Hercus 260 - Morse Tapers & centres.

[ventureoverland]

Guys,
Quick question, am I right in thinking that the Headstock taper on my 260 is a MT3 and Tailstock is MT2?

Next question...

I don't have a headstock dead centre or dog drive plate.

I have however turned up a 60^ point that I can put in the 3 jaw and made a dog that drives off a chuck jaw.

How successful / easy is my home made method compared to spinning off the chuck, spinning on the drive plate and throwing in the dead centre?

I find it a bit of a pain to skim the dead centre every time it goes into the chuck and every time I think to myself about accuracy and runout in the 3 jaw, but then this maybe quicker and just as accurate as swapping out.

What's the "best practice" method and why, or is it a case of six and two threes?

Thx
J


Thx
Jon

[pipeclay]

Your spindle taper is M/T4 .

You would require a M/T4 centre or an M/T 4 to M/T 3/2 sleeve and then a centre to suit this.

The tailstock is M/T2.

The only real disadvantage of using the 3 jaw chuck to hold a piece of material to become your drive centre would be the length you would lose between centres if working with long stock.

Having to return your centre each time it is removed from the chuck is quick,easy and accurate,once turned the chuck runout dosent matter.

There is no problem with using this method over a spindle centre and drive plate,apart from the length issue.

[ventureoverland]

Many thanks. This is good news! I have the long bed version so 99.9% of the time length shouldn't be a problem for me.

I'll keep as I am!

Thanks.


Thx
Jon

[ventureoverland]

MT4... Good job I checked

It's good news for me I guess. I've got the long bed 260 so length between centres for 99.9% of my work will not be a problem

I'll stick with my Heath Robinson method if length is the only disadvantage. My $$ can then be spent elsewhere

Thanks.


Thx
Jon

[nadroj]

I was taught that the proper way to get an accurate centre is to put it into the spindle, then cut it at 60 degrees. Soft centre + top slide set to angle.
Relying on total cleanliness and freedom from dents could lead to errors otherwise, but of course not all work needs to be super accurate.
That applies whether it's a Morse taper or chuck held centre.

May the Swarf be with you.

Jordan

[Ueee]

Hi Jon,
I use centers in my 3 jaws all the time. I find setting the compound to 30deg and using a standard tool on the back of the job, and the lathe on reverse the easiest. I do have camlock noses though.
One thing to watch for is that you do the chuck up tight enough so that as your work gets warm it doesn not force the center back into the chuck. A turned shoulder would fix this I guess, although would limit the amount you can skim the center before it is too short.

Ew

[ventureoverland]

Thanks Ew.

When I turned my centre for the chuck I gave it a shaft of approx 15mm and a shoulder of maybe 25mm.

I currently have maybe 10-15mm length of 25mm and then the 60^ point. The idea being it should take a few skims before I need I worry about turning another one!

I'm guessing a light skim in reverse would be ok / carry minimal risk or the chuck un-doing?



Thx
Jon

[Ueee]

You will probably never have a problem. I like doing it this way as you don't have to lean over the lathe to get to the compound handwheel. But then my lathes are a lot bigger than a hercus so it is probably not such a problem.
I also find it is better to start at the fat end and drag the tool back towards the point. Otherwise the rotation direction could actually be wrong for the very start of the cut.

Ew

[ventureoverland]

...Otherwise the rotation direction could actually be wrong for the very start of the cut...

???? Can't get my head around that one!


Thx
Jon

[Ueee]

???? Can't get my head around that one!


Thx
Jon

Imagine cutting say a 1mm DOC (i know you woundn't need to but it makes it easier to imagine) Starting at the point of the center. You effectively cutting from the wrong side of the work to the correct side. You tool touches the point and then starts cut on both sides of center until the tool moves past the new center point.

Ew

[ventureoverland]

Got it! When you put it like that it makes much more sense (to me).

Thanks for explaining.



Thx
Jon

[allterrain50]

Just for the record the sleeve supplied with the 260 when new was an mt4-mt2, picture attached. That is not rust but preservative compound. The only real advantage I can see from using a turned centre in the chuck is you can get a lot closer to the headstock.
Mal