Live center

hesstool · Jan 2, 2008

I bought a CNC rated (5000 rpm) Royal live center a couple months back and immediately put it to use when I was turning some Niobium. Out of the box the fit seemed a little tight, but I was eager to use it. It's been a little while, but I think I was using about 100 psi for the tailstock pressure. After the 35th part, the center was friction welded to the workpiece and broke off. Now I have a semi-bullnose live center!

My question is this: Are live centers adjustable to free up the spindle? There is a SHCS at the butt end of the taper shank but I haven't played with it yet. Of course I ask this because I now have another job to run that requires the center.

WILLEO6709 · Jan 2, 2008

I have good success with Riten centers. Figure out the ratio of tailstock thrust to actual center load. My lathe has about 7000 lbs. tailstock thrust at 600 psi, so I have to back my pressure down around 80-100 psi to get a small center to survive. I have a few royal as well, but don't use them as often as the riten's. Some of the centers have coolant slingers so coolant does not contaminate the lube in the bearings. I have best luck with this type. I think Royal has a repair program if you can afford to wait a week or so.

Tonytn36 · Jan 2, 2008

Call Royal. Tell them the thrust load and RPM you are using. This is very important in the selection of a live center. We use both Royal and Ritten. It is _very_ important they know the thrust loading and RPM. Royal does have a rebuilding program.

SIM · Jan 2, 2008

I had bought a Royal center and had the tip shear off at relatively low pressure on the secound piece I ran. Actually I was using one of my little off brand Southbend centers prior to using the "New Center". Anyway I called them, gave them all the partiluliars and they replaced it quickly with no hassle.

hesstool · Jan 2, 2008

Thanks SIM, that makes me feel better. Since you're all urging me to do so, I'll give them a call and see what they can do for me. It's worth a shot, especially if it's at no cost.

BTW, I just checked the tailstock pressure and it was 150 PSI when loaded. And since I've only used it on one job previously, that must be the setting I had it at when the tip was smoked off. I also looked at the program I was using and it was running a direct spindle speed of 2400 rpm.

WILLEO6709 · Jan 3, 2008

150 psi is a meaningless number.... your machine manual should rate XXXXX lbs force at XXX pressure. Translate that PSI into pounds alone for center selection. Seems not everyone uses the same size cylinder in their tailstocks( or maybe I am odd man out with a 32 year old Cincinnati MO series Universal).

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