Thread: Cheap Live Centres

Skoda_light_centers.jpg

This is how an affordable yet reasonably accurate small life center... err....... rotating..... live centre looks like inside.
The larger screw (item11) is to plug the oil fill hole. Chris

Originally Posted by Steamwhisperer

The thumb on the centre is a momentary thing and should never be left there. In fact I used to get a right bollicking if I put my hand on the headstock as doing that would put the lathe out of alignment while machining...well, that's what they said anyway.

I guess it would depend on the lathe but it certainly true of mine. Though how often it would matter is something else. What I was told was "don't lean on the machine, if you're to lazy to stand up get a chair."

Unlike the old days when they many not have had a choice, I'd (almost*) never use a dead center for roughing.
Also the feeds and speeds for carbide wouldn't do them much good, but I mostly use HSS.
Most the half centers I've used are more about doing small work with small centers on large dead centers(though yes I've seen that you can face the end of larger work with one but I've never done that. Looks like a great way to get swarf in the center but sometimes I guess you got to do that you got to do)

Stuart

*generally dead centers have less over hang and smaller diameter that can be handy.

Originally Posted by bob ward

............ it damn near burnt my hand it was that hot.

I know nothing of live centre temperatures as I usually use mine for just 2 or 3 minutes at a time. Is it normal for a live centre to get very hot? Is my live centre on its way to becoming a dead centre? Should I be considering CTC's offerings?

Bought a 3mt carbide tipped live centre from CTC. It turns freely, doesn't burn my hand, life is good.

Before you jam it too far into the tailstock ram... Make sure it gets knocked out automatically.... I had to add an extension to a live centre I bought from CTC for the Hercus...

How much run-out?

Shameless plug for one of the best liVe centres available. Anywhere. Made right here in Oz. You get what you pay for, and in this case that includes supporting one of the few Australian manufacturers still standing!

http://www.pipertools.com.au/lathe_centres.htm

Seeing as I posted I'd add that if you're knocking your lathe's headstock out by resting your hand on it, I'd suggest you have more to worry about than how accurate your tailstock centre is! Dead centres are virtually never used on lathes in industry these days, the advent of inexpensive bearings and insert tooling pretty much makes dead centres redundant. Piper's live centres are accurate to 3/5 micron (depending on the model) TIR, which I'd say is "sufficient"

You cannot "over-lubricate" a tailstock centre, the pressure of the centre will easily expel any excess lubricant, it just makes more of a mess if you use grease. For lubricant use an EP grease or oil (I use oil), mix in some graphite powder with it if you wish. Drill your centres correctly, neither too deep, nor too shallow, from what I've seen the most common error is to drill them too shallow and the centre bottoms out. Finally, mark your headstock centre and replace it in the same position each time, it will avoid the need to swing your compound around to true it up on all but the most critical of jobs.

Pete

Edit: if your existing live centre is getting excessively warm, it could be because it was OVER lubricated and not under lubricated. If they've rammed the bearings full of grease they will get quite hot as the grease churns. If it were lack of lubrication, you'd likely find it destroyed itself soon after, whereas over-lubrication will get hot without the inevitable following self-destruction of no lube.

Another Australian manufacturer of live centres and other tools is Daintree tools.

http://www.carmet.com.au/catalogues/...-catalogue.pdf

Originally Posted by toolman49

### ?, checked the revolving point of the live centre it was concentric, lightly oiled the live centre arbor and rotated it in the tailstock barrel and found it had. 05mm runout. I suppose ya gets what ya pays for, I rotated the live centre until the bar was parallel and spot drilled a witness mark which will have to do until I can afford a Skoda or Vertex live centre.

Pardon my ignorance, I haven't used a lathe for ten years or so, and haven't tried anything high precision for more than 30.

But I am thinking that if you have an properly aligned tail stock (horizontally and vertically) and a live centre with runout in the taper, would not rotating the taper to minimise the runout in the horizontal plane transfer the issue to the vertical plane and either raise or lower the point of the centre, which in turn would also result in turning a taper instead of the desired parallel?

Originally Posted by malb

would not rotating the taper to minimise the runout in the horizontal plane transfer the issue to the vertical plane and either raise or lower the point of the centre,

Sure it would. BUT a error in the vertical plane will give you stuff all taper V the same error in the horizontal plane.

Stuart

Originally Posted by Bryan

How much run-out?

Checking runout with a .01mm DTI 10mm back from the point, TIR is an estimated .007 to .008mm. I get the same result with the centre either unloaded or cranked up tight with a job between centres.


Now that I have a good live centre to use I was going to dismantle my 6 or 7 year old Hafco semi-live centre to see if I could improve it but I can't find a way in. I'm thinking that the innards have all been loaded/press fitted through the front, and that the makers never intended them to be serviced. Any thoughts?

Hi Bob,

Mine is a little like that. The outer shell is rolled over at the back. You would have to machine the lip off in order to dismantle it.

How much would you expect to pay for a Aussie Made live centre and how do they compare to say that CTC?

I need a #2 & # Morse taper, or a #2 with a sleeve. Any disadvantage to using the sleeve?

I would not use a sleeve. I currently have an mt3 skoda I bought when I got my first lathe. I am now using it in a sleeve in my Thai lathe. If I flip the sleeve around 180deg my centers are out considerably. I would expect to pay upwards of $200 for a new piper. FWIW my skoda doesn't even make the needle on a tenth indicator move at all.

Ew

Edit, oops autocorrect changed skoda to skids....

Work bought a new Piper standard duty centre (MT4) for $185 from memory.

Michael