Machinist Q

[C9]

I have a small dividing head that I use to machine pieces on a small mill.

One problem is, when a chuck is adapted to it in the 'chuck horizontal' mode (chuck face is flat to the world) it's too tall for a lot of projects.
The chuck in use is a 6" and fairly thin fwiw.
A bigger mill would be nice, but it's not in the cards right now.

The vibration from the mill end cutter strikes me as being hard on the dividing head.
In most cases I'm machining aluminum and using a 1" two flute cutter - since I don't have any larger four flute cutters.
I do run a fairly high speed and the infeed is reasonable.

To that end, I've been thinking of making a chuck adaptor device for my 8" rotary table.
I know you can simply clamp them to the rotary table, but dialing it in each and every time is a drag.

What I'm thinking of is knocking out a one steel piece plate with 1 1/2 x 8 threads on one side that will accept the chucks I use and the other end fit the internal taper of the rotary table.
The trick here as you may have figured is to cut the taper just right so that the adaptor plate goes flat onto the rotary table's flat surface as well as key into the taper without ending up loose and sloppy or overly tight which could possibly damage the rotary table's internal taper.

I'm probably missing the obvious, but I'm all ears.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Rocket Scientist Chris]

Jay - I have a similar problem, but on a smaller scale - 4 inch rotary table and a 4 inch chuck. I was thinking of making a conical head "centering pin" for the turntable so it could be quickly lined up under the spindle. My turntable has a threaded hole instead of a tapered hole, but the idea is the same. http://www.jalopyjournal.com/ubbthreads/images/graemlins/smile.gif
I'm thinking a similar, conical "centering pin" could be made for the chuck. Something that would sort of self-center itself in the chuck. Chuck center to spindle could be established from there.
Just my train of thought, I guess. http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif Anyone else have any thoughts?

[Isaak_M]

we kind of have a similar deal going on at school for a 4th axis cnc rotary table. It has a face plate (which doesn't appear to come off), but really needs a chuck of some sort to be useful. I think the plan there is to make a chuck adapter plate of some sort that will bolt to face plate. you might want to see if there are any readily available chuck adapters with the thread you're looking for.
as far as chatter goes: i'd be more concerned about pounding out the spindle bearings (over the long term) on a light machine than any issues with the dividing head. Most diving heads I've seen look to be of fairly robust construction.

[C9]

After seeing the posts and doing a little more thinking about it, here's what I think will work for me.

A 'center pin' with the rotary table taper on one end and the 1 1/2 x 8 threads with appropriate guide shoulder for the threaded chuck end.

One end would look like the threaded spindle nose on the lathe and a little further down another shoulder - larger OD, stepped out from the above shoulder is accurately cut.
This second lower shoulder would precisely fit a 3/8" blanchard ground plate 8" OD and accurately sized center hole with internal shoulder that registers on the 'center pin'.
The plate would have four holes drilled 90 degrees apart so as to match the T-nut size and the holes would be countesunk so allen bolt heads would be below the surface.
It might require a thicker plate or turning a touch off the allen bolt's head so a chuck could lay flat on the plate.
That would allow the use of chucks larger than the rotary tables table.

In use, you'd insert the tapered end of the 'center pin' into the rotary table, give it a light tap with a small plastic or rawhide hammer to seat it - not too hard though or it could be tough to get out.

The plate goes on next and is accurately centered by the plate's bore over the 'center pin' lower shoulder.

The plate's internal shoulder helps to hold down the 'center pin'.
It's conceivable the plate could use a drilled and tapped hole with setscrew to help keep the 'center pin' from rotating or vibrating loose so you'd probably be ahead to set this up while you're building the adaptive pieces.

Bolt the plate down.

Lastly, the chuck is screwed on and seated and you're ready to go.


Granted, you could make this adaptor piece out of one chunk of metal, but the two piece device would be easier - and take a lesser amount of metal.
The difficult part in making a one-piece unit is getting the taper to seat properly and have the plate flat onto the table at the same time.

Nothing a little Prussian Blue couldn't do I suppose.

In the end, maybe a simple adaptor plate with threads & shoulder for the chuck, flat face both sides - cept for the threaded portion - drilled 90 degrees apart for the T-nuts and aligned with a dial indicator would do it.
It doesn't take that long to dial it in, but an accurate adaptor piece would be nice.

Biggest thing I've found with lathes & mills at home is that they're a hobby unto themselves.
You can get so involved in making tools for them that your hot rod project will get covered with stacked up cardboard boxes and dust.

Not that I've ever done that.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/tongue.gif

[C9]

Junk . . . what junk?

Roadster?

Where? http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif