Seig C4 'TIR' problem

[woodmark75]

Hi, Just bought a new C4 from Ebay in the Uk. Have just finnished removing all the red grease,adjusting gibs, backlash and oiling etc. When I went to start machining a small length of aluminium bar I had problems centering it. I thought the problem was maybe the internal jaws on the 3 jaw chuck weren't ground parallel. I have since measured the 'T.I.R' with a dial indicator and then a dial test indicator and the spindle was out by 0.25mm! I have emailed the company I bought it from and I'm still waiting to hear back.
I can only asume ether the spindle hasn't been machined correctly or it's down to the tapered bearings or the the point at which they mount in the head. All of these problems would need a full strip down to fix.
This is my first ever lathe so any help or advice would be greatly appreciated. Thanks

[eartaker]

I had this problem when I received my 9X30... It could be a number of things. Remove the chuck baseplate and check the spindle. If you have a deviation there then it is the spindle and nothing you can really do. If not put the chuck baseplate back on and check the baseplate. if that isnt the problem then it is the chuck itself. Post some pics of what you are measuring and how.

[woodmark75]

Thanks eartaker. I first took a measurement from the bar in the chuck, then the O.D of the chuck and my final measurment was from the O.D of the spindle. I'll take the chuck off tomorrow and get a reading from the I.D of the spindle. In all reviews I read TIR was generaly pretty good and I knew it would obviously vary from machine to machine but 0.25mm/0.009842" makes this lathe a non starter! Having checked the lathe and the parts drawing it shows the plate the chuck mounts on is part of the spindle. All I can think of to remedy this problem is to torque up the 2 bolts on the end of the spindle and if this fails to replace the bearings. Otherwise I'm £925 out of pocket.

[RotarySMP]

As eartaker said, you need to drop that chuck and measure the bore of the spindle, and the chuck aligning feature on the nose. then you will know whether it is the spindle or the chuck.

If it is the spindle, I would highly recommend that you don't crank up the spindle preload bearing nuts. It may well be that there is some casting sand or swarf misaligning a bearing. If you can not get the seller to simply replace the machine, then strip down the head stock and clean everything thoroughly before repacking the bearing grease and reassembling it. If that fixes the problem then you also got a chinese kitset lathe "some assembly required".

When I finrst got my 7x, I had to strip and clean it as it had casting sand in vearious crevices.

Most of these CCL (cheap chinese lathes) have pretty low spindle runout. Mine is only a couple of tenths (0.0001").

The chinese bearings are pretty crappy. Replacing then with a set of western bearings is also worth doing. Replaceing the ball bearings with a set of taper roller bearings is popular mod on the 7x's, which reducese chatter.

[ImanCarrot]

Just on the off chance... you do have the chuck jaws inserted into the right individual numbered sockets? ie, they're stamped 1, 2 and 3 and the chuck should have 1, 2 and 3 stamped on it too.

Don't flame! just in case! it's easily missed.

[RotarySMP]

If you have the jaws inserted in the wrong order , you will be much further off center than 0.25mm.

[woodmark75]

I've taken the 3 jaw chuck off and measured the runout inside the spindle bore and behind the flange which is part of the spindle ie non removable. The TIR on the spindle is 0.26mm/0.01.24". The centre of the spindle shaft has very low runout. This model is fitted with tapered roller bearings. Haven't heardb back from the seller so I'm gonna keep emailing/phoning him to either get a swap for a new machine. If he won't do this then I'll have to press the spindle & bearings out. I'll check the spindle in v blocks then go from there. I would hope the least the seller would do would be to supply new bearings and spindle if needed.

[RotarySMP]

Bummer. If the spindle bore has no run out, yet the chuck indexing feature on the nose has 0.26mm TIR then they seriously screwed up the machining of that one.

[eartaker]

Check the chuck base plate as I did in this video.
[nomedia="http://www.youtube.com/watch?v=9G05I7KqDjc"]YouTube - Chuck Base Deviation[/nomedia]

If you get a deviation like I did then you can fix the problem by facing off the baseplate.

[woodmark75]

When I said " Centre of the shaft". I meant length ways, although I did take a measurement from the spindle bore/ Morse taper. Have since checked the spindle/shaft on a set of V-blocks and it's fine. I've got a set of tapered roller bearings on the way (30206/32007 ). These are Jap'se spec so it's worked out as an upgrade. The vendor did get in touch and he's payed for the bearings. So hopefully I'll be up and running shortly. Thanks for the advice given. Mark

[eartaker]

Nice, if you still have the problem after you install the bearings I would check the base plate. If it is the baseplate the machine is fine and it was just the chuck. I got my machine down to .05mm/.002" TIR by facing off the baseplate. I am also thinking about running a boring bar down the inside of my chuck jaws.

[RotarySMP]

Glad the seller came to the party with decent new bearings. It is a bit disappointing for a new machine, but you should end up with a better machine than standard this way.