover a roller-bearing Atlas for the Price of a plain-bearing Craftsman. Many of the lathe's castings carried standard Atlas "M6" numbers including the designation M6-2 cast into the headstock of those models fitted with roller bearings. Other parts were marked: countershaft assembly M6-20B; bed L9-1; tailstock M6-5; cast cover on cross-slide M6-37; headstock belt cover M6-22; changewheel cover hinge M6-85 and changewheel cover M6-28.
A proper tumble-reverse mechanism was fitted to the changewheel drive, the leadscrew threaded 0.5" Acme and a dial-thread indicator was included in the standard equipment.
Although the headstock carried a 2 Morse taper centre, the tailstock was only a No. 1 Morse and that probably represented, together with the tiny feed-screw micrometer dials, the only specification failings in an otherwise well-designed and specified little lathe.
A version of the Atlas/Craftsman 6-inch was also made, numbered 101.07300, without a backgear assembly where, instead of a separate countershaft, an integral assembly and motor-mount was used pivoted from two lugs on the back of the lathe bed. Belt tension provided by a long rod screwed into the countershaft casting and clipped into a hole cut in the front face of the headstock. The system was arranged to work in exactly the same manner as that employed on some versions of the Craftsman 12-inch lathe where two rings were fastened to the shaft with the outside face of one, and the gap between the two, forming location points that allowed the bar to be pushed back and pressed down to tension the belt then lifted and pulled forwards to release it. To give some degree of adjustment to the final tension setting the other end of the bar was threaded into the body of the countershaft This is a rarely-encountered machine and few can have been sold. Should any reader encounter this or other novel versions of the lathe the writer would be pleased to hear from them.
Although the two machines are very different, confusion has arisen in the past between the Atlas-made 6" Craftsman with another lathe sold be Sears, the "Craftsman 80" made by AA (the "Double A" Company). The AA was a very inexpensive machine and cost, in the mid 1950s, as little as $48 compared to the $160 of the Atlas.
Introduced in the early 1970s, with a distinctive "square" styling, the Mk 2 version of the Craftsman 6-inch was identical to its Atlas brother and dispensed with the speed-reducing countershaft - the 8-speed drive being taken directly from the motor by a tensioned V belt to a multi-step pulley mounted outboard of the left-hand end of the headstock spindle; a picture of the Atlas version can be seen here.