Live/Rotating centres

[Paulteggs101]

Hi Guys,
Have a machinist complaining about a generic make live center I have given him.
He uses a Doosan turning center and says that because he has a hydraulic tail stock that it has to be a branded Röhm live center.

I smell a rat here and think he just want it because of the name.

Now, there's no doubt the Röhm will perform at a high level, but his argument that a non-branded one won't even work from the get-go is surely wrong?

Can anyone advise please?

Many thanks in advance

 

[Mtndew]

Is that generic live center made for a cnc?
Thrust load would destroy a normal center.

 

[Paulteggs101]

Thanks for the reply sir,
That's my question, are there Live Centers made specifically for manual lathe that can't be used in CNC? Same morse taper etc.

 

[Cole2534]

The points are generally different on CNC style centers to allow better access with stick tools.

 

[Mtndew]

Thanks for the reply sir,
That's my question, are there Live Centers made specifically for manual lathe that can't be used in CNC? Same morse taper etc.

I already answered this. Get a good live center that can handle the thrust load of a hydraulic tailstock.
Spend the money.

 

[gregormarwick]

Also there has to be a mechanism to remove it. Some cnc tailstocks require the use of a draw-off nut and every one of those that I have ever seen is a Rohm.

 

[steve-l]

I already answered this. Get a good live center that can handle the thrust load of a hydraulic tailstock.
Spend the money.

WOW, your reply sounds like BS to me. It does not pass my smell test. I admit that I have never used a hydraulic tail stock, You may very well be correct, but because my BS sensor is firing, I need to verify why there is a difference in centers and what the actual spec difference is. I have not found a reference for this. If you have one, please let us know.

 

[Mtndew]

WOW, your reply sounds like BS to me. It does not pass my smell test. I admit that I have never used a hydraulic tail stock, You may very well be correct, but because my BS sensor is firing, I need to verify why there is a difference in centers and what the actual spec difference is. I have not found a reference for this. If you have one, please let us know.

I don't give a fuck if it passes your "smell test" or not.
But if you want to "verify" this for yourself then go buy a cheap piece of shit center with shit bearings. Pop it into a cnc lathe, run it 3000 rpm while holding a heavy part.
Oh and be sure to stand REALLY close to the part while it's running so you can see the results for yourself.

 

[???]

WOW, your reply sounds like BS to me. It does not pass my smell test. I admit that I have never used a hydraulic tail stock

WOW, your stupidity amazes me. You first admit that you have never used a hydraulic tail stock then you call BS. My very keen sense of smell acquired over a lifetime of BS detection in the metal working environment says that someone saying they don't know something should generally shut up and listen as they may well acquire knowledge.

 

[RJT]

Riten makes all kinds of live centers, some specifically for CNC

Live Centers | Riten.com

 

[gregormarwick]

Before you guys go for each others throats, here are some facts.

• All cnc lathes have the ability to adjust the force on the tailstock, regardless of hydraulic or ballscrew driven
• All remotely decent live centres (even some chinese ones) come with thorough documentation of their speed and load capacities
• A live centre needs to be selected according to the requirements of the part being made

There is absolutely nothing preventing anyone from using any live centre in a cnc lathe provided that they run it within it's rated specification.

If you put a little high speed centre designed for a 50kg suspended load and 100Kgf force and crank the tailstock pressure up to run a 500Kg part then you're going to have a bad time.

So don't do that, and that's about the only rule.

 

[Cole2534]

I'd not at all be surprised if the mechanical tailstock on a 16" Monarch or ATW would deliver more thrust than a hydraulic unit.

Either way, it's up to the operator.

 

[rjwalker1973]

+1 on what Gregor said. Know what the requirements are for the part load and the limits of the live center.

 

[russmill]

I used to use riten and royal live centers mounted in the lower turret on mill-turns. They had a heavy-ass internal spring with color bands (green yellow red) to indicate proper thrust. They were expensive and worked very well, I can't imagine trying to use a sub-standard center in a CNC, hydraulic or otherwise.

I use a cheapie on a Haas TL-2 at home with a manual quill, and runout isn't bad but it gets hotter than acceptable if used very long

 

[???]

Before you guys go for each others throats, here are some facts.

Exactly why I posted, if he stopped and waited before posting a stupid response he would have learnt a lot.

He uses a Doosan turning center and says that because he has a hydraulic tail stock that it has to be a branded Röhm live center.

I smell a rat here and think he just want it because of the name.

The statement that the machine needs a Rohm centre just shows that he lacks a basic understanding of how a centre is designed.

 

[Ox]

I have used a hydraulic and air op tailstocks very little. (MT5 biggest)
Ball screw opp defacto tailstocks enough.
I even made my own live center recently so's to fit as I was running outt'a daylight.

I have no clue what makes the centers in one of those any special to my Monarch.

Following this thread to see what's what....


---------------------

I am Ox and I approve this here post!

 

[Northman Ind.]

the uh... desparity in comments here is uh.. interesting

Unless its some weird brand specific tail stock, a morse taper is a morse taper, one that fits, fits.
There are any number of different brands, shapes, sizes, and expense with live centers, and its been covered it needs to be rated for the work load, and have enough clearance for the work to be done, the name scribbled on the side is secondary to fit form and function.

As for the fandancy spring loaded centers (the ones with the groovy color bands) I've used em, didn't do anything markedly different than a fixed version, and was more then overkill in a standard tailstock, as the pressure is adjustable, though I've seen em used in a dual turret lathe... that had a perfectly functional sub spindle.. but I tried not to engage with that particular "machinist"

 

[Northman Ind.]

Though I will add, the cheapest import junk you can get, might just be the junk you have on your desk doing nothing... spending a little money on quality tools isn't always a bad thing (I don't think I'd buy the Rohm version, but I wouldn't not use a chinesium one either... just wouldn't trust it much)

 

[eKretz]

A good center is a good center. If you overload even a good center, it will shit the bed. Don't use more pressure than you need, whether it's a manual tailstock or a hydraulic one. Over and out.