So I got this cheap live center on eBay, and have some questions

WobblyHand

WobblyHand

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Yes, I should know better. Just asking for an opinion on what this means. Bought a live center that advertised it's "accuracy" at 0.000197". It's not particularly smooth rotating. It's significantly rougher than a different live center that I have. Seems like its full of grit, maybe it is. Installed it in the tail stock, and I measured it with my Interapid tenths DTI. As you might imagine, this resulted in a TIR of, yes, 0.0004", double the accuracy.

What I got, doesn't match the picture, either. Close, but not the same. There's a screw in the end of the taper. Photo doesn't show that. It was relatively inexpensive - another warning sign, a whopping $38. Seller did have a 99.4% favorable rating.

Worth the fight to return it? Sort of a parts kit for a rebuild? I actually would like an extended nose on it, a little more than what is there. Complain and get some price knock down? Cave in?

What does accuracy mean in this context?

Yes, I saw the Royal live centers - that's far out of my price range.
 
TIR is double the eccentricity so in that context, the stated .000197" doubled would be .000394" which would agree with your measurement.
 
RJSakowski said:
TIR is double the eccentricity so in that context, the stated .000197" doubled would be .000394" which would agree with your measurement.
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That's pretty much the case. What bugs me is the roughness, the fact it is different than the pictures, and a suspicion it won't last very long (due to the rough bearings).

A second potential thing is I am a bit nervous about the taper. I need to measure it, not sure it really is MT3. I think it may have slightly too steep of a taper. Have to figure out how to measure the taper. As I recall one uses 123 blocks
 
WobblyHand said:
That's pretty much the case. What bugs me is the roughness, the fact it is different than the pictures, and a suspicion it won't last very long (due to the rough bearings).

A second potential thing is I am a bit nervous about the taper. I need to measure it, not sure it really is MT3. I think it may have slightly too steep of a taper. Have to figure out how to measure the taper. As I recall one uses 123 blocks
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I would just blue it and check for fit in your tailstock.
 
GrifterGuru said:
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I was typing a reply and saw the message was deleted. Think you had some valid points. Maybe the "accuracy" spec was shady, maybe not. What I received is not as pictured. The bearings really are poor, and the part has some seriously sharp edges, that I'd have to knock down before using. In essence, it's not quite fit for purpose.
 
WobblyHand said:
That's pretty much the case. What bugs me is the roughness, the fact it is different than the pictures, and a suspicion it won't last very long (due to the rough bearings).

A second potential thing is I am a bit nervous about the taper. I need to measure it, not sure it really is MT3. I think it may have slightly too steep of a taper. Have to figure out how to measure the taper. As I recall one uses 123 blocks
Click to expand...
PICS? Chinese?
I wonder if it requires a load to smooth the bearings out. I don't know.
 
I've bought 3 really nice older live centers on ebay in the last couple of years. 2 were made in Japan and one in eastern europe. none were particularly expensive. all are very smooth turning. why not send it back for being rough turning? ebay is very good about returns.
 
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