Live Center Question?

[Robert Cepek]

Hi Folks -

I have a question for you regarding live centers. I have a grizzly VS lathe (which is great) but it is very hard to make sure that the head stock and live center are perfectly aligned. (they do align point to point when pushed together) yet when you spread them apart and put the mandrel in place they are never perfect. So I went searching and I found that the standard live center with a 15 degree cone does not balance right. I have heard that I 60 degree cone is better. I found a local supplier (PTS) that sells 60 degree DEAD centers for as little as three bucks. I'm thinking of trying one out, So has anyone ever used a dead center will it generate too much heat on the mandrel and ruin it? any advice would be great for this. I have also looked at littlemachineshop.com and seen that they have a standard 60 degree live center for 13 but for three bucks a piece I can't beat the price. Also would a chuck work even better and if so could you recommend one and what they cost?

[Carole Valentine]

Robert, I am not sure a new center will solve your problem. Sounds like your lathe bed may be out of kilter a bit if the centers line up on contact but not as you move the tailstock away and install a mandrel. This is assuming your mandrel is straight and properly machined! Have you tried a different mandrel just to check? If the same thing happens with other mandrels, the bed could be racked a bit or there could be some unevenness in the underside of the clamp rails that is throwing the tailstock out of alignment. Just a thought.

[Robert E Lee]

Robert, I think you need a 60 degree for pen mandrels and it needs to be a live center to keep the heat down. grizzly.com or harborfreight.com price not to bad.
Bob

[Chris Barton]

First, I would do as Carole suggested and check the mandrel. I have had serious problems with some of the so called "professional mandrels" that woodcraft sells. I have had to return 4 because they were not strait and true, and it didn't matter which lathe they were on. One way to check this is to position the tailstock center close to but not touching the end of the mandrel once it is in the headstock and slowly rotate the headstock while watching the way the end of the mandrel moves in relation to the center on the tailstock. If it wobbles then it's the mandrel and not the center. Also, all this about 60 vs 30 vs cone... If it is a live center it shouldn't matter. The point of the live center should touch the indent on the mandrel but, not be crushed into it. Being a live center it will rotate with the mandrel and it shouldn't cause any significant wear on the live center. Lastly, if you look at the Griz website and search "centers" you will find an entire host of good live centers at reasonable prices. Good luck!

[Ernie Nyvall]

DO NOT BUY A DEAD CENTER!!!

Robert, I've been turning pens for about 2 months now so the problems you are having are fresh on my mind. My pointy live center was bottoming out in the mandrel and I wore off two of the points on the live centers. The steel on those short black steel live centers is not hard enough to stand up. I wore one of those off. Still though the idea was that something was out of kilter. Not the case.
Here's what I found: If a person accidentally or knowingly comes across the right combination of mandrel/live center, all the other problems are pertinent. However, I solved my problem that was very much like yours when I bought the 60 degree live center from Penn State (good hard metal) and the adjustable Woodcraft mandrel. This mandrel has deep enough hole so that it rides the shoulder of the live center. It has run true for the last 40 pens.

Chris had trouble with this mandrel as he wrote above, but my new live center in a different company's professional mandrel wobbled like crazy. So evidently you run in to lemons. I unpackaged the mandrel at woodcraft and had them run it on their lathe with my live center before I bought it. They were happy to accommodate. So for me it was the combination of a mandrel with a deep hole and a hard steel 60 degree live center.

Note: I did find a problem with the Woodcraft mandrel that is not adjustable. Where some mandrels screw down into the tapered part about an inch, the woodcraft one only has about 3/8" of threads. It wobbled and that's just not deep enough to hold something straight. IMHO

DO NOT BUY A DEAD CENTER.

I hope this helps.

Ernie

[David Dixson]

This article may help you diagnose where your problem lies:

http://www.woodturnerruss.com/Pen12a.html

And here's a solution for a reasonably priced live center:

http://www.littlemachineshop.com/products/product_view.php?ProductID=1189

Hope this helps,

Dave

[Jim Bell]

I had the same problem with my mandrels and live center. Here is how I did mine. Buy an adjustable mandrel. Penn state and Woodcraft both make a good one. I purchased a One Way live center. Before doing anything else I carefully filed (blunted) the tip of the live center to allow proper seating in to the mandrel taper. Extend the mandrel to the desired length leaving the mandrel shaft loose enough to adjust. Adjust live center to make contact with end of mandrel. The contact pressure must be enough to seat the live center to the mandrel but be careful not to push the mandrel back. Tighten collet. At this point check your tail stock pressure and adjust accordingly. If you are satisfied turn on lathe. At this point I lay a 1/2" spindle gouge on the spinning mandrel and check for "bounce". If all is well the gouge will simply lay happily on the shaft. If not loosen the collet and check your alignment. I say all this assuming you have a working knowledge of a lathe and lathe safety. I have 5 mandrels and once correctly adjusted have never had to change any of them. Hope this helps,
Jim