micro-lathe plans (popular mechanics)

RAFTSMEN, modelmakers and otherswho need a small metal-turning lathe

can make one almost entirely from scrapmaterial available in junk or auto-wreck-ing yards. A chuck may have to be pur-chased, but many turning jobs can be donebetween centers or on an improvised face-plate. The lathe shown here has a swingof 41/2 in. A larger one, of course, can bemade by changing the proportions.

In. making the ways, Fig. 1, select straight

lengths of angle iron. These can be filedon the inner surfaces so that the slide block,Fig. 7, will travel true to within about. 001in. For finishing them smooth, a piece offine emery cloth wrapped around a file orblock is rubbed over the ways as in Fig. 2.One of the end blocks is drilled for a leadscrew as shown in Figs. 6 and 7. This shouldnot be done, however, until the carriageand slide block are positioned on the lathe,to assure locating the lead screw at the

C

LEAD SCREW ANGLE-IRON WAYS

END BLOCK

TAPPED

IRON FEETANGLE-

ASSEMBLY OF BED WAYS

proper height. The screw is secured bycollars and rotated by a gear wheel takenfrom a discarded hand drill. Or, almost anysmall crank or a wheel fitted with a knobwill do. To allow maximum travel of thecarriage, the screw should not be cut tolength until all other working parts are inplace and ready for use.

The carriage is shown in Figs. 8 and 10.For the small work done on a lathe of thissize, the feed-screw thread should be fine.The tool post can be raised, lowered orturned in any direction. Even the tool itselfcan be rotated because it is round, beingformed from an old drill bit.

For the head and tailstock, shown in Figs.3, 9, 12 and 13, overhead-valve tappet as-semblies from an auto motor are used. Oneof the two tailstock bearings, Figs. 8 and 13,has a stud which fits a groove in the tail-stock spindle and locks it. Both headstockbearings should have oil cups as shown inthe detail of Fig. 5. The two sets of bearingsupports are mounted on two plates asshown, after being aligned. This is done bypassing the original rocker-arm spindlethrough all four bearings, then locating theholes to be drilled in the mounting plates.Now, with both sets of supports in correctposition on the ways, the plate on whichthe headstock bearings are mounted isbolted to the ways. The tailstock plate,however, is movable. Itis fastened to a spacingbar as in Fig. 12; thebolts through the platedo not pass through the

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ways. The assembly can be locked by ascrew through a bottom plate as shown inthe circular detail of Fig. 8. To check thealignment, the carriage can be used as illus-trated in Fig. 11: with the tool touching thespindle near the headstock, the carriage ismoved toward the tailstock. If the bearingsupports are in alignment, the tool willtouch the spindle uniformly throughout itstravel from end to end.

After using the rocker-arm spindle toalign the bearings, suitable lengths are cutoff, one for a sliding fit of the tailstock spin-dle, Fig. 9, and the other, for the headstock,reamed at one end to take an adapter onwhich the chuck is screwed. The tailstock

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A - Slide block, . 625 x ¾ x 2¼ in. Rides inside bedB - Saddle plate, ¼ x 1 ½ x 4 in.C - Spacer plate, ¼ x 1.125 x 4 in.D - Cross-slide way, .375 x 1 ½ x 3¾ in.E - " gib, .375" x 4 in. key stock; 2 req'dF - " top plate, ¼ x 2¼ x 4 in.G - " retainer, .062 x ½ x 4 in.H - Front panel for cross slide, ¼ x .687 x 2¼ in.

K E YPLATE SCREWED

TO SLIDE BLOCK

spindle is fitted with a small chuckand a wood handle. In order to usea tailstock center and other attach-ments having a No. 1 Morse taperyou can make an adapter whichscrews on the spindle. Bronze bush-ings are inserted in the headstockand pulleys are fitted on the head-stock spindle as in Fig. 4. A coun-tershaft as shown in Fig. 14 is nec-essary and may be mounted con-veniently on the bench behind thelathe. With a four-step cone pulleyas shown, it is possible to provide aconsiderable range of speed as re-quired for various turning jobs.