Soft centres...

Ok, let's start off by admitting that I'm not in the best of moods:-
1) The "heavy duty" Hilti breaker that I hired this morning wouldn't break
through the crust of an apple crumble, let alone the 5" of concrete shed base
that I was trying to remove.
2) The Milwaukee Kango hammer that I got (at additional cost) from another
hire shop had one of the chisels that had either been annealed or sharpened
beyond it's useful life.. The end looked like a dog-bone after 10 minutes.
3) Someone was less tight than me and just out-sniped me on an Ebay auction.
What's really winding me up is that I think I must be the only person left in
the empire that still does turning between centres. When turning between
centres one takes a skim of the live centre. Usually less than a thou. To
ensure that it really is central. This means that live (soft) centres are, to
some extent, a consumable item. Both of my soft centres are getting to the
point that they need replacing. I asked around at the Leamington exhibition,
but no-one seemed to have brought any with them.
Tonight, I looked around the web sites of most of the suppliers I use and
can't find soft centres on any of them.
Have I got to buy a load of MT2 soft arbours and make my own bloody soft
centres now from now on? or have they been declared illegal or something?
Mark Rand (in a bit of a foul mood)
RTFM
Reply to
Mark Rand
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Getting sniped on ebay is almost as bad as getting involved in something else and forgetting what time it is.... which I did tonight.
Re the centres, it's supply and demand. Nobody uses them since rotating ones became cheap enough to have a couple knocking around. I've got some larger ones in a box but I don't think there is anything that small (The Ward 2A takes parallel shank centres in the toolpost)
Peter -- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:
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Reply to
Peter A Forbes
But you DON'T USE A ROTATING CENTRE IN THE BLOODY HEADSTOCK!!!
I think I need a long rest in a dark place!
Mark Rand RTFM
Reply to
Mark Rand
Soft centre's ? Ear of bat, tongue of newt ? whatever next.
Just stick a lump of EN crap in the 3 jaw, drill it with your best import centre drill, DON'T REMOVE and stuff a ball bearing up the hole and you have a custom centre that runs true to a gnat's bollock at fifteen paces [ approx ]
Reply to
John Stevenson
When the the ball falls out turn the EN crap 60 deg to a be your new soft centre - to be trued each time it is replaced.
Jim
Reply to
pentagrid
cant give you any advice on live centres ... but concrete breaking, i can ...
hollow out under the concrete ...it will make a world of difference ...just 6 inches at a time will do ...
you see the soil underneath absorbs the blow of the breaker .
give it a try and see
all the best.mark
Reply to
mark
Was it a 505?
Sure. In the US, they turn between centers, and in Germany between "Spitzen". :-))
That can be reground? At least I do!
Nick
Reply to
Nick Mueller
Myford used to do them - part No. 70/1249 although a quick check this evening was unable to find them on the Myford site. So far I have not had to skim mine, after a rigorous spindle clean with a bottle brush and a good tap with a odd bit of brass mine shows no run out with a 0.002mm clock (app 0.0001") which is unbelievable but true!
Brian
Reply to
brian
Given that the first thing you have to do after fitting a soft centre in the headstock is to true it up anyway, doesn't sound like too much of a hardship to cut your own from a blank arbour.
Regards, Tony
Reply to
Tony Jeffree
Of course the best way to do this is to lift the concrete, dig a hole, put the concrete back, and then use the breaker :)
igmc
Dave
Reply to
dave sanderson
I'd think you capable of turning the back end from raw stock and then after inserting it into the taper, turning the front end.
The other day to skip a step, I ordered some Thompson shafting (Rc 62) to make a part with a turned down end. The poor lathe squealed like a pig turning that small end but I ended up with a rod that would run in the linear bearings of an assembly machine that can't be down for long w/o having to send out for heat treat.
Wes
Reply to
Wes
I bought a headstock centre which looks like a collet, it has a hard centre in the middle and is pulled in by the headstock drawbar. It is keyed like a collet so it is always replaced in the same orientation unlike a MT. It seems to work fine and avoids having to reset the topslide over to turn the taper (which is easy, but requires fiddling with a dial gauge afterwards to get the machine to turn parallel afterwards). I'm sure it is not quite as accurate, but it doesn't seem bad.
When I do want soft centres I turn them up (between centres!) from steel blanks; as the headstock taper isn't a Morse taper, but something obscure!
Alan
Reply to
Alan Bain
Hi,
What is the point of a soft centre anyway ? I know you can true them up but aren't hard centres ground to spot bollock tolerances anyway ? And aren't they hard enough not to need fiddling with ?
I'm genuinely interested to know btw.
Regards,
Mike
Reply to
Mike
I spotted some 'headstock centres' presumably soft on the Chronos website today.
Bob
Reply to
Bob Minchin
Hmm. Have to phone them up and find out.
regards Mark Rand RTFM
Reply to
Mark Rand
Have you considered turning up a cylinder about 3/4" dia. by 3/4" long wtha stub about 5/16" dia and 1/2" long, facing of the centre and drilling and reaming it to take the stub which could be fixed with Loctite 601 or 603 and allowed to cure before reforming the cone. Alternatively I had occassion to modify a genuine "Jacobs" chuck arbour from J6 to J33 as was impressed with how well it machined, giving a beautiful finish and suspect one would make a very superior soft centre. Millhill stock genuine "Jacobs" arbours.
Regards Brian
Reply to
brian
But how can you be sure there are no tiny nicks or particles that prevent the centre from running dead true? Truing in place eliminates that possibility, even in the event of imperfect location. Of course there's nothing wrong with not truing if the job doesn't have to be very precise.
Reply to
Jordan
WRONG!
Brian
Reply to
brian

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