Live Center / Dead Center?

[Andre]

I only have and use dead centers, I find any good quality black moly grease works well in them. Forget about oil! I've turned the ends of shafts blue from oil. From my understanding moly particles act basically as ball bearings to reduce friction.

One of these days I'd like to try some fine lead filings mixed in with the grease, and see if that provides any positive benefits.

 

[HBilly1022]

Thanks Guys. I just finished with the snow but it's still coming down. I did take a break for dinner but I spent about 6 hrs in total plowing, moving and blowing snow. Hope that's it for a while. I have hobbies that need tending to.

The taper on the 3" round was essentially from 3" to 0" but I couldn't quite get to zero so it ended up being about 3/4" at the tail stock. I made a taper attachment and used that to produce the taper. I'm pretty sure the drill bit I used was a centering bit. It does have a short section of small diameter bit that goes into a 60* flare. I cut the hole to the end of the flare, ie the widest part. Just to make sure I will check a tool store to see if that is the right name for the part and that I did not use a spotting drill.

I'm a little tired from all the snow work so I'm going to relax with an adult beverage and get back to normal activities tomorrow. Maybe I can check the run out . I don't have anything perfectly straight but I read somewhere that I could just turn something in the 3 jaw then take measurements at 6" from the chuck, then rotate the stock 180* and take another measurement. I'll see if I can get the time tomorrow.

 

[Navy Chief]

I use this for lubing dead centers and have no issues with it:
http://www.readytool.com/CMD.htm

like the others I suspect that the runout you experienced was from removing the work from the chuck and replacing it, it is nearly impossible to get it aligned exactly the same when replacing it.

 

[schor]

As Navy Chief said, use high pressure lube.

 

[Wreck™Wreck]

A live center has issues with runout and less secure support for a heavy workpiece.

A live center of sufficient capacity and accuracy for the work at hand is perfectly suited to lathe work and are used worldwide everyday. You will find the cost unacceptable I suspect, this is no reason to make broad claims that they are inaccurate however.

This is the first company name the came to mind by the way, there are others. http://www.royalproducts.com/product.cfm?catID=8&id=1
Riten also makes excellent products.

Not trying to be contrary at all, yet telling someone without experience that is merely looking for guidance that LC's have "run out issues"is misleading and unhelpful at best. A better approach would be to advise someone asking such a question that if they require sub .001" acuracy with long term repeatability then the $97.95 harbour freight or grizzly LC would not be an excellent choice in that application. This way a persistent misconception may be avoided.

 

[JimDawson]

WOW, I haven't heard the name, "White Lead' in eons. Yes it was the go to lubricant many years ago. Then came "Lubriplate" which is still available. Here is some reading on "White Lead".

https://en.wikipedia.org/wiki/White_lead

"Billy G"

I still have a pint of it, I think it was bought back in the late 50's. I use it very sparingly and only when I really need it. And with great care as to PPE!

 

[HBilly1022]

So I got a little time today and chucked the 3" round again and this time there was no visible wobble in the live center. I thought I did everything the same as last time but for some reason it was better this time.

I also checked and I did use a centering bit for establishing the live center hole.

Now I will go back to the shop and turn something so I can check the 3 jaw run out.

 

[John Hasler]

I use anti-sieze to lubricate dead centers. Works fine as long as the pressure is correct.

 

[Wreck™Wreck]

So I got a little time today and chucked the 3" round again and this time there was no visible wobble in the live center. I thought I did everything the same as last time but for some reason it was better this time.

Excellent learning experience here, If you want to get the best from a center live or dead, indicate the part at the chuck BEFORE drilling the center hole. Adjust the chuck by whatever means available be it an adjustable chuck mount, soft jaws or shims. If the center is not concentric with the chuck this will cause problems at the tail stock end, this often happens with cold rolled steel and aluminum round stock which is not terribly round as produced.

As an exercise put an indicator in the chuck, push the tail stock close enough to indicate it, put a dead center in the tail stock ram and spin the chucked indicator around it, a handheld mirror used to read the dial on the backside helps. Beware this may keep you up at nights if you are chasing tenth's at all times.

 

[RJSakowski]

.....Not trying to be contrary at all, yet telling someone without experience that is merely looking for guidance that LC's have "run out issues"is misleading and unhelpful at best. A better approach would be to advise someone asking such a question that if they require sub .001" acuracy with long term repeatability then the $97.95 harbour freight or grizzly LC would not be an excellent choice in that application. This way a persistent misconception may be avoided.

The OP was questioning whether it was better to use a live or a dead center. I was simply listing the pros/cons of each. A live center has bearings which buy necessity have play. Since the center itself rotates, any irregularities in the center geometry or wear can contribute to runout. It is less secure because there is more hardware hanging out at a further distance from the socket. When spinning a 3" diameter x 10" long piece of steel on a small lathe, this can be an issue.

I have used live centers myself for more than forty years almost to the exclusion of dead centers. I do so because I like the convenience of using the center without need of lubrication.

However, the OP stated that he was experiencing wobbling when he switched to a live center which lead me to believe that perhaps his live center wasn't up to the task.