The dilemma

A dilemma was presented with the demise of Myfords. To replace my ageing Myford ML7 or even contemplate replacing the spindle, bed re-grind and/or bearings plus maybe a few other spares would inevitably be very expensive.  I have have always maintained Myford’s produced well made machines but the methods they used to manufacture many of these things relied on a lot of skilled manual labour which inevitably resulted in very high costs.  It cannot be disputed the parts from Myford are very well made, engineered and hand finished to high quality standards but when it comes to buying this quality it is completely out of step with competitive offerings that are equally as accurate if not always as well crafted. 

The other dilemma I faced with the ML7 was that it was by design old and since replaced by the superior S7 however although much of the S7 was better there was still an ML7 under-lying the design upgrade, and it still had many failings eg. the spindle through-hole diameter was severely limited until very recently. 

Myfords and their apparent desire to continue with their old manufacturing ways and design seem to live in the hope that buyers would recognise the high quality workmanship and overlook the associated high cost.  It is only when you are thinking of buying a new lathe that the true costs of a Myford become known since the bare bones machine requires many ‘extras’ before it is truly functional - when I bought my ML7 even the electric motor was extra and the gearbox was very, very expensive but beautifully designed and made. 

Despite this approach by Myfords to live on their reputation and loyal, almost religious followers it was clearly evident that sales of new lathes were the exception and many were taking the ‘risk’ to by an import.  This, I consider one of the prime reasons Myford folded though I do wonder if they really wanted to continue on into the future.

All this is now somewhat academic because buying a new Myford S7 is no longer feasible even if one is prepared to lash out a large amount of cash and those few that are currently available following the closing sale do not have any warranty.  Spares are still apparently going to be made available but these will eventually run out and then their replacements may be made to lesser standards or refurbished used machine parts. 

Now consider the dilemma of buying a used lathe.

Buying a used lathe is a game of chance and the problems most likely with used machines is bed way wear and spindle/bearing wear not to mention misuse.  Many used lathes are very nicely presented and look like they are in pristine condition but this is unlikely to be the case.  For example, my ML7 was my second lathe so I made all my mistakes on the first, a Drummond and have looked after it with much care.  Despite being 40+ years old there is little wear in the bed and when properly set up it can produce accurate work but it has done a lot of work and inevitably some parts have been repaired or replaced and recently the white metal bearings re-scraped and refitted but this is a lathe of known use and has been well looked after by an engineer. 

There is another problem especially with the Myford lathes, they are very vulnerable. This is often attributable to misuse by unskilled owners not correctly installing and aligning the lathe.  The bed can easily be subjected to twisting and Myfords even mention this technique to set up the lathe for accuracy, which is acceptable if done as a last resort and only when the lathe has been installed on a level base.  I am certain when they originally ground the bed ways the jigs used would have allowed zero twist and the castings were all well aged to remove casting stresses, so applying large amounts of twist to gain ‘accuracy’ is in my view a sign that things are not right!  All this is hidden when you buy a used machine and bad management in setting up a lathe, applying too much twist to the bed will over a long time destroy the accuracy and in extreme cases apply permanent misalignment only cured by a re-grind!

Next, consider buying a lathe that has overcome some of the limitations inherent in the Myford design.  This usually means buying a bigger and heavier machine. 

Bigger in most cases gives larger capacity and heavier provides more mass to absorb cutting forces.  So it would appear the solution is simple, find a used lathe as big as needed, not too heavy and problem solved or is it?  Once again the used lathe often comes with an unknown history.  If it has an industrial background you can be sure it has been well used and possibly abused but for certain must have suffered wear and in need of corrective attention sooner or later.  Another source is ex-college machines which always look good and will not have done much mileage but will have suffered abuse and neglect as students have a knack of doing what they shouldn’t do and once more it becomes a gamble.  Taking the gamble can often be a good one especially if you have time to inspect and wait for the best machine to come onto the market but beware that with many industrial lathes repairs and parts can be extremely expensive.


Decision time

Because it is impossible for me to spend time inspecting used lathes I decided the only option was to either stick with the ML7, buy a new import lathe or keep the ML7 and buy an import lathe.  I chose the latter option since the ML7 is actually in good condition, well looked after and for small work easier to use.

It would seem the choice available of import machines is large but surprisingly it is not when you set the size and weight requirements.  The other requirement I wanted was a lathe of simple design basically to limit the number of problems that may exist when it comes to buying import machines being of low cost.  Having experienced several import milling machines it is clearly apparent one should consider the purchase as a kit needing to be checked over and parts re-fitted where needed. 

This statement may seem to kill off the buying of an import machine but this is not necessarily the case since the manufacturing processes and machinery used to mill and grind these machines is actually of very high capability and modern!  It is the fitting of parts and small parts that usually suffer because manual labour is unskilled or lacking any quality awareness.  With these thoughts in mind the choice of lathes came down to just one and then a choice of two suppliers selling almost identical machines but closer examination revealed differences thus the source manufacturer or assembler is different.  This decision then comes down to reputation of the seller and other buyers experience which is an invaluable measure of quality, capability and work needed to get a good end product.

The lathe I settled on was the BH600G supplied by Warco.  The lathe has been around in various forms for several decades so I guess/hope problems will have been sorted over this time.  The other thing with this lathe is that it is a belt drive, not unlike the Myford, and has a back gear for slow speeds so the design can be considered ‘traditional’. 

As expected with import lathes all the extras are included so the total cost is significantly less than a new or even used Myford and comes with more capacity.  This then leaves the major issue of quality which is of crucial importance.  As I mentioned I shall check and refit  the smaller parts so quality really comes down to bed accuracy and headstock/spindle and tailstock alignment. The bed ways are modern design, induction hardened and ground. 

Checking other users opinions revealed that this model was consistently accurate but would benefit from a thorough check and fit of ancillary parts such as the cross slide and compound slide.


Arrival and installation

A quick visit to Warco and the lathe purchased and delivery scheduled which in my case involved transport off the mainland!  Delivery was prompt and a boxed machine including a separate stand sat on the workshop floor.  Warco do some preliminary checks which was the case as the box had been opened to include some extra oil ordered. I had already done some preparation by changing things around in the workshop so that the BH600G would fit in the same position previously occupied by the Myford.  Although the BH600G is considerably heavier and has greater capacity the footprint is only marginally bigger needing about 7” extra length and width.  Fortunately for me, my friends Jack and Mike turned up with a 1 ton engine hoist and managed to manoeuvre the lathe onto the stand and then roll into place.  The stand is in two parts with a thin connecting sheet but really both end parts take all the load.  While adequate they do the job but a cast iron stand or these reinforced would be better but they were included in the price and good enough for home workshop use. 

I decided to ensure the lathe and stand were correctly levelled and this took some considerable time but eventually all was sorted using a Starrett 6” machine level of 0.005” per foot accuracy and later actual machining tests.  In hindsight it would have been better to prepare the floor with a new levelled concrete surface and floor bolts but maybe this will be done at a later time should any change in the levels become noticeable over time.  (see update at foot of this article)


Checking and findings

I decided to strip all parts other than the apron and headstock spindle as these are probably better left if no problems are apparent. 


The compound slide was scraped (not the typical Chinese haphazard massacrer), I suspect the pre-machining was actually good and to close tolerances and so needed just superficial scraping for good oil retention.  Maybe they have invested in a mechanism to do the scraping (other than ham fisted people) as it looked very good, although not in the class of traditional hand scraped machine slides but even some of these were latterly done my a mechanised scraper for effect and to demonstrate quality. 

I later decided to check just how good the scraping was with engineer’s blue and while not brilliant it was passable.  Spending about an hour I managed to get a better contact area which could still be improved but the return may only be very marginal.  The screw backlash was minimal and the slide moved smoothly.  Despite this I stripped it down to check, clean and lubricate but frankly was more than pleased with the quality and performance. 

The dovetails on these machines is quite a bit larger than the Myford and the unit has more mass plus the taper jib method, when well fitted, provides simple and accurate adjustment.  All the dials (for all slides) are dual but not engraved so it now depends on how long the markings remain?


The cross slide was initially stubborn to strip and this was due in part to paint and the grease hardening on the hand wheel spindle.  As with the compound the quality was equally good however a not uncommon problem became apparent concerning the positioning of the screw nut.  I have seen this before and usually it is to do with the height position but this had a close fitted (light press) pin in the top of cross slide body which was fixed to the nut using an M6 screw and thus moved the pin to the correct vertical height.  The feed screw bearing housing is attached to the saddle and should pull up to give correct alignment, this is done when the nut and screw are at the shortest distance.  Alignment of the nut to the screw needs to be done with care so that the nut is at the correct hight relative to

the slide screw bearing and also in the horizontal plane.  Initially I thought it was out of horizontal alignment but there is a degree of movement as the M6 screw which fixes the nut has some lateral play.  The trick is to tighten the M6 screw gradually while moving the slide and this ensures the nut aligns correctly.

Since I had found the compound slide scraping, as supplied was poor I decided to check out the cross slide.  It seems the sliding surfaces were originally machined by grinding and then scraped.  In the case of the cross slide the saddle part was scraped only and on testing it the scraping was once again poor.  I think they now use a mechanised scraper and the intent is purely to provide some oil space however good sliding surfaces should be scraped to also provide a good amount of contact area to the sliding surfaces.  After a couple of hours scraping (a job I did for most of my apprenticeship, and hated!) the blued and gave a reasonable amount of contact.  Once again more could be done but the gain is marginal but the remedial work done is a massive gain from that delivered.  This is to be expected with import machines as this process requires skill and time and so I fully expected to do this and was only relieved the scraping done as delivered was not like some I have seen in past machines which probably did more to damage the machine than leaving a rough machined surface!

 

Chucks - the 3-jaw is from a named Chinese supplier and of good quality while the 4-jaw is unnamed.  These are quite big and heavy which once again helps absorb cutting forces.  Testing the 3-jaw I used a 10” piece of 0.5” silver steel and surprisingly even at the extreme end there was only marginal run-out.  Then decided to see how the 4-jaw performed.  When I bought this lathe I was not over-joyed that it had a screw fixing to the spindle rather than the modern cam-lock. 

The chuck, like the cross slide was very firmly attached and again I think this was due to the grease or whatever they use drying to become an adhesive!  After normal persuasion and a longish bar extending from the jaws using a lump hammer managed to break the seal without resorting to using the gears to lock rotation.  Normally, I would have not used the lump hammer and manually used the headstock belt to provide the ‘shock’ force but this being a new lathe the spindle was definitely quite hard to move.  The 4-jaw is adequate, but not precision. However, it will suffice for general work.  The removal of chucks from the spindle is no longer difficult and comes free with moderate hand force.  (note - there are two stops fitted to retain the chuck to the spindle when used in reverse which is a welcome addition - missing on the Myford!)


Counter Shaft/Back Gear - As mentioned the headstock spindle was tight and inspecting the counter shaft revealed it had a tight spot which needed some basic re-fitting to cure.  The back gear mechanism is very substantial but also needed re-adjusting to give the correct meshing.  To engage or disengage the back gear relies on a small pin latching to the spindle pulley, this is not difficult to use but now helped by marking (chisel stamp) where the pulley and pin align which helps enormously.


Tool Turret - as supplied there is a 4-station turret of substantial dimensions.  I decided to buy a Chinese made QCTP of the piston type because they are so much easier to get tool height.  The QCTP fixing plate as supplied was ground and slightly hardened but I could, with a carbide end mill machine the T-slot to fit.  The turret had an indexing pin which was a spring loaded pin sitting on the top of the compound so I decided to retain this as a method of preventing the QCTP from sliding out of the slot as it is a very heavy unit and would do real damage if it accidentally came free.  I remade the pin using silver steel and drilled it through and tapped M4 so that if it became stuck it could be easily removed.  Later I shall fit a rear tool post which may incorporate the turret.


Feed Gear Box - This is a conventional Norton styled gearbox with two selectors giving an enormous range of screw cutting imperial and metric.  Feeds are also from the same gearbox but drive a specific feed shaft which I like rather than use the screw cutting shaft and wearing it unnecessarily.  The front cover easily comes off to reveal the inner mechanism which was duly cleaned

and re-lubricated.  No problems were found. Replaced the steel roll pin on the shaft with an aluminium one to shear more readily. 

The finest feed setting using the standard gearbox set-up was a little course (0.0047”) however using a 28t gear to replace the 40t gear in the train reduced this to a more acceptable feed.


Change Gear Drive - The spindle provides a 40t driver gear of 1.5mod to mesh with the conventional tumbler arrangement.  This unit was stripped as it needed re-alignment as the tumbler operating lever was not quite correct however this was easily adjusted.  The output driver gear from the tumbler has on its shaft a flanged gear which can be used to mesh to either the 120t or 127t gear.  As supplied it had a 40t gear and this was found to be a sloppy fit due to a machining error on reaming (Warco replaced this very speedily) and the fitter had tried to cover the bad fit using a washer.  Why?  It always pays to inspect every part as Chinese fitters are probably untrained and seem unable to realise a part that is wrongly made.  I decided not to buy a gear head drive lathe simply because problems of this type are often difficult to spot in a gear head drive and when they fail the result can be costly and noisy!  The gears, other than the tumbler mechanism are all 1.25mod and on inspection found to be reasonably made but having a fair bit of variability regarding backlash. 

While this is not a major problem but again it shows that Chinese parts rarely go through any full and intensive checking process to select good sizing.  The one very good aspect of the gear train is that very few additional gears (supplied) are needed to give a massive and comprehensive range of screw cutting tpi range.

I intend to replace the existing tumbler mechanism with a completely new one currently being designed by an expert engineer Graham Meek.  His very clever mechanism provides the ability to instantly reverse the screw cutting direction without having to stop the main spindle.  This is a mechanism, often found on high end lathes like the Hardinge, provides a much better screw cutting experience thanks to an auto stop feature once the end of a thread cut is reached.  This is good for even close up threading to a shoulder and so very desirable.  As with all clever mechanisms it is not always easy to design and working with GM has proved this as he must be constantly frustrated by my requests for additional features however we remain on good terms, thankfully, and I supply an endless stream of dimensions and pictures.  The man is a genius because he works to very high standards and will not compromise just to get round a tricky situation. 

This will be a major project to be include at a later date.


Belt Changing - This was a problem I had guessed would need urgent attention.  When at Warco I asked if they would demonstrate how to change motor pulley belt and the look on the face of the man in question gave me sufficient information without letting him suffer further!  The problem is actually relatively simple to resolve and involves adding a plate and lever so that one can lever the motor upwards to its highest position and then lock it at that position. 

The belt is now dead easy to swap over. 

I have the machine close to a wall and this gives very limited access to the motor pulley.  Thanks to the ever cautious H&S people there is fitted a cover prevented access to the motor pulley from the end, this makes sense but not if it then becomes very difficult or near impossible to change the belt over!  Solution was to remove the guard and replace it with a vertical bar to which the nearby wiring was lashed to prevent any possibility of it tangling with the motor pulley.  This ‘new guard’ while not completely covering the motor pulley still provides sufficient warning that one does not attempt to play around when the motor is live.  Once the belt is swapped over to the desired pulley the lock, a handle, is undone and the motor drops to tension the belt, any additional adjustment can now easily be made and using the handle to lock the motor so that it will remain in that position.


Tailstock - This was stripped and cleaned and later realigned.  The centre marking was pretty near but if moved this always needs to be done with a test bar. 

The tailstock ejects taper tools but with the drill taper it does this with the spindle at 1”.  The solution, not a fault with the lathe, is to remove the tang from the taper and shorten it as needed.


Accessories - Supplied a neat plastic tool box with chuck parts, taper sleeves and centres all of good quality.  Not so good, a screw driver and oil can which were put in the trash!  The Fixed Steady was also of dubious quality and needed to be treated as a set of castings to make the hinge and other surface accurate - this was typical Chinese shoddy work but in this case able to be renovated.


Final checks and installation - Satisfied with things (much better than anticipated, it has to be said) the machine was run for 10 minutes at each speed starting from slowest speed in back gear to ‘break in’ the spindle main taper bearings.  Lighting - suppliers have these at inflated high prices and I made my own version which comprised a ceiling down-lighter with an 12v MR16 50W bulb and transformer for the total cost of £7 new!  This not only looks good but is an excellent light.

Accuracy checks have shown the BH600G to meet those supplied showing it to be capable of accurate work.

The overall finish of the lathe is very good with many ground surfaces and well painted.  Some less obvious parts such as castings are pretty rough although this does not impact on the machine performance. Why do they not ‘fettle’ cast parts?  My time working in the foundry demanded that all castings  were rough ground (fettled) to remove obvious casting imperfections and feeds - I guess this costs time and money!


Conclusion

Overall - the machine is better than expected but it pays to closely inspect and rectify any bad fitting of parts before they cause a later problem.

I have always advocated that the installation of a lathe and subsequent levelling to be critical and despite these intentions I made a serious error on installing this lathe.  The concrete floor of the garage (workshop) seemed reasonable and so I did not check further and the design of the BH600G stand has fixing holes in the base but too close together!  Now if the stand is bolted to studs in set in the floor then being too close is not a major disaster but I had decided to depend simply on the weight of the machine without fixing bolts which is not uncommon practice.  On finding the concrete base to be far from flat and level it was necessary to alter the base of the stand using some additional 15mm thick x 50mm HRS bar.  The intention was to use the existing (too close) holes to have bolts which fastened to the bar with some nuts to provide height adjustment.

Big mistake!

While the levelling could easily be accomplished the rigidity of the lathe was compromised so I then, as a makeshift added some wedges to the surrounding stand perimeter which sort of worked but far from ideal.  The solution was relatively simple and the HRS bars were made longer than the width of the stand by 2” either side and the bar permanently bolted to the stand using the too close holes but now using holes drilled in the 2” extension and these were now the height adjustment bolts.  The end result is the lathe can easily be adjusted for levelling purposes and is totally stable thanks to the extended base width. 

On reflection I think the stands should have included a welded attachment lug to extend the footprint width but the stands are included in the purchase price and as such minimal thought has gone into their design other than able to support the overall weight of the lathe.  Attempting to make these changes with the lathe assembled in position is both difficult and time consuming and had I given more thought about the installation I would have saved myself all this work!

SEE FOLLOW UP ARTICLE ON CURING LATHE NOISES


 
CHOOSING AND BUYING A NEW LATHE
by Graham Howe