Major? Spindle play

Hi. Im very new to machining (no lathe work since high school ... I'm now 58).

I've recently purchased a Vevor 7x16 mini lathe, which im still setting up.

It,s not bolted down yet, but I'm a little concerned at the play in the headstock. I didn't realise 'till I started checking for parralell.

When I noticed that if I even try to turn the chuck by hand i an getting some serious play.

Measuring the job (a 30 odd cm x 30mm piece of aluminium round stock in a 3 jaw), just putting my hand on the chuck to turn it is registering 15 increments (0.01mm each on the dti) of play, both back and forward. That is 0.15mm, yes? Or is my maths wrong?

This is also reproducible with the lathe running (but not warmed up).

This is too much, isnt it? Can i do much (anything?) without new bearings? Should I be talking to the manufacturer?

Any feedback would be much appreciated.

Peter.

P.s. i can attach a shrot video if there's somewhere to do so, or could email it to anyone who wants to see.

Hi Peter, see here for posting Photos & Videos

Regards Nick.

P.S. Welcome to the Forum.

Edited By Nicholas Farr on 02/05/2023 07:10:20

Thanks, Nick, that's great. Pretty straightforward too. Only problem is that my vid is an mp4.

Ill see if i can do something at work tomorrow to grab some stills from it. (Or maybe just re-take a series of shots showing the situation).

Cheers.

Video has to be hosted elsewhere, Youtube has no problem with MP4

As it is new why not contact vevor before you start playing with things that may invalidate any warantee.

Edited By JasonB on 02/05/2023 07:43:35

Yeah, that's why im here asking about it. It really is too much play, isnt it?

Spindle bearings can usually be adjusted. There are many slight variations between the generic Mini lathes so how yours adjusts and what type/quality of bearings are fitted is hard to know. See if they can talk you through adjusting the bearings, though you don't always get much in the way of customer support at the low end of the price range.

It's grossly excessive. If you bought the lathe new then don't attempt any rectification yourself, reject it as not fit for purpose and get a refund. Vevor have a mixed reputation, for obvious reasons!

I do think vevor will talk to me. They assured me they would help if i had any issues.

But as far as i can see, the only adjustment is going to be tightening down the nut on the other side of the headstock. And there doesn't seem to be any runout so I'm not sure how much i could tighten them down without causing binding. ...which is why I'm asking about other options. They may just be cheap bearings. In which case replacing them with new cheap bearings is not going to be much of a solution.

I can try to get vevor to upgrade them but im not sure how that'll go. Which is why I'm wondering whether i may actually have to upgrade them in the end. Its not something i want to do, but...

What I really need to know is whether this is as serious defect as i think it is or whether Vevor are likely to tell me "no, thats normal. It will settle down with use" or some such.

Thanks for your thoughts.

Thank you John. Thats what i need to know.

Yeah, you should see the state of the quills (ill post a photo or two of the crosslide quill) and the undersides of the slides. But i was sort of getting into slowly fixing everything and eventually making it into a machine worth owning. I had figured this is what you get for a $1000 (600 quid?) Lathe.

Ill see what vevor will come at.

Doesn't sound good, but:

How straight and round is the Aluminium rod? I guess it's extrusion stock rather than an accurate test bar. If so, a better test is put a short length of the rod in the chuck, no longer than 3x diameter, and turn it down by a millimetre or so. Then see what the DTI makes of the turned diameter. Measure how the lathe cuts, not the accuracy or otherwise of stock metal.

Next suspect is the chuck. Might be faulty, but If the rod isn't round, the best 3-jaw chuck in the world won't hold it straight. Take the turned rod made above and put the machined end into the jaws, leaving enough of the turned diameter protruding to test it with the DTI. It won't be perfect, but 0.05mm isn't unreasonable.

Have you removed and replaced the jaws? For accuracy they go into particular slots, and the chuck body is usually stamped with a zero, 1 or dot to identify the first slot (the jaws are also numbered 1,2,3)

If unsatisfactory, take the chuck off and make sure the back and spindle flange are clean - no paint or burrs etc.

With the chuck off, use the DTI to test about 10mm inside the spindle. The spindle hole should be accurately ground to take a machine taper, and bad readings here indicate bearing problems.

Put the chuck back on carefully, making sure it stays properly seated in the register as the nuts are tightened.

Don't jump too quickly to conclusions. Measuring at the 0.02mm level seems straightforward, but is actually difficult. For example, a DTI applied to a rod is only good for measuring rotating error, and running it lengthwise is untrustworthy.

Beginners often start by measuring their new toy, but I don't recommend it. Instead, measure the work it produces, and only when that's wrong look for causes. It's much easier to measure small work accurately with a micrometer than a big machine with a wobbly DTI.

Noting that mini-lathes aren't high-precision tools, working to about 0.02mm in capable hands, with luck the machine and chuck are 'good enough'. However, lemons do occasionally reach customers. What happens then depends on where you live and who it was bought from. In the UK, the supplier would normally replace or money-back a faulty machine. There's always a negotiation, sometimes painless, sometimes difficult.

Fingers crossed, your new lathe cuts metal as well as it should.

Dave

Did you get a test cert with the lathe? As that should show what is acceptable.

My Warco shows 0.08 per 100mm as the limit so even if you were using a test bar in the spindle at 300mm stickout upto 0.24mm would be in spec let alone allowing for chuck errors and a bent bar.

Thanks Dave.

The Al stock is just extruded bar stock. Nothing special; but it does have its ends turned down some. i did turn it down to pretty close to 30mm, a quarter inch or so from the chuck. 100 mm out, the same settings turned it down to a little over 29.5mm. something amiss. But in looking into this, I noticed that if i turned the chuck by hand the dti went waaay off. Fifteen full increments. 0.15mm. this happens with minimal pressure... just enough to begin turning the chuck. So its not that the chuck is off centre or out of round (though it may well be)...The issue is that its virtually moving from side to side with the pressure of one finger. If i can push a job that far off centre with a finger, how far is a cutting tool going to move it? (I can find out ...the dti is solid)

I will remove the chuck and check the measurements inside the taper. But not tonight.

Also, my chuck jaws are all numbered 4 (all 3 of them). I will centrepunch some dots before i remove the jaws.

I was trying to measure the work, not the machine. But then i ran into this issue. It seems like it needs to be fixed before i can ask anything of the machine. I guess I'll see how Vevor respond.

Thanks for all your thoughts,Dave. And for your advice. Much appreciated.

Cheers,

Peter.

No cert, Jason.

Heres some pictures of the crosslide quill to amuse you all...

Peter, can you confirm if this 15mm either way is RUNOUT when the chuck is rotated or PLAY when pressure is applied to the end of the bar

I haven't seen lathes or welders on Vevor UK for quite a while now

I used to visit them regularly but gave up trying

Edited By Ady1 on 02/05/2023 10:40:16

Yeah, the 0.15mm is play, back and forward (away from and towerds the operator)as you put pressure on the chuck (or, i guess on the end of the bar being worked).

There is no noticable runout in the bearings. They feel tight.

This model is a new model for vevor here.

https://m.vevor.com.au/metal-lathe-c_10121/vevor-mini-metal-lathe-machine-7-x-16-800w-precision-benchtop-power-metal-lathe-150-2500-rpm-continuously-variable-speed-with-3-9-3-jaw-metal-chuck-tool-box-for-processing-precision-parts-p_010943528473

Aha.

Vevor Australia

Hmmm. I maybe should've mentioned that.