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Smart & Brown "Model L" Lathe - Page 2

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A complete Data Pack is available for the Smart & Brown Model L

Rarest of the headstocks was the PGH (hand draw tube) and PFH (lever-closer). This unit was similar in arrangement to the PLH, but with the same bearing system as the PDH with a bronze front bearing and, at the rear, a pair of high-precision, pre-loaded ball races . However, it also incorporated a 3 : 1 epicyclic reduction gear within the pulley - which, obviously, could not run in its own bearings divorced from the spindle. The nose was 13/4" in diameter, with an 8 t.p.i. thread and a handwheel draw-bar to close the collets - if a lever-action collet closer was fitted the model type changed to PFH. This type can be instantly identified by the epicyclic gear engagement lever in front of the left-hand bearing.

For high-speed work, up to 3,500 r.p.m., headstock type PDH was recommended: this used a bronze front bearing, like the others, but fitted at the rear with a pair of high-precision, pre-loaded ball races that could take both journal and end thrust - and which required no adjustment. With a bore of 29/32" and a collet capacity of 11/16", the spindle was screwed on its nose, but only with a fine thread for mounting a collet-closing cap, it could not accept chucks or other screwed fittings. As the cap on the front was used to compress collets, no draw-bar system was available and the collets had to be of the dead-length type.

Headstock Type PRH -  identical to the PLH but with a lever-action collet closer

The standard compound screw-feed unit for toolroom work was the Type CSP; this had the usual type of long-travel top slide - 4.5 inches - that could be swivelled through 60 each side of zero, though the graduations only extended to 45. The Acme feed screws ran through phosphor-bronze nuts, with that on the cross slide adjustable to take out backlash.

If an indexing 4-way toolpost was needed the covered-way slide Type CXP could be fitted in place of the top slide on the Type CSP. The slide had a maximum travel of 3 inches, an Acme-form feed screw running through a backlash-adjustable bronze bush and six closely-spaced gib-strip adjustment screws to ensure the best possible sliding action with the minimum of flex

For special work a slide having quick-feed, coarse-pitch threads was offered, the Type CUP. This utilised the standard screw-feed cross-slide casting (though no doubt it could have been built onto a lever-feed unit if required) but fitted with a rear toolpost and a heavily-constructed top-slide equipped with extra-wide and deep (but exposed) bevelled ways. Both screws had Acme threads, with a 1/5" lead, running through backlash-adjustable bronze nuts with front and back stops provided on the cross feed and one stop on the top. The unit was, in many ways, very similar to the No. 27 slide produced for the Swiss Mikron lathe

For production work the compound rest type CTP was offered; this was an all-lever-feed slide, through rack-and-pinion gearing, with a maximum longitudinal travel of 3.5 inches and all ways covered against the wearing effects of swarf and dirt. Front and back stops were fitted to both movements (protected under the slideways) and the makers claimed that they would: ...maintain size irrespective of the degree of pressure exerted.

To compliment the bed-mounted 6-station capstan unit a 3-inch travel cut-off slide (a forming slide in American parlance) was listed; this unit, the Type CWP, could be either lever or screw-operated and was fitted with stops and toolposts at front and back.

6-station bed-mounted capstan unit for 3/4-inch stem tools

Later turret Slide Part LRST

Screw-feed version of the cut off slide (Part CWP) with front and rear toolposts and adjustable stops.

Hand draw-tube and lever-action collet closers . The former was available as the standard type SB.109 or as the SB.100 fitted with a ball-thrust race to assist with the easier closing of large collets. The lever-action unit, SB.111, could be fitted to all headstocks - the castings being ready-bored to receive the unit

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A complete Data Pack is available for the Smart & Brown Model L

Smart & Brown "Model L" Lathe
email: tony@lathes.co.uk
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