Centre runout, live or dead!

Centre runout, live or dead!

Post by Adrian Hodgso » Tue, 14 Sep 1999 04:00:00



Just a note for comments on the news group.

I have purchased several Centres (solid type and have found the
following.
When I put the centre in the head stock and rotate the spindle I have
noted up to 10thou movement in the DTI a have been using.  ie the actual
centre is not centered on the rotating axis but out by 5 thou.

Mind you when only paying 4 to 5 (UKP for a standard centre and around
24 for a live centre should I expect better?

Has any one else noticed this run out on centres or is it just a
cheapish english design.
--
Cheers Adrian


 
 
 

Centre runout, live or dead!

Post by Gerald Mille » Tue, 14 Sep 1999 04:00:00


Check your socket for an embedded chip! Then check socket runout.

--

Gerry
London, Canada


Quote:
> Just a note for comments on the news group.

> I have purchased several Centres (solid type and have found the
> following.
> When I put the centre in the head stock and rotate the spindle I have
> noted up to 10thou movement in the DTI a have been using.  ie the actual
> centre is not centered on the rotating axis but out by 5 thou.

> Mind you when only paying 4 to 5 (UKP for a standard centre and around
> 24 for a live centre should I expect better?

> Has any one else noticed this run out on centres or is it just a
> cheapish english design.
> --
> Cheers Adrian




 
 
 

Centre runout, live or dead!

Post by Tony Jeffr » Tue, 14 Sep 1999 04:00:00




Quote:
>Check your socket for an embedded chip! Then check socket runout.

>--

>Gerry
>London, Canada



>> Just a note for comments on the news group.

>> I have purchased several Centres (solid type and have found the
>> following.
>> When I put the centre in the head stock and rotate the spindle I have
>> noted up to 10thou movement in the DTI a have been using.  ie the actual
>> centre is not centered on the rotating axis but out by 5 thou.

>> Mind you when only paying 4 to 5 (UKP for a standard centre and around
>> 24 for a live centre should I expect better?

>> Has any one else noticed this run out on centres or is it just a
>> cheapish english design.
>> --
>> Cheers Adrian



...and (sneaking in quickly before Robert Bastow gets there first <g>)
in any event, if you want the most accurate results, you machine the
centre *in situ* to make sure that any spindle runout & any runout in
the original machining of the centre are of no consequence.

Regards,
Tony

Website: http://www.jeffree.u-net.com/
When replying, delete "X." from the Email address to remove anti-SPAM measures.

 
 
 

Centre runout, live or dead!

Post by Slink » Tue, 14 Sep 1999 04:00:00


Quote:



> >Check your socket for an embedded chip! Then check socket runout.

> >--

> >Gerry
> >London, Canada



> >> Just a note for comments on the news group.

> >> I have purchased several Centres (solid type and have found the
> >> following.
> >> When I put the centre in the head stock and rotate the spindle I have
> >> noted up to 10thou movement in the DTI a have been using.  ie the actual
> >> centre is not centered on the rotating axis but out by 5 thou.

> >> Mind you when only paying 4 to 5 (UKP for a standard centre and around
> >> 24 for a live centre should I expect better?

> >> Has any one else noticed this run out on centres or is it just a
> >> cheapish english design.
> >> --
> >> Cheers Adrian


> ...and (sneaking in quickly before Robert Bastow gets there first <g>)
> in any event, if you want the most accurate results, you machine the
> centre *in situ* to make sure that any spindle runout & any runout in
> the original machining of the centre are of no consequence.

By reading some of the posts in this NG I doubt that many here have
neither the
knowledge nor the means to machine a center in the spindle. Most centers
I've
used have been too hard to machine by turning and had to be ground using
a tool post grinder.

- Show quoted text -

Quote:
> Regards,
> Tony

> Website: http://www.jeffree.u-net.com/
> When replying, delete "X." from the Email address to remove anti-SPAM measures.

 
 
 

Centre runout, live or dead!

Post by Adrian Hodgso » Tue, 14 Sep 1999 04:00:00


Quote:


> > >Check your socket for an embedded chip! Then check socket runout.

> > >> Has any one else noticed this run out on centres or is it just a
> > >> cheapish english design.
> By reading some of the posts in this NG I doubt that many here have
> neither the
> knowledge nor the means to machine a center in the spindle. Most centers
> I've
> used have been too hard to machine by turning and had to be ground using
> a tool post grinder.

In answer to some points here?

I can put a DTI on the spindle outside face and on the inside taper and
not notice any run out, ditto the 3 to 2 morse adapter I fit to take the
centres.

When I fit the centres the 2 morse taper i.e. outside runs true but the
centre point in not true.  you can actually see the run out.

On the live centre, if the shaft is held and the outer rotated one will
not notice any run out.  But if you rotate the shart you see run out!!!

Also aware of the fact that one needs to use a grind stone to correct
the point, problem here is I dont have one yet, just picked up motor and
have to figure way of mounting stone and whole assembly on bead.

I did also clean the inside of a brand new just out of box morse taper
sleeve to check the measurements, As said when using a DTI on the
outside taper of the centre it runs true.

I think it is just a case of badly ground bits, but wonder how many are
out there?
--
Cheers Adrian


 
 
 

Centre runout, live or dead!

Post by Adrian Hodgso » Tue, 14 Sep 1999 04:00:00


Quote:

> ...and (sneaking in quickly before Robert Bastow gets there first <g>)
> in any event, if you want the most accurate results, you machine the
> centre *in situ* to make sure that any spindle runout & any runout in
> the original machining of the centre are of no consequence.

I thought, and I am probably wrong, that the ends of the centres are
case hardended and then then very finely ground to remove any
irregularities.  Or.  That the end was hardend and tempered to take the
load and wear put on the end, to machine the centre would require the
thing to be annealed? and then machined and then hardend and tempered
again, each time removing the centre from the machine and refitting
would this not loose the accuracy of placement?

I understand that a centre fitted in to the headstock need not be as
hard as it would rotate with the work and therefore not have the
friction, but syill needs to cope with the pushing away from cutting
tool load.

This is getting to deep, the main problem that brought this to me, was
when fitting a centre to the tail stock and checking alignment with
centre in headstock, I noticed dfferences between centres, this led to
the tests.
--
Cheers Adrian


 
 
 

Centre runout, live or dead!

Post by Robert Basto » Tue, 14 Sep 1999 04:00:00


Read again good son!

There are LOTs of people on this list with both the Knowledge and the Means.
Plus a heck of a lot more, without the "means" who could figure out a way to do
it in a pinch.

Me?  I got both..and still prefer a swift smack with a hammer  8^)

***ut

Quote:

> By reading some of the posts in this NG I doubt that many here have
> neither the
> knowledge nor the means to machine a center in the spindle. Most centers
> I've
> used have been too hard to machine by turning and had to be ground using
> a tool post grinder.

 
 
 

Centre runout, live or dead!

Post by Robert Basto » Tue, 14 Sep 1999 04:00:00


Quote:

> ...and (sneaking in quickly before Robert Bastow gets there first <g>)
> in any event, if you want the most accurate results, you machine the
> centre *in situ* to make sure that any spindle runout & any runout in
> the original machining of the centre are of no consequence.

Ah, Kind Sir, you do me to kindly methinks.

Me..I just smack it with a hammer 'til it learns some manners!  ;^)

teeheenut

 
 
 

Centre runout, live or dead!

Post by Mike Grah » Tue, 14 Sep 1999 04:00:00


Quote:

>Me?  I got both..and still prefer a swift smack with a hammer  8^)

  This *would* be a *** hammer, right?

--
Mike Graham, mikegraham at sprint dot ca
Caledon, Ontario, Canada (just NW of Toronto).

Raiser of animals.  Weldor of metals.  Driver of off-road vehicles.
Writer of FAQs.  Keeper of the faith, and all around okay guy.

 < homepage currently off-line due to change of ISP; back soon >

 
 
 

Centre runout, live or dead!

Post by Fidl » Tue, 14 Sep 1999 04:00:00


I Had the same problem with my Atlas lathe. Couldn't get good alignment using
the 3 to 2 adapter so I purchased a M3 center to fit directly in the spindle.
That even had to be tried in different positions before I found one that was
dead on, then marked both spindle and center so I could repeat easily. After
that was successful it was a matter of turning a shaft and checking diameter at
each end and setting the tailstock over until they were the same. Good luck.
Clint
 
 
 

Centre runout, live or dead!

Post by Robert Basto » Wed, 15 Sep 1999 04:00:00


Of course..I only use *** centers!!

Teeheeheenut

Quote:


> >Me?  I got both..and still prefer a swift smack with a hammer  8^)

>   This *would* be a *** hammer, right?

> --
> Mike Graham, mikegraham at sprint dot ca
> Caledon, Ontario, Canada (just NW of Toronto).

> Raiser of animals.  Weldor of metals.  Driver of off-road vehicles.
> Writer of FAQs.  Keeper of the faith, and all around okay guy.

>  < homepage currently off-line due to change of ISP; back soon >

 
 
 

Centre runout, live or dead!

Post by Mike Grah » Wed, 15 Sep 1999 04:00:00


Quote:

>Of course..I only use *** centers!!

  And delrin cutters, I presume.  8-)

--
Mike Graham, mikegraham at sprint dot ca
Caledon, Ontario, Canada (just NW of Toronto).

Raiser of animals.  Weldor of metals.  Driver of off-road vehicles.
Writer of FAQs.  Keeper of the faith, and all around okay guy.

 < homepage currently off-line due to change of ISP; back soon >

 
 
 

Centre runout, live or dead!

Post by Glenn Ne » Wed, 15 Sep 1999 04:00:00



Quote:
Jeffree) writes:

>...and (sneaking in quickly before Robert Bastow gets there first <g>)
>in any event, if you want the most accurate results, you machine the
>centre *in situ* to make sure that any spindle runout & any runout in
>the original machining of the centre are of no consequence.

>Regards,
>Tony

And then matchmark the spindle and center so you can put it back in the same
orientation ... did I get that right Robert ;)'
Glenn Neff
Medford OR
 
 
 

Centre runout, live or dead!

Post by Glenn Ne » Wed, 15 Sep 1999 04:00:00



Quote:

>Also aware of the fact that one needs to use a grind stone to correct
>the point, problem here is I dont have one yet, just picked up motor and
>have to figure way of mounting stone and whole assembly on bead.

AFAIK hard centers are for the tailstock and softer centers are for the
headstock so you can true them with a bit.

Glenn Neff
Medford OR

 
 
 

Centre runout, live or dead!

Post by Glenn Ne » Wed, 15 Sep 1999 04:00:00



writes:

Quote:
>Ah, Kind Sir, you do me to kindly methinks.

>Me..I just smack it with a hammer 'til it learns some manners!  ;^)

>teeheenut

I'm taking notes now ...after I wipe the coffe off the screen... would that be
an air hammer or just a regular ol eingineerss maul??

:)

Glenn Neff
Medford OR