email: tony@lathes.co.uk
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Holbrook Lathes - Model 5P Plain Precision

Manuals are available for Holbrook lathes

Holbrook Home Page   Holbrook Model B & C No. 8   

Holbrook Model B No. 9   Holbrook Model T Lathes

Model 5P Precision Plain Lathe  Holbrook Minor 1960s - 1980s

An Apprenticeship at Holbrook   Holbrook Edgar Lathe   Serial Numbers

Holbrook Model C No.10   Holbrook Type B13, B17 & B21

Typical of the better class of machine tool offered by Holbrook until the late 1930s, the 5"" x 24" Plain Precision Lathe Model 5P was a comparatively expensive machine. Lacking backgear and screwcutting, it was intended to compliment more sophisticated lathes and would have been of little use as the only lathe in a general-engineering workshop.
Deep and very heavy, the bed had strong cross ribbing and the V and flat ways were "
hand scraped to a master plate". The headstock used a hardened and ground No. 1 Morse taper spindle lapped into conical bearings made from hardened and ground steel. Adjuster collars were fitted to set the bearing-to-spindle clearance with the end thrust taken out in the (even then) old-fashioned way against a bracket bolted to the headstock's left-hand face. Three different headstocks were available: a special unit with a built-in thread-chasing attachment, a conventional one for 11/4-inch wide flat-belt (driven from a powered countershaft) and a lighter-duty, V-groove pulley type for use when the lathe was on the maker's "standards" (cast-iron legs) and driven by a round leather "gut" rope from a treadle-operated flywheel.  Betraying their late 19th-century design origins the headstocks were all of comparatively light construction and had the same 1-inch 10 t.p.i nose thread and ability to pass just a 3/8" diameter bar.
Of the expected type for this sort of lathe, the compound slide-rest had a 7-inch travel top slide thought formed, in this case, from an  unusually long casting with (surprisingly) only two gib-strip adjustment screws. The top slide could be swiveled to any angle and its  base was engraved with degree marks to 45-degrees each side of zero. The unit was clamped to the bed not by the usual hand screw but by a long lever working an adjustable eccentric clamp. The feed screws were of Acme form and ran through adjustable bronze nuts; however, as standard, no micrometer dials were fitted - though they were on the options' list. The cross-slide ways and feed screw were both covered to protect then from damage by swarf.
Although not shown in the pictures, at the rear of the bed was a fitting common at the time - two useful (lipped) wooden tool trays mounted one above the other. The lower was 42-inches long by 18-inches wide and the upper 22-inches by 18-inches. In addition a wooden tool cupboard was slung beneath the bed on a pair of cast-iron  rails.
Like many similar plain-turning lathes of the period, the Holbrook 5P could be fitted for light production work and was available with a self-contained, bolt-on "sub-bed" assembly. Mounted on this was a compound rest where the short 1
3/4-inch cross travel was operated by a toggle-action lever (with front and rear stops) and the longitudinal feed by another lever working through rack-and-pinion gearing. In addition, the whole of the compound rest could be propelled along the sub-bed by a large, full-circle counter-weighted handwheel with the drive, again, through a rack-and-pinion. A rotating stop was mounted on the right-hand side of the unit but, unaccountably, had just two individually adjustable screws - not the six that were required. Mounted on the top slide was a flat-topped and T-slotted 6-station turret complete with six tool holders: Two were used to securing 1/2-inch diameter circular tools, two for pillar-style "American-style" holders for conventional turning tools and two pillar holders for broad flat tools used for forming and broaching, etc.
The tailstock carried a 1 Morse taper spindle, locked by a proper screw-down pad, while the unit was secured to the bed by a captive handle working on an eccentric cross shaft. Supplied as standard with the lathe two sizes of T rest and 2 steel spanners and a Tommy bar. The power lathe came complete with a fast-and-loose countershaft unit for wall or ceiling mounting.
Accessories included a swiveling vertical milling slide with  7-inches of travel table, machine vices, a 9" x 8" saw table, a fixed steady in the form of an old-fashioned "cone-boring plate" and a wide variety of collets including ring and step types with a capacity of up to 3
1/4 inches..

Holbrook 5-inch Precision Plain lathe with a conventional 11/4-inch wide flat-belt drive spindle for drive by a wall or ceiling-mounted countershaft

Holbrook 5-inch precision Plain-turning lathe with the lighter-duty, V-groove pulley headstock used when the lathe was on the maker's "standards" and driven by a treadle flywheel and round leather "gut" rope

Holbrook thread-chasing unit.
For very precise thread-generating work the lathe was available with a thread-chasing attachment. Whilst most makers offered similar devices in a bolt-on form Holbrook required the customer to invest in a complete headstock assembly. However, whilst this was much more expensive, it did mean that the accessory was properly engineered, completely self-contained and driven directly from a gear on the end of the headstock spindle; it did not have to rely upon any intermediate gears or bed-mounted components. The chaser (threading tool) was carried on a bar slideway running through a long tunnel bored through the back of the headstock casting. The toolholder was fitted with a micrometer dial and screw-adjustable depth stop whilst a tapered stop on the feed mechanism could set to halt the cut at any point. An unusual and timesaving feature of the Holbrook unit was the provision of a weight to automatically lift the chaser from the job on disengagement and return it to the start position. Happily, with the chasing assembly swung back out of the way, the headstock functioned as normal for ordinary turning jobs.

Manuals are available for Holbrook lathes

Holbrook Home Page   Holbrook Model B & C No. 8   

Holbrook Model B No. 9   Holbrook Model T Lathes

Model 5P Precision Plain Lathe  Holbrook Minor 1960s - 1980s

An Apprenticeship at Holbrook   Holbrook Edgar Lathe   Serial Numbers

Holbrook Model C No.10   Holbrook Type B13, B17 & B21

Holbrook Lathes - Model 5P Plain Precision
email: tony@lathes.co.uk
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