Turning Between Centres

[Maryak]

Hi Guys,

I've noticed in a couple of posts that when turning between centres, the soft centre is held in a 3 jaw chuck.

I've not seen it done that way before.

Please, why is it done this way ??? ???

Thanks
Bob

 

[kvom]

I think you saw my posts.

The shop doesn't have the slotted dog plates handy AFAIK. The jaws work just fine given that the leg of the dog is long enough for contact.

 

[Brian Rupnow]

Maryak--The biggest reason is that it saves me the agravation of having to remove the chuck and install the faceplate.

 

[Maryak]

kvom, Brian.

Thanks for helping me out, I understand much better now :

Regards
Bob

 

[Mcgyver]

that's the way machinists do it, because its quick and accurate. skim any piece of steel to put a 60 degree cone on it and there's zero run out

 

[Maryak]

Mcgyver,

Makes a lot of sense, funny how you can't see the wood for the trees sometimes

Regards
Bob

 

[Mcgyver]

on our little lathes it might not matter that much, but i can see why you'd want to avoid changing tool on a larger lathe......but I like to pretend I'm a machinist so that's how i do it ;D

 

[John S]

Because if you mount the centre in the headstock as is standard on some gap bed lathe you finish up with the saddle over the gap and unsupported.
Also you often have run out of bed length to get a bed stop on and still reach the end of the work.

Using a quickly trued up centre in the chuck will have the effect of moving the job down the bed a bit.

As others have mentioned it's also for the inherently idle

.

 

[Maryak]

Thanks Guys, for all the good reasons for the 3 jaw chuck approach. :bow:

Filed away in my "I must remember that" box.

Best Regards
Bob

 

[Dhow Nunda wallah]

Maryak, I've taken a similar approach myself.
Chuck up a bit of steel and put a point on it, then weld a "dog" on the end of the workpiece which will engage one of the chuck jaws. This allows you to turn all the way down the piece.
The dog is, of course cut/ground off after turning.

I may be a lazy bastard, but I'm good at it

 

[Maryak]

Dnw,

I may be a lazy bastard, but I'm good at it

Spoken like a true Ozzie

I can see that you well are aware that the first step to becoming a Genius is laziness

Best Regards
Bob :big: :big:

 

[Brass_Machine]

Alright. so I am a little goofy. I think I understand this concept (forgive me guys, I am not a machinist by trade)... but I would like to see some pictures of this setup. Anybody care to share some?

Eric

 

[Brian Rupnow]

Alright. so I am a little goofy. I think I understand this concept (forgive me guys, I am not a machinist by trade)... but I would like to see some pictures of this setup. Anybody care to share some?

Eric

Eric--Have a look at the second last page of my double horizontal build, the part where I am machining the cylinder caps from a peice of bar stock---There is a good picture of it there.

 

[kvom]

Also this:

 

[Brass_Machine]

So what is preventing the piece from spinning when you start to turn on it? Or what keeps it spinning? The dog leg thingie (is it a dog leg?)

Eric

 

[wareagle]

Eric, it is called a lathe dog. And it turns the workpiece between the centers. There is a set screw on the lathe dog that grips the work piece, and the opposite end of the dog contacts the chuck for rotation.

 

[Brass_Machine]

Eric, it is called a lathe dog. And it turns the workpiece between the centers. There is a set screw on the lathe dog that grips the work piece, and the opposite end of the dog contacts the chuck for rotation.

Thanks WE!

I think I understand.

Eric

 

[Randolph]

It will probably be considered by some to be shameless self-promotion : but Chapter 14 of my book, Building Shop, is titled Turning Between Centers. I think Home Shop Machinist magazine will be printing the article in an upcoming issue.

 

[DickDastardly40]

It will probably be considered by some to be shameless self-promotion

Promotion perhaps but shameless, I don't think so; it's not like you were recommending your book by pretending to be other than the writer.

May I suggest you post the ISBN number of your book and perhaps an Amazon link to it in the for sale section.

Al

 

[rake60]

Randolpf I can see where a post like that might be viewed as "shameless self-promotion"

On the other hand, if someone such as myself had actually bought that book and found it to
be not only informative, but written by an author who speaks my language and shares my sense
of humor, it would be perfectly acceptable for them to add a link like this one to to their post.

http://www.randolphsmachineshop.com/buildingshop.htm

Very nicely written!
It is a book that you can learn from, laugh at and know that the man who wrote is is not only
a good writer, he's a machinist!

Rick