CURING STRANGE NOISES ON A NEW LATHE
By Graham Howe

WHENEVER you are in the workshop and turn on a machine and hear something strange then it is likely all is not right and needs investigating!  After many years in this hobby (>50) I have often heard these sometimes alarming noises and from experience been able to instantly decide if it is just a passing problem of minor importance or more worryingly something that needs immediate attention and sometimes lengthy investigation. 

As the years pass I am able to resolve many of these things quickly as they have happened before but every now and then something new pops up and understanding the problem becomes a major task.  As you might expect, until you accurately identify the cause of a problem the solution cannot be implemented. 


Jumping to the wrong conclusion

This may sound trite but often I jump to the wrong conclusion too quickly and blindly attempt to resolve something that is totally unconnected with the real problem and even make things worse!  I think this is a curse all of us have to live with as it is so easy to jump in without adequate thought or proper investigative analysis.  This happened very recently to me with the acquisition of my new lathe, an imported Chinese one which has been in production for several decades and other owners, all say how happy they are with it, once they have sorted out the expected problems. 

In the case of my Chinese imported lathe, the BH600G from Warco, I fully expected the major areas needing attention would be those that involved parts that fit together rather than the machining of parts and in general, this often proves to be a good assumption.  My BH600G was of traditional design being a belt drive from the motor to the counter shaft which included a back gear arrangement for low speeds, a similar arrangement to that used on Myford lathes.  


Important areas

The main areas of importance, regarding accuracy, are basically the bed and spindle which fortunately do not require too much fitting skills as the parts are usually pre-assembled before machining and then finish ground.  After testing the alignment and quality of the lathe bed it was very good and well within the published tolerances. 

I spent a lot of time installing the lathe, cleaning all the parts, scraping the cross slide and compound slide, re-fitting the chuck to its back plate and performing a number of basic tests with the lathe doing some turning on mild steel bar.  I had, incidentally exchanged the supplied tool post with another Chinese imported QCTP (Quick Change Tool Post) mainly for the convenience of quickly setting the cutter tool to the correct centre height. With all this done I was a little disturbed when a strange ‘ticking’ noise occurred and progressively got louder as time went on. 

My immediate thoughts were a faulty motor, probably influenced by reading odd forum comments about quality issues with imported motors.  I then reflected that the motor on my imported band saw had suffered terrible conditions having been soaked on more than one occasion yet had refused to die after some 25 years of abuse.  This contrasts with my Myford lathe motor which was a British made one (Brookes Compton, I think) from a maker of impressive reputation yet had failed several times during the last 20 years, but continues to limp along. 


It must be the motor!

My experience from past dealings with electric single phase motors told me it must be a loose plate inside which holds the starter mechanism but the noise was very cyclic and seemed to originate from other places as well.  I was maybe trying to over-convince myself this was the case since having spent so long installing the lathe close to the back wall, removal of the motor was going to be a tricky and painful exercise and even more so if it then turned out not to be faulty! 

It then occurred to me that a  similar ‘ticking’ noise had happened on the milling machine (yet another Chinese import with 3-phase motor) and that was because the pulley keyed to the motor shaft by two grub screws had come loose allowing the pulley to oscillate and thus the resultant noise.  Yes, that’s it, but on checking both grub screws were very tight.  The next thought was the surrounding wires, metal guard plates and bits that were possibly being ‘caught’ as the pulley or belt revolved and I then thought about the ‘fix’ I had made to enable the motor to be easily raised for belt changing, but again after looking around, everything was as it should be and the annoying ‘ticking’ continued. 

It must be the motor because everything else had by now been eliminated I convinced myself, but the thought of removing it was not popular as I had since injured my left arm and that would be needed to extricate the motor from its platform as it is very heavy, especially so at arms length. Reluctantly,  I resolved to pretend the noise was of minor concern and train myself to block it out of my hearing.  Unfortunately, I am not that easily satisfied and while I enjoy problem solving I hate to give in especially as every time I start the lathe it reminds me how inadequate I am! 


Still ticking

A few days went by and the ‘ticking’ continued and by doing so continued to annoy me!  I decided to start again and analyse the problem more carefully and decided the best approach would be to properly identify the real source of the noise.  If it was the motor then I was definitely in for a painful time and possibly a delay if the motor needed replacing.  By starting the machine I went about isolating the noise source and it soon became evident it was not the motor as the ticking was only heard when I looked down from the saddle area towards the motor but looking from either end of the motor the noise was considerably less, so this revelation absolved the motor of all blame. 

So what the hell was it? 

The back gear was not connected but even when engaged the noise was just the same and the counter shaft was completely silent which left the only other area the spindle and output gear train.  The latter was easy to check by disengaging all the gears. 

The spindle was more of a problem to check and I dreaded to think about the consequences.  But the spindle was the only part left that rotated and so it must be the bearings - oh no not the bearings please no!  I placed my ear close to the back end bearing seat and rotated the spindle by hand and could hear the tick on each turn and then moved to listen at the chuck end and the noise was even louder - that’s it - the roller bearings are faulty! 

This was not good news as I did not want or expect to strip down the bearings which had probably only a few hours running but it seemed I had no choice and so wisely, as it turned out, decided to leave it for a few days.  This tactic is one often adopted when all else fails as I hoped miraculously it would self heal.  Unfortunately not, and since I was not keen to start stripping the spindle I listened again this time more closely to hear exactly when and what possibly could cause the ticking noise as I decided even a broken roller or even worse a missing roller in the bearing would on slow turning reveal its identity. 


Joyful moment

While doing this I realised I had not checked all of the rotation parts and the one forgotten was the chuck which, of course, was fixed to the spindle end.  I removed each of the chuck jaws but still the ticking continued however by placing my ear close to the chuck body it was a joyful moment as it came obvious the ticking was from within the chuck body!  With chuck back plate removed the innocent looking scroll cover plate, a cast iron disc which has little purpose other than to stop swarf from getting into the scroll was loose!  The three attachment screws were very sloppy and the plate was rocking back and forth with what now was a joyful ticking sound and after tightening silence ruled once more.   

A long story but after 50+ years in this game I thought I had experienced all the problems that might occur and especially those associated with imported machines, but this taught me that it pays to think hard before jumping in and be thankful if you have injured your arm, as it slows down the ‘quick fix’ action process.  Every now and then, the problem is new and from an unexpected source, proving there is always more to learn.   

Total investigation time many,many hours, fixing time 10 minutes! 



Gear train ‘ringing’

The gears on the BH600G  make a ‘ringing’ noise which is not pleasant when working the lathe and the gear train is needed for activation of the power feeds.  The gear train comprises a few gears mainly of 1.5 &1.25 module and 20 deg PA, the largest being a compound 120/127t gear which seems to be the culprit of the ‘ringing’ noise. 

The gears are well made and properly meshed together with the correct clearance but still produce this characteristic ring and I decided to try a few things to reduce or even eliminate the noise.  Now the big compound gear has 4 large holes which make it look pretty but apart from that and reducing weight I cannot for the life of me see why they bothered with them and so convinced these holes were the cause I initially attached a backing plate (made from thin wood composite). This made some minor improvement to dull the ‘ringing’ and so I progressed onto filling the holes with silicon but this made little difference. 

I had, of course tried oiling and light grease but this too didn’t work out.  In desperation I removed my backing wood plate as it was really ineffective and decided the best approach was to add insulation to the inside of the gear casing.  The noise would still be there but hopefully sound proofed!

While waiting for a trip to town to buy the insulation material (polystyrene sheeting), I asked others in the forums who have the same lathe which in the USA is the Grizzly G9249 as they too must have to suffer this noise. 

A single reply simply said: ”use Open Gear oil.” 

I have never heard of that but after a little research it seems it has a sticky additive and while providing lubrication it also sticks to the gear teeth and I guess provides a minute barrier of sticky oil between the gear teeth in mesh.  As I already had a similar sticky oil at hand which is made for the garden hedge cutter blades I decided to apply a few drops - noise dramatically reduced, no high pitched ringing!  Thanks to the person who knew how to solve this and replied to my cry of help.

The insulation turned out to be ineffective but finding a supplier on Ebay for the correct ‘open gear oil’  this worked wonderfully.  It is a horrible black oil applied with an aerosol spray (which didn’t!) but a small quantity dripped out onto the gears.  Result, oil did not splash and stayed on the gears and the noise was considerably reduced to an acceptable level even at higher speeds.

SEE ALSO GRAHAM’S ARTICLE ON BUYING HIS NEW LATHE