Long nose live center

[mksj]

When you consider the clearances and accuracy, some will be tight at first and then spin more freely with time. It also may be the design and type/configuration of the bearings. I have the Skoda with interchangeable noses and moves quite smoothly but has been used. My standard point live centers also move freely, but I have the same Shar's as you had, it was very tight and gritty which improve somewhat with oil flushing. I would run the Skoda for a bit longer and with some tension on it. As mentioned often the seals and the bearings need to bed in. There is a flat head screw in the middle of the body which is for oil, should be instructions on that in the box.

 

[Larry$]

A couple of years ago I bought one of the cheap Chinese extended nose ones. It didn't hold up at all. I recently bought the $135+- (less 20% Black friday sale) one from Shars. Seems OK, so far. They also list one for about twice the price. I like the idea of it having a port for relubing. The catalog said it was made so the bearings could be tightened after it wears. Don't know how that is done. No instructions. The catalog shows a tapered outer race on the roller bearing. Must be a way to tighten a threaded ring. The load rating and max speed are way beyond what my lathe will do. My standard LC from PM still works fine.

 

[LeChuck]

Zero instructions with the Skoda other than the little piece of paper telling you to run it for a few minutes. There are 2 screws on it. A smaller one towards the front, and a large one in the middle of the body.

 

[mksj]

Larger screw in the center of the body and mind also includes the tail end. It is pre-lubed from the factory so I would not add any oil. Give it some time to break in.

 

[LeChuck]

Thanks! Yeah, I'll try it as soon as I have a stick to turn down to size and see how it handles it and if it loosens. The issue with the Shars was that the center offered too much resistance at 1100rpm so the teeth of the stebcenter in the head just ripped out of the resin. The stick started wobbling, making of course random cuts, then just fell off, being basically ruined. No problem with the cheap center, which can handle the speed. Hopefully this one will too. The resin requires good pressure so it doesn't loosen up in rotation, but not so much that it will start bending. Offers its own different challenges compared to metal

 

[NCjeeper]

I have a shars one. Had it a few years now and no issues so far.

 

[NC Rick]

Hello,

Anyone has a good MT3 long nose live center that they are happy with, has lasted, and can recommend?

I bought this one from Shars:

3 MT Morse Taper Long Nose High Speed Medium Duty CNC Live Center

www.shars.com

I'm having to return it because it started dragging after just a few uses turning down resin blanks to diameter and a couple blanks just sheared off of my stebcenter, as the live center couldn't handle 1000rpm anymore. I switched back to the cheaper one I had bought from PM and it works fine, but would like something that lets me get closer, and give more clearance away from the tailstock.

I don't want to get another copy of the same one.

I have the Shars one in mt4 and use it a lot, it's over 3 years old and I am pleased with it. My small one is very old, made in the USA by "Motor company " iirc.

 

[LeChuck]

Just a follow up on this. I was able to use the new Skoda for the first time this weekend, as I needed to turn some new resin blanks. It worked the same as the Shars, with my cut failing within one inch of starting. I'm beginning to think that these heavier duty centers are fine for metal but have too much rolling resistance for resin. I cannot apply as much pressure as they seem to require and I have to turn between centers. After the fail, I cut off the ends and immediately switched back to the cheaper center, and it worked perfectly.

 

[Larry$]

The preload on my new Shars seems fairly high, so some resistance. Is there anything wrong with the cheapy? Alternative, use a dead center and a little lube of some sort. Alternative #2: make yourself a spring loaded live center with the ideal nose design for your work and the perfect spring load.

 

[LeChuck]

There is nothing inherently wrong with the cheap one, except for the fact that it's not an extended nose and I can only get so close with a cutter. 15mm is about the smallest diameter I can cut. It's fine, but I'd like to be able to get closer when needed, down to 13mm, and still be able to use the live center on a longer part. The other issue is that with it being a smaller center, it's also shorter and that means the tailstock is very extended to make up for the extra space taken by my DRO scale installation. Again this is ok but when turning down a 9 inch long stick, getting some chatter in the middle, less extension would probably be better. I can use the compound to make up for that but then it seems less rigid and I have to adjust it again after that. This work has quite a few steps so reducing their number is a good thing.