Pre-owned Lathes A guide to Inspecting before you Buy Hardly a day passes when we don’t receive a call from somebody somewhere around the world who has purchased a used Myford Lathe, often unseen at that. Subsequently they have come to appreciate that their good purchase was not really as good as they had anticipated, and it had dawned upon them that to bring their lathe back to Myford standards could be more complicated and costly than originally budgeted for. Myford have been building Lathes since 1934, during our most productive period our output was about 500 lathes a month and to our knowledge most of these Lathes are somewhere around the globe, many still working hard for their owners.

Henry Royce said “the best is the cheapest in the end, the quality will remain when the price is forgotten”. This short Guide is intended to help people inspect and evaluate a Myford Lathe before buying. Almost every used Myford Lathe is capable of being returned to it’s original specification, it’s a matter of time, skill and access to genuine Myford components. Here we tell you how to carry out a basic inspection and how faults are rectified when we carry out a Factory Rebuild. The fate of old Lathes depends on how hard they have worked and how well they’ve been treated; some are broken for spares, others are sold on the used machinery markets.

Some come back to us for Rebuilding and returning to full service. This Guide is an inside view of how and where our Lathes wear and what we do to reinstate their working accuracies. I hope it will help you find your Myford Lathe. Regards Chris Moore Managing Director Myford Ltd Myford Lathes that have worked hard will have wear in differing areas depending upon their history. So during inspection one or more faults will be detected. This Guide takes you through this inspection process and explains how wear is detected and accuracy reinstated. We start with the Headstock of a Myford Super 7, the footnotes explain Rebuild procedures and the differences across the model range.

But first run the Lathe... 1

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Run the Lathe Wherever possible run the Lathe under power. Check that the Lathe will run comfortably at both its highest speed in the open drive range and its lowest speed in the back geared range. The Headstock Spindle June 1958 S/N SK8128. The clutch is an expanding sleeve operating in the 4 step countershaft pulley. At times they proved temperamental in service and spares are now difficult. It is not a straight forward job to fit the current clutch. Visually inspect both the bull wheel on the headstock spindle (mandrel) and the back-gear cluster for broken teeth. Check the condition of the pulley and the bronze gear that forms part of the back gear mechanism.

Check that the rear angular contact bearings have not had grease pumped into them as it will mean dismantling and de-greasing. All the lubrication nipples on Myford Headstocks are for oil with the exception of the two nipples on Series 10 Lathes fitted with taper roller bearings which should be greased. Myford 254S and Plus Headstocks We run the headstock prior to dismantling the lathe to check for bearing wear and undue noise and if required replace. Flush the headstock to clean and refit the headstock to the bed, reset pre-load on taper roller bearings. Replace cone pulley clamp washers, check headstock for alignment and if required correct.

If the machine is fitted with a countershaft clutch check that this engages smoothly, there is no slippage and that there are no alarming noises. Pay particular attention to the countershaft clutch unit on early Super 7 Lathes, manufactured up to Check that the main drive belt between the countershaft and headstock spindle is in good condition. Belt replacement involves dismantling the headstock on all but 254 Lathes. Myford ML10 Plain Bearing Headstock We refit headstock to bed. Check spindle in bearings for running clearance if excessive wear fit replacement spindle. Refit spindle assembly with new vee belt and thrust race.

Adjust end collar to give correct loading on thrust race and correct axial float to the spindle. Check headstock for alignment. Now you will need a 0.0001” (0.002mm) Dial Test Indicator with magnetic stand set to read off the spindle register face (see photo) Release the belt tension from the countershaft to headstock spindle and revolve the spindle gently by hand. You would expect to see a reading of between 0.0003” and 0.0004” (0.008 and 0.01mm) Anything greater indicates that attention is necessary. Myford ML10, Speed 10 and Diamond 10 Headstocks We refit headstock to bed, wash excessive grease from the bearings, check for bearing wear and if required replace.

Refit the spindle assembly complete with new vee belt to the headstock, adjust the end collar to give correct pre-load on the taper roller bearings, check headstock for alignment. Procedures used in Factory Rebuilding ML7 Headstocks We reassemble the headstock to the bed. Re-scrape the headstock bearing to the spindle. Refit the spindle assembly complete with new vee belt to the headstock. Re-shim the headstock bearing caps for correct running clearance. Adjust end collar to give correct loading on thrust race and correct axial float to the spindle. Check and correct, if necessary, the spindle alignments.

Myford Super 7 and ML7-R Headstocks We re-scrape headstock front bearing to spindle and refit headstock to the bed. Fit a new pair of angular contact bearings to the rear of headstock. Refit the spindle assembly complete with new vee belt and wick to the headstock. Adjust the end collar to give correct pre-load on the angular bearings and make axial adjustment to the spindle to give correct running clearance at the front bearing. Check the spindle alignments and correct if necessary. 2 3

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was discontinued in 1972 at S/N K107657 for ML7 Lathes and S/N SK108891B for Super 7 Lathes. To establish what the bed measured when new take measurements at the extreme right hand end of the bed as this rarely gets used. Make a comparison with a measurement taken approximately 6-8” (150-200mm) from the spindle nose at the point where the saddle is most often used. If the variation in thickness of the bed shears is more than 0.005 (0.127mm) or the variation in the width across the front shear or both shears is more than 0.003” (0.076mm) then the bed will most definitely require a bed and saddle regrind.

Take a firm hold of the toolpost stud, to determine if there is back to front movement in the cross slide (see photo). This will indicate the backlash in the feed screw and nut. If there is excessive movement you may not be able to adjust it out and a new feed screw and nut will be required (if the toolpost stud is loose in the top slide top a replacement casting will be required). Visually inspect the condition of the cross slide and top slide tops, check the condition of the tee slots. Look at the jib adjusting screws, if in poor condition it may also indicate a hard life.

Check these and 254 Lathe beds with a 0-1” (0-25mm) micrometer to measure for wear on Procedures used in Factory Bed & Saddle Regrinding All Lathe models The nominal thickness of the shears (bedways) on a finished new Myford bed is approximately 0.5” (12.70mm). The maximum that may be removed from the top of the bed is 0.025” (0.635mm) before complications occur in aligning the apron with the rack and leadscrew. During a Myford Factory Bed and Saddle Regrind metal removal is kept to a minimum, however it may be necessary to reduce the thickness of the shears between 0.005 (0.127mm) and 0.010 (0.254mm) to get back to a sound top surface.

In theory it’s possible to regrind a bed between 2 and 5 times. Indeed, as our records show, this has been done for a number of customer owned lathes. Procedures used in Factory Carriage Rebuilding All Lathe models Regrind the tops of both cross slide and top slide. Refit the toolpost stud and fit a new anti torque in a new position. When re-assembled check for facing cut against alignment jig. The nominal thickness of the shears Note: It is not possible to do a full bed and saddle regrind on an ML10, Speed10, or Diamond 10 Lathe. At best the top of the bed can have 0.005” (0.127mm) removed, a once only operation, so your visual inspection is crucial.

4 5 The Lathe Bed and Saddle Along with the Headstock these are the the thickness of the bedways (shears). key components that form the basic structure A 1-2” (25-50mm) micrometer to check for of the Lathe. First make a visual inspection wear across the front bed ways on narrow guide concentrating on the area to the right of the gap. beds and a 4-5” (100-125mm) micrometer to If the bed has indentations, hack saw marks and measure across the bedways of a wide guide generally looks untidy it will indicate hard use. Series 7 Lathe bed. Finally a 5-6” (125-150mm) There are two types of bed for the Series 7 Lathes.

micrometer to measure across the bedways The earlier bed, referred to as a narrow guide bed of a 254 Lathe. The Carriage Again the visual inspection is very important. First check the top slide of the saddle where the cross slide sits. On Super 7 and 254 Lathes the saddle is scraped to the cross slide, look at the condition of the scraping marks. If the cross slide has worn a groove in the saddle then the saddle will be scrapped, as we cannot hold it in our jig to regrind the underside, as in bed and saddle grinding.

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Gearboxes and changewheels Engage the tumbler reverse lever and check that the drive train to the leadscrew functions properly. If the Lathe is fitted with a quick change gearbox run this through the 8 speed selections on the front of the gearbox to ensure that neither the tumbler selector gear nor the gears on the cone or layshaft are damaged, these can be complex to replace. Remember you must stop the Lathe before moving the selector lever. Check that the selector lever on top of the gearbox also functions correctly.

(This can be done with the gearbox running.) Procedures used in Factory Rebuild Super 7 and ML7 Changewheel Check and refit leadscrew, checking bushes in right hand and left hand brackets, set engagement of half nuts. Refit changewheel guard and drive train from headstock spindle to leadscrew fitting standard set of changewheels. Super 7B and ML7B Gearboxes Remove Quick Change Gearbox lid and flush out. Refit gearbox to lathe. Check and refit leadscrew checking bushes in the right hand bracket and setting engagement of half nuts. Refit gearbox guard, backplate and drive train to spindle. Fit new rack pinion, hand traverse pinion and Oilite bushes as required.

Check leadscrew, half nut and replace as necessary. Refit half nuts and check for closing balance on jig. Refit apron to lathe, check and adjust rack pinion for meshing with rack. The Leadscrew and Apron A visual inspection is all that’s needed. Compare the leadscrew’s centre section where most of the work is done with that at the back of the machine. Are the threads worn or are they becoming ‘sharp’? If there appears to be too much play in the saddle when the leadscrew is engaged a pair of half nuts will often bring the play back within tolerances. 254S and Plus, Gearboxes wear or damage and rectify as necessary. Refit gearbox to lathe.

Check and refit leadscrew setting half nut engagement and checking bushes in right hand bracket. Refit drive guard and backplate and drive train to spindle. 254S & Plus Fit new rack pinion, hand traverse pinion and Oilite bushes as required. Check leadscrew half nut and replace as necessary. Refit apron to lathe. Check and adjust rack pinion for meshing with rack. ML10, Speed 10 and Diamond 10 Changewheel Check and refit leadscrew, setting engagement of half nuts. Refit changewheel guard and drive train from headstock spindle to leadscrew fitting standard set of changewheels.

Procedures used in Factory Re-assembly of Apron Super 7 & ML7 Non-Powerfeed Fit new rack pinion and hand traverse pinion if worn and new Oilite brushes where required. Check leadscrew, half Ml10, Speed 10 & Diamond 10 Fit new hand traverse pinion and counter pinion as required. Check leadscrew half nuts and replace as necessary. Refit half nuts and complete assembly. Refit apron to lathe. 6 7 nut and replace where necessary. Refti half nuts and complete assembly. Refti apron to lathe, check and adjust rack pinion for meshing with rack. Super 7 Powerfeed or amaged, mber the ver rrectly. ning.) build , checking eft hand of half in from ard set arbox rbox to screw nd box ny obvious y as lathe.

gagement efti drive le. 0 ent of e train standard

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