New lathe work holding tips - jaws

[ThickChips]

Hi all,

I will preface the post by apologizing in advance for the noobie questions on lathe workholding, as its not my expertise. 

We have a new machine with a Samchully 12" chuck. The chuck shipped with some basic un-cut soft steel jaws.. The nature of our work is relatively loose tolerancing +/- .010.  Our work is also relatively big. from 4" to 12" dia and mostly steel.

 

What I am looking to get info on is, what is a good solution for our work? Do I need to cut a set of jaws for every component we make (runout tolerances are virtually  inexistent with some of this work)? 

Or can I get away with using a "universal" style step jaw like seen here:  https://www.mscdirect.com/product/details/54219217

And lastly, maybe a quick-change solution exists that would make setups easier for us? 

Brand new lathe and want to get it right from the start.

 

 

Appreciate the feedback.

 

[AHarrison1]

2 hours ago, ThickChips said:

Hi all,

I will preface the post by apologizing in advance for the noobie questions on lathe workholding, as its not my expertise. 

We have a new machine with a Samchully 12" chuck. The chuck shipped with some basic un-cut soft steel jaws.. The nature of our work is relatively loose tolerancing +/- .010.  Our work is also relatively big. from 4" to 12" dia and mostly steel.

 

What I am looking to get info on is, what is a good solution for our work? Do I need to cut a set of jaws for every component we make (runout tolerances are virtually  inexistent with some of this work)? 

Or can I get away with using a "universal" style step jaw like seen here:  https://www.mscdirect.com/product/details/54219217

And lastly, maybe a quick-change solution exists that would make setups easier for us? 

Brand new lathe and want to get it right from the start.

 

 

Appreciate the feedback.

 

Your 'quick change' solution would be a collet style chuck system

https://royalproducts.com/product-line/royal-cnc-collet-chucks/quick-grip/

This is what we have installed on our lathe with collets ranging from 1/2" dia to 3" dia.

Anything above that then I am putting the 3 jaw back on.

The jaws you showed will work very well as the hardened teeth tend to bite into the workpiece.

Another plus to those is that your jaw limit is dictated by how much travel the t-nut has in the slot. 

Another option

https://schunk.com/fileadmin/pim/docs/IM0019026.PDF

[ThickChips]

56 minutes ago, AHarrison1 said:

Your 'quick change' solution would be a collet style chuck system

https://royalproducts.com/product-line/royal-cnc-collet-chucks/quick-grip/

This is what we have installed on our lathe with collets ranging from 1/2" dia to 3" dia.

Anything above that then I am putting the 3 jaw back on.

The jaws you showed will work very well as the hardened teeth tend to bite into the workpiece.

Another plus to those is that your jaw limit is dictated by how much travel the t-nut has in the slot. 

Another option

https://schunk.com/fileadmin/pim/docs/IM0019026.PDF

Hi,

Thanks for your input.

I'm familiar with the royal QG. They don't make anything for the stock sizes I listed. I was wondering if anyone had experience with other modular jaw systems that can be used, like the schunk system you linked.

 

As for the hard jaws - If my work ranges from 4 - 12", do you think one size would suffice (12 inch maximum chucking diamter), or would it be wise to get sets of various "maximum" chucking diameters?

Thanks a lot

 

 

[AHarrison1]

It will depend on how much travel the t-nut has, I would hazard a guess and say about 2 " travel which would give you a range of 4" to 8".

On our 10" chuck the t-nut only has a travel of +/- 0.85". I don't know if the t-slot length increases as you go up in chuck size.

So then yes, sets of various max diameters would probably be your best bet.

Hopefully others more in the know might chime in.

[JParis]

1 hour ago, ThickChips said:

If my work ranges from 4 - 12"

If a lathe is doing work in that much of a variation lathe, and it's not bar work...softjaws are almost certainly, going to be a way of life...

 

[ThickChips]

16 hours ago, AHarrison1 said:

It will depend on how much travel the t-nut has, I would hazard a guess and say about 2 " travel which would give you a range of 4" to 8".

On our 10" chuck the t-nut only has a travel of +/- 0.85". I don't know if the t-slot length increases as you go up in chuck size.

So then yes, sets of various max diameters would probably be your best bet.

Hopefully others more in the know might chime in.

@AHarrison1

I'm just wondering what the max chucking diameter of those jaws even means? Is that based on any radius that the mfg cuts on them? Or is it based on hole position relative to jaw ends?

[AHarrison1]

15 minutes ago, ThickChips said:

@AHarrison1

I'm just wondering what the max chucking diameter of those jaws even means? Is that based on any radius that the mfg cuts on them? Or is it based on hole position relative to jaw ends?

 

Most manufacturers will say that the max workpiece dia should not exceed the dia of the chuck or the T-slot nut should not over shoot the T-slot or that the outer extents of the jaws does not exceed the chuck dia.

Ive heard or read all three at some point or another.

There is a difference between chuck dia and chucking dia, in my opinion anyway.

The Samchully link you shared earlier to me says that the max chuck size is 6".

Speak to your tool provider/sales rep. They will do the leg work for you as far as research and providing solutions go. ( underlined because it is probably the most sensible advise a can give you)

Speaking to them also helps preventing you from dis-appearing down a rabbit hole.

My setup here is Royal collet on main spindle up to 3" (max bar stock for this machine). With 1/2" dia increments in collet sizes.

Anything over 3" and I swap out the collet system for the 3 jaw chuck and soft jaws.

Sub-spindle is 8" 3 jaw chuck with a master soft jaw size of 3" dia. I then have interchangeable  ALU inserts that are 3" od to fit the master jaw and then bored to whatever

finish dia I need.