Bolt Together Lathe

METAL-TURNING LATHEBuilt from Stock Parts

by Frank Beatty

USING STANDARD PARTS and stockmaterials that are available almostanywhere, you can build this metal-working lathe with only a few tools.Because of simplification of the assemblyin order to make the unit easy for anyoneto build, the lathe as pictured anddetailed cannot be rated as a precisiontool. It is simply designed to do practicalwork within reasonable limits. Asdetailed, the lathe swings 4¼” over thebed and takes 10” between centers.Standard pipe and fittings are used toform a frame on which the headstock,tailstock and bed are fitted.

The first step is to assemble the pipe andfittings. Do this before any other partsare made or stock cut to dimension. Thereason for this first step is that in themanufacture of standard pipe there areallowable variations and some changes indimensions of lathe may be necessarybecause of these variations. The pipeassembly consists of one 14” length ofl½” pipe, two close nipples, two tees, twofloor flanges and one pipe plug (optional)for closing the tee at the headstock endof the assembly.


Screw the parts tightly together and thenmount on a hardwood base as in Figure5. Later, when the countershaft, motorand motor mount are added to theassembly, a second piece is attached tothe first, making an L-shaped base aspictured in Figs. 1 and 2.

Also at the onset it should be noted thatthe spindle-thread characteristics are notgiven. The reason for this is that chucksare available to fit spindles threaded½”-24, ½”-20 and ¾”-16. You can use a½” or ¾” spindle and have it threaded totake any one of these chucks. Theoriginal lathe spindle was threaded ½”-20

and is suitable only for light work. A solidspindle is, of course, much simpler andless expensive to make or have madethan is a hollow spindle with a #0 or #1Morse taper. For turning work betweencenters, the solid spindle requires aspecial 60° center with driving pin (Figure5). This center and the spindle can bemade in a machine shop at a verynominal cost.


The headstock-spindle bearing (Figure 5)are held on the pipe tee by means of U-bolts and a saddle block of hardwood.One face of the saddle is shaped to thecontour of the tee; the other is facedwith a ⅛” steel plate on which the padsof the pillow blocks rest. The purpose ofthe steel plate is to make it easier toalign the bearing sleeves when theassembly is bolted in place. Cut thesaddle about ⅛” thicker (about 2½”)than indicated. Then assemble the partstemporarily.

Next, build up the tailstock, assemblingfrom parts as indicated in Figure 5.Then, assemble the bed on pipe frame.Slide the tailstock on to the bed andcheck the alignment of the centers bothvertically and horizontally. Anymisalignment can be corrected byreducing the height of the saddle and bytapping the bed lightly to shift it on thefame. Once the centers are aligned,tighten the parts permanently in place.

The toolpost, toolpost slide and theactuating screw are shown in anexploded view at the lower right in Figure5 and are shown in more complete detailin Figure 7, 8 and 9. In this assembly,the tool is moved in either direction byturning the handwheel at the end of thelathe bed. The actuating screw consistsof the lead screw (A), the split nut (B)and the split-nut cam (C), Figure 5.These parts were purchased ready-madefrom the manufacturer of a 6” metal-turning lathe. An alternate assembly forrunning the carriage right and left wouldbe to attach a rack to the underside of

the flat bed and fit a handwheel andpinion gear in the carriage apron, thepinion engaging the rack. This assemblywould shift the carriage somewhat fasterand for ordinary work would be quite aseffective as the use of the lead screw.

The toolpost, toolpost slide and theactuating screw are shown in anexploded view at the lower right in Figure5 and are shown in more complete detailin Figure 7, 8 and 9. In this assembly,the tool is moved in either direction byturning the handwheel at the end of thelathe bed. The actuating screw consistsof the lead screw (A), the split nut (B)and the split-nut cam (C), Figure 5.These parts were purchased ready-madefrom the manufacturer of a 6” metal-turning lathe. An alternate assembly forrunning the carriage right and left wouldbe to attach a rack to the underside ofthe flat bed and fit a handwheel andpinion gear in the carriage apron, thepinion engaging the rack. This assemblywould shift the carriage somewhat fasterand for ordinary work would be quite aseffective as the use of the lead screw.


The toolpost, toolpost slide and the actuating screw areshown in an exploded view at the lower right in Figure5 and are shown in more complete detail in Figure 7, 8and 9. In this assembly, the tool is moved in eitherdirection by turning the handwheel at the end of thelathe bed. The actuating screw consists of the leadscrew (A), the split nut (B) and the split-nut cam (C),Figure 5. These parts were purchased ready-madefrom the manufacturer of a 6” metal-turning lathe. Analternate assembly for running the carriage right andleft would be to attach a rack to the underside of theflat bed and fit a handwheel and pinion gear in thecarriage apron, the pinion engaging the rack. Thisassembly would shift the carriage somewhat faster andfor ordinary work would be quite as effective as the useof the lead screw.

Likewise, the tool post, detailed in Figure 7, can besupplanted by a standard tool post from a small lathe.It can be mounted by having a small block of tool steelT-slotted at a local machine shop and drilled andtapped for the guide rods and the screw. Thisassembly would, of course, allow more latitude inadjustment of the cutting tool.In the original lathe, the carriage consists of two steelplates stacked, and an apron built up from three steelplates and a hardwood spacer; the latter also servingas a housing for the split-nut assembly. Figures 5, 7, 8and 9 show quite clearly how the parts are assembled.Figure 9, the sectional view, shows the relationship ofthe parts when the carriage is fully assembled. Note inFigure 5 that the lead-screw-bearing plates areattached to the pipe tees with screws; the latter beingturned into holes drilled and tapped into the pipe-teeflanges. These holes should not be drilled and tappeduntil the carriage is fully assembled with the lead screwin position. Only then can the bearing plates beaccurately located.


Care must be taken to fit the carriage todie flat bed so that it moves along the fulllength of the bed without side play at anypoint. It is best to temporarily fit theparts tightly, then free them by polishingthe edges and top of the bed with fineabrasive or with an oilstone. The sameprocedure should be carried out whenfitting the parts of the tool-post assembly(Figure 7) and the tailstock (Figure 5).Hand fitting and hand stoning of thesliding parts give a smooth slow motionessential to the performance of the latheand to accurate work. It is especiallyimportant that the tool post movethroughout its entire travel without anytendency to rock on the supporting plate.It should move on the slides (rods) witha slight amount of friction and shouldseat firmly on the supporting plate.

The countershaft (Figures 1, 2 and 6) isdetailed in Figure 5. It can be built fromany parts at hand, or available, that will

serve the purpose. Although the originalcountershaft was mounted in ball-bearinghangers, sleeve-bearing hangers will doquite as well. Standard shaft hangershaving a range of adjustment sufficientto give clearance for the countershaftand drive pulley will eliminate thenecessity of blocking up the hangers asdetailed. Adjustable hangers can bebolted directly to the base. Constructiontime also can be saved by purchasing thecradle motor mount rather than making itup as detailed. Or, if desired, you cansimply bolt the motor directly to thehardwood base and rely on the slottedmotor base to provide adjustment fortensioning the belt. Pulleys of thediameters given will give ample speedrange for turning nearly all metals. Use amotor of 1750 RPM.***

POPULAR MECHANICS, April 1959

Bolt Together Lathe

Documents

Transcript of Bolt Together Lathe