myford Ml7 lathe problems

[gavin comptonParticipant @gavincompton68796]

hi all

i been trying to pratice turning for when my new flywheel is delivered but i having trouble tracking down a few problems i got with my lathe its a 1947 ml7 with white metal bearings.

problems are

1: if i turn bit of stock then undo the chuck and rotate the stock then clamp up i find the stock is no longer centred. is this normal ???

2: i get very poor finish on all work ,brass is ok not mirror finish but smooth everything else is very rough feels more like a file !!!!

i placed a dial on the chuck and used wood to lever it up and i got 0.18mm movement is this too much ?????

ive checked bearing blocks are clamped down and checked the clamp nut on end of the spidle. i checked all slides etc,spent all day griding tools even tryed carbine tipped tools basicly im at a lost other than thinking the 0.18mm movement is too much ????????????????????

thanks

Gavin

[gavin comptonParticipant @gavincompton68796]

[Chris Evans 6Participant @chrisevans6]

I have not used a Myford lathe but your 0.18mm seems excessive. I would think 0.04/0.05mm to be about right.

Someone with Myford experience will be along to advise. It is normal to lose the centering after undoing the chuck, plus remember the chuck could be over 60 years old as well as the lathe.

[Martin ConnellyParticipant @martinconnelly55370]

Removing and replacing a workpiece in the chuck is just about guaranteed to put it in a different and non centred position. That is why most people will say machine all features that need to be concentric without removing the part from the chuck.

I do not know what material you are practicing on but some steels will always give a poor finish. In the meantime make sure you are working with suitable feeds and speeds for the material. It is easy to be too aggressive or too timid when you have no experience. Published values are a good starting point, adjust slightly to see what different values have on finish.

Martin

[gavin comptonParticipant @gavincompton68796]

Hi all

i got a new 3 jaw chuck and a few problems been sorted 😀 first i not longer get a massive centre changes so no more oval cuts :D. also finish is alot better but will get better once new cross slide t-bolts come ,i noticed cross slide was rocking a small amount ,went to do t-bolts up and they just failed.

thanks

gavin

[Rufus RoughcutParticipant @rufusroughcut]

Hi Gavin

A rule of thumb for the novice in that round stock is in most cases not round, you will need to make is round, I found when starting out that using stock slightly larger than the required end result was the best start point and before any lateral machining insert the rod as far in the chuck as you can conceivably get it leaving a bit sticking out and centre drill with tail stock drill un-chuck and repeat at the other end you can now centre the work piece between the chuck and tail stock centre and machine a length from the tail stock end long enough to fit in the chuck if the stock piece is long un-ckuck it flip it round and repeat, using many light cuts will give many practice opportunities to centre and round a piece of stock and you will get a better view and feel of how oval round stock is and then you can proceed to cut down the stocks length with more confidence.

Do you have an ML7 Manual, if not please e-mail and I'll send you one ( [email protected])

Rufus

[Author]

Posts