Live centre play in bearing

This topic has 12 replies, 11 voices, and was last updated 20 August 2017 at 12:01 by Ady1.

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19 August 2017 at 20:51 #312925
Hevanscc
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@hevanscc
A while back I bought a live centre from one of the usual suppliers, for use in a prospective project. So, the day arrived for turning between centers this week but I noticed, on first use, that there was a distinct wobble at the tailstock end. On further examination I found that there was visible play in the bearing.

Being relatively new at this game I am trying to avoid jumping to conclusions but I suspect that this should not be so. Any advice gratefully received.

Hywel
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19 August 2017 at 20:51 #18621
Hevanscc
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@hevanscc
19 August 2017 at 21:38 #312933
Nick_G
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@nick_g
.

So long as it's play in the centre and not your tailstock return it ASAP

I spent considerable time (and money) finding a decent live centre. – Some are cheap. ……….. Far too cheap.! Others are expensive. ………… Far too expensive.!

It can be a minefield. (well at least I found it to be so) My best live centre is a small bodied long nose Rohm which I find is ideal for model engineering as it allows you to still get the tool in on small dia's. But I feel it needs to be shown some respect and I avoid if possible using for interrupted cuts on large square bar etc.

Nick
19 August 2017 at 22:03 #312944
Hevanscc
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@hevanscc
Thanks, I'll try and dig out the receipt or else it will be straight in the bin, having already ruined one job.

Another lesson learned after parting with the folding stuff . . .
19 August 2017 at 22:16 #312947
Clive Foster
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@clivefoster55965
As its a modern unit most likely is a badly made one.

However there was at least one decent quality old style live centre that normally has a little play in it when unloaded. Separate races and loose balls inside I think so if you do manage to get it apart there are a lot of things to catch.

I have what looks to be one such with a bent spindle. Blowed if I can see how it comes apart.

Clive.
19 August 2017 at 23:27 #312955
Hopper
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@hopper
Posted by Hevanscc on 19/08/2017 22:03:58:

Thanks, I'll try and dig out the receipt or else it will be straight in the bin, having already ruined one job.

Another lesson learned after parting with the folding stuff . . .

No need for that. The problem is cheap Chinese bearings. Replace the bearings with a good brand name product such as SKF, Timken, FAG, Naachi etc and you will most likely have a good piece of kit. Even the good quality bearings are cheap to buy.
19 August 2017 at 23:43 #312958
duncan webster 1
Participant
@duncanwebster1
If it's not the bearings the point might not be concentric with the bearing seats. If that is the case rig up a means of stopping it rotating, put it in the headstock and re-machine it. Best of course is to return it if you can
20 August 2017 at 09:32 #312973
Chris Evans 6
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@chrisevans6
I have used a "Skoda" live centre for over 20 years now and not new when I acquired it. A small long nose one is on my shopping list but there is always other things to buy.
20 August 2017 at 10:15 #312978
Andrew Tinsley
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@andrewtinsley63637
I inherited a live centre with a lathe. It has always turned true. A few weeks ago I picked it by the nose (silly thing to do!). I heard a click and on close examination I found longitudinal play of maybe 5 to 10 thou! I got a touch bothered and set it up with a bar in the lathe and it still turned true, maybe the play is meant to be there?

My best live centre is one I purchased in a shop in Austria 40 years ago (maybe an Emco). I remember trying to explain what this item was to an airport security bloke who checked my hand luggage! Blowed if I could remember what a live centre was in German! In fact I don't think I ever knew. Talk about a long winded explanation! At the time my German was mainly Schweitzer Deutsch and the Austrian is almost a different language. Happy days!

Andrew.
20 August 2017 at 10:54 #312986
Ian S C
Participant
@iansc
I use Skoda #2MT live centres, I'm on my second one. For about 15 years the first one got a fairly heavy hammering, and the bearings in it collapsed, I took it to the agents to see about over haul, but parts alone would cost more than the price of a new one.

Ian S C
20 August 2017 at 11:18 #312994
Mick B1
Participant
@mickb1
I've got a cheap Chinese running centre I bought about 15 years ago. The cylindrical casing around the bearing is very visibly eccentric, but the point itself is true enough to turn parallel within 2 tenths over 4 inches if the tailstock's properly adjusted (which it wasn't on delivery of the lathe). I guess the wobble induced by the eccentric casing might become a problem if I was turning tiny diameters to microns tolerances, but I'm not.
20 August 2017 at 11:20 #312995
KWIL
Participant
@kwil
Andrew T,

The longitudinal play should disappear when you load it against the job next time. There is normally little restraint in that axis other than the normal slop of the front radial bearings, the thrust bearing taking the axial load.
20 August 2017 at 12:01 #313003
Ady1
Participant
@ady1
Replace the bearing if it's wobbly

If you still have too much overhang for a heavier job you can use a fixed steady on the body of the centre which can take it to a better level of stability/stiffness, useful if you only have an MT1 tailstock

Edited By Ady1 on 20/08/2017 12:03:54
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