BUYING A USED LATHE
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. 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. I hope it will help you find your Myford Lathe. Regards Chris Moore
Managing Director, Myford Ltd.
Myford Ltd

Pre-owned lathes

A guide to inspecting before you buy

Myford has 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.

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.

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, and explain rebuild procedures and the differences across the model range.

But first 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.

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 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.

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.

Headstock spindle

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.

Now you will need a 0.0001in. (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 0.0004in. (0.008 and 0.01mm) Anything greater indicates that attention is necessary.


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 V-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 V-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.

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.

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 V-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.

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 V-belt to the headstock, adjust the end collar to give correct pre-load on the taper roller bearings, check headstock for alignment.


The Lathe Bed and Saddle

Along with the headstock these are the key components that form the basic structure of the lathe. First make a visual inspection concentrating on the area to the right of the gap. If the bed has indentations, hack saw marks and generally looks untidy it will indicate hard use.

There are two types of bed for the Series 7 lathes. The earlier bed, referred to as a narrow guide bed was discontinued in 1972 at S/N K107657 for ML7 lathes and S/N SK108891B for Super 7 lathes.

Check these and 254 Lathe beds with a 0-1in. (0-25mm) micrometer to measure for wear on the thickness of the bedways (shears). A 1-2in. (25-50mm) micrometer to check for wear across the front bed ways on narrow guide beds and a 4-5in. (100-125mm) micrometer to measure across the bedways of a wide guide Series 7 Lathe bed. Finally a 5-6in. (125-150mm) micrometer to measure across the bedways of a 254 Lathe.

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 6-8in. (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 0.005in. (0.127mm) or the variation in the width across the front shear or both shears is more than 0.003in. (0.076mm) then the bed will most definitely require a bed and saddle regrind.

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 0.005in. (0.127mm) removed, a once only operation, so your visual inspection is crucial.

Procedures used in factory bed and saddle regrinding

All lathe models

The nominal thickness of the shears (bedways) on a finished new Myford bed is approximately 0.5in. (12.70mm). The maximum that may be removed from the top of the bed is 0.025in. (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 0.005in. (0.127mm) and 0.010in. (0.254mm) to get back to a sound top surface. In theory it’s possible to regrind a bed between two and five times. Indeed, as our records show, this has been done for a number of customer owned lathes.

Next time we continue with how to make your lathe good as new.

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