Although a revolutionary machine in so many ways, everything about the 9-Series minimal appearance would seem to suggest that the management's direction to the designer was, "Use the smallest amount of metal that allows a component to do its job so that we have the maximum profit per unit" - and it is instructive to compare it to the later, more fully-developed, heavier and rigid 10-inch and 12-inch machines shown on other pages. The lathe was not fitted with backgear (unless, in later years, specified with a simplified drive as one of the cheaper Unit Plan machines) but instead used a "double-reduction" V-belt system running on a Hyatt roller-bearing countershaft unit bolted to the back of the headstock. The lathe's ingenious drive was protected under a United States patent No. 1909522 in the name of James G. Collins - but assigned to the Atlas Press Company, by whom, presumably, he was employed. The application was filed on March 8th, 1932 and granted on the May 16th, 1933.
In its "high-speed" position the Collins drive was entirely conventional; a small pulley on the motor drove a large pulley on the swing-head of the countershaft from which three direct-drive speeds, of 220, 370 and 600 rpm, were transmitted to a matching 3-step pulley on the headstock spindle. To obtain the low-speed range takes rather longer to explain than to set-up in practice. The countershaft-pulley shaft was formed in two concentric parts, the right-hand side carrying a large, single pulley that was driven separately from the headstock 3-step pulley by a small pulley fastened to its right-hand face. Normally the small right-hand countershaft pulley just idled, but a "shift collar", inboard of the left-hand countershaft bearing, could be moved to the right to bring it into action. When moved the collar unlocked itself from the shaft and two pins, which extended from its side, went completely through the 3-step pulley and entered the single pulley on its right-hand side - and so locked the two together as a "floating unit". The eventual outcome of these various manipulations was that the drive went from motor to countershaft, countershaft to headstock, back from headstock to countershaft and then, using the 3-speed pulley, back to the headstock to give three slow speeds of 47, 80 and 130 rpm. Although the maker's instructions do not mention the point, some method of releasing the 3-step spindle pulley must also have been provided, otherwise it could not have acted as a drive transmitter. Scrutiny of the picture below should instantly make this interesting down-up-down 'modus-operandi' a little clearer. If you have one of these lathes, but no headstock-spindle drive belts, a good starting point is to try 30-inch belts on the two right-hand pulleys and a 31-inch on the left. The drive, although it eliminated costly backgears, cannot have been a success: with just belt drive it is difficult to get a really low gear ratio (and the slower the belts run the greater their tendency to slip) and it was (and still is) surprisingly difficult to machine sets of pulleys, and purchase quantities of accurately-sized V belts so that a multi-step drive works without the need for some small adjustment in tension when the belt is moved from one speed to another. In addition, as the pulleys wear, the difficulty of setting the belts "just so" increases. On the Atlas some compensation for differences in belt length could be partially made by adjusting the setting of the countershaft bearings in their simple but ingenious "floating" housings with, of course, the whole head further adjustable for belt tension against an over-centre locking bar.
Because the Atlas was (for so light a machine) capable holding rather large pieces of metal, Collins's original idea of low speeds being provided entirely through belts was almost certainly dropped because in "low-gear", when the cutting tool was applied to the edge of a 10" diameter piece of steel, the drive was - to put it kindly - hard pushed to cope. A conventional backgear system was used on the later 10-inch lathes - and the problem solved.
Hardened and ground, the No. 3 Morse taper spindle had an 8 U.S.F thread, a 0.75" bore and ran in "Babbit" bearings, each with a cap packed up on shims that could be delaminated in 0.002" strips (just like a Myford ML7) to allow adjustment for wear. The headstock assembly, with the bearings sitting on top of unbraced columns, was typical of contemporary small-lathe practice; reference to the pictures below will illustrate how this part was greatly improved on later models.
To reverse the direction of the automatic carriage drive a "leadscrew-reverse gearbox", containing a bevel-gear arrangement was bolted to the bed at the headstock-end of the lathe. This device worked well, but unfortunately was prone to damage by impatient, ham-fisted operators. Although Atlas retained this gearbox on machines marketed under their own name until the revised lathes of 1959, on Craftsman branded models from around mid 1936 it was replaced by an ordinary and very effective "tumble-reverse" mechanism. The first version used a simple (and slow to operate) bolt-to-secure lever (exactly like the South Bend 9-inch) while later models had a more convenient type with a spring-plunger that obviated the need to find a hunt down the right wrench. The 6-inch and Mk. 1 (pre-1958) 12-inch lathes both used ordinary changewheels on the tumbler assembly, a 20t on the front stud, a 24t at the rear and a 16/32 compound gear beneath on the output stud..
No power cross feed was fitted on this, or early versions of the 12" model that replaced it; indeed, the first models had their saddle and apron cast as one, with short bracing flanges supporting an extension of the saddle that formed the front part of the cross-slide ways. Of particularly light construction, the cross-slide was cast in Zamak, a material not ideal for resisting torsional stresses. As some disgruntled owners discovered, bolting down the top slide could twist the assembly and stiffen the cross-slide action. On a positive note, a choice of beds was offered having between-centre capacities of 18", 24", 30" and 36".
From 1936, and the introduction of the "conventional" tumble-reverse 12" machine, the lathe developed steadily and became both more robust and reliable as various components were redesigned or improved; the new model was available in both 8 and 16 speed versions (the latter by simply fitting a two-step pulley to motor and countershaft) and both with and without backgear. The least expensive lathe on its introduction was catalogued as the 8-speed, 18 inches between centres, non-backgeared Model "99 PM 2028" at $63.50 whilst the most expensive was the "99 PM 2030" with a capacity between centres of 36 inches and a price of $93.95. Models with 18, 24, 30 and 36 inches between centres were available. Without backgear the speed range was: 170, 270, 430, 504, 680, 832, 1298 and 2100 rpm; with backgear the range became a much more useful: 32, 50, 74, 88, 120, 142, 170, 210, 270, 350, 430, 504, 680, 832, 1298 and 2100 rpm. In 1939 power cross feed became available on the De-lux models and in 1941 16 speeds were made standard across the range with a corresponding increase in price to $89.50 for the cheapest version. Prices continued to rise steeply as war-time conditions took over: in 1942 the range spanned $105 to $165 and in 1943, the last year that the Craftsman power Tools catalog was to appear until 1948, $125 to $179.50 - an effective doubling in ten years of production.
When Craftsman lathes became available to the civilian market again in 1948 (and in line with a similarly restricted model range from Atlas) just two versions were available both with headstock roller bearings and full belt guarding as standard: the "99 TM 2075 had a capacity of 24 inches between centres and was priced at $197 while the 36" between-centres "99 TM 2079" was listed at $212.
In 1947 Atlas offered a screwcutting gearbox on their 10F model but it was not until 1951 that the Craftsman version was so equipped. The box appears to have been manufactured in several versions: the first was intended for retrofitting to existing lathes (Type 101.07403 and earlier models) with the original, thinner 3/8" bed ways; the second was adapted to fit the 1/2" thick way machines and the third, equipped with a safety-overload slip clutch, possibly introduced on the heavily revised lathe (sometimes carrying a "Commercial" badge) of 1959 - though a later date in the 1960s has also been suggested.
Numbers used on the identification plates for the 12-inch Craftsman lathe varied according to many factors including the bed length and type of motor fitted; some machines had an extra zero on the end of the following selection including early types often marked: 101.27580, 101.27590, 101.28930, 101.28940, 101.28950, 101.28970 and later versions with, amongst other designations: 101.20140, 101.20280, 101.20300, 101.20320, 101.20650, 101.20670, 101.20690, 101,20710, 101.20730, 101.20750, 101.20770, 101.20790, 101.27440, 101.27430, 101.07301, 101.07303, 101.07360, 101.07361, 101.07362, 101.07363, 101.07380, 101.07381, 101.07382, 101.07383, 101.07400, 101.07401, 101.07402, 101.07403, M2075, M2743, M2079 and M2744. etc. The different numbers referred to various combinations of bed length, motor type, etc.
If you have a 12-inch Craftsman with other numbers, the writer would be very interested to hear from you.
For details of Craftsman lathe accessories, look in the Atlas Archive