Live center tip

[knottyharry]

Here is my problem.. The tip of my live center is being eaten away.
The diameter of it is being reduced to a little bit of nothing. Back about 1/16 or a little more. Should the taper of the live center, and the taper of the mandrel both be 60 degrees?
From an earlier post, I read where the pilot hole in the end of the mandrel might not be drilled deep enough...and that might be my case.
It is real close for depth. I will check more on it tomorrow.
I don't put any more pressure on the mandrel than i feel is necessary, usually just sliding the tailstock up to it and then just touching up the pressure just a very little.
If I have to replace the live center, then tell me what is the difference between the cupped center and a regular center...and which one is better and why?
This really has me puzzled.
Thanks
Harry

 

[goldentouch]

I have the Oneway live center and you can take the tip out and change it. I am not sure why you tip is wearing. I haven't noticed any wear to speak of on mine. It could be a softer metal. Maybe some of the others have had a similar problem or suggestion.

 

[Gregory Huey]

Yes it should be a 60 degree to 60 degree fit. It sounds lke your pilot hole is shallow in your mandrel. Have you tried a diffrent one?

 

[Daniel]

Hary,
this sounds like the same thing that happend to me when I first started turning.
I bought a live center from sears and the tip started wearing really quickly.
there where two reasons I found for this.
one was my tools where not sharp enough requiring that I apply to much force to get a cut. second the Sears live center is for wood only. it is not hard enough to have metal on metal pressure. eventually the first one wore completely off. I bought a second for emergency reasons. but also ordered a heavy duty live center from the little machine shop.
no where at all on that one. it is a metal lathe live center and only cost aboout $10.00 more.

 

[jkirkb94]

I don't know what lathe you have but maybe this link will help:http://www.penturners.org/forum/topic.asp?TOPIC_ID=2129&SearchTerms=live,centers This is where I learned about removable live centers. Kirk[8D]

 

[cwasil]

I think there is alot to be said about having sharp tools in this problem. Here is what I believed was happening to me...I wasn't sharpening my tools correctly so as I tried to cut I was actually bending the mandrel slightly away from me which was having a "braking" effect on the live center. I swore every once in awhile I'd see a little puff of smoke come from that joint. I have a jet lathe and I don't doubt that they put the cheapest live center they could find on the machine (poor quality steel) but I think sharp tools would just about eliminate this problem.

I'll find out if my theory is correct since I just purchased a new center and was "trained" at work by a co-worker who makes and sharpens knifes as a hobby.

I guess my only question to you would be how often do you sharpen your tools?

Now that I think about it, that would probably be one of the most useful articles ever written on this board...how to sharpen tools with and without special fixtures.

 

[Randy_]

I don't know about other lathes; but my JET mini came with a very sharp point that I think is designed to be used only on wood. It has about a 30° point that I don't think would last very long when used with a steel mandrel. Based upon recommendations by other members of this board, I have ordered a live center from the Little Machine Shop that has a 60° tip designed for used with metal rather than wood. With shipping, it cost right at $20. You can get something similar from HF for less money, I think; but I don't have one close to me.

 

[knottyharry]

Thanks everyone for your responses.
I have a Grizzly lathe 35 1/2 inches. But i guess it is possible that the center could be for wood???? Just one of the things I have to check on. I know the pilot hole in the mandrel is going to be real close for the depth of the point on the center.
Up till now I have tried sharpening my tools by hand, and I think I do a fairly good job but they still may not be as sharp as they could be. However Santa must have thought I was pretty good this year, as I did receive a new set of chisels and a Wolverine sharpening jig for Christmas. I'll have to see how much difference this makes.
As for how often do I try to sharpen the chisels, I may touch them up 2 or 3 times while turning the pen blanks, just to try and keep them sharp.
I will also check into the rest of the information that you passed along to me and thanks again.
Harry

 

[wpenm]

I'm glad I read these posts because I'm having the same problem. Guess I'll have to change to a better live center.

 

[Rifleman1776]

If it is turning it shouldn't be wearing away. Check your bearings. A 'regular' center can be forced so much you will split your wood. A 'cup' will stop.

Originally posted by knottyharry
<br />Here is my problem.. The tip of my live center is being eaten away.
The diameter of it is being reduced to a little bit of nothing. Back about 1/16 or a little more. Should the taper of the live center, and the taper of the mandrel both be 60 degrees?
From an earlier post, I read where the pilot hole in the end of the mandrel might not be drilled deep enough...and that might be my case.
It is real close for depth. I will check more on it tomorrow.
I don't put any more pressure on the mandrel than i feel is necessary, usually just sliding the tailstock up to it and then just touching up the pressure just a very little.
If I have to replace the live center, then tell me what is the difference between the cupped center and a regular center...and which one is better and why?
This really has me puzzled.
Thanks
Harry

 

[wayneis]

A couple things here, one the center that comes with the Jet is pretty cheap and add that to the fact of most that have it are new to turning pens so its pretty easy to wear it out. I bought a new one from Grizzly and then each time I start to turn I put a drop of oil on the tip. When I am ready I put the drop of oil and move the centerup just untill it starts to turn and back it out just a touch until it stops turning.

Wayne

 

[knottyharry]

I haven't had a chance to check on this problem due to the flu.
But as soon as I get back into the swing of things I'll let you know what I find out for sure.
It sounds like there are centers for wood, and centers for metal. Which would make sense. Just never thought about it before now. I just assumed the center would work on both.
I did write to the little machine shop and am waiting to hear back.
Will keep you posted on my findings.
Thanks for the replys.
Harry

 

[woodwish]

I seem to use the opposite approach on tightening. I bring the center up and make sure it has good contact, and maybe a turn of the wheel on the tailstock to be sure. I am also careful to not tighten too much to keep from warping the mandrel. I personally think the tip needs to be in solid contact so it has enough pressure to keep it spinning. If it is not spinning at the same rate as the mandrel then it is wearing away, but if they are turning at the same speed it is doing it's job of holding up the tail end of the mandrel. I have turned several hundred pens using the same cheap stock live center that comes with the Delta midi and it is as sharp as the day I got it.

And how often do I sharpen tools? Often! If it feels dull in use or isn't working as smooth as I think it should I sharpen. The grinder is right next to my lathe and I usually never even stop the lathe, just sharpen the tool I am using if it needs it and go back to making shavings. When I first starting turning I was really afraid to sharpen, afraid I would ruin the tool, but I finally realized that a dull tool is worthless anyway.

My $.02 worth anyway-

 

[Mac In Oak Ridge]

Woodwish, It took me a long time to learn that lesson. I worried about wearing away my lathe tools. One day it hit me that they were an expendable. I would polish and hone and strop with oil stones and leather. Took forever to get sharp after use.

Once I figured out that you use them and toss them I started sharpening with a grinder. Used my old Sears 3500 rpm with a white wheel. This Christmas our local Woodcraft had a sale on a slow speed 8" machine, $75. Santa brought me one under the tree. Got it set up and it works great. One step away from my lathe. Flip the switch, 5 seconds, sharp tool and back to turning. Love it!

 

[woodspinner]

MackThat is why i have a Tomec. When you sharpen you remove almost nothing. Tools last much longer. In my opinion thr cost of Tormek is justified by tool life and thus dollar savings.

Good turning and be safe
Bill in Casa Grande, AZ.

 

[rlmill]

I noticed wear on my live center when I started turning pens, I just stuck a piece of poplar in the lathe and turned a 'sacrificial center' that stays stuck on the end of the live center. When it wears I will take a couple of minutes and turn a new one.

 

[Fred in NC]

Rob, I have done that too. Instead of a point, I make a slightly tapered hole to take the end of the mandrel.

Some live centers have replaceable tips. You knock them out with a rod inserted from the small end of the Morse taper. A tip for use with the pen mandrel can be made easily. Corian might work for that.

 

[cjthomas]

This is a problem that I have noticed with the center provided with my lathe as well. Thanks for all of the experiences and solutions posted here.