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Cazeneuve HB 500/750 (22-inch and 30-inch swings)
The HB Series lathes were truly impressive machines - the 500/700 lathes for example, with centre heights of approximately 8 and 10 inches respectively, had beds which were 15.75 inches wide - and so far exceeded that old rule-of-thumb for a toolroom-class lathe which states that the width of the bed must be at least equal to the centre height.
They were made in three different centre heights and their models numbers - HB 500, HB 575 and HB 725 - represented the maximum diameter that could be swung over the bed. The lathes could be ordered in a variety of specifications, to suit particular purposes: with and without full screwcutting, with a straight, gap or semi-gap bed, in a variety of bed lengths and with different spindle speed ranges.
The 500/700 model illustrated above could be fitted with either a 7 or 12 HP motor; with the 7 HP motor a choice of four different speed ranges was offered, each range having a total of 18 speeds: 12.5 to 1000 rpm 16 to 1250 rpm 20 to 1600 rpm 25 to 2000 rpm With the 7 Hpmotor installed the ranges available changed to: 20 to 1600 rpm 25 to 2000 32 to 2500 40 to 3200
The headstock spindle and gears were lubricated by a pressure-feed system using filtered oil - no part of the rotating mechanism was oiled by splash and a built-in hand pump was provided to force oil in and dirt out from under the cross and top slides and saddle.
Certain restrictions were imposed on the specification which customers could choose: lathes with beds which exceeded 5 feet in length were restricted to a maximum speed of 1600 rpm - whilst those longer than 6 feet and 8 inches were, wisely, limited to 1600 rpm.
A No. 5 Morse-taper headstock spindle was common to both 500 and 575 models but whilst the former had a bore of 119/32" (40.5 mm) the larger lathe had its increased to just over 50 mm.
The micrometer dials were especially large and very clearly calibrated, and allowed readings down to 0.0001" (0.0025 mm). A graduated dial was also fitted to the carriage handwheel - which itself was fitted with a "counterweight" to help the operator move the mass of the heavy carriage more easily. Both power sliding and surfacing feeds were fitted with stops to disengage the drive and, in addition (as an unusual feature) an adjustment was provided to vary the effort required to disengage the feed.
The cross slide was made of steel - in a deliberate effort to provide extra rigidity when it was locked and heavy cuts were being made - and the cross slide screw ran submerged in oil. The 4-way toolpost was a Cazeneuve patent, capable of repeating its location to within a claimed 0.0001".
Screwcutting - where fitted - was by an enclosed gearbox able to generate 73 metric and, by changing one gear on the quadrant to a 127 tooth wheel, 73 English threads.
Lathes with gap beds were able to swing a maximum diameter of 2.625" (HB 500) or 29.5" (HB 575). The total width of the gap on both models was 9.25" and metal up to 6.6875 thick could be run inside the gap on a faceplate.
On certain Cazeneuve models (HB-18 amongst them) an unusual mechanism was included (operated by a lever on top of the headstock) that disengaged the spindle from the drive train but left the feed and screwcutting system engaged. In short, with the spindle disengaged all the power feeds to the carriage and cross slide were still available and could be used to cut splines and keyways using the carriage feed - the only drawback being that no provision was included to index the spindle..
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