# Live Center / Dead Center?



## HBilly1022 (Dec 27, 2015)

I am new to machining and recently bought my first lathe, a King Canada 10 x 22 (same as Grizzly G0602) and have spent the last month learning / playing and working out some of the bugs. My intro lists a bunch of bugs that I have fixed so far, based on information from this site. In the process of learning I have turned a few small pieces of steel rod 1" and less plus a 3" round that I tapered over a 10" length, for an anvil I am making. At first I used a dead center in the tail stock and the 3 jaw chuck in the spindle but found that the dead center would get hot and if I put oil on it it would smoke and stink up the shop. So I bought a live center thinking that would be better but with the heavy 3" round it would wobble and no matter what I tried, I could not get it to spin on center.

Based on my reading so far, it appears that the dead center is better to use but what is used for lubrication. Does there need to be some sort of drip system to lube it or just let it get hot?


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## RJSakowski (Dec 27, 2015)

A live center has issues with runout and less secure support for a heavy workpiece.  As you have found out, a dead center has issues with friction.  You need to use lubrication or risk damaging the center and/or the workpiece.  I usually put some oil in the pilot hole prior to seating the center.  Even then, you may have to back the center out and re-lubricate from time to time.  

Dead centers are also very sensitive to the seating force.  You need enough force to securely seat the center but not so much as to greatly increase the friction and subsequent heating. After extended turning the workpiece can expanding length, increasing the force so checking and readjust the tailstock as work progresses is a good practice. Turning at a lower speed is also beneficial.


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## David S (Dec 27, 2015)

Welcome HBilly,

How did you make the centre in order to receive the point of the live centre?  Assuming a half decent live centre there is no way it should be wobbling around if it is seated properly in the tail stock and the point is in the machined centre hole.

David


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## HBilly1022 (Dec 27, 2015)

David S said:


> Welcome HBilly,
> 
> How did you make the centre in order to receive the point of the live centre?  Assuming a half decent live centre there is no way it should be wobbling around if it is seated properly in the tail stock and the point is in the machined centre hole.
> 
> David



I used what I think is called a centering or starter drill bit in a drill chuck set in the tail stock. The drill bit is one of the ones with a short section of 60 degree taper, to match the dead / live center. 

The live center is not a good quality one. The box states it is a medium duty one and it only cost $70 CAD. It was ok on the smaller diameter rod but when I removed the 3" round to check for fit and put it back into the 3 jaw there was a very pronounced wobble in the tip of the live center. I mounted the stock by setting it loosely in the 3 jaw (lined up with the register marks I made before taking it out) and then moved the live center up to is and slowly moving it into the tapered hole until it was seated. Then I tightened the 3 jaw one adjuster at a time and each was tightened in several stages. Tried that a couple of times but no luck. 

I can tell from this experience that I really need to get the lathe onto something solid. Right now I have it sitting on a mobile scaffold.

RJ, I may have to play around with the amount of  force I use with the dead center. I'm pretty sure I ended up with it being more than what it should have been. I'm guessing the _right_ amount is just enough to prevent wobble.


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## David S (Dec 27, 2015)

Have you checked the run out of your chuck with an indicator.  It sounds to me that you did the centre drill, did some work, removed the work piece, and then re-chucked it and now it is wobbling.  I think is what I am understanding.

I would be instructive to check the run out on a 3" piece, and then re-chuck and see how repeatable it is.  Where ever possible it is best not to remove the work piece from the chuck and then try and put it back.  Sometimes it is better to remove the chuck with the work piece still in it if you want to check it out.

David


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## HBilly1022 (Dec 27, 2015)

Thanks David.

I recall when I first set up the lathe I used a piece of cold roll I had in the shop that looked to be straight (it's all I had) and chucked that in the 3 jaw and used that to check the run out. I checked it at the 3 jaw and 12" out and believe it was ok but my memory is not what it used to be. I will do another check when I get some time. Right now I'm stuck in the house with an all day chore but will have to stop soon to go and deal with the snow that fell last night and is still coming down. There's over a foot of fresh stuff. This will be at least a 4 hr job, if I don't have to use the snow blower. If I do that will turn into a 6 hr job. Hopefully I can get back out to the shop tomorrow and check.


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## mzayd3 (Dec 27, 2015)

I have heard of using white lead grease on dead centers. Don't know that you can even get that stuff anymore. I would try a white lithium grease or something along those lines. As far as your live center goes, it sounds like either the center on the part was moved or the tail stock needs to be adjusted laterally.


Sent from my iPhone using Tapatalk


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## Bill Gruby (Dec 27, 2015)

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"


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## joshua43214 (Dec 27, 2015)

If you just keep putting off dealing with the snow, it will eventually just melt on its own 

You have had good suggestions so far.
Dead centers are more precise than live centers, but a good live center will give the same results as a dead center unless you are holding under 5 tenths tolerance. You can get live centers this good, but they are not worth it IMO unless you are doing a lot of work like that.
I use a lube meant for dead centers, and it works really well. Just search for "center lube" from who ever you buy supplies from. It has more in common with hypoid gear oil than cutting oil - it needs to both bear pressure and sliding action.
Make sure you use a center drill, not a spotting drill. The drill should have a small diameter tip coming back to a 60* shoulder and the larger diameter. The drill you described sounds like a center drill. The little tip on the drill serves two purposes: it prevents the center from bottoming out on it's tip, and is a reservoir for oil. Just get a good dab of oil into the hole and put some on the center and it will be fine. If you will be using the dead center a lot, it is worth investing in quality center drills, and possibly a center hone. The better the finish on the center hole, the better it will center and the longer the center will last. I sometimes just put the corner of a fine slip stone or 320 paper into hole and polish it a bit before using the dead center (make sure you clean the hole out afterwards). Don't make the hole too perfect, you need some scratches for the oil to go in, you just want to polish off the chatter and burs.
The center should be just tight enough to support the work, but not so tight it is oil starved. The work should ride on a film of oil. With a little practice, you will get the feel for it. The ram will have sort of a sticky feel to it when you withdraw it as you over come the surface tension of the oil.

I doubt the problem you had is with the live center. Even the cheapest live center should not wobble. One of my centers is a medium duty live center from Grizzly, it works just fine and I use it often. More likely the work just did not go back into the lathe the same as it came out. This is common, and even more common with 3jaw chucks. Generally speaking, people do not remove work from a 3jaw chuck if they need to put it back exactly where it was. A really good chuck will get you really close (you may have paid less for the lathe than a good chuck), a cheap chuck will get you in the same country. If you need to remove the work and put it back in, there are a few options. Use a 4jaw and put it back reliably. Get a good "set true" chuck. Turn between centers (this is the most reliable way).
You can get it back in pretty well by putting marks on the chuck and work like you did. Add to that running the center up into the work before tightening the chuck and you will be even closer. You said you cut a taper on the work. Did you cut the taper by moving the tail stock off-center? I am not sure it would ever be possible to put the work back in a chuck on center if this is so. You should also use a live center when possible do it this way. If you do have to use a dead center, you will have to drip lube on it very frequently.
I was once a proponent of tightening all the keys on my 3jaw. The fine folks here set me right on this subject, you should use just the same key every time. 3" x 10" is a bit much for a 5" 3jaw and is pushing the limits of your lathe a tad. I would suggest using the 4jaw for work this massive in general. I just don't see being able to reliably drill a center hole with a piece of stock that large hanging out in the wind on a chuck that small. The 4jaw will grip much tighter and allow you to get it properly centered for drilling.


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## Bob Korves (Dec 27, 2015)

HBilly1022 said:


> I am new to machining and recently bought my first lathe, a King Canada 10 x 22 (same as Grizzly G0602) and have spent the last month learning / playing and working out some of the bugs. My intro lists a bunch of bugs that I have fixed so far, based on information from this site. In the process of learning I have turned a few small pieces of steel rod 1" and less plus a 3" round that I tapered over a 10" length, for an anvil I am making. At first I used a dead center in the tail stock and the 3 jaw chuck in the spindle but found that the dead center would get hot and if I put oil on it it would smoke and stink up the shop. So I bought a live center thinking that would be better but with the heavy 3" round it would wobble and no matter what I tried, I could not get it to spin on center.
> 
> Based on my reading so far, it appears that the dead center is better to use but what is used for lubrication. Does there need to be some sort of drip system to lube it or just let it get hot?


HBilly, you stated that you turned a taper on the 3" material over a 10" length.  How much taper?  Did you create the taper by moving the tailstock over?  If so, you may be having several problems.  First, you cannot really chuck your stock in the 3 jaw chuck while is is also offset at the tail stock.  The chuck jaws are trying to make the work turn straight.  Tightening the 3 jaw while the tail stock is moved over will cause a tremendous side load on the tailstock center.  I assume that you would have needed to tighten the chuck jaws after the work was mounted and offset.  Besides the tailstock being pushed sideways, the chuck would not be able to close completely and would be gripping the work with the base of some jaws and the tops of the other jaws.  That would cause the jaws to loosen on the work and I also think that could explain your wobble.  Apart from the side load on the dead center, you also have an angle with the work that is not 60 degrees if the tailstock is offset, so the work will only be resting on a single line contact that is not concentric with the dead center surface, but changing its contact in a rubbing motion from tip to base ends of the dead center contact, rubbing and making friction while doing so.  The only real way to do tapers by offsetting the tailstock is to turn the work between centers, using plenty of lubrication on both centers and not pushing the centers into the work more than enough to keep it from having side play.  No smoke allowed, which leads to galling of the centers.  You can use your 3 jaw to make and to hold a center for the spindle end.  You will need to buy or make a dog to turn the work, and the jaws of the chuck can drive the dog.


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## Andre (Dec 27, 2015)

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.


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## HBilly1022 (Dec 27, 2015)

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.


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## Navy Chief (Dec 28, 2015)

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.


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## schor (Dec 28, 2015)

As Navy Chief said, use high pressure lube.


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## Wreck™Wreck (Dec 28, 2015)

RJSakowski said:


> 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.


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## JimDawson (Dec 28, 2015)

Bill Gruby said:


> 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!


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## HBilly1022 (Dec 28, 2015)

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.


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## John Hasler (Dec 28, 2015)

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


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## Wreck™Wreck (Dec 29, 2015)

HBilly1022 said:


> 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.


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## RJSakowski (Dec 29, 2015)

Wreck™Wreck said:


> .....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.


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## HBilly1022 (Dec 30, 2015)

Wreck™Wreck said:


> 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.



What are "tenth's"? I see this mentioned on other threads but not being a machinist I'm not sure what that means.

I didn't get a chance to try the indicator in the chuck today so I might sleep tonight.   I will give it try tomorrow, if time permits. We have all the family coming for a belated Christmas  so I have a lot of preparations to get done before they arrive.

Last night I put a dead center in the tail stock and ran it up to a piece of material I turned to a point in the 3 jaw and discovered they did not line up horizontally. So I adjusted the tail stock to get them lined up. I also checked the run out on the 3 jaw, based on a piece of material I turned in it, and found the run out 1" from the jaws was nominal ( maybe 0.00025") hard to tell on my el cheapo indicator. At 6 " from the jaws there was a 0.002" variation between the lowest and highest reading. So I gather that means the run out is 0.001" at 6". Is that right? I'm not sure if I have already trued the backing plate and chuck for the 3 jaw or not. I know I did for the 4 jaw but I have spent so much time trying to make things right on this lathe that I forgot what I have already done. Might be time to make a list of the stuff I do from now on so I don't have to recheck. The 4 jaw had a terrible wobble in it and when checked there was a 0.012" face wobble and 0.010" OD wobble. I pulled the backing plate and it was bad too. So I trued that and now the 4 jaw is way better. I can't recall the results but I was happy with it. It still has the OD issue but I can't fix that since I don't have any cutters long enough to reach that far back. 

This is my first lathe and I've a had a lot of issues with it. The lathe issues are listed in my intro and I have decided to just work my way through them rather than keep returning the machine to the dealer and waiting for replacements.  Besides my 30 day return period is now up and I would have to pay to ship it to the service center for any warranty work. That would likely cost an arm, leg and other important body parts plus I would be without it for an extended time frame, each time it went back. I think I am getting close to resolving the major issues and then I can get down to learning how to run it rather than fix it. Sure can be frustrating at times but thanks to sites like this I can find the info I need to address the issues I've found so far.


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## JimDawson (Dec 30, 2015)

HBilly1022 said:


> What are "tenth's"? I see this mentioned on other threads but not being a machinist I'm not sure what that means.



One tenth of a thousandth.  0.0001


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## planeflyer21 (Dec 30, 2015)

HBilly1022 said:


> What are "tenth's"? I see this mentioned on other threads but not being a machinist I'm not sure what that means.



1/10,000th of an inch or, as stated above, 1/10th of 1/1,000th.  In decimal format as such:  0.0001"

Us machinists have our own odd language. Especially when we pinch a body part.


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## Charles Spencer (Dec 30, 2015)

This may be slightly off on a tangent, but turning between centers seems to have the best results for me when I want fairly tight tolerances.  Of course you have to ensure that your centers are aligned.  

If you haven't seen it yet, I'd recommend looking at "How To Run a Lathe" by South Bend.  It you can download it for free here:

http://vintagemachinery.org/mfgindex/detail.aspx?id=1617&tab=3


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## chips&more (Dec 30, 2015)

I have live centers (LC), dead centers and dead centers with carbide tips. For the metal lathe operations I use the live centers. For the OD grinder operations, I use the dead centers. A good quality live center is not going to have any bearing play, it’s all under preload. For the HM, I see no problem in using a LC for metal lathe operations. And a helpful shop NOTE: if your work radically deviates from the datum center line when between centers. Then, I would recommend using a monobloc/conical center drill instead of a 60° center drill. It makes the marriage between the 60° point and the angled hole more conducive…Good Luck, Dave.


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## HBilly1022 (Dec 30, 2015)

Charles Spencer said:


> This may be slightly off on a tangent, but turning between centers seems to have the best results for me when I want fairly tight tolerances.  Of course you have to ensure that your centers are aligned.
> 
> If you haven't seen it yet, I'd recommend looking at "How To Run a Lathe" by South Bend.  It you can download it for free here:
> 
> http://vintagemachinery.org/mfgindex/detail.aspx?id=1617&tab=3



Thanks for that link. I downloaded all the files and when I get some time I will turn my monitor sideways and start reading. 

A tenth is 0.0001" ------- WOW that's small. I'm pretty sure the stuff I have turned so far has ridges in it way bigger than that. But with time, reading, help from here and practice I should get better.

I find it comical that I bought the lathe and a bandsaw at the same time, with the expectation that these will make my life easier. The bandsaw has done that, because I simply use it and the job gets done. The lathe however has turned into a whole new learning process which has occupied a LOT of my time since getting it. The more I use it, the more I find out that I need to learn . This could take over my life for a while.


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## BarnyardEngineering (Dec 30, 2015)

No offense intended here but one thing I haven't seen clearly laid out yet is the fact that even the best 3-jaw chucks have a few thousandths of an inch of runout. Enough to make a visible "wobble" in the work if the work is not chucked up exactly in the same place as before.

From what I'm told, a 3-jaw chuck that is within .003" from the factory is considered excellent quality.


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## joshua43214 (Dec 30, 2015)

To elaborate on the "tenths" discussion.
Machinists work and talk in thousandths, so something like 1/2" is verbalized as "500 thousandths."
When working with 1/10,000 precision, we use the word "tenth."
Something like 0.0125" would be verbalized as "twelve thousandths and five tenths," which could be simply shortened to "twelve and five tenths." Alternatively it could be verbalized as "twelve and a half thousandths," or even less commonly "twelve point five thousandths."

When using the metric system, we always speak in millimeters. 0.02mm is simply "point zero two millimeters," or "two hundredths of a millimeter.

Many of us avoid the use of the word "mil" because it can cause confusion. Properly speaking in our field, a mil is 1/1000", but some metric people use the word mil as a short form of millimeter or millionth of a meter (0.001mm). This is actually a micrometer (it used to be called a micron). So if you come across diagrams or plans that use mils, they should be imperial measurements and interpreted as 0.001" not something metric.


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## tcarrington (Dec 30, 2015)

Having worked through several issues on a G0602, which I really like, I would opine that your chucks may not be on a face plate which is perpendicular to the lathe axis of rotation. My three jaw was about 0.002 inches non-perpendicular at the edge of the face plate and the four jaw - way more. after a lot of measuring, some figuring and research, and getting trued, they are now OK. This improved my experience turning larger and longer items. A thinner bar, say 1/2 inch will bend enough to hit the center on the tail stock, while the 3 inch diameter bar, not so much. Maybe this will help locate the source of the problem. It is way too easy to try a bunch of things that don't solve the problem and actually cover up the real source. Until you get the workpiece in the chuck rotating on the axis of the lathe, you will have all sorts of problems. Also, If you got you center hot enough, that might also be a source of continued probl


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## Wreck™Wreck (Dec 30, 2015)

HBilly1022 said:


> What are "tenth's"?
> 
> Last night I put a dead center in the tail stock and ran it up to a piece of material I turned to a point in the 3 jaw and discovered they did not line up horizontally. So I adjusted the tail stock to get them lined up. I also checked the run out on the 3 jaw, based on a piece of material I turned in it, and found the run out 1" from the jaws was nominal ( maybe 0.00025") hard to tell on my el cheapo indicator.
> 
> ...


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## Techie1961 (Dec 30, 2015)

I remember talking to my instructor many, many years ago and he corrected me on the terms "live center" and "dead center" and I'm curious to see if others have heard this before. He told me that a live center is a center that is rotating such as you would find in the headstock when turning between centers on a lathe. A dead center is in a non-rotating fixture such as a tailstock. When using a ball bearing center in a tailstock, he told me that was called a rotating dead center (because it's mounted in a "dead" holder) and a solid center is called a non-rotating dead center.

Anyone else heard of this before?  I know that most will refer to a spinning center in a tailstock as a "live center".


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## John Hasler (Dec 31, 2015)

Techie1961 said:


> I remember talking to my instructor many, many years ago and he corrected me on the terms "live center" and "dead center" and I'm curious to see if others have heard this before. He told me that a live center is a center that is rotating such as you would find in the headstock when turning between centers on a lathe. A dead center is in a non-rotating fixture such as a tailstock. When using a ball bearing center in a tailstock, he told me that was called a rotating dead center (because it's mounted in a "dead" holder) and a solid center is called a non-rotating dead center.
> 
> Anyone else heard of this before?  I know that most will refer to a spinning center in a tailstock as a "live center".


I've never heard that before.  Sounds unnecessarily complicated.


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## stupoty (Dec 31, 2015)

Charles Spencer said:


> This may be slightly off on a tangent, but turning between centers seems to have the best results for me when I want fairly tight tolerances.  Of course you have to ensure that your centers are aligned.
> 
> If you haven't seen it yet, I'd recommend looking at "How To Run a Lathe" by South Bend.  It you can download it for free here:
> 
> http://vintagemachinery.org/mfgindex/detail.aspx?id=1617&tab=3



I try and do any turning that requires tight tolerances or may need to be removed from lathe and fliped end for end between centers,  it's definetly a good easy way to get repeatability and very usefull if you dont have top end chucks that are  in tip top condition.

Stuart


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## Big Bore Builder (Dec 31, 2015)

Techie1961 said:


> I remember talking to my instructor many, many years ago and he corrected me on the terms "live center" and "dead center" and I'm curious to see if others have heard this before. He told me that a live center is a center that is rotating such as you would find in the headstock when turning between centers on a lathe. A dead center is in a non-rotating fixture such as a tailstock. When using a ball bearing center in a tailstock, he told me that was called a rotating dead center (because it's mounted in a "dead" holder) and a solid center is called a non-rotating dead center.
> 
> Anyone else heard of this before?  I know that most will refer to a spinning center in a tailstock as a "live center".



Absolutely.

Old school terms, which I use all the time as I am 68 and "Old School".

Live center is the one in the headstock that rotates, or moves, hence it is "live".

Dead center is the one in the tail stock that does not rotate, hence it is "dead".

Another note, in olden times the live center was soft so wear could be easily observed, then the center was reground.   Tail stock dead center was hardened and usually marked with a ring around the center just below the cone.    The apprentice that put the live or dead center in the wrong place on the lathe got his knuckles rapped!!  Today's centers are almost always hardened.

Ball bearing center is the one in the tail stock that has ball bearings to allow the 60 degree cone to rotate with the work piece.   It is not a live center!!

Centers must be maintained.  Even the ball bearing centers.   Quality live centers have precision bearings with zero clearance.

Grinding a ball bearing center to true it up.   Same procedure for the live center and the dead center.  The resistance from the lubricant in the bearings is sufficient to allow grinding with a light cut, yet still allowing a slow rotation of the cone with respect to the center body, giving uniform grinding.  The lathe spindle is under power and turning when grinding.




Each of my lathes (I have 3) has dedicated centers.  Match marked for each lathe.  The live center for each lathe is ground in that lathe's spindle and index marked to the spindle prior to removing the center after grinding.

There is somewhat of an "art" in properly using centers without damaging the dead center.  Adequate lube of the proper type and a sensitive feel when tightening the tail stock hand wheel.  Don't push the lube out!

Three dead centers freshly ground.  They go into a protective tube (Old end mill plastic tubes) for storage.




Live center for my 14x40, freshly ground.   The no.3 center is match marked to the 3/5 sleeve and stays there.   The 3/5 sleeve is match marked to its lathe.    Also goes in a protective plastic tube when not in use.




A dog plate for my 13x36 with threaded spindle.    The 14x40 also has its dog plate, but in D4 camlock.  Do not let the big slot fool you, both dog plates have balance weights on the back side.




CMD center lube has been around a long time.  I started using it in the 1960's.  Good stuff.  Way back it came in an aluminum tube that always cracked when you rolled it up like a tooth paste tube, with some of the lube coming out of the cracks when you squeezed it.   A real pain and much of it was wasted.

A funny note, when I started work in a machine shop (sweeping floors and cleaning out chip pans) I learned by watching the "Old School Guys".      They were in their 60's and apprenticed prior to WWII.  Now I am68 years and have joined the "Old School Fraternity".


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## BGHansen (Dec 31, 2015)

Techie1961:  My dad taught Industrial Arts from 1960 - 1989.  He was taught that the center under power was the live center and the one in the tail stock was the dead center same as you referenced.  He called a ball bearing tail stock center a rolling dead center.  

I think generally the accepted semantics now is the ball bearing tail stock is called a live center.

Bruce


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## planeflyer21 (Jan 2, 2016)

The terminology for live and dead centers sounds familiar but I remember one of my instructors using the term "floating center", in reference to a ball bearing center in the tailstock.


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## kingmt01 (Jan 2, 2016)

Live under power & dead in the tail stock is the way I first heard it. But I've not said anything to go against the grain seeing it different here. I think the catalogs call the ball bearing centers live centers also. I have a roller center, soft centre, & a hard center but I rarely use a center for more then setting tool height.


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## bfd (Jan 31, 2017)

machinists are basically lazy so instead of having to say 1 tenthousandth of an inch we shortened it to tenths so .0023 would be said as 2and 3 tenths. .0025would be 2 and a half thousandths bill


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## Bill Gruby (Jan 31, 2017)

Because we find shorter ways to say things or do things does NOT make us lazy, it shows we are smarter.  Not the least bit amused by that comment.

 "Billy G"


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## David S (Jan 31, 2017)

Now Billy settle down.  We know we aren't lazy, it is just a figure of speech.  Hmmm on second thought...just perhaps I ... ah forget it.

David


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## British Steel (Jan 31, 2017)

joshua43214 said:


> Many of us avoid the use of the word "mil" because it can cause confusion. Properly speaking in our field, a mil is 1/1000", but some metric people use the word mil as a short form of millimeter or millionth of a meter (0.001mm). This is actually a micrometer (it used to be called a micron).



Nope, that's a micrometre, a micrometer is one of those fancy G-clamps ;0)

Dave H. (the other one)


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## T Bredehoft (Jan 31, 2017)

Back to indicating chuck and tailstock.  
1) normally chucks are expected to be not much closer to zero than .003
2) No indicator should be expected to not react to gravity as it is rotated about a horizontal axis. 

Use your indicator without rotating it about a horizontal axis, it will not be accurate if it is rotated about a horizontal axis. To verify this, mount a magnet base on the face of a chuck, put the indicator on the top of the chuck and rotate it 90º.

To align chuck and tail stock, a test bar, center drilled on one end and turned to one diameter for its length, should be used.  Mount it in the chuck and check that it is concentric to the spindle, shim the bar or move the chuck until you have zero (or nearly so) runout at the chuck, then engage the live center with enough pressure to turn the center with the chuck, snug but not TIGHT. mounting the indicator on the saddle, and against the test bar, first check the top for parallel the ways. Once this is correct, check the side toward you from end to end. If it is not parallel, adjust the tail stock sideways and check again until there is no runout. 
Without a test bar, it can be done by turning a piece between chuck and live center, but it's not as quickly accurate and takes a lot longer.


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## bfd (Jan 31, 2017)

what tom above is referring to is bar sag this occurs because of the indicator weight and any supporting weight that plays on the indicator you can still do it that way aslong as you mount the indicator the exact same way when you test it as to when you use it. take the indicator and mount it on a solid bar 4" pipe works well. zero it on top and rotate the pipe 180 degrees. read the indicator on the bottom say .002" out bar sag is then .oo1" but when you use it you still figure on a .002" reading so if you check your tailstock and you get.002" you are on center. the bar way is much simpler. but I thought I would explain it anyway bill


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## bfd (Jan 31, 2017)

bill I got the lazy comment from an old time machinist I apprenticed to way back when. his saying was necessity is not the mother of invention but laziness is. so he would say we invent our own language cause we are lazy don't want to say 1 tenthousandths when we can say 1 tenth bill


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## Tozguy (Feb 1, 2017)

Use of the word 'lazy' bothers me too. Although 'lazy' is commonly used to mean a variety of things but there are better more accurate descriptives for what drives us towards simplicity and expedience.


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